Thesis Prospectus Draft - iLumina Digital Collection | UNCW

Transcription

A COMPARISON OF INLET-INDUCED GEOMORPHIC CHANGES RELATED TO
UNMODIFIED INLETS ALONG A SAND RICH COASTAL SYSTEM
Launna Carvalho Sampaio
A Thesis Submitted to the
University of North Carolina Wilmington in Partial Fulfillment
of the Requirements for the Degree of
Master of Science
Department of Geography and Geology
University of North Carolina Wilmington
2011
Approved by
Advisory Committee
Michael Benedetti
Douglas Gamble
William Cleary
Michael Smith
Chair
Accepted by
Digitally signed by Robert Roer
DN: cn=Robert Roer, o=UNCW,
ou=Graduate School and Research,
[email protected], c=US
Date: 2012.05.22 10:22:13 -04'00'
________________________________
Dean, Graduate School
This paper has been formatted with a style that is consistent with the
Journal of Coastal Research
ii
TABLE OF CONTENTS
ABSTRACT................................................................................................................................... iv
ACKNOWLEDGEMENTS ........................................................................................................... vi
LIST OF TABLES ......................................................................................................................... ix
LIST OF FIGURES ..................................................................................................................... xiii
INTRODUCTION ...........................................................................................................................1
Objectives ................................................................................................................................... 3
Regional Setting .......................................................................................................................... 4
Background and History ............................................................................................................. 6
Tidal Inlets .............................................................................................................................. 8
The Ebb Tidal Delta .............................................................................................................. 10
Inlet Sediment Bypassing ..................................................................................................... 11
METHODOLOGY ........................................................................................................................13
Shoreline Change Measurement ............................................................................................... 17
Delineation of Shoreline Change Zones ................................................................................... 20
Shoreline Rate of Change Calculation ...................................................................................... 21
RESULTS ......................................................................................................................................21
Bear Inlet Changes .................................................................................................................... 22
Bear Island Changes ............................................................................................................. 30
Brown’s Island Changes ....................................................................................................... 34
Brown’s Inlet Changes .............................................................................................................. 38
Onslow Beach Shoreline Changes ........................................................................................ 46
Brown’s Island Changes ....................................................................................................... 49
AMBUR Data ........................................................................................................................... 54
DISCUSSION ................................................................................................................................56
Bear Inlet – Bear Island Shoulder ............................................................................................. 57
04/1938 – 10/1949 ................................................................................................................ 57
11/1949 – 03/1962 ................................................................................................................ 58
03/1962 – 12/1974 ................................................................................................................ 59
12/1974 – 03/1989 ................................................................................................................ 59
03/1989 – 08/1990 ................................................................................................................ 61
08/1990 – 09/1996 ................................................................................................................ 61
09/1996 – 03/2001 ................................................................................................................ 63
03/2001 – 03/2003 ................................................................................................................ 64
03/2003 – 10/2006 ................................................................................................................ 65
10/2006 – 10/2008 ................................................................................................................ 66
Bear Inlet – Brown’s Island Shoulder....................................................................................... 66
04/1938 – 11/1949 ................................................................................................................ 66
11/1949 – 03/1962 ................................................................................................................ 67
03/1962 – 12/1974 ................................................................................................................ 68
12/1974 – 03/1989 ................................................................................................................ 69
03/1989 – 08/1990 ................................................................................................................ 70
08/1990 – 09/1996 ................................................................................................................ 71
09/1996 – 03/2001 ................................................................................................................ 72
03/2001 – 03/2003 ................................................................................................................ 73
iii
03/2003 – 10/2006 ................................................................................................................ 74
10/2006 – 10/2008 ................................................................................................................ 75
Brown’s Inlet – Brown’s Island Shoulder ................................................................................ 76
04/1938 – 01/1945 ................................................................................................................ 76
01/1945 – 04/1958 ................................................................................................................ 77
04/1958 – 03/1962 ................................................................................................................ 77
03/1962 – 12/1974 ................................................................................................................ 79
12/1974 – 10/1993 ................................................................................................................ 80
10/1993 – 06/2002 ................................................................................................................ 82
06/2002 – 03/2003 ................................................................................................................ 83
03/2003 – 10/2006 ................................................................................................................ 84
10/2006 – 10/2008 ................................................................................................................ 84
Brown’s Inlet – Onslow Beach Shoulder.................................................................................. 85
04/1938 – 01/1945 ................................................................................................................ 85
01/1945 – 04/1958 ................................................................................................................ 86
04/1958 – 03/1962 ................................................................................................................ 86
03/1962 – 12/1974 ................................................................................................................ 89
12/1974 – 10/1993 ................................................................................................................ 89
10/1993 – 06/2002 ................................................................................................................ 92
06/2002 – 03/2003 ................................................................................................................ 93
03/2003 – 10/2006 ................................................................................................................ 93
10/2006 – 10/2008 ................................................................................................................ 94
SUMMARY AND CONCLUSIONS ............................................................................................94
LITERATURE CITED ..................................................................................................................98
APPENDIX ..................................................................................................................................101
iv
ABSTRACT
Bear and Brown’s Inlets are small barrier island systems located in the northeastern
sector of Onslow Bay along the shoreline reach characterized by high relief, sand-rich barrier
islands. Bear Inlet (BEI) separates Bear Island to the northeast from Brown’s Island to the
southwest while Brown’s Inlet (BRI) borders Brown’s Island on its southern margin and
separates the barrier island from Onslow Beach to the southwest. Due to their unmodified nature
they are exemplary sites to study the linkage between inlet changes and the response of the
adjacent oceanfront shorelines.
Both inlets are relatively stable systems having been confined to narrow migration
pathways since 1872. This study utilizes and evaluated two Geographic Information System
(GIS) software extensions (DSAS and AMBUR) that are specifically designed to measure
shoreline change. Since 1938 the BEI throat has migrated southwestward 592 m at an average
rate of 8.5 m/yr while the BRI has migrated to the southwest a distance of 355 m at an average
rate of 5 m/yr. The net migration direction is opposite the inferred direction of sediment
transport.
While the position of the throat segment of the ebb channel of both inlets have changed
comparatively little (BRI: 137 m; BEI: 700 m) from 1938 to 2008, the outer bar segment of the
channel shifted across a comparatively wider zone that ranged from 700 m (BEI) to 1,100 m
(BRI). Since 1934 a minimum of six cycles of channel deflection and reorientation have
occurred. Consequently the ebb-tidal deltas have undergone significant shape changes, which in
turn have altered the ebb delta’s breakwater effect along the opposing oceanfront shorelines. The
decadal long accretion and erosion patterns are responses to the above-mentioned changes.
v
Generally speaking, for a given period of time, the oceanfront shorelines along the adjacent
barriers are characterized by opposing shoreline change patterns.
From this study, the measurements obtained from both DSAS and AMBUR GIS
extensions were very comparable and show that although each GIS extension package had
slightly different operating assumptions, the results of shoreline change from 1934 to 2008 for
Brown’s and Bear Inlets evaluated by these methods were very similar.
vi
ACKNOWLEDGEMENTS
I would like to show my gratitude to all the faculty and staff of the Geography and
Geology Department, for their willingness to help me in any way they could, for their kindness
and smiles. I thank Dr Halls for all the computer space she provided for me to work on my
project, for helping countless times with GIS software and for the many encouraging words she
gave me all this time I’ve been a grad student at UNCW. I thank Dr Liz Hines for her words of
wisdom, her patience and her friendship when I was her lab assistant and even after that. My
gratitude also goes to Professor Shew, for being the best teacher I’ve ever had! His will to learn
and to share knowledge have always been an inspiration to me.
I could not forget to thank Catherine Morris and Anne Sutter from the Geography and
Geology department office for their help in countless times and for our conversations ranging
from parenthood to professional future. I also thank Sharon Day from the USACE Wilmington
District Office and Ken Richardson from NCDCM for providing aerial photographs for my
research.
A great deal of gratitude goes to my advisors, Dr William Cleary and Dr Michael Smith.
Thanks, Dr Cleary, for accepting me as your student in the first place. You gave me the
opportunity of a lifetime. Thank you so much for sharing your vast knowledge of coastal
processes and thank you very much for your honesty while I was doing my research and writing
this thesis. Dr Smith, thank you for taking me as your student after Dr Cleary retired and thank
you for not giving up on me. I wouldn’t be writing this section now if it weren’t for you.
I would like to thank all my friends, the ones I’ve met here and the ones I left in Brazil.
Thank you for all the conversations, advice and encouragement. You guys made my life here
way better and my experience studying abroad remarkable!
vii
I extend my gratitude to my family, specially my mom, for making my “American
dream” possible and for her faith in me, even in times when I did not believe in myself.
Obrigada, mãe! Te amo! Many thanks go to my husband and to my son, my “partners in crime”.
Their love and patience while dealing with a tired, moody and sometimes frustrated graduate
student on a daily basis were very important to me.
And last but not least, to the one that answers by many names, but I have the privilege to
call Him Abba, my Heavenly Father. To Him are the honor, the glory, the power and the worship
forever and ever!
viii
LIST OF TABLES
Table
Page
1.
Bear Inlet Ebb channel migration rates from April 1938 to October 2008. ..................... 28
2.
Summary Bear Inlet data from April 1938 to October 2008. ........................................... 30
3.
Brown’s Inlet Ebb Channel migration rates...................................................................... 45
4.
Brown’s Inlet values of IMW, Baseline width and ebb channel orientation from
1872 to 2008. .................................................................................................................... 46
5.
Summary of changes that occurred in Bear and Brown’s Inlets and their adjacent
shorelines……………………………………………………………...............................95
A1.
Compilation of data and time periods used to create the dataset of historical
shorelines for the study of Bear Inlet .............................................................................. 101
A2.
Compilation of data and time periods used to create the dataset of historical
shorelines for the study of Brown’s Inlet ........................................................................ 102
A3.
Bear Inlet Bear Island and Brown’s Island zone-wide net changes between
the periods of 1872-1938 and 1938-2008. ...................................................................... 103
A4.
Summary of Bear Inlet Bear Island and Brown’s Island zone-wide shoreline
change by period. Cumulative changes from April 1938 to October 2008 are
listed in bold.................................................................................................................... 104
A5.
Summary of Brown’s Inlet Brown’s Island and Onslow Beach zone-wide
shoreline change by period. Cumulative changes from January 1934 to October
2008 are listed in bold. ................................................................................................... 106
A6.
Summary of Bear Inlet Bear Island and Brown’s Island zone-averaged
cumulative shoreline change from April 1938 to October 2008.................................... 107
A7.
Summary of Bear Inlet Bear Island and Brown’s Island zone-averaged
cumulative shoreline change from April 1938 to October 2008..................................... 108
A8a.
Summary of Bear Inlet Bear Island cumulative shoreline change along
transects I1 through BE3 from April 1938 to October 2008. ........................................ 109
A8b.
transects BE4 through BE9 from April 1938 to October 2008. ...................................... 109
ix
A8c.
transects BE10 through BE15 from April 1938 to October 2008. .................................. 110
A8d.
Summary of Bear Inlet Brown’s Island cumulative shoreline change along
transects I1 through BR3 from April 1938 to October 2008 .......................................... 110
A8e.
Summary of Bear Inlet Brown’s Island cumulative shoreline change
along transects BR4 through BR9 from April 1938 to October 2008. .......................... 111
A8f.
Summary of Bear Inlet Brown’s Island cumulative shoreline change
along transects BR10 through BR15 from April 1938 to October 2008. ...................... 111
A9a.
Summary of Brown’s Inlet Brown’s Island cumulative shoreline change
along transects I1 through BR3 from January 1934 to October 2008. .......................... 112
A9b.
along transects BR4 through BR9 from January 1934 to October 2008. ...................... 112
A9c.
along transects BR10 through BR15 from January 1934 to October 2008. .................. 113
A9d.
Summary of Brown’s Inlet Onslow Beach cumulative shoreline change
along transects I1 through OB3 from January 1934 to October 2008. ........................... 113
A9e.
along transects OB4 through OB9 from January 1934 to October 2008. ....................... 114
A9f.
along transects OB10 through OB15 from January 1934 to October 2008. ................... 114
A10.
Summary of Bear Inlet Bear Island and Brown’s Island zone-wide
shoreline change by period.using AMBUR Cumulative changes from April
1938 to October 2008 are listed in bold. ........................................................................ 115
A11.
Summary of Brown’s Inlet Brown’s Island and Onslow Beach zone-wide
shoreline change by period using AMBUR. Cumulative changes from January
1934 to October 2008 are listed in bold. ......................................................................... 117
A12.
Summary of Bear Inlet Bear Island and Brown’s Island average shoreline
cumulative changes for each zone using AMBUR ........................................................ 118
A13.
Summary of Brown’s Inlet Brown’s Island and Onslow Beach average
shoreline cumulative changes for each zone using AMBUR ......................................... 119
A14a. Summary of Bear Inlet Bear Island shoulder cumulative shoreline change
from Inlet transect (IT) to transect BE5 from April 1938 to October 2008
x
using AMBUR ................................................................................................................ 120
A14b. Summary of Bear Inlet Bear Island cumulative shoreline change along
transects BE6 through BE11 from April 1938 to October 2008 using
AMBUR. ......................................................................................................................... 120
A14c. Summary of Bear Inlet Bear Island cumulative shoreline change along
AMBUR. ......................................................................................................................... 121
A14d. Summary of Bear Inlet Bear Island cumulative shoreline change along
AMBUR. ......................................................................................................................... 121
A14e. Summary of Bear Inlet Bear Island cumulative shoreline change along
AMBUR. ......................................................................................................................... 122
A15a. Summary of Bear Inlet Brown’s Island cumulative shoreline change along
transects IT through BR5 from April 1938 to October 2008 using
AMBUR. ......................................................................................................................... 122
A15b. Summary of Bear Inlet Brown’s Island cumulative shoreline change along
transects BR6 through BR11 from April 1938 to October 2008 using
AMBUR. ............................................................................................................................. 123
A15c. Summary of Bear Inlet Brown’s Island cumulative shoreline change along
AMBUR. ......................................................................................................................... 123
A15d. Summary of Bear Inlet Brown’s Island cumulative shoreline change along
AMBUR. ......................................................................................................................... 124
A15e. Summary of Bear Inlet Brown’s Island cumulative shoreline change along
AMBUR. ......................................................................................................................... 124
A16a. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along
transects IT through BR5 from January 1934 to October 2008 using
AMBUR. ......................................................................................................................... 125
A16b. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along
transectsBR6 through BR11 from January 1934 to October 2008 using
AMBUR. ......................................................................................................................... 125
xi
A16c. Summary of Brown’s Inlet Brown’s Island cumulative shoreline
change along transects BR12 through BR17 from January 1934 to
October 2008 using AMBUR. ........................................................................................ 126
A16d. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along
transects BR18 through BR23 from January 1934 to October 2008 using
AMBUR. ......................................................................................................................... 126
A16e. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along
transects BR24 through BR30 from January 1934 to October 2008 using
AMBUR. ......................................................................................................................... 127
A17a. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along
transects IT through OB5 from January 1934 to October 2008 using
AMBUR. ......................................................................................................................... 127
A17b. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along
transects OB6 through OB11 from January 1934 to October 2008 using
AMBUR. ......................................................................................................................... 128
A17c. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along
AMBUR. ......................................................................................................................... 128
A17d. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along
AMBUR. ......................................................................................................................... 129
A17e. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along
AMBUR. ......................................................................................................................... 129
xii
LIST OF FIGURES
Figure
Page
1.
Location of the study area (National Agriculture Imagery Program,
hereafter NAIP) ................................................................................................................... 1
2.
Bear and Brown’s inlet locations from a 1889 USGS chart (A) and from a 2008
Digital Orthophoto (B). Reference points for location comparison in red.
Sources: UNC Library Archives (A) and NAIP (B). .......................................................... 2
3.
Oblique aerial photograph depicting Brown’s Inlet, Onslow Beach and the
location of the submarine headland, the boundary between sand-rich barrier
islands to the northeast and sand-poor barrier islands to the southwest
(toward the top of photograph). Source: William Cleary. .................................................. 5
4.
Possible initial locations of Bear and Brown’s inlets’ ebb channels
(blue dashed lines). Distance of migration of inlet opening (white arrows) to
the location of the ebb channel in 2009. Photographic source: NAIP. ............................... 7
5.
Idealized Inlet Morphology and Processes (Hayes, 1980).................................................. 8
6.
Sediment bypassing along mixed-energy coasts using the ebb tidal and delta
breaching model similar to what occurred along Bear and Brown’s Inlets
during the period from April 1938 to October 2008. Source: FITZGERALD, 1988. .......... 12
8.
Aerial photographs illustrating the changing morphology of Bear Inlet from
April 1938 to October 2008. The dashed lines represent the location and
position of the ebb channel. Photographic Source: USACE Wilmington,
NC District Office and NC Department of Agriculture. ................................................... 15
9.
Aerial photographs illustrating the changing morphology of Brown’s Inlet
from April 1938 to October 2008. The dashed lines depict the location and
alignment of the ebb channel. Photographic Source: USACE Wilmington,
NC District Office and NC Department of Agriculture. ................................................... 16
10.
Position and alignment of Brown’s Inlet’s ebb channel and ebb tidal delta in
October 2008. Also depicted are the Inlet Minimum Width (IMW), the
static inlet baseline (black dashed line) and the configuration of the shoreline
(blue line) in 2008. Photographic source: NAIP. .............................................................. 17
11.
Location of transects used to calculate shoreline change for Bear Inlet (A)
and Brown’s Inlet (B). Three transects within the inlet shoreline and 15
along the oceanfront shoreline were constructed. Transects were named after
the island in which they were located and numbered from closest to the inlet
(1) to farthest (15). Photographic source: NAIP. .............................................................. 19
xiii
12.
Location of the shoreline change zones for Bear Inlet (A) and Brown’s Inlet (B).
Source: NAIP. ................................................................................................................... 20
13.
Aerial photograph of Bear Inlet in 2008 showing examples of marsh islands,
recurved dune ridges and the apparent surface area of the ebb tidal delta. Note
the size of its tidal basin compartment and its wide floodway. Photographic
source: NAIP ..................................................................................................................... 22
15.
Bear Inlet minimum widths from 1938 to 2008. The maximum and minimum
widths are labeled. ............................................................................................................ 24
16.
Bear Inlet with the configuration of the ebb channels from April 1938 to
October 2008. Photographic source: USACE Wilmington District Office. ..................... 24
17.
Bear Inlet ebb channel azimuths from April 1938 to June 2008. Azimuths
greater than 180° indicate orientation to the southwest (toward Brown’s Island)
and azimuths less than 180° indicate orientation toward the northeast
(toward Bear Island). Shore-normal ebb channel orientation is considered
to be approximately 180 degrees. ..................................................................................... 25
18.
Examples of Bear Inlet ebb channel and ebb shoals complex configurations
from April 1938 to October 2008, grouped by periods in which channel
deflection and ebb delta breaching episodes occurred. Ebb channel
orientation is indicated by colored tracks with degrees bearing values.
Shore-normal ebb channel orientation at Bear Inlet is approximately
180 degrees. Photographic Source: USACE Wilmington, NC District Office................. 26
19.
Bear Inlet ebb channel migration in meters from April 1938 to October 2008.
The negative values (represented by red bars) indicate that the channel was
moving toward Bear Island. The positive values (represented by blue bars)
represent the periods in which the channel migrated toward Brown’s Island. ................. 28
20.
Bear Inlet width and ebb channel orientation changes from April 1938 to
October 2008. The minimum inlet width of 293 meters occurred in March 2003,
a period in which the ebb channel was roughly with the same orientation (165°)
since March 2001. Spits on both shoulders of Bear Inlet were formed during
this period and the baseline width was 559.3 meters. The maximum width
occurred in 1938 when the ebb channel was skewed toward Brown’s Island,
with its most southwestern orientation (225°). During the times in which the
channel was in approximately shore-normal position (December 1985 and
May 1994) the widths were low (424.6 m in 1985 and 402.9 m in 1994) and
the values of the baseline widths were among the lowest (452 m in 1985 and
458 m in 1994). ................................................................................................................. 29
21.
Cumulative average changes of Bear Island shoulder (Bear Inlet) from
April 1938 to December 2008........................................................................................... 31
xiv
22.
Cumulative average changes for Browns Island shoulder (Bear Inlet) from
April 1938 to October 2008 .............................................................................................. 34
23.
Aerial photograph of Brown’s Inlet in 2008 showing examples of recurved
dune ridges and vegetated parabolic dunes, along with the location of the ebb
channel and the apparent surface area of the ebb tidal delta. Photographic
source: NAIP. .................................................................................................................... 39
24.
Brown’s Inlet Net changes from 1872 to 1938 and from 1938 to 2008.
From 1872 to 1938 (represented by the blue bars), Brown’s Island shoulder
eroded along transects closest to the inlet and accreted on the remaining
transects. Onslow Beach shoulder accreted along all transects during the
same period. From 1938 to 2008 (red bars), Onslow Beach shoulder accreted
along all transects and Brown’s Island shoulder eroded along all transects. .................... 40
25.
Brown’s IMW (Inlet Minimum Width) from 1872 to 2008. The maximum
inlet width was 433 m in March 2003 and the minimum inlet width of 129 m
was measured in October 1983. ........................................................................................ 40
26.
Brown’s Inlet ebb channels from 1938 to 2008. Source: NAIP ....................................... 41
27.
Brown’s Inlet ebb channel azimuths from April 1938 to June 2008. Shorenormal ebb channel orientation is considered to be approximately 180
degrees. The maximum azimuth was 235º in April of 1938, when the
channel was oriented toward Onslow Beach and the minimum azimuth was
in August 1959 when the channel was oriented toward Brown’s Island. ......................... 42
28.
Brown’s Inlet examples of channel deflection and ETD breaching from 1938
to 2008. Source: USACE North Carolina Wilmington District ........................................ 43
29.
Brown’s Inlet ebb channel migration from 1938 to 2008. The negative
values (red) indicate that the channel was moving toward Brown’s Island.
The positive values (blue) represent the periods in which the channel migrated
toward Onslow Beach. The maximum migration to the southwest was during
the period of 1962 to 1974, when the ebb channel migrated 156 m (13 m/yr)
to SW. The maximum migration to the northeast was during the period of 2003
and 2006 when the ebb channel migrated 76 m at a rate of 25 m/yr. ............................... 44
30.
Brown’s Inlet width and ebb channel orientation changes from April 1938 to
October 2008. .................................................................................................................... 45
31.
Average cumulative changes for Onslow Beach shoulder (Brown’s Inlet)
from April 1938 to October 2008 ..................................................................................... 47
32.
Average cumulative changes for Brown’s Island shoulder (Brown’s Inlet)
from April 1938 to October 2008. .................................................................................... 50
xv
33.
Bear Inlet Average Cumulative Changes for Zones I and II from April 1938
to October 2008 acquired using DSAS (in red) and AMBUR (in dark blue).
Bear Island shoulder, located northeast of Bear Inlet, had a cumulative average
erosion of 26.3 m along Zone I using AMBUR and a cumulative average
erosion of 27.9 m using DSAS. Along Zone II for the same shoulder, the
cumulative average erosion was 6.7 m and 6.6 m (AMBUR and DSAS,
respectively). Brown’s Island shoulder of Bear Inlet has had cumulative
average erosion of 23.3 m (AMBUR) and 26.7 m (DSAS) along Zone I and
cumulative average erosion values of 38 m (AMBUR) and 38.1 m (DSAS)
along Zone II. .................................................................................................................... 55
34.
Brown’s Inlet Average Cumulative Changes for Zones I and II from April 1938
to October 2008 acquired using DSAS (in red) and AMBUR (in dark blue).
Brown’s Island shoulder had a cumulative average accretion of 0.08 m along
Zone I using AMBUR and a cumulative average accretion of 0.59 m using
DSAS. Along Zone II for the same shoulder, the cumulative average erosion
was 11.3 m and 11.29 m (AMBUR and DSAS, respectively). Onslow Beach
shoulder had cumulative average accretion of 78.7 m (AMBUR) and 77.9 m
(DSAS) along Zone I and cumulative average accretion of 53.8 m (AMBUR)
and 54.7 m (DSAS) along Zone II. ................................................................................... 56
35.
Bear Inlet morphologic and shoreline changes from April 1938 to October
1949 (A) and from November 1949 to March 1962 (B). The blue-colored
arrows represent marginal flood channels, the sand-colored arrows represent
swash bars and the yellow-colored arrows represent spit development.
Photographic source: USACE Wilmington District Office. ............................................. 57
36.
Bear Inlet morphologic and shoreline changes from December 1974 to March
1962 (C) and from December 1974 to March 1989 (D). The blue-colored
arrows represent marginal flood channels, the sand-colored arrows swash
bars, the yellow-colored arrows represent spit development and the pinkcolored arrows represent the presence of linear bars. Photographic source:
USACE Wilmington District Office. ................................................................................ 59
37.
Bear Inlet morphologic and shoreline changes from March 1989 to May
1990 (E) and from May 1990 to September 1996 (F). The blue-colored arrows
represent marginal flood channels, the sand-colored arrows swash bars, the
yellow-colored arrows represent spit development and the pink-colored arrows
represent the presence of linear bars. The dashed square is representing the
location of an accretion bulge. Photographic source: USACE Wilmington
District Office. .................................................................................................................. 62
38.
Bear Inlet morphologic and shoreline changes from September 1996 to March
2001 (G) and from March 2001 to March 2003 (H). The blue-colored arrows
represent marginal flood channels, the sand-colored arrows swash bars,
the yellow-colored arrows represent spit presence or development and
xvi
the dashed square is representing the location of an accretion bulge.
39.
Bear Inlet morphologic and shoreline changes along Bear Island shoulder from
March 2003 (I) to October 2006 and from October 2006 to October 2008 (J).
The blue-colored arrows represent marginal flood channels, the sand-colored
arrows swash bars, the yellow-colored arrows represent spit presence or
development and the pink-colored arrows represent the presence of linear bars.
40.
Bear Inlet morphologic and shoreline changes along Brown’s Island shoulder
from April 1938 (A) to November 1949 and from November 1949 to March
1962 (B). The blue-colored arrows represent marginal flood channels, the
sand-colored arrows swash bars, the yellow-colored arrows represent spit
presence or spit development and the pink-colored arrows represent the
presence of linear bars. The dashed rectangles represent the presence of
accretion bulges and the dashed orange ellipse mark the possible location
of an ebb delta breaching episode. Photographic source: USACE Wilmington
District Office. .................................................................................................................. 67
41.
Bear Inlet morphologic and shoreline changes along Brown’s Island
shoulder from March 1962 (C) to December 1974 and from December 1974
to March 1989 (B). The blue-colored arrows represent marginal flood channels,
the sand-colored arrows swash bars, and the pink-colored arrows represent the
presence of linear bars. Photographic source: USACE Wilmington District
Office. .............................................................................................................................. 69
42.
from March 1989 to May 1990 (E) and from May 1990 to September 1996 (F).
The blue-colored arrows represent marginal flood channels, the sandcolored arrows swash bars, and the pink-colored arrows represent the presence
of linear bars. Photographic source: USACE Wilmington District Office. ...................... 71
43.
from September 1996 to March 2001 (G) and from March 2001 to March
2003 (H). The blue-colored arrows represent marginal flood channels, the sandcolored arrows swash bars, and the orange-colored arrow represent spit
development. Photographic source: USACE Wilmington District Office. ...................... 73
44.
from March 2003 to October 2006 (I) and from October 2006 to October 2008
(J). The blue-colored arrows represent marginal flood channels, the sandcolored arrows swash bars, and the yellow-colored arrow represents spit
presence or development. Photographic source: USACE Wilmington
District Office. .................................................................................................................. 75
xvii
45.
Brown’s Inlet morphologic and shoreline changes along Brown’s Island
shoulder from March 2003 to October 2006 (I) and from October 2006 to
October 2008 (J). The blue-colored arrows represent marginal flood channels,
the sand-colored arrows swash bars, and the yellow-colored arrow
represents spit presence or development. Photographic source: USACE
Wilmington District Office. .............................................................................................. 76
46.
shoulder from May 1958 to August 1959 (C) and from August 1959 to
November 1960 (D). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars, and the yellow-colored arrow
47.
shoulder from November 1960 to March 1962 (E) and from March 1962 to
December 1974 (F). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars, and the yellow-colored arrow
48.
shoulder from December 1974 to October 1983 (E) and October 1983 to
October 1984 (F). The blue-colored arrows represent marginal flood channels,
the sand-colored arrows swash bars, and the pink-colored arrows represent
linear bars. Black dashed rectangles represent the presence of accretion bulges.
49.
shoulder from October 1984 to January 1987 (I) and January 1987 to October
1993 (J). The blue-colored arrows represent marginal flood channels, the sandcolored arrows swash bars, and the pink-colored arrows represent linear bars.
50.
shoulder from October 1993 to June 2002 (K) and from June 2002 to March
2003 (L). The blue-colored arrows represent marginal flood channels, the
sand-colored arrows swash bars, and the pink-colored arrows represent linear
bars. Black dashed rectangles represent accretion bulges. Photographic
source: USACE Wilmington District Office. ................................................................... 83
51.
shoulder from March 2003 to October 2006 (M) and from October 2006 to
October 2008 (N). The blue-colored arrows represent marginal flood channels,
the sand-colored arrows swash bars, and the pink-colored arrows represent
linear bars. Black dashed rectangles represent accretion bulges. Photographic
xviii
source: USACE Wilmington District Office. ................................................................... 84
52.
Brown’s Inlet morphologic and shoreline changes along Onslow Beach
shoulder from April 1938 to January 1945 (A) and from January 1945 to
May 1958 (B). The blue-colored arrows represent marginal flood channels and
the sand-colored arrows swash bars. Black dashed rectangles represent
accretion bulges and the orange ellipse represents a potential site for an
ebb delta breaching episode. Photographic source: USACE Wilmington
District Office. .................................................................................................................. 85
53.
Brown’s Inlet morphologic and shoreline changes along Onslow Beach shoulder
from May 1958 to August 1959 (C) and from August 1959 to November
1960 (D). The blue-colored arrows represent marginal flood channels, the
sand-colored arrows swash bars and the pink-colored arrow represent linear bars.
54.
shoulder from November 1960 to March 1962 (E) and from March 1962 to
December 1974 (F). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars and the pink-colored arrows
represent linear bars. Photographic source: USACE Wilmington District Office............ 88
55.
shoulder from December 1974 to October 1983 (G) and from October 1983
to October 1984 (H). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars and the pink-colored arrows
represent linear bars. Photographic source: USACE Wilmington District Office............ 90
56.
shoulder from October 1984 to January 1987 (I) and from January 1987 to
October 1993 (J). The blue-colored arrows represent marginal flood channels,
the sand-colored arrows swash bars and the pink-colored arrows represent
linear bars. Photographic source: USACE Wilmington District Office. .......................... 91
57.
shoulder from October 1993 to June 2002 (K) and June 2002 to March 2003
(J). The blue-colored arrows represent marginal flood channels and the
pink-colored arrows represent linear bars. Black dashed rectangles represent
accretion bulges. Photographic source: USACE Wilmington District Office. ................. 92
58.
shoulder from March 2003 to October 2006 (M) and from October 2006 to
October 2008 (N). The blue-colored arrows represent marginal flood channels,
the sand colored arrows represent swash bars and the pink-colored arrows
represent linear bars. Photographic source: USACE Wilmington District
Office. ............................................................................................................................... 94
xix
INTRODUCTION
Bear and Brown’s inlets are two unmodified, relatively stable, transitional and waveinfluenced inlets located in the central portion of Onslow Bay, North Carolina (Fig. 1). The inlets
are situated along a coastal reach that is characterized by wide and relatively high, formerly
progradational barrier islands. The barrier islands within this reach, extending from Beaufort
Inlet to Browns Inlet, contain 15 to 20 times the volume of sand that comprises the typical
transgressive barrier islands farther to the southwest (CLEARY, 1996).
Bear inlet separates the western margin of the sand-rich, undeveloped Bear Island
(location of Hammocks Beach State Park) from Brown’s Island, a military-controlled barrier
island to the southwest. Brown’s Inlet separates the western margin of Browns Island from the
northeastern margin of Onslow Beach, another military-controlled barrier island (Fig. 1).
Figure 1: Location of the study area (National Agriculture Imagery Program, hereafter NAIP)
Both Bear and Brown’s inlets have existed at relatively the same location and have been
found in coastal charts of the area dating from the 19th century (Fig. 2; UNC Library Archives).
Figure 2. Bear and Brown’s inlet locations from a 1889 USGS chart (A) and from a 2008 Digital Orthophoto (B).
Reference points for location comparison in red. Sources: UNC Library Archives (A) and NAIP (B).
These two inlet systems have not been studied in great detail, bordering undeveloped
barrier islands that have not been subject to anthropogenic impacts. However the North Carolina
(N.C.) Division of Coastal Management (NCDCM) has initiated a coast-wide effort to obtain all
available data dealing with oceanfront shoreline changes, inlet system changes and the nature of
the adjacent shoreface for a Beach and Inlet Management Plan for the next 50 years (NC BEACH
AND INLET MANAGEMENT PLAN,
2011). The current data set lacks detailed information
pertaining to the nature and causes of shoreline and inlet-induced change related to these two
unique systems. An additional reason to study these inlets is that they are located on the western
boundary between sand-rich barrier islands to northeast and sand-poor barrier islands to the
2
southwest. In the study area, both Bear and Brown’s Inlets are located in the Northern Province
defined by RIGGS et al. (1995). The Northern Province is the coastal region in which availability
of unconsolidated sediment is greater. However, the southwestern portion of Browns Inlet is
located in the Southern Province, where there is only a thin and highly variable veneer of sand
and mud of Quaternary age (CLEARY and RIGGS, 1999).
Objectives
The primary objective of this study was to compare the behavior of Brown’s and Bear
Inlets through the acquisition of a robust data set that was used in an attempt to identify
predictive relationships between inlet conditions and the response of the adjacent inlet and
oceanfront shorelines. Questions addressed in this study included:
1) Are these systems exhibiting similar spatial and temporal changes in terms of
morphology and the attendant shoreline response?
2) Are the nature and timing of ebb-delta breaching and the bar-bypassing events
similar and if so are the adjacent shorelines responding in a similar manner?
3) What length of shoreline do these inlets control and which inlet parameter
(channel shift, channel alignment, ebb delta symmetry, etc.) or combination
thereof exerts the greatest control?
From both management and research perspectives it is important to understand the
difference or similarity in the behavioral patterns of these inlets with respect to long-term
stability (both locational and morphologic changes) given their close proximity and similar
hydrodynamic conditions.
3
Regional Setting
The North Carolina coast lies along the northern flank of the Georgia Bight, a 1,200 km
coastal reach extending from Cape Hatteras, North Carolina to Cape Canaveral, Florida (HAYES,
1980). The coast of North Carolina consists of a sequence of large capes and associated shoals,
barrier islands, spits and occasional headland areas. A natural division of the North Carolina
coast occurs near Cape Lookout. North of this Cape, the islands are separated from the mainland
by wide open-water sounds, contrasting with the south where the estuaries that back the barrier
islands are narrow and nearly filled with marsh (CLEARY and PILKEY, 1996).
Onslow Bay, located between Cape Lookout and Cape Fear, borders nearly half of North
Carolina’s 515-kilometer long shoreline (Figure 1). The shoreface in this region is underlain by
primarily sedimentary geologic units that range in age from Miocene to Plio-Pleistocene
(SNYDER et al., 1994). The sediment cover of the shoreface in this area is highly variable owing
to the nature of the underlying rock units. The general deficiency of sediment results from low
fluvial input and lack of sediment exchange along Long Bay and Raleigh Bay (CLEARY and
PILKEY, 1968; RIGGS et al., 1995). Small Coastal Plain draining rivers empty into this coastal
segment and this was probably the scenario during the late Pleistocene. As a consequence of the
small fluvial system contribution, it is not surprising that this area also has the lowest
sedimentation rate along the United States East Coast Shelf (CLEARY and PILKEY, 1968).
The 13 barrier islands of Onslow Bay shoreline have a wide variety of physiographic
forms, from overwash-dominated narrow barriers islands (sand-poor barriers islands) to sandrich barriers islands with large dunes and no washovers. The approximate boundary between
sand-poor and sand-rich barriers islands occurs along Onslow Beach (OB) (Figure 3) where a
4
submarine headland composed of Tertiary limestone and sandstone forms a prominent
protuberance along the coast (RIGGS et al., 1999).
Bear and Brown’s inlets are located on the north and south shoulders of Brown’s Island, a
4.5 km barrier island with an average width of 600 m. The island has been classified as altered
beach ridge barrier island (CLEARY, 1996). Large vegetated parabolic dunes characterize some
portion of this island and the existence of large steep spillover lobes in the adjacent estuary
provides evidence for the landward migration of the sand dunes.
Bear Island is similar in nature to Brown’s Island and is characterized by large and
variably vegetated parabolic dunes, some of which are actively migrating into the adjacent
marsh.
Figure 3. Oblique aerial photograph depicting Brown’s Inlet, Onslow Beach and the location of the
submarine headland, the boundary between sand-rich barrier islands to the northeast and sand-poor barrier
islands to the southwest (toward the top of photograph). Source: William Cleary.
Onslow Beach, a 12.9 km barrier island controlled by the military, is separated from
Browns Island by Brown’s Inlet to the northeast. This barrier island is the fifth longest in the
5
string of barrier islands that form the Onslow Bay shoreline and straddles the boundary between
two sand-rich and sand-poor barrier islands. CLEARY and RIGGS (1998), in their inspection of
aerial photographs and historic maps, revealed that Onslow Beach is composed of essentially two
barrier island segments and a transition zone, each with a distinct history and morphology. The
northeastern segment, which is the portion of the island investigated in this study, extends
approximately 4 km southwest from Brown’s inlet and is characterized by multiple dune ridges
which are 7 to 9 m high with a maximum width of 150 meters. This barrier island segment is the
southernmost former regressive shoreline that occurs between Cape Lookout and Cape Fear and
is part of the extensive regressive barrier sequence that extends west of Cape Lookout.
Tides in this region are semi-diurnal and have a mean range of 0.92 m (CLEARY and
RIGGS 1998). Since the islands bordered by Bear and Brown’s Inlets are oriented northeast to
southwest, the waves propagate out of the east northeast to southwest and have an average height
of 0.73 m (CLEARY and RIGGS 1998) and average wave period 7.52 seconds.. The average net
longshore transport from 1976-1995 was 208,173cy/yr to the west (USACE 2004).
Background and History
Little detailed work has been published on Brown’s and Bear Inlets and only a few
studies provide any information to compare their behavior. CLEARY and HOSIER (1987) provided
information dealing with physiographic changes along Onslow Beach. CLEARY (1996) published
a general overview of the Onslow Bay shoreline and the tidal inlets that occur along this region.
Work by LANGFELDER et al. (1974) measured inlet parameters such as minimum inlet width,
updrift and downdrift shoulder migration for this region, and included some description of the
Brown’s and Bear Inlets. An atlas of all tidal inlets that occur along North Carolina coast was
6
published by CLEARY and MARDEN (1999) and the work of SAULT (1999) described the general
behavior of Brown’s and New River inlets from 1938 to 1997.
The reconnaissance study conducted by SAULT (1999), with limited shoreline data,
indicated that Brown’s inlet’s ebb tidal delta has shifted about 380 m to the southwest during the
last six decades. Cyclical shoreline changes along the northern and southern shoulders have been
influenced by changes in the position and location of the ebb channel.
Little is also known about the historic behavior of Bear Inlet, but it is likely that the initial
position of the inlet was controlled by the location of an ancestral fluvial channel of Bear Creek
(Figure 4). A regional reconnaissance analysis of modern and historic maps suggests that shifting
of the ebb channel through the years is responsible for shoreline changes along adjacent barrier
islands (CLEARY and MARDEN 1999).
Figure 4. Possible initial locations of Bear and Brown’s inlets’ ebb channels (blue dashed lines). Distance
of migration of inlet opening (white arrows) to the location of the ebb channel in 2009. Photographic
source: NAIP.
7
Tidal Inlets
A tidal inlet (Figure 5) is defined as an opening in the shoreline through which water
penetrates the land and allows an exchange of water, sediment, nutrients and pollutants between
the open ocean and the back barrier estuary (CLEARY and MARDEN, 1999). The main channel of
a tidal inlet is maintained by tidal currents, which strongly influence the general dynamics of
barrier island shorelines interrupting the longshore transport of sediment, affecting both the
supply of sand to the adjacent beaches and the erosional-depositional processes along the inlet
shoreline. The extent to which these systems interrupt the transport along shore depends on the
local wave climate and tidal range (RIGGS, 1980). The greatest changes along barrier islands
occur in the vicinity of inlets, and these changes are a direct consequence of tidal inlet processes
such as inlet migration, sediment bypassing and sand losses to the back barrier among other
processes (DAVIS and FITZGERALD, 2004).
Figure 5. Idealized Inlet Morphology and Processes (Hayes, 1980)
The number and length of barrier islands are controlled by the size and number of tidal
inlets, which are primarily a function of the tidal range and bay area (HAYES, 1975). Along
8
microtidal coasts where tidal ranges are less than 2.0 m, the barrier islands are generally long and
continuous, interrupted by few tidal inlets. However, along mesotidal coasts where the tidal
range is between 2.0 and 4.0 m, the barrier islands are short and tidal inlets are more frequent
(HAYES, 1975).
Tidal inlets not only trap sediment but they are also responsible for long-term oceanfront
erosion. This is caused by accumulation of sediment on the ebb tidal deltas, sediment transport
into the back barrier of the environment and loss of sand to the littoral system. Although
landward transport is a common process among flood-dominated inlets (where flood currents are
greater than ebb currents) it can also occur in other inlets due to storm events. During these
events, increased wave energy produces higher rates of sand transport towards inlets from
adjacent beaches and towards ebb tidal deltas (FITZGERALD, 1988).
A tidal inlet can suffer loss of sand caused by many processes. The building of recurved
spits into the back barrier is considered one process responsible for sand loss at tidal inlets (Fig.
5). These spits result from the combined processes of flood tidal currents and refracted waves.
The other process responsible for sand loss in tidal inlets is associated with inlet migration
(HAYES, 1980). In this situation, sediment transported into the inlet and deposited on the updrift
side is not replaced by loss of sediment on the erosional side of the channel.
HAYES (1994) classified the inlets that occur along the Georgia Bight (from Cape
Hatteras, North Carolina to Cape Canaveral, Florida) as tide-dominated, wave-dominated or
transitional, depending on the dominant energy type. Transitional inlets, such as Bear and
Brown’s Inlets have a highly variable morphology controlled by wave and tidal energy. They
have abundant shoals choking the inlet throat with one ebb channel and one or more secondary
flood channels (CLEARY, 1996).
9
The Ebb Tidal Delta
Several types of sand bodies are associated with tidal inlets. Among these sand bodies,
located on the seaward shoals of an inlet, are the ebb tidal deltas. Figure 5 illustrates the
morphologic components of a typical inlet. These sand bodies represent huge reservoirs of sand
and are formed by the interaction of waves and tidal currents and their overall morphology
(HAYES, 1980). The extent to which these features are developed is a function of the tidal prism
and the exposure to wave energy (HAYES, 1994). The morphological units of an ebb tidal delta
(HAYES, 1980) include an ebb channel flanked by linear bars. Swash bars are separated from
barrier islands by a marginal flood channel that transports ocean water to the back barrier island.
The terminal lobe marks the seaward extent of the ebb delta.
Regardless of size, these seaward shoals influence the ends of the barrier islands acting as
natural breakwaters and modifying wave energy incident to the shoreline. Waves that approach
the islands refract in such a manner that a region of sediment transport reversal occurs downdrift
of the inlet (HAYES, 1994).
Along mixed energy coasts, slight changes in volume of the ebb tidal delta can
significantly affect the sand supply to adjacent beaches. When the location or the symmetry of
the ebb channel is changed, there is a simultaneous change in the pattern of erosion and accretion
on the adjacent shorelines (CLEARY, 1994). If the bay is filled, either naturally or as a result of
anthropogenic alteration of the circulation, it will result in a decrease in the inlet tidal prism and
consequently reduce the size of the ebb tidal delta. This decrease in size of the ebb delta
ultimately leads to accretion along one or both adjacent shorelines. The reverse scenario occurs
in terms of shoreline change if natural causes or anthropogenic activities result in an increase in
10
the tidal prism of an inlet which leads to the expansion of the ebb delta volume and shoreline
erosion.
Inlet Sediment Bypassing
Sediment bypassing is the transport of sand from one side of the tidal inlet to the other
side. This process controls the location and rate of sand nourishment to the downdrift barrier
island. BRUN and GERRITSEN (1959) first described the natural mechanisms of inlet sediment
bypassing by comparing the maximum discharge through an inlet to the alongshore sediment
transport. The methods by which sediment is transferred across tidal inlets are: 1) wave-induced
sand transport along the terminal lobe; 2) transport of sand in channels; and 3) migration of tidal
channels and sand bars. (FITZGERALD, 1988)
In order to explain sediment bypassing along mixed energy coasts, FITZGERALD (1988)
proposed six models to explain sediment bypassing around mixed energy inlets. These models
include inlet migration and spit breaching, stable inlet processes and ebb tidal delta breaching
(FITZGERALD et. al, 2000).
Although the models of sediment bypassing proposed by FITZGERALD (1988) are based
on inlets which are mixed-energy tide-dominated and Bear and Brown’s Inlets are classified as
mixed-energy wave-dominated, the mechanism of sediment bypassing referred to as ebb delta
breaching is similar to what occurred on both inlets studied and therefore is described in this
study and depicted in Figure 6.
Ebb tidal and delta breaching occurs at tidal inlets that have stable throat positions, but
whose main ebb channels cyclically migrate downdrift (Figure 6). The dominant direction of
longshore transport at these sites produces a preferential accumulation of sediment on the updrift
side of the ebb-tidal delta. The sediment accumulation causes a downdrift deflection of the main
11
ebb channel, which at some inlets may ultimately impinge against the downdrift inlet shoreline.
This pattern of channel migration commonly induces erosion along the adjacent beach. A severe
deflection of the main channel produces flow at the inlet that is hydraulically inefficient.
Eventually, this condition results in the ebb discharge being diverted to a more direct seaward
pathway through the ebb-tidal delta.
The breaching process can occur gradually over a period of 6 to 12 months or
catastrophically during a single storm when discharge of floodwaters increases the scouring of
the ebb currents. Once formation of the new channel is completed, it will convey most of the
inlet tidal prism. Thus, the abandoned channel gradually fills with sediment deposited by both
tidal and wave generated currents. The breaching process commonly results in the bypassing of a
large portion of the ebb delta sand. Some of this sand fills the old channel, while the rest forms a
subtidal or intertidal bar complex that migrates onshore ultimately attaching to the landward
beach. The entire developmental process takes from 5 to 10 years to complete (FITZGERALD, et.
al, 2000).
Figure 6. Sediment bypassing along mixed-energy coasts using the ebb tidal and delta breaching model
similar to what occurred along Bear and Brown’s Inlets during the period from April 1938 to October 2008.
Source: FITZGERALD, 1988.
12
METHODOLOGY
Aerial photograph sets from 1938 to 2008 and historic coastal charts dating from 1850 to
1934 were analyzed to determine the influence of Bear and Brown’s Inlets on the adjacent
shorelines. Photographs were obtained from a variety of sources including the U.S. Army Corps
of Engineers, Wilmington District, (USACE), the U.S. Marine Corps, the North Carolina
Division of Coastal Management (NCDCM) and NC National Agriculture Imagery Program
(NAIP).
After initial observations of changes and trends, representative years (sets) of
photographs were selected for the study. Photographs best representing the spatial extent of the
study area were chosen. Although most recent photographs are color, some earlier coastal
flyovers utilized black and white photography.
Color photographs obtained at low tide reveal more identifiable and mappable features,
and are more easily rectified. High quality black and white photographs were also used when
color photographs were unavailable for a given year. Sets of photographs cover the extent of
proposed Inlet Hazard Areas (IHAs) as designated by the North Carolina Division of Coastal
Management (NCDCM). Photographs with common scales were preferentially selected for
analysis. The USACE, NCDCM and NAIP provided 20 sets of high-quality photographs that
cover Bear Inlet, and 19 sets of photographs that cover Brown’s Inlet (Tables A1 and A2,
APPENDIX). The scale of the photographs used in this study ranged between 1:12,000 and
1:20,000.
The aerial photographs were scanned and georectified using ArcGIS™ version 9.2. The
photographs of Bear inlet were rectified using the Onslow County Department of GIS Digital
13
Orthophotographic Quarter Triangles. For Brown’s inlet, the Orthophotographs were provided
by the North Carolina Division of Coastal Management (NCDCM).
The process of orthorectification provides geographical coordinates for any given point
on an aerial photograph. Ground Control Points (GCP) representing the same location when
possible on aerial photographs and the reference DOQ photograph were chosen. HUGHES et al.
(2006) assessed the accuracy of georectified aerial photographs. They found that GCP type
exerted a less consistent influence on test-point accuracy, suggesting that although hard-edged
points are favored as GCPs, some soft-edged points (trees/shrubs) may be used without adding
significant error (HUGHES et al., 2006). In this study, due to the undeveloped characteristic of
the area where streets or houses were not available, features such as trees and shrubs were
utilized for a total of at least 8 GCP’s per photograph. The Root Mean Square (RMS) Error
resulted from each rectification was recorded to determine the georectification error, which is the
pixel size multiplied by the RMS size (Tables A1 and A2, APPENDIX).
A time series of georectified aerial photographs illustrating the historical and
contemporaneous changes at Bear and Brown’s Inlets were produced. They were used to
compare and contrast the morphological inlet features and adjacent shoreline change relative to a
1938 base year photograph and to each other. Figures 8 and 9 depict the changing morphology of
Bear and Brown’s Inlets.
14
Figure 8. Aerial photographs illustrating the changing morphology of Bear Inlet from April 1938 to
October 2008. The dashed lines represent the location and position of the ebb channel. Photographic
Source: USACE Wilmington, NC District Office and NC Department of Agriculture.
15
Figure 9. Aerial photographs illustrating the changing morphology of Brown’s Inlet from April 1938 to October 2008.
The dashed lines depict the location and alignment of the ebb channel. Photographic Source: USACE Wilmington, NC
District Office and NC Department of Agriculture.
After georectification, the shoreline positions were digitized based on the location of the
wet/dry line visible on the photographs. This line represents the maximum high water position
during a given tidal cycle and is widely used to digitize shoreline positions because it relatively
easy to identify on historical aerial photographs (CROWELL et al. 1991). Inlet morphological
features, including the ebb tidal delta, ebb channel position and alignment and the adjacent linear
bars were also digitized. All digital shoreline files were projected to North Carolina State
16
Projection using the NAD 1983 datum and the GRS 1980 spheroid. All projections were placed
in meter units prior to analysis by DSAS and AMBUR.
Inlet minimum width was determined by measuring the minimum distance between the
wet/dry lines on opposite sides of the inlet throat. Baseline inlet width was determined by
measuring the inlet width along a static digital baseline. The October 2008 shoreline, ebb
channel, and ebb tidal delta for Brown’s are shown in Figure 11, as well as the location of inlet
minimum width for October 2008 and static inlet baseline.
Figure 10. Position and alignment of Brown’s Inlet’s ebb channel and ebb tidal delta in October 2008. Also
depicted are the Inlet Minimum Width (IMW), the static inlet baseline (black dashed line) and the
configuration of the shoreline (blue line) in 2008. Photographic source: NAIP.
Shoreline Change Measurement
To provide a better understanding of changes within each inlet and along the adjacent
shorelines, baselines parallel to the shoreline were constructed with two onshore for Brown’s
Inlet and two onshore and one offshore for Bear Inlet. From these baselines, transect lines at
intervals of 100 m perpendicular to the shoreline were created to measure the amount of
17
shoreline change and the nature of bar-bypassing over the years. The ArcGIS™ DSAS (Digital
Shoreline Analysis System) version 4.2 extension was used to collect shoreline change data
along each transect. Transects were numbered consecutively with transect 1 located closest to the
inlet throat on the south shoulder of each inlet. Shoreline movement and rates of change were
calculated by measuring between the baseline and historical high water lines.
DSAS is a freely available software application that works within the Environmental
Systems Research Institute (ESRI) Geographic Information System (ArcGIS) software. DSAS
computes rate-of-change statistics for a time series of shoreline vector data. Version 4.2 was
released in August 2010 and is compatible with ArcGIS 9.2 and above. It is supported on both
Windows XP and Vista operating systems (THIELER et al., 2009).
In order to compare results, a software package called AMBUR (Analyzing Moving
Boundaries Using R) version 1.0 was also used to collect shoreline change data along each
transect (JACKSON, 2010; JACKSON et al., in press). In order to be able to compare and contrast
the results from both software packages, the same baselines were and the distance between
transects was 50m.
The AMBUR package for the R software provides a collection of functions for assisting
with analyzing and visualizing historical shoreline change (JACKSON, 2010; JACKSON et al., in
press). The package allows import and export of geospatial data in ESRI shapefile format, which
is compatible with most commercial and open-source GIS software.
Transects were named after the island on which they were located (e.g., BR for Browns
Island shoulder, BE for Bear Inlet shoulder, OB to Onslow Beach shoulder and IT for transects
located within the inlet throat). They were numbered consecutively, starting closest to each inlet
(Figure 12). Due to the horizontal extent of the majority of the digital shorelines, this study used
18
15 transects located along each shoulder of the inlet for the data acquired through DSAS and 30
along each shoulder for the data acquired through AMBUR so as to cover the same distance
covered by DSAS.
Measurements of the movement of ebb channels and the inlet widths were also made in
order to evaluate erosion or accretion patterns as well as cycles of morphologic change within
each inlet system. Migratory histories of the ebb channels were determined using the digitized
shorelines.
Figure 11. Location of transects used to calculate shoreline change for Bear Inlet (A) and Brown’s Inlet (B). Three
transects within the inlet shoreline and 15 along the oceanfront shoreline were constructed. Transects were named
after the island in which they were located and numbered from closest to the inlet (1) to farthest (15). Photographic
source: NAIP.
19
Delineation of Shoreline Change Zones
When describing shoreline changes, previous studies commonly have grouped transects
into shoreline change zones (MARDEN 1999; JACKSON, 2004; BUDDE, 2008, ROSE, 2009). A
shoreline change zone is defined as a segment of the shoreline displaying an overall difference in
magnitude of erosion or accretion from adjacent reaches due to one primary influencing factor,
such as an inlet, or combination of factors (JACKSON, 2004). Rather than averaging transect
changes over an entire shoreline segment, in this study changes were averaged by zone to
provide a better understanding of the extent of inlet influence.
This study utilized the location of the NCDCM IHA and the distance from the inlet to
delineate and subdivide shoreline change zones (Figure 12). The Inlet Zone (IZ) on each inlet
shoreline segment includes transects located within the inlet throat. Zone I includes transects
located within and beyond the IHA and Zone II includes the remaining oceanfront shoreline.
Figure 12. Location of the shoreline change zones for Bear Inlet (A) and Brown’s Inlet (B). Source: NAIP.
20
Shoreline Rate of Change Calculation
DOLAN and FENSTER (1991) suggested using the linear regression rate (LRR) method if
the purpose of a study is to better understand the impact of episodic events on long-term rates.
Because this study addresses inlet influences on shoreline change, long-term shoreline change
rates were calculated using the LRR method in AMBUR (JACKSON, 2010, JACKSON et al., in
press). The LRR method utilizes all historical shoreline positions and the rate of change is the
slope of the line that is the least-squares distance to the actual shoreline points (JACKSON, 2004).
Although outliers in the data can affect the LRR, it is the most appropriate method for
determining erosion rates since 1938 in this investigation.
This study also utilized a separate method for calculating short-term rates of change. The
EPR (End Point Rate) method was useful when describing shoreline changes subsequent to ebb
channel orientation changes. The EPR of change during a given period was determined by
dividing the distance of change from the first and last date by the number of elapsed years.
RESULTS
Shorelines are dynamic features in a constant state of change. Several factors, including
incident and refracted waves, tidal currents, underlying geologic framework, frequency and
magnitude of storms, sea-level rise, tidal inlet changes, and anthropogenic modifications can
determine the variability of shoreline change. Unfortunately, no established methods exist that
are able to statistically relate these external factors to long-term erosion and only apparent
shoreline change trends and influences may be ascertained from analyses of the dataset and
visual inspections of aerial photographs (JACKSON, 2004).
Information pertaining to inlet morphology changes and erosion and accretion trends for
each of the inlet shoulders is presented in this section. Due to the similarities between the data
21
obtained from DSAS and the data obtained from AMBUR, data obtained from DSAS are
described and discussed in this study in more detail. The shoreline change data reflect ebb
channel orientation and, accordingly, are presented by time periods; the beginning of each time
period is marked by an ebb channel orientation change. To facilitate the determination of the
spatial influence of each inlet, shoreline changes are grouped by zone. Tables listing inlet
parameters and the oceanfront shoreline changes obtained using both DSAS and AMBUR are
located in the Appendix section.
Bear Inlet Changes
Bear Inlet is a larger system than Brown’s Inlet (BRI) and is characterized by a more
extensive tidal basin compartment as well as a larger floodway, shown in Figure 13.
Figure 13. Aerial photograph of Bear Inlet in 2008 showing examples of marsh islands, recurved dune ridges and the
apparent surface area of the ebb tidal delta. Note the size of its tidal basin compartment and its wide floodway.
Photographic source: NAIP
Analyzing the photographs and the shorelines acquired for this study the shoreline
influenced by Bear Inlet was morphologically different from the period of 1872 to 1938 and
22
from 1938 to 2008, showing different erosion and deposition patterns between these two periods
(Figure15). From 1872 to 1938, the Bear Island shoulder experienced accretion whereas Brown’s
Island experienced erosion during the same period. From 1938 to 2008, however, both Bear
Island (except the Inlet Transect) and Brown’s Island shoulders eroded. In order to avoid
distortions in the cumulative changes and in the other rates used in this study, the 1872 shoreline
was excluded from the GIS dataset.
Figure 14. Bear Inlet net changes from 1872 to 1938 (red bars) and from 1938 to 2008 (blue bars). The
negative values represent erosion and the positive values represent accretion. From 1872 to 1938 there was
accretion close to the inlet along both Bear and Brown’s Islands, coastwise erosion along Brown’s Island
and coastwise accretion along Bear Island. From 1938 to 2008 erosion occurred along the shorelines of
both Bear and Brown’s Islands and accretion along the Inlet Transects.
Figure 15 depicts the variation in inlet minimum width for Bear Inlet from 1872 to 1938.
The maximum width was 787 meters in 1938 and in 1974 the width reached its minimum of 287
meters. The average minimum width was approximately 448 meters.
23
Figure 15. Bear Inlet minimum widths from 1938 to 2008. The maximum and minimum widths are labeled.
The orientation of the ebb channel as it crosses the outer ebb delta can have profound
effects on shoreline change by promoting or limiting sand-bypassing within the inlet system to
adjacent beaches (JACKSON, 2004). Bear inlet’s ebb channel have undergone several cycles of
deflection of variable length that played an important role on the configuration of the shoreline.
Because of the inlet’s relatively wide floodway, the ebb channel has deflected on both the inner
and the outer bar segment of the channels from 1938 to 2008. The distance in which the channels
deflect on the inner portion is approximately 30 m wider than the distance on the outer bar
(Figure 16).
Figure 16. Bear Inlet with the configuration of the ebb channels from April 1938 to October 2008. Photographic
source: USACE Wilmington District Office.
24
The orientation of Bear Inlet’s ebb channel has changed continuously since April 1938,
as depicted in Figure 17. The maximum azimuth was 231º (March 1962), with the channel
shifted toward Brown’s Island while the minimum azimuth was 140° (May 1994) when the
channel was roughly in shore-normal position.
Figure 17. Bear Inlet ebb channel azimuths from April 1938 to June 2008. Azimuths greater than 180° indicate
orientation to the southwest (toward Brown’s Island) and azimuths less than 180° indicate orientation toward the
northeast (toward Bear Island). Shore-normal ebb channel orientation is considered to be approximately 180
degrees.
Examples of portions of cycles of ebb channel deflection and re-orientation are depicted
in Figure 18. From April 1938 to October 1949 the channel shifted from oriented toward
Brown’s Island with an azimuth of 225° to a position with an azimuth of 193° as consequence of
an ebb-delta breaching episode.
25
Figure 18. Examples of Bear Inlet ebb channel and ebb shoals complex configurations from April 1938 to October
2008, grouped by periods in which channel deflection and ebb delta breaching episodes occurred. Ebb channel
orientation is indicated by colored tracks with degrees bearing values. Shore-normal ebb channel orientation at Bear
Inlet is approximately 180 degrees. Photographic Source: USACE Wilmington, NC District Office.
Deflection towards Brown’s Island occurs between October 1949 and August 1959
(Figure 18 A); in March 1962 the ebb channel is oriented toward Brown’s Island with an azimuth
of 231° (Figure 18 B). Between March 1962 and December 1974 the ebb tidal delta breached
again and channel deflected toward Bear Island with an azimuth of 153°. In September 1984 the
ebb channel was oriented toward Bear Island (Figure 18 C), assumed a shore-normal position
between September 1984 and December 1985 (Figure 18 C) and went to a slightly northeast
position toward Bear Island between December 1985 and January 1987 (azimuth from 178° to
145°) (Figure 18 C). The position of the ebb channel in March 1989 was roughly the same as in
26
1987 (Figure 18 D) but it deflected slightly toward Brown’s Island through another possible ebb
delta breaching episode between March 1989 and August 1990 (azimuths from 168° to 215°)
(Figure 18 D). From 1990 to October 1993, the ebb channel assumed an orientation toward Bear
Island with an azimuth of 140° (Figure 18 D). Between October 1993 and May 1994 the channel
shifted from toward Bear Island to a shore-normal position of 185° (Figure 18 E). Following
another ebb delta breaching episode the channel shifted towards Brown’s Island between May
1994 and September 1996 with an azimuth of 217° (Figure 18 E). Between September 1996 and
March 2001 the ebb channel shifted to a northeastern orientation toward Bear Island probably
after another ebb delta breach (azimuths from 217° to 165°) (Figure 18 E). Between March 2001
and March 2003 the channel deflected toward Bear Island and shifted toward Brown’s Island
probably between March 2003 and October 2006 due to another ebb-delta breaching episode
(azimuths from 165° to 218°) as depicted in Figure 18 F.
From March 2006 to October 2008 the channel moved from an orientation toward
Browns Island to one going toward Bear Island as consequence of the development of a spit on
Brown’s Island shoulder (Figure 18 F).
The ebb channel not only shifted going toward one shoulder to another but the inlet
migrated horizontally as well. Figure 19 depicts the ebb channel migration over the inlet baseline
from 1938 to 2008. The maximum inlet migration to the northeast was between 1996 and 2001,
when the inlet migrated 158 meters (31.8 m/y). The maximum migration to the southwest was
between 2006 and 2008 when the ebb channel migrated 280 meters at a rate of 140 m/y. For the
period of time studied, the dominant inlet migration was to the southwest at a rate of 8.5m/yr.
27
Figure 19. Bear Inlet ebb channel migration in meters from April 1938 to October 2008. The negative values
(represented by red bars) indicate that the channel was moving toward Bear Island. The positive values (represented
by blue bars) represent the periods in which the channel migrated toward Brown’s Island.
Table 1 Bear Inlet Ebb channel migration rates from April 1938 to October 2008.
Bear Inlet Ebb Channel Migration Rates (m/y)
Period
Ebb Channel
1838-1949
16.7
1949-1959
-4.5
1959-1962
74.9
1962-1974
-2.6
1974-1984
12.8
1984-1985
10.8
1985-1987
3.1
1987-1989
-2.3
1989-1990
-43.0
1990-1993
5.6
1993-1994
-9.2
1994-1996
30.8
1996-2001
-31.8
2001-2003
-64.0
2003-2006
33.4
2006-2008
140.1
1938-2008
8.5
Bear Inlet minimum widths correlated roughly with the orientation of the ebb channel
(Figure 20). There is a time lag of variable length between the drastic changes in ebb channel
28
orientation and changes in inlet minimum width and in baseline width showing that the shoreline
does not change as rapid as the changes in ebb channel orientation. The minimum inlet width of
293 meters occurred in March 2003, a period in which the ebb channel was roughly with the
same orientation (165°) since March 2001; spits on both shoulders of Bear Inlet were formed
during this period and the baseline width was 559.3 meters. The maximum width occurred in
1938 when the ebb channel was skewed toward Brown’s Island, with its most southwestern
orientation (225°). During the times in which the channel was in approximately shore-normal
position (December 1985 and May 1994) the widths were low (424.6 m in 1985 and 402.9 m in
1994) and the values of the baseline widths were among the lowest (452 m in 1985 and 458 m in
1994).
Figure 20. Bear Inlet width and ebb channel orientation changes from April 1938 to October 2008. The minimum
inlet width of 293 meters occurred in March 2003, a period in which the ebb channel was roughly with the same
orientation (165°) since March 2001. Spits on both shoulders of Bear Inlet were formed during this period and the
baseline width was 559.3 meters. The maximum width occurred in 1938 when the ebb channel was skewed toward
Brown’s Island, with its most southwestern orientation (225°). During the times in which the channel was in
approximately shore-normal position (December 1985 and May 1994) the widths were low (424.6 m in 1985 and
402.9 m in 1994) and the values of the baseline widths were among the lowest (452 m in 1985 and 458 m in 1994).
During the period in which no drastic changes in ebb channel orientation occurred
(Between December 1974 and December 1985) the values of baseline widths were decreasing
29
gradually (from widths of 611 m in 1974 to 395 m in 1985). However, when the channel shifted
toward Bear Island (175° to 148°) in January 1987, the inlet and baseline widths did not suffer as
drastic changes as did the channel orientation (inlet width ranged from 424.6 m in 1985 to 472.2
m in 1987 and baseline width ranged from 452 m in 1985 to 518 m in 1990). The periods of, or
right after, possible ebb delta breaching episodes (sometime between 1938 and 1949, 1962 and
1974, 1990 and 1993, 1996 and 2001, and 2003 and 2006) were not followed by drastic changes
in the values of the inlet and baseline widths.
Table 2 Summary Bear Inlet data from April 1938 to October 2008.
Bear Inlet
Date
Orientation
IMW
Baseline Width
(mm/dd/yyyy)
( °)
(m)
(m)
04/25/1938
225
787.3
789.9
10/21/1949
193
332.0
673.4
08/16/1959
200
519.8
605.8
03/13/1962
231
349.0
745.7
12/01/1974
153
286.6
611.9
09/19/1984
178
426.5
485.9
12/22/1985
176
424.6
452.0
01/14/1987
145
472.2
518.1
03/25/1989
168
407.4
522.8
05/08/1990
215
406.2
453.6
10/29/1993
140
500.2
590.4
05/07/1994
185
402.9
458.2
09/15/1996
217
487.3
624.2
03/10/2001
165
638.3
712.6
03/10/2003
165
292.8
559.3
10/14/2006
218
390.1
415.1
10/03/2008
165
498.2
498.2
Bear Island Changes
Inlet zone (IZ) along the Bear Inlet shoreline segment includes three transects
located at the inlet (Figure 13A). Zone I includes transects BE1 through BE8 which are located
within and right outside the IHA. Zone II includes transects BE9 through BE15. The shoreline
30
segment in Zone II will be referred to as the non-IHA oceanfront shoreline. Cumulative
shoreline changes for each zone on Bear Island are shown in Figure 21.
Figure 21. Cumulative average changes of Bear Island shoulder (Bear Inlet) from April 1938 to December 2008.
Inlet Zone (IZ)
The inlet zone (IZ) was the most variable segment along Bear Island with respect to
shoreline change between April 1938 and October 2008. The IZ had an average of 162 m of
cumulative average accretion since April 1938 at an EPR of 2.3 m/yr and a LRR of 3.7 m/yr
(Table A4). Among the transects within the IZ the Inlet Transect (IT) was the most variable
one, with an cumulative average accretion of 182 m at an EPR of 2.6 m/yr and LRR 4 m/yr.
Between April 1938 and October 1949 the IZ shoreline reach retreated 41 m at an EPR
of 3.7 m/yr. Accretion on Bear Island resumed and dominated the following period from
October 1949 to August 1959 when the shoreline prograded an average of 128 m (12.8 m/yr
EPR). During the subsequent period from August 1959 to March 1962 erosion resumed at an
average total of 35 m (11.6 m/yr EPR). Accretion dominated the inlet zone from March 1962
31
to September 1984. The IZ migrated toward Brown’s Island an average of 170 m (7.7 m/yr
EPR). Between September 1984 and December 1985 the zone retreated 33 m at 33 m/yr EPR.
Accretion trends characterized the IZ of Bear Island from December 1985 to May 1989 with an
average of 99 m (25 m/yr EPR). From May 1989 to October 1993 erosion resumed within the
inlet zone when the shoreline retreated 109 m (27.2 m/y EPR). From October 1993 to May
1994 accretion occurred along the IZ shoreline reach and the shoreline advanced seaward an
average of 31m (31m/yr EPR).
Erosion dominated the IZ shoreline from May 1994 to March 2001when the shoreline
retreated an average of 55 m (8 m/yr EPR). From March 2001 to March 2003 the shoreline
advanced seaward an average of 131 m at an EPR of 65.5 m/yr. During the last period studied
(March 2003 to October 2008), erosion occurred along the Inlet Zone and the shoreline
retreated an average of 121 m at 24 m/yr.
Zone I
The segment of the shoreline referred to as Zone I includes some transects located
within the IHA and others east of the current IHA (Figure 13A). The shoreline within this zone
had a cumulative average erosion of 61 m (- 0.9 m/yr EPR and + 0.04 m/yr LRR) (Table A4).
Between April 1938 and October 1949, the Zone I shoreline reach retreated an average
of 74 m (7 m/yr EPR). The maximum average erosion was 124 m along transect BE2.
Accretion on Bear Island oceanfront dominated the period from October 1949 to August 1959
when the shoreline prograded an average of 64 m at 6 m/yr EPR. The maximum accretion
occurred along transect BE1 (141 m). During the period between August 1959 and March 1962
erosion resumed amounting an average of 71 m, 24 m/yr EPR. The Maximum erosion during
this period was along transect BE1 (105 m). Accretion dominated the shoreline within Zone 1
32
from March 1962 to September 1985. This shoreline segment prograded an average of 77 m (3
m/yr EPR). BE1 was the transect with the highest accretion of 117 m recorded in 1984. From
December 1985 to January 1987 the shoreline along this zone retreated an average of 33 m at
(16.5 m/yr EPR). Accretion resumed and dominated the shoreline along Zone I from March
1989 to October 1993 at an average of 42 m (10.5 m/yr EPR). The highest accretion was found
along transect BE1 (50 m measured in May 1990). From May 1994 to March 2001 erosion
dominated Zone I (average 56 m from May 1994 to September 1996 28 m/yr EPR) with a
maximum erosion of 96 m along transect BE1. Accretion resumed between March 2001 and
March 2003 with an average of 46 m, 23 m/yr. Erosion resumed and dominated along Zone I
between October 2003 and October 2008 (average of 45 m at 9 m/yr). Maximum erosion was
measured in 2008 along transects BE1 and BE2 (49 m).
Zone II
Zone II is the easternmost shoreline zone along Bear Island (Figure 13A). The shoreline
within this zone had a cumulative average erosion of 18 m, EPR 0.3 m/yr and LRR of + 0.1
m/yr from April 1938 until October 2008 (Table A4).
Between April 1938 and October 1949 the Zone II shoreline retreated an average of 33
m (3 m/yr EPR). Accretion on Bear Island resumed and dominated the period from October
1949 to August 1959 when the shoreline prograded an average of 30 m (3 m/yr EPR). Between
August 1959 and March 1962 erosion occurred once again at an average of 45 m (EPR of 15
m/yr). Accretion dominated the shoreline along Zone II from March 1962 to December 1974
and prograded an average of 72 m (6 m/yr EPR).
The shoreline along Zone II eroded from December 1974 to January 1987 an average of
37 m (3 m/yr EPR). From March 1987 to May 1993 the shoreline along Zone II accreted at an
33
average of 23 m (4 m/yr EPR). From May 1994 to October 2008 there were five alternating
periods of erosion and accretion along the non-IHA segment of the shoreline. The maximum
erosion episode occurred between May 1994 and September 1996 at an average of 39 m, EPR
of 18 m/yr. The maximum accretion episode occurred between March 2001 and March 2003 an
average of 28 m, 14 m/yr EPR.
Brown’s Island Changes
The segment of the shoreline along Brown’s Island influenced by Bear Inlet was also
divided into two oceanfront shoreline zones and one inlet zone. Inlet zone (IZ) along includes
three transects located at the inlet shoreline (Figure 13A). Zone I includes transects BR1
through BR8 which are located within and east of the IHA. Zone II includes transects BR9
through BR15. The shoreline segment in Zone II will be referred to as the non-IHA oceanfront
shoreline. Cumulative zone shoreline changes on Brown’s Island are depicted in Figure 22.
.
Figure 22. Cumulative average changes for Browns Island shoulder (Bear Inlet) from April 1938 to October 2008
34
Inlet Zone (IZ)
The inlet zone (IZ) was the most variable segment on Bear Island with respect to
shoreline change between April 1938 and October 2008. The IZ had a net average accretion of
30 m at an EPR of 0.4 m/yr and a LRR of -1.4 m/yr. The Inlet Transect (IT) was the most
variable transect along the IZ with a cumulative average accretion of approximately 61 m (EPR
of 0.9 m/yr and a LRR of -1 m/yr).
Accretion dominated the IZ shoreline from April 1938 to December 1949. During this
period, the shoreline prograded an average of 176 m at a rate of 16 m/yr. The maximum
accretion was recorded in the vicinity of the Inlet Transect (IT). The period from November
1949 to March 1962 is characterized by erosion along the Inlet Zone, which retreated 120m at
9m/yr. The highest erosion value (87m) was measured along transect I2. From March 1962 to
December 1974 accretion dominated the shoreline within the Inlet Zone. The shoreline
prograded an average of 135 m at a rate of 11 m/yr. The maximum accretion of 160 m was
measured along transect I2.
The period between December 1974 and September 1984 is characterized by erosion
along IZ. During this time the shoreline retreated 111 m at 9 m/yr. The highest erosion value
(168 m) was measured along transect IT. From September 1984 to December 1985 accretion
dominated the shoreline within the IZ and the shoreline prograded an average of 43 m at a rate
of 43 m/yr. The maximum accretion of 63 m was measured along transect I2.
Between December 1985 and May 1990, erosion dominated the shoreline within the IZ
with an average of 116 m (23 m/yr EPR). The maximum erosion value was measured at
transect I2 (100 m). Accretion dominated the four-year-period between May 1990 and May
35
1994 and the shoreline prograded an average of 53 m at rate of 13 m/yr. The maximum
accretion was measured along transect I2 in (98 m in January 1987).
Erosion dominated the IZ shoreline from May 1994 to March 2001 with the shoreline
eroding an average of 115 m at a rate of 16 m/yr. The maximum erosion was measured in the
vicinity of transect I2 (152 m). From March 2001 to October 2006 accretion was dominant and
the shoreline within the IZ prograded an average of 181 m at a rate of 36 m/yr. The maximum
accretion was measured at transect I2 (146 m). From October 2006 to October 2008 erosion
became dominant with an average of 97 m at 48.5 m/yr. The maximum erosion was 132 m in
the vicinity of the IT.
Zone I
The segment of the shoreline referred to as Zone I includes some transects located
within the IHA and others east of the current IHA (Figure 13A). The shoreline within this zone
had a net average erosion of 79 m (1 m/yr EPR and 1.7 m/yr LRR) (Table A2).
From April 1938 to August 1959 the shoreline along Zone II was dominated by
accretion. The shoreline prograded an average of 60 m at 3 m/yr. The maximum accretion of
83 m was measured at transect BR2 (November 1949). Erosion occurred from August 1959 to
March 1962, an average of 61 m (20 m/yr EPR). The maximum advance landward of 109 m
was measured along transect BR7.
Accretion resumed from March 1962 to December 1974 at an average of 33 (2.5 m/yr
EPR). The maximum accretion was measured along transect BR7 (55 m). Erosion occurred
from December 1974 to September 1984 with an average of 64 m at an EPR of 6 m/yr.
Maximum erosion of 73 m occurred along transect BR4. Accretion dominated until December
1985 with an average of 20 m at 20 m/yr and a maximum accretion along transect BR8 (35 m).
36
Erosion was dominant at the shoreline along Zone I from December 1985 to September
1996. During this period of 11 years the shoreline eroded an average of 77 m at 7 m/yr.
Accretion occurred from September 1996 to March 2001 when shoreline the shoreline along
Zone I accreted 44 m at 9 m/yr.
From 2003 to 2008 there were 2 episodes of erosion and 2 episodes of accretion.
Erosion occurred twice in the 5-year period: one from March 2001 to March 2003 when the
shoreline eroded 24 m at 12 m/yr and another from October 2006 and October 2008 when 21 m
erosion occurred at 11.5 m/yr. From 1996 to 2001 the shoreline along Zone I accreted an
average of 44 m at 9 m/yr. Accretion of 9 m occurred from March 2003 and October 2006 at 3
m/yr. BR3 was the transect with the maximum erosion (27 m).
Zone II
The Zone II segment of the shoreline comprises the easternmost transects of Brown’s
Island shoulder. The shoreline along this zone had a average net erosion of 97 m at 1.4 m/yr
(EPR) and 1.3 m/yr (LRR).
From April 1938 to November 1949 erosion occurred along Zone II at an average of 17
m (1.5 m/yr EPR). The maximum erosion was measured along transect BR15 (26 m). From
November 1949 to September 1984, there were alternating periods of erosion and accretion.
Accretion dominated the shoreline along Zone II from November 1949 to August 1959, when
the shoreline prograded an average of 52 m at 5.2 m/yr. The maximum accumulation was
recorded in the vicinity of transect BR10 (71 m).
The following three years were characterized by the erosion along Zone II shoreline.
From August 1959 to March 1962 there was an average erosion of 73 m at 24 m/yr. Transects
BR9 and BR10 were the ones where the highest erosion values occurred (87 m). The shoreline
37
along Zone II prograded 65 m from March 1962 to December 1974, at 5.4 m/yr EPR. The
maximum accretion value was measured along transect BR15 (82 m).
Between December 1979 and September 1984 the shoreline along non-IHA zone
eroded 77 m at 15 m/yr. The maximum erosion value was measured along transect BR15 (94
m). Zone II accreted an average of 28 m from September 1984 to January 1987 at 10 m/yr. The
maximum progradation of 34 m was measured along transect BR15.
Erosion was dominant once again from January 1987 to March 1989 with an average of
30 m at15 m/yr. Transect BR15 had the highest erosion value (34 m). Accretion dominated the
Zone II shoreline from March 1989 to October 1993 at an average of 19 m and 5 m/yr EPR.
The maximum accretion value was measured in the vicinity of transect BR15 (18 m in May
1990).
The period between October 1993 and September 1996 was dominated by erosion
along Zone II shoreline at an average of 52 m and 17 m/yr EPR. The maximum erosion value
was of 32 m along transect BR15. Between September 1996 and March 2001 the shoreline at
Zone II accreted an average of 33 m at 6.6 m/yr. Transect BR10 was the transect with the
maximum accretion (42 m).
Erosion dominated Zone II from March 2001 to October 2008, when the shoreline
eroded an average of 46 m and at 6.5 m/yr. The highest value of erosion was of 24 m at BR10.
Brown’s Inlet Changes
Brown’s Inlet is similar in nature to Bear Inlet (BEI), being relatively stable. However
it is smaller (approximately 75% of BEI size) and it is confined to a smaller tidal basin. Since
the dredging of the AIWW (Atlantic Intercoastal Waterway) around 1930, it is confined to a
smaller space due to its proximity to the waterway. (Figure 24).
38
Figure 23. Aerial photograph of Brown’s Inlet in 2008 showing examples of recurved dune ridges and vegetated
parabolic dunes, along with the location of the ebb channel and the apparent surface area of the ebb tidal delta.
Photographic source: NAIP.
The shoreline divided by Brown’s inlet was also different between the period from 1872
to 1938 and from 1938 to 2008 and also presented different erosion and deposition patterns
during these two periods (Figure 24). From 1872 to 1938, Brown’s Island shoulder eroded along
transects closest to the inlet and accreted on the remaining transects with the highest changes
occurring farthest from the inlet. Onslow Beach shoulder accreted along all transects during the
same period. From 1938 to 2008, Onslow Beach shoulder accreted along all transects and
Brown’s Island shoulder eroded along all transects during the same period. In order to avoid
distortions in the cumulative changes and in the other rates used in this study, the 1872 shoreline
was also excluded from the GIS dataset for Brown’s Inlet.
39
Figure 24. Brown’s Inlet Net changes from 1872 to 1938 and from 1938 to 2008. From 1872 to 1938 (represented
by the blue bars), Brown’s Island shoulder eroded along transects closest to the inlet and accreted on the remaining
transects. Onslow Beach shoulder accreted along all transects during the same period. From 1938 to 2008 (red bars),
Onslow Beach shoulder accreted along all transects and Brown’s Island shoulder eroded along all transects.
Figure 25 depicts the variation in IMW (inlet minimum width) for Brown’s Inlet from
1872 to 1938. The maximum inlet width was 433 m in March 2003 and in 1983 the inlet width
reached its minimum value of 129 m.
Figure 25. Brown’s IMW (Inlet Minimum Width) from 1872 to 2008. The maximum inlet width was 433 m in
March 2003 and the minimum inlet width of 129 m was measured in October 1983.
Even though it is smaller and confined to a much smaller area the position of the ebb
and channels have changed significantly, influencing the erosion and accretion patterns along
Onslow Beach and Brown’s Island shoulders. These changes in channel orientation caused the
40
ebb delta to undergo significant changes in shape which have caused alterations in the ebb tidal
delta (ETD) breakwater effect along opposite oceanfront shorelines.
Brown’s inlet’s ebb channel has been characterized by several channel deflection episodes,
that have played an important role in the configuration of the shoreline. Brown’s Inlet’s channel
(except at January 1945 and April 1938) have deflected along a distance of 137 m within the
throat and along a distance of 1100 m across the outer bar segment (Figure 26).
Figure 26. Brown’s Inlet ebb channels from 1938 to 2008. Source: NAIP
The orientation of Brown’s Inlet’s ebb channels have changed repeatedly from April
1938 to October 2008 (Figure 26). The maximum azimuth was 235º in April of 1938, when the
channel was oriented toward Onslow Beach and the minimum azimuth was 150° in August 1959
when the channel was oriented toward Brown’s Island (Figure 27).
41
Figure 27. Brown’s Inlet ebb channel azimuths from April 1938 to June 2008. Shore-normal ebb channel orientation
is considered to be approximately 180 degrees. The maximum azimuth was 235º in April of 1938, when the channel
was oriented toward Onslow Beach and the minimum azimuth was in August 1959 when the channel was oriented
toward Brown’s Island.
Figure 28 depicts portions of various cycles of channel deflection in Brown’s Inlet from
April 1938 to October 2008. From April 1938 to December 1945 the ebb channel shifted from a
southwest orientation toward Onslow Beach at an azimuth of 235° to an approximately shorenormal position (176°). The 17 year period from December 1945 from March 1962 was
characterized by channel deflection. The channel remained to a roughly shore-normal orientation
and slightly towards Brown’s Island with an azimuth ranging between 176° (December 1945),
165° (April 1958 and November 1960) and 150°-152° (August 1959 and March 1962).
Ebb delta breaching occurred during the period from March 1962 to December 1974,
when the channel shifted from roughly toward Brown’s Island (152° azimuth) to roughly toward
Onslow Beach (199° azimuth). From December 1983 to October 1993 the channel deflected
from a shore-normal orientation (183° azimuth in October 2003) to a southwest orientation
toward Onslow Beach (maximum azimuth of 215° in January 1987).
Another ebb delta breaching episode occurred between October 1993 and June 2002,
when the channel shifted from 205° azimuth in October 1993 to a shore-normal position (180°
42
azimuth) in June 2002. From March 2003 to October 2008 the channel deflected from a roughly
shore-normal orientation in March 2003 (170° azimuth) to slightly toward Onslow Beach (193°
azimuth in 2006) and slightly toward Brown’s Island (168° azimuth in 2008).
Figure 28. Brown’s Inlet episodes of channel deflection and ETD breaching from 1938 to 2008. Source: USACE
North Carolina Wilmington District.
43
The ebb channel not only shifted going toward one shoulder to another but the inlet
migrated to the southwest as well. Figure 29 depicts the ebb channel migration along the inlet
baseline from April 1938 to October 2008. The maximum southwest channel migration was
during the period of 1962 to 1974, when the ebb channel migrated 156 m (13 m/yr) to SW.
The maximum migration to the northeast was during the period of 2003 and 2006 when
the ebb channel migrated 76 m at a rate of 25 m/yr (Table 3). From the period of time studied,
the dominant direction of inlet migration was to the southwest at a rate of 5 m/yr.
Figure 29. Brown’s Inlet ebb channel migration from 1938 to 2008. The negative values (red) indicate that the
channel was moving toward Brown’s Island. The positive values (blue) represent the periods in which the channel
migrated toward Onslow Beach. The maximum migration to the southwest was during the period of 1962 to 1974,
when the ebb channel migrated 156 m (13 m/yr) to SW. The maximum migration to the northeast was during the
period of 2003 and 2006 when the ebb channel migrated 76 m at a rate of 25 m/yr.
44
Table 3. Brown’s Inlet Ebb Channel migration rates.
Brown’s Inlet Ebb Channel Migration Rates (m/yr)
Periods
1938-1945
1945-1958
1958-1959
1959-1960
1960-1962
1962-1974
1974-1983
1983-1984
1984-1987
1987-1993
1993-2002
2002-2003
2003-2006
2006-2008
1938-2008
Ebb Channel
20.5
7.2
43.5
-35.7
-13.1
13.0
17.3
30.9
9.3
-2.6
-7.6
35.5
-25.2
58.7
5.1
There is a rough correlation between ebb channel orientation, IMW and baseline width.
The values in IMW and baseline width changed with changes in channel orientation, although
there is time lag of variable length between changes in ebb channel orientation and the variation
in IMW and baseline width (Figure 30). Values of baseline width and IMW for Brown’s Inlet are
listed in Table 4.
Figure 30. Brown’s Inlet width and ebb channel orientation changes from April 1938 to October 2008.
45
Table 4. Brown’s Inlet values of IMW, Baseline width and ebb channel orientation from 1872 to 2008.
Brown’s Inlet Summary Data
Date
01/01/1872
04/25/1938
01/24/1945
05/04/1958
08/16/1959
11/20/1960
03/13/1962
12/01/1974
10/03/1983
10/03/1984
01/13/1987
10/29/1993
06/05/2002
03/10/2003
10/14/2006
10/03/2008
Orientation
(°)
N/A
235
176
165
150
165
152
199
183
205
215
205
180
170
193
168
IMW
(m)
189
182
332
322
352
286
306
243
129
200
328
329
373
433
328
358
Baseline Width
(m)
228.9
358.8
380.4
426.8
386.7
474.8
327.8
208.9
344.9
413.0
443.8
524.3
482.5
366.5
397.6
228.9
Onslow Beach Shoreline Changes
The southwestern shoulder of Brown’s Inlet was divided into three zones. The closest
zone to the inlet, referred to as Inlet Zone shoreline, contains transects located within the IHA
(Transects IZ1 through IZ4). One transect was separated within the IZ and called Inlet Transect
(IT) (Figure 13). Values of cumulative average changes for Onslow Beach shoulder are depicted
at Figure 31.
46
Figure 31. Average cumulative changes for Onslow Beach shoulder (Brown’s Inlet) from April 1938 to October
2008
Inlet Zone (IZ)
The Inlet Zone (IZ) is the closest one to the inlet and the most variable of the three zones,
with an average net erosion of 301 m, 5 m/yr EPR and LRR.
From January 1934 to April 1938, the shoreline along IZ accreted an average of 61 m at
15 m/yr. The maximum accretion value was measured along transect IZ1 (158 m). From April
1938 to January 1945 an ebb delta breaching event might have been indirectly responsible for
erosion along IZ at an average of 91m (13 m/yr). Maximum erosion was measured in the vicinity
of transect IZ1 (270m). From January 1945 to December 1974, channel deflection slightly to the
NE (toward Brown’s Island) led to erosion along the shoreline within Zone I. The shoreline
eroded an average of 186 m (6.4 m/yr). A maximum erosion of 107 m was measured along IZ2.
Between December 1974 and October 1983 the shoreline prograded an average of 70 m
at (7.7 m/yr). The maximum accretion of 108 m was measured along IZ1. Between October 1983
and October 1993 the ebb channel deflected to southwest with no evidence of ebb delta
47
breaching episodes. During this period, erosion occurred at an average of 237 m (24 m/yr). The
maximum erosion was measured along IZ1 (139 m).
Between October 1993 and June 2002 the shoreline along IZ accreted an average of 28 m
(3 m/yr). Channel deflection to the northeast, (toward Brown’s Island) was the probable cause of
erosion from October 2006 to October 2008 at an average of 62 m (31 m/yr EPR).
Zone I
Zone I contains transects located within and east of the IHA (OB1 thru OB8). From 1934
to 2008 this zone showed an opposite trend compared to the IZ, displaying an average net
accretion of 146 m (2 m/yr EPR and 1.6 m/yr LRR). This segment of the shoreline was also
affected by changes in channel alignment.
Accretion was dominant along the shoreline from January 1934 to May 1958 with an
average 90 m at 4 m/yr. The highest accretion occurred along transect OB8 (63 m). The period
between 1958 and 1962 was characterized by erosion at an average of 69 m (17 m/yr). Maximum
shoreline loss was recorded at transect OB8 (68 m). An ebb delta breaching event between
March 1962 and December 1974 was the likely cause of accretion along Zone I. This segment of
the shoreline prograded an average of 51 m (4 m/yr).
From December 1974 to October 1983 the shoreline retreated an average of 4 m (0.4
m/yr). Between October 1983 and October 1984 accretion of 20 m (20 m/yr) occurred. Erosion
occurred from October 1984 to January 1987 with an average of 25 m (8 m/yr). Accretion
resumed and dominated the shoreline within Zone I from January 1987 to March 2003 with an
average of 89 m (5.5 m/yr). The shoreline within Zone I retreated an average of 37 m between
48
March 2003 and October 2006 (12 m/yr) followed by accretion from October 2006 to October
2008 with a 30 m average (15 m/yr).
Zone II
Zone II contains the westernmost transects along shoreline of Onslow Beach investigated
in this study. It contains 7 transects (OB9 to OB15) and it is considered to be the zone least
influenced by Brown’s Inlet. From the period of 1934 to 2008 this segment of the shoreline had a
net average accretion of 95 m (1.3 m/yr EPR and 0.9 m/yr LRR). Accretion dominated the
shoreline within Zone II from January 1934 to May 1958 at an average of 100 m (4 m/yr).
During the period from May 1958 to March 1962 erosion dominated the Zone II shoreline an
average of 84 m (21 m/yr).
Accretion was dominant from March 1962 to October 1984, when the shoreline
prograded an average of 71 m (3 m/yr). Alternate periods of erosion and accretion occurred
along Zone II shoreline from October 1984 to June 1998. The maximum erosion was between
October 1984 and January 1987 (59 m at an EPR of 20 m/yr). During the period of June 1998 to
March 2003 accretion occurred at an average of 23.5 m (5 m/yr).
The landfall of hurricane Ophelia on the North Carolina coast in 2005 was likely the
responsible for an erosion of 19 m between March 2003 and October 2006. Between October
2006 and October 2008 accretion occurred at an average of 19 m (9.5 m/yr).
Brown’s Island Changes
The northeastern shoulder of Brown’s Inlet was also divided into three zones. The zone
closest zone to the inlet, called Inlet Zone, contains transects located within the IHA (Transects
IZ1, IT and IZ2), Zone I contains transects located east of the IHA (transects BR1 through BR8)
49
and Zone II, which contains transects farthest from the inlet (BR9 thru BR15). Values of
cumulative average changes for Brown’s Island shoreline are depicted at Figure 32.
Figure 32. Average cumulative changes for Brown’s Island shoulder (Brown’s Inlet) from April 1938 to October
2008.
Inlet Zone
The Inlet Zone (IZ) is the closest one to the inlet and the most variable of the three zones,
with a cumulative average accretion of 381 m (5 m/yr EPR and a LRR). Although the ebb
channel does not change its alignment to the same degree and as rapidly as Bear Inlet’s ebb
channel, the constant deflection that occurs is sufficient to promote significant changes along the
IZ.
Accretion dominated the shoreline within the Inlet Zone from January 1934 to May 1958.
In 24 years, the shoreline prograded an average of 141 m (6m/yr). From May 1958 to August
1959 the shoreline along IZ eroded an average of 3 m (3 m/yr). Accretion became dominant
again from August 1959 to November 1960 when the shoreline prograded an average of 51 m
50
(51m/yr). From November 1960 to March 1962 erosion resumed and dominated this shoreline an
average of 25 m (12.5m/yr).
From March 1962 to October 1983 the shoreline accreted an average of 252 m at 12
m/yr. From October 1983 to October 1984 the shoreline along the Inlet Zone eroded an average
of 64.5 m (64.5 m/yr). Accretion dominated the inlet zone from October 1984 to October 1993 at
an average of 52 m (6 m/yr). From October 1993 to June 1998 the shoreline reach along the inlet
zone eroded an average of 64.5 m (13 m/yr).
Accretion resumed and became dominant along the inlet zone from June 1998 to March
2003 when the shoreline prograded an average of 11 m (2 m/yr). From March 2003 to October
2006 erosion was dominant along the inlet zone at an average of 7 m (2 m/yr). Accretion was
dominant in the last 2 years of the dataset created in this study. From October 2006 to October
2008 the shoreline prograded an average of 38 m at a rate of 19 m/yr.
Zone I
Zone I comprises transects located within and eastward the IHA (BR1 thru BR8). From
1934 to 2008 less variation occurred along this zone at a cumulative average erosion of 45 m,
(0.6 m/yr EPR and 0.75 m/yr LRR). This segment of Brown’s Island was also affected by
changes in channel orientation but the changes were less extreme than in the Inlet Zone.
From January 1934 to April 1938 the shoreline long Zone I accreted an average 35 m (9
m/yr). The maximum accretion value was of 39 m in the vicinity of transect BR7. From April
1938 to January 1945 the shoreline within Zone I retreated an average of 51 m (7m/yr), reaching
its maximum retreat along transect BR1 (60 m).
51
Accretion resumed and became dominant along Zone I from January 1945 to August
1959. During this period of time the shoreline reach prograded an average of 63 m (4.5 m/yr) and
the maximum accretion value was measured along transect BR1 (78 m in May 1958). Between
August 1959 and December 1974 erosion resumed and dominated along the shoreline within
Zone I. During 15 years, the shoreline eroded at an average of 59 m (4 m/yr EPR). The
maximum erosion value was of 61 m measured in the vicinity of transect BR1 (December 1974).
From December 1974 to October 1984 accretion was dominant. In this ten-year period
the shoreline reach along Zone I prograded an average of 46 m (4.5m/yr). The maximum
accretion value of 79 m was measured along transect BR1. Erosion resumed and became
dominant from October 1984 to June 2002. In approximately 18 years this portion of the
shoreline retreated an average of 72 m (4 m/yr). The maximum erosion value was measured
along transect BR1 (42 m).
Accretion became dominant from June 2002 to March 2003, when the shoreline within
Zone I accreted an average of 7 m (7 m/yr). The maximum accretion value was measured at the
vicinity of transect BR4 (11 m). The three-year period between March 2003 and October 2006 is
characterized by erosion along Zone I at an average of 17 m (6 m/yr EPR). The maximum retreat
was of 27m along transect BR8. From October 2006 to October 2008 the shoreline along Zone I
accreted, at an average of 3 m (1.5m/yr) with its maximum accretion of 15 m measured along
transect BR8.
Zone II
The shoreline delimited by Zone II includes transects BR9 to BR15 and is the farthest
zone from the inlet. Like along Zone I, the shoreline along Zone II showed less variation than
52
what was recorded within the Inlet Zone. The shoreline along Zone II had a cumulative average
erosion of 42 m from January 1934 to October 2008 (0.56 m/yr EPR 0.52 m/yr LRR).
From January 1934 to April 1938 the shoreline within Zone II prograded an average of
37 m (9 m/yr). The maximum accretion value was measured in the vicinity of transect BR15 (40
m). From April 1938 to May 1958 erosion became dominant along the shoreline within Zone II.
In 20 years the shoreline retreated an average of 60 m (3 m/yr), and the maximum erosion value
of 38 m was recorded in January 1945 in the vicinity of transect BR9.
Accretion resumed and became dominant from May 1958 to August 1959 at an average
of 25 m (25 m/yr). The maximum accretion value was found at transect BR9 (32 m). The portion
of the shoreline along Zone II eroded once again from August 1959 to December 1974 at an
average of 35 m, (2 m/yr). The shoreline retreated the most along transect BR15 (28 m).
From December 1974 to October 1983 the shoreline reach within Zone II prograded an
average of 37 m (4 m/yr), with the maximum value measured in the vicinity of transect BR15
(41m). From October 1983 to January 1987 erosion became dominant again along Zone II. In
approximately three years the shoreline retreated an average of 7 m (2m/yr). The maximum
erosion value of 11 m was measured along transect BR12.
The six-year period between January 1987 and October 1993 was characterized by
oceanfront accretion within Zone II. During this period of time the shoreline reach prograded an
average of 10 m (2 m/yr). The maximum accretion value of 14.5 m was measured in the vicinity
of transect BR15. From October 1993 to June 2002 this portion of Brown’s Island eroded an
average 32 m (3.5 m/yr). The maximum erosion values for this period of time was measured at
transect BR11 (32 m).
53
Two periods of accretion and one period of erosion were identified for the shoreline
within Zone II from June 2002 to October 2008. The accretion periods occurred between June
2002 and March 2003 (2 m average accretion, EPR of 2 m/yr) and from October 2006 to October
2008 (2 m average accretion, EPR of 1 m/yr). The erosion period occurred between March 2003
and October 2006 at an average of 19 m (6.5m/yr). The maximum accretion value was measured
along transect BR9 in October 2008 (11 m) and the maximum erosion value of 23 m was
recorded in the vicinity of transect BR12 (October 2006).
AMBUR Data
AMBUR, a GIS extension used to study shoreline change (JACKSON, 2010, JACKSON
et al., in press.) was used in order to compare and contrast the results in shoreline change
acquired using DSAS for Bear and Brown’s Inlets and their adjacent shorelines. Transects were
spaced 50 m from each other (in DSAS the distance between transects was 100 m), baselines and
the shoreline data were the same as DSAS, as well as the confidence interval of 95%. The
cumulative average changes for zones I and II were very similar to the ones recorded using
DSAS for both Bear and Brown’s inlets. Due to this similarity, this section of this study
describes the results obtained from DSAS.
Figure 33 depicts the average cumulative changes for Bear Inlet from April 1938 to
October 2008. Bear Island shoulder, located northeast of Bear Inlet, has had a cumulative
average erosion of 26.3 m along Zone I using AMBUR and a cumulative average erosion of 27.9
m using DSAS. Along Zone II for the same shoulder, the cumulative average erosion was of 6.7
m and 6.6 m (AMBUR and DSAS, respectively).
54
Brown’s Island shoulder of Bear Inlet has had cumulative average erosion of 23.3 m
(AMBUR) and 26.7 m (DSAS) along Zone I and cumulative average erosion values of 38 m
(AMBUR) and 38.1 m (DSAS) along Zone II.
Figure 33. Bear Inlet Average Cumulative Changes for Zones I and II from April 1938 to October 2008 acquired
using DSAS (in red) and AMBUR (in dark blue). Bear Island shoulder, located northeast of Bear Inlet, had a
cumulative average erosion of 26.3 m along Zone I using AMBUR and a cumulative average erosion of 27.9 m
using DSAS. Along Zone II for the same shoulder, the cumulative average erosion was 6.7 m and 6.6 m (AMBUR
and DSAS, respectively). Brown’s Island shoulder of Bear Inlet has had cumulative average erosion of 23.3 m
(AMBUR) and 26.7 m (DSAS) along Zone I and cumulative average erosion values of 38 m (AMBUR) and 38.1 m
(DSAS) along Zone II.
Figure 34 depicts the average cumulative changes for Brown’s Inlet from April 1938 to
October 2008. Brown’s Island shoulder, located northeast of Brown’s Inlet, has had a cumulative
average accretion of 0.08 m along Zone I using AMBUR and a cumulative average accretion of
0.59 m using DSAS. Along Zone II for the same shoulder, the cumulative average erosion was of
11.3 m and 11.29 m (AMBUR and DSAS, respectively).
55
Onslow Beach shoulder of Bear Inlet has had cumulative average accretion of 78.7 m
(AMBUR) and 77.9 m (DSAS) along Zone I and cumulative average accretion of 53.8 m
(AMBUR) and 54.7 m (DSAS) along Zone II.
Figure 34. Brown’s Inlet Average Cumulative Changes for Zones I and II from April 1938 to October 2008 acquired
using DSAS (in red) and AMBUR (in dark blue). Brown’s Island shoulder had a cumulative average accretion of
0.08 m along Zone I using AMBUR and a cumulative average accretion of 0.59 m using DSAS. Along Zone II for
the same shoulder, the cumulative average erosion was 11.3 m and 11.29 m (AMBUR and DSAS, respectively).
Onslow Beach shoulder had cumulative average accretion of 78.7 m (AMBUR) and 77.9 m (DSAS) along Zone I
and cumulative average accretion of 53.8 m (AMBUR) and 54.7 m (DSAS) along Zone II.
DISCUSSION
Previous studies have demonstrated that changes in tidal inlet morphology, specifically
ebb channel orientation changes, have the potential to influence accretion and erosion patterns on
adjacent shorelines (FITZGERALD, 1984; FENSTER and DOLAN, 1996; CLEARY and MARDEN,
1999; ROSE, 2009). Shoreline change along the inlet shorelines in the study area has been
extremely variable since April 1938; shoreline change rates ranged from -48m/yr to +41m/yr
56
(Tables A3 and A5). The data indicate that shoreline change rates increase markedly following
changes in inlet morphology, specially ebb channel deflection and ebb delta breaching events.
As stated before, the results from AMBUR and DSAS are more than 87% similar. Due to
the high similarity between the data acquired using AMBUR and the data acquired using DSAS
this section is based upon the results obtained through DSAS.
Bear Inlet – Bear Island Shoulder
04/1938 – 10/1949
Between April 1938 and October 1949 a possible ebb delta breaching episode is the
likely cause of average erosion throughout all three zones along Bear Island Shoulder (41 m
along the Inlet Zone, 74 m along Zone I and 33 m along Zone II). During this breaching episode,
the ebb channel orientation changed from 225° azimuth, with its outer portion toward Brown’s
Island and its upper portion adjacent to Bear Island shoulder, to an alignment of 193° (Figure 35
A).
Figure 35. Bear Inlet morphologic and shoreline changes from April 1938 to October 1949 (A) and from November
1949 to March 1962 (B). The blue-colored arrows represent marginal flood channels, the sand-colored arrows
represent swash bars and the yellow-colored arrows represent spit development. Photographic source: USACE
Wilmington District Office.
57
The ebb tidal delta adjusted to the new aligned ebb channel and, its position no longer
offered protection to Bear Island shoulder shoreline. This change in ebb tidal delta morphology
caused erosion along the shoreline, waves and tidal currents transported sediment inside the inlet
throat, creating what would become a spit, decreasing the inlet width from 791 m to 332 m
(Figure 35A).
11/1949 – 03/1962
The period between November 1949 and March 1962 was characterized by deflection of
the ebb channel and no apparent evidence of ebb delta breaching (Figure 35 B). The ten years
during which the ebb channel remained at a slightly shore-normal position (193° in November
1949 and 200° in August 1959) favored progradation along all three zones, greater at the
transects closer to the inlet (average of 128 m at Inlet Zone, 64 m at Zone I and 30 m at Zone II).
Hurricane Hazel (1954) made landfall between the North Carolina and South Carolina border but
there were no noticeable changes in the accretion pattern on this shoulder.
In March 1962 the ebb channel’s orientation changed from a slightly shore-normal
position to toward Brown’s Island in its outer portion (231° orientation) (Figure 35 B). The ebb
tidal delta became smaller and could no longer protect the shoreline along Bear Island shoulder,
leading to erosion throughout all three zones (35 m along the Inlet Zone, 71 m along Zone I and
45 m along Zone II). Sediment brought into the inlet throat by waves and tidal action created
linear bars parallel to the ebb channel on the side toward Bear Island shoulder. A spill over
channel approximately at the center of the ebb tidal delta is also noticeable in March 1962
meaning that potential ebb delta breaching event was likely to occur in the next period.
58
03/1962 – 12/1974
The impact caused by the Ash Wednesday storm in February 1962 is likely the cause of
the ebb delta breaching episode that occurred in this period. The storm caused the ebb channel to
shift drastically from a 231° orientation with its outer portion toward Brown’s Island to a 153°
orientation (Figure 35 B). Unexpectedly, accretion occurred along all three zones of Bear Island
shoulder ranging from 75 m along the inlet zone, 63 m along zone I and 72 m along zone II. The
storm also made the inlet wider and the ebb tidal delta smaller, which probably helped to
accretion trend to continue during the 12 years of this period.
12/1974 – 03/1989
The period between December 1974 and March 1989 is characterized by multiple ebb
channel deflection episodes but no evidence of ebb delta breaching (Figures 36 C and D). The
constant change in the ebb channel orientation caused alternate erosion and accretion patterns,
depending on which shoulder the channel was toward to.
Figure 36. Bear Inlet morphologic and shoreline changes from December 1974 to March 1962 (C) and from
December 1974 to March 1989 (D). The blue-colored arrows represent marginal flood channels, the sand-colored
arrows swash bars, the yellow-colored arrows represent spit development and the pink-colored arrows represent the
presence of linear bars. Photographic source: USACE Wilmington District Office.
From December 1974 to September 1984 the inner portion of the ebb channel deflected
128 m to the southwest whereas its outer portion went toward Bear Inlet from a 153-degree
59
azimuth to a 178-degree azimuth (Figure 36 D). The channel toward Bear Island shoulder, along
with the morphology of the ebb tidal delta (although it became smaller the symmetric
configuration remained) allowed the development of a defined marginal flood channel and the
break-water effect along the ebb tidal delta favored Bear Inlet shoulder with the development of
a horizontal spit. Zones I and II also accreted due to the new configurations of the ebb tidal delta
and the ebb channel, but apparently Zone II was slightly eroded (2 m average) because the
influence of the ebb tidal delta was less significant.
In December 1985 the inner portion of the channel deflected 11 m to the southwest but
the outer portion assumed a more shore-normal position (176° azimuth) (Figure 36 D). The ebb
tidal delta became a bigger but the slight change in the channel and ebb delta configurations led
to an erosion along all transects of Inlet Zone (average 33 m), accretion along transects BE1 thru
BE3 and BE7 thru BE8 and erosion from BE4 to BE6 along Zone I and erosion in all transects of
Zone II except transects BE9 and BE14. The three transects that suffered erosion on Zone I are
probably located where the null-point effect was located at that time, which is the place in which
the trend is the opposite as the one that is occurring due to the location of the ebb tidal delta.
Tidal and wave currents are the responsible for the increasing amount of sediment within the
inlet throat, which made the minimum and baseline widths slightly smaller than in September
1984.
The outer portion of the ebb channel deflected once again toward Bear Island shoulder
(orientation changed from 176° azimuth in December 1985 to 145° azimuth in January 1987)
(Figure 36 D). The new orientation of the ebb channel combined with the presence of a welldeveloped flood channel favored the progradation of the horizontal spit on Bear Island shoulder
but the new configuration of the ebb tidal delta did not provide protection along all three zones,
60
causing accretion along the Inlet Zone except on transect IZ1 and erosion along all the transects
of zones I and II. The opposite trend along transect IZ1 was probably because of the changes in
the shape of the spit, not meaning erosion along this area during this period of time.
The sediment brought to the inlet throat due to the action of wave and tidal currents
caused the channel to bend to the southwest, changing its outer portion slightly (Figure 37 E).
The horizontal spit formed on Bear island shoulder continued to develop, swash bars welded to
Bear Island shoulder creating what would become an accretion bulge and accretion would
happen along Inlet Zone and Zone I due to the new configuration of the ebb channel. The
shoreline along Zone II however, would still erode, under the effect of the prior channel
orientation.
03/1989 – 08/1990
The orientation of the ebb channel changed from 168° azimuth in March 1989 to 215°
azimuth in August 1990 due to a possible ebb delta breaching episode (Figure 37 E). Although
there is no evidence in the March 1989 photograph that prove that a breaching episode actually
happened, as the channel changed its orientation, the sediment within the portion of the previous
ebb channel became available to the shoreline along Bear Island shoulder, causing accretion
along the oceanfront shoreline within zones I and II (averages of 26 m and 15 m respectively)
through sediment bypassing to the northeast.
08/1990 – 09/1996
The period between August 1990 and September 1996 is characterized by at least three
ebb channel deflection episodes which caused erosion or accretion depending on the channel
orientation (Figure 37 F). In October 1993 the ebb channel deflected 4 m to the southwest but the
61
outer portion went toward Bear Island, changing its orientation from 215° azimuth (March
1989) to 140°azimuth. The new configuration of the ebb channel along with the new
configuration of the ebb tidal delta (smaller in size but more symmetric than it was in March
1989) caused erosion on Zone I (average 83 m) but accretion on most transects of zones I and II
(averages of 13 m and 5 m respectively). Transects that did not suffer accretion along Zone II
(transects BE14 and BE15) were probably influenced more by the littoral drift than by the ebb
channel or the ebb tidal delta.
Figure 37. Bear Inlet morphologic and shoreline changes from March 1989 to May 1990 (E) and from May 1990 to
September 1996 (F). The blue-colored arrows represent marginal flood channels, the sand-colored arrows swash
bars, the yellow-colored arrows represent spit development and the pink-colored arrows represent the presence of
linear bars. The dashed square is representing the location of an accretion bulge. Photographic source: USACE
Wilmington District Office.
In May 1994 the inner portion of the ebb channel deflected 9 m to the northeast and the
outer portion deflected to the southwest, causing the channel to assume a shore-normal position
(185° azimuth) (Figure 37 F). This changes in channel configuration altered the morphology of
the ebb tidal delta (became smaller than in October 1993) and caused the development of a
marginal flood channel adjacent to Bear Island shoulder. Sediment transported by the marginal
flood channel caused the inlet zone to accrete (average 31 m) as well as transects BE1 thru BE3
along Zone I. The remaining of transects along Zone I and 4 out of 7 transects of Zone II eroded
62
in May 1994, but not enough to make the averages high (average for Zone I was of -1m and
average for Zone II was zero).
Hurricane Fran made landfall in North Carolina in September 6th 1996, a few days before
the photograph used in this study for September 1996 was taken (Figure 37 F). Probably because
of the hurricane, the channel changed its orientation (185° azimuth in May 1994 to 217° azimuth
in September 1996) and the shoreline reach along all three zones eroded (average 2 m along Inlet
Zone, 56 m along Zone I and 39 m along Zone II. The Inlet Transect and the transect IZ1 were
exceptions to the trend (average accretion of 37 m and 41 m respectively), probably because of
their location within the inlet, not as exposed as the transects along the oceanfront shoreline. The
shoreline was likely accreting due to the probable shore-normal position of the channel but it was
wiped out by Hurricane Fran storm. Because these two transects were in some extent protected,
they “preserved” the trend that was dominant before the hurricane made landfall.
09/1996 – 03/2001
An ebb delta breaching episode characterizes the period between September 1996 and
March 2001 of Bear Inlet. In this breaching episode the ebb channel’s orientation went from
217° azimuth in September 1996 to 165° azimuth in March 2001 and the inner portion of the
channel deflected 159 m to the northeast, as it is depicted on Figure 38 G. The inlet became
wider, the ebb tidal delta became bigger and the shoreline within Inlet Zone and Zone I eroded
(average 53 m along Inlet Zone and 11 m along Zone I). Zone II suffered erosion along transects
BE9 and BE10 (4 m and 1 m respectively) and accretion from transect BE11 thru BE15 (average
accretion of 5 m). The first two transects of Zone II eroded like transects along Inlet Zone and
Zone I probably because they were still influenced more by the inlet system than by the action of
waves and tides combined.
63
This period is also characterized by the influence of several hurricanes that hit the coast
close to the study area, such as Bertha (1996), Bonnie (1998) and Floyd (1999). So many
hurricanes are likely the cause of the erosion throughout the zones closer to the inlet and the little
accretion on transects farther from it.
Figure 38. Bear Inlet morphologic and shoreline changes from September 1996 to March 2001 (G) and from March
2001 to March 2003 (H). The blue-colored arrows represent marginal flood channels, the sand-colored arrows swash
bars, the yellow-colored arrows represent spit presence or development and the dashed square is representing the
location of an accretion bulge. Photographic source: USACE Wilmington District Office.
03/2001 – 03/2003
From March 2001 to March 2003 the channel kept its orientation (165° azimuth) (Figure
38 H). The existence of a marginal flood channel in March 2001 is probably the responsible for
the development of a big spit extending from Bear Island shoulder to the flood tidal delta of Bear
Inlet. The position of the channel also favored the shoreline along the three zones, which
accreted without exceptions (average 131 m along the Inlet Zone, 46 m along Zone I and 28 m
along Zone II). The ebb tidal delta reached its smallest size and one of the smallest inlet widths
(293 m) and the amount of sediment within the inlet throat and flood tidal delta changed the
configuration of the channels that feed Bear Inlet with water from the estuary. The size of the
marsh islands within the estuary was increased by the more availability of sediment in the flood
tidal basin of Bear Inlet.
64
03/2003 – 10/2006
Figure 39 I depicts the morphologic changes in Bear Inlet and Bear Island shoulder
Between March 2003 and October 2006. The ebb channel orientation changed from 165°
azimuth toward Bear Island to 218° azimuth toward Brown’s Island, likely due to another ebb
delta breaching episode. This change in ebb channel orientation eroded the spit formed between
March 2001 and March 2003 as well as the shoreline along the zones (average erosion of 88 m
along Inlet Zone, 8 m along Zone I and 4 m along Zone II). Accretion bulges could be identified
by analyzing the photographs and the dataset designed in this study. One is located at the vicinity
of transect IZ3 and the other one is located at the vicinity of transects BE8 (Zone I) and BE9
(Zone II). The configuration of the channels within the estuary was changed again, becoming
more like the configuration on previous periods investigated in this study.
Figure 39. Bear Inlet morphologic and shoreline changes along Bear Island shoulder from March 2003 (I) to
October 2006 and from October 2006 to October 2008 (J). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars, the yellow-colored arrows represent spit presence or development and
the pink-colored arrows represent the presence of linear bars. Photographic source: USACE Wilmington District
Office.
The changes stated above (erosion along the shoreline, ebb delta breaching episode,
sudden and drastic change in the ebb channel orientation, erosion of the spits and change in the
65
configuration of the channels within the flood tidal delta) might have been caused by hurricane
Ophelia, which made landfall in North Carolina as a Category I hurricane in September 2005.
10/2006 – 10/2008
The period between October 2006 and October 2008 is characterized by the development
of a horizontal spit on Bear Island shoulder (Figure 39 J). The development of this spit forces the
inner portion of the ebb channel to deflect 280 m to the southwest toward Brown’s island
followed by the outer portion of the ebb channel, which orientation ranged from 218° azimuth in
October 2006 to 165 ° azimuth in October 2008. This new channel configuration causes the
minimum width to increase, the size of the ebb tidal delta to decrease and the shoreline along the
three zones to erode without exceptions (average 33 m along Inlet Zone, 37 m along Zone I and
16 m along Zone II). The reason for the erosion trends along Bear Inlet shoulder might be the
elongated morphology of the ebb tidal delta in October 2008 which does not offer any protection
to any zones of the shoreline.
Bear Inlet – Brown’s Island Shoulder
04/1938 – 11/1949
Figure 40 A depicts the morphologic changes along Brown’s Island shoulder from the
period between April 1938 and November 1949 is characterized by the development of a
recurved spit along Brown’s Island shoulder and accretion along the Inlet Zone and Zone I at
averages of 176 m and 31 m respectively. An ebb delta breaching episode that occurred between
April 1938 and October 1949 (ebb channel shifted from an orientation of 225° azimuth in 1938
to 193° azimuth in 1949) is likely the responsible for the accretion along the two zones. A welldeveloped marginal flood channel adjacent to Brown’s Island had likely provided sediment that
66
led to a spit development along Brown’s Island shoulder. Farther from the inlet, erosion of 17 m
average was recorded along Zone II.
Figure 40. Bear Inlet morphologic and shoreline changes along Brown’s Island shoulder from April 1938 (A) to
November 1949 and from November 1949 to March 1962 (B). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars, the yellow-colored arrows represent spit presence or spit development
and the pink-colored arrows represent the presence of linear bars. The dashed rectangles represent the presence of
accretion bulges and the dashed orange ellipse mark the possible location of an ebb delta breaching episode.
Photographic source: USACE Wilmington District Office.
11/1949 – 03/1962
Deflection of the ebb channel occurred between November 1949 and March 1962 with no
apparent evidence of ebb delta breaching events (Figure 40 B). The ten years in which the ebb
channel remained at a slightly with the same orientation (193° azimuth in November 1949 and
200° azimuth in August 1959) allowed accretion at two of the three zones along Brown’s Island
shoulder, greater at the Zone II (average of 29 m at Zone I, 52 m at Zone II). The Inlet Zone
retreated (average of 65 m) probably because of the slight advance of the ebb channel as it was
deflecting toward Brown’s island. Hurricane Hazel (1954) made landfall between the North
Carolina and South Carolina border but there were no noticeable changes in the accretion pattern
on this shoulder. Although erosion was recorded along Inlet Zone, the spit formed in the
previous period continued to develop, but inside the inlet, toward the flood tidal basin.
67
In March 1962 the outer portion of the ebb channel deflected 26 m to the northeast,
changing its orientation to toward Brown’s Island in its outer portion (231° azimuth) (Figure 40
B). The ebb tidal delta became smaller and combined with the new orientation of the ebb channel
led to erosion along all three zones (55 m along the Inlet Zone, 61 m along Zone I and 73 m
along Zone II).
Sediment brought into the inlet throat by waves and tidal action contributed to the
continuous development of the recurved spit growing toward the flood tidal basin of the inlet
system (Figure 40 B). A spill-over channel approximately at the center of the ebb tidal delta is
also noticeable in March 1962 (Figure 40 B) meaning that an ebb delta breaching episode could
have occurred in the next period.
03/1962 – 12/1974
The impact caused by the Ash Wednesday storm in February 1962 is probably the cause
of the ebb delta breaching episode that occurred between March 1962 and December 1974
(Figure 41 C). The storm caused the ebb channel to shift drastically from a 231° azimuth with its
outer portion toward Bear Island to a 153°azimuth. Accretion along all three zones of Brown’s
Island shoulder was also measured, ranging from 135 m along the inlet zone, 33 m along zone I
and 65 m along zone II. The recurved spit that had been developed since November 1949 was
eroded, the inlet became wider and a horizontal spit began to develop on Brown’s Island
shoulder during this period (Figure 41 C).
68
Figure 41. Bear Inlet morphologic and shoreline changes along Brown’s Island shoulder from March 1962 (C) to
December 1974 and from December 1974 to March 1989 (B). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars, and the pink-colored arrows represent the presence of linear bars.
12/1974 – 03/1989
Figure 41 D depicts the morphologic changes along Bear Inlet and Brown’s Island
shoulder during the period between December 1974 and March 1989. Multiple ebb channel
deflection episodes happened but no evidence of ebb delta breaching episodes. The constant
change in the ebb channel orientation caused alternate erosion and accretion patterns, depending
on which shoulder the channel was toward to.
From December 1974 to September 1984 the inner portion of the ebb channel deflected
128 m to the southwest whereas its outer portion went toward Bear Inlet from 153°azimuth to
178° azimuth (Figure 41 D). The southwestern deflection of the upper portion of the ebb channel
caused erosion along Inlet Zone at an average of 111 m. The ebb delta became smaller and
preserved its symmetric shape, but the change in size and the northeastern deflection of the ebb
channel caused the shoreline along zones I and II to erode as well (averages of 64 m and 77 m
respectively).
In December 1985 the inner portion of the channel deflected 11 m to the southwest but
the outer portion assumed a slight shore-normal position (176°). The ebb tidal delta became a
69
little bigger but the slight change in the channel and ebb delta configurations led to deposition
along all transects of Inlet Zone (average 43 m), accretion along all transects of Zone I (average
20 m) and deposition in all transects of Zone II (average 28m). Tidal and wave currents are the
responsible for the increasing amount of sediment within the inlet throat, which made the
minimum and baseline widths slightly smaller than in September 1984.
The outer portion of the ebb channel deflected once more toward Bear Island shoulder
(orientation changed from 176° azimuth in December 1985 to 145° azimuth in January 1987).
The new orientation of the ebb tidal delta favored the build up of what would become an
accretion bulge on Brown’s Island shoulder and the ebb tidal delta became smaller in size and in
a new configuration, causing erosion along the Inlet Zone (average of 75 m) and slight erosion
along all the transects of zones I (average of 9 m). Along Zone II, some transects eroded
(transects BR11, BR12 and BR15), others prograded (BR10, BR14) and others remained
constant (BR9 and BR13). The overall average of zone II was zero (remained constant), meaning
that the changes in ebb channel orientation and ebb delta morphology did not have the same
influence as along the zones closer to the inlet.
The sediment brought to the inlet throat due to the action of wave and tidal currents
caused the channel to deflect to the southwest, changing its outer portion slightly. But this small
change in ebb channel configuration did not change the erosion that started in January 1987:
erosion occurred along all transects of the 3 zones on Brown’s Island shoulder (39 m average
along Inlet Zone, 17 m average along Zone I and average of 30 m along Zone II).
03/1989 – 08/1990
Ebb delta breaching episode might have occurred between March 1989 and August 1990
(Figure 42 E), although there is no evidence in the 1989 photograph that proves the occurrence
70
of such episode. The orientation of the ebb channel changed from 168° azimuth to 215° azimuth
in August 1990 and the inner portion of the ebb channel deflected 43 m to the northeast (Figure
42E). Erosion still occurred along some transects of Inlet Zone and Zone I, causing the total
negative average (2 m on both zones). All transects along zone II experienced progradation, at an
average of 12 m for the zone.
Figure 42. Bear Inlet morphologic and shoreline changes along Brown’s Island shoulder from March 1989 to May
1990 (E) and from May 1990 to September 1996 (F). The blue-colored arrows represent marginal flood channels,
the sand-colored arrows swash bars, and the pink-colored arrows represent the presence of linear bars. Photographic
08/1990 – 09/1996
Figure 42 F depicts the morphologic changes to Bear Inlet and Brown’s Island shoulder
from the period between August 1990 and September 1996. At least three ebb channel deflection
episodes could be noticed, which caused erosion or accretion depending on the channel
orientation. In October 1993 the ebb channel deflected 17 m to the southwest but the outer
portion went toward Bear Island, changing its orientation from 215° azimuth (March 1989) to
140° azimuth. The new configuration of the ebb channel along with the new configuration of the
ebb tidal delta (smaller in size but more symmetric than it was in March 1989) caused accretion
along all three zones, trend that began in August 1990, but some transects along the zones
71
experienced erosion (transect I2 along the Inlet Zone and transects BR2, BR3 and BR6 along
Zone I). Zone II experienced accretion along all transects at an average of 7 m. A recurved spit
on Brown’s Island shoulder was developed between August 1990 and October 1993 (Figure 42
F).
In May 1994 the inner portion of the ebb channel deflected 9 m to the southwest and the
outer portion also deflected to the southwest, causing the channel to assume a shore-normal
position (185° azimuth). This changes in channel configuration altered the morphology of the
ebb tidal delta (became smaller than in October 1993) and allowed the development of a
marginal flood channel adjacent to Brown’s Island shoulder. Sediment transported by the
marginal flood channel caused the inlet zone to accrete (average 42 m) but the new configuration
of the ebb tidal delta and the ebb channel led to erosion along all transects of Zones I and II
(averages of 23 m and 24 m respectively). The recurved spit developed between August 1990
and October 1993 is still present and bigger in May 1994 on Brown’s Island shoulder.
Hurricane Fran made landfall in North Carolina in September 6th 1996, a few days before
the photograph used in this study for September 1996 was taken. Probably because of the
hurricane, the channel changed its orientation (185° azimuth in May 1994 to 217° azimuth in
September 1996) and the shoreline reach along all three zones eroded (average 105 m along Inlet
Zone, 26 m along Zone I and 28 m along Zone II). The innermost portion of the recurved spit
was preserved and was not wiped out by the storm of Hurricane Fran.
09/1996 – 03/2001
An ebb delta breaching episode characterizes the period between September 1996 and
March 2001 along Bear Inlet (Figure 43 G). In this breaching episode the ebb channel’s
orientation went from 217° azimuth in September 1996 to 165° azimuth in March 2001 and the
72
inner portion of the channel deflected 160 m to the northeast. The inlet became wider, the ebb
tidal delta became bigger and the shoreline reach within Inlet Zone eroded (average 10 m)
whereas the shoreline reach along zones I and II suffered accretion (44 m average along Zone I
and 33 m average along Zone II) likely because sediment was bypassed to the southwest thanks
to the breaching episode.
Figure 43. Bear Inlet morphologic and shoreline changes along Brown’s Island shoulder from September 1996 to
March 2001 (G) and from March 2001 to March 2003 (H). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars, and the orange-colored arrow represent spit development.
This period is also characterized by the influence of several hurricanes that hit the coast
close to the study area, such as Bertha (1996), Bonnie (1998) and Floyd (1999). So many
hurricanes might be the cause of the erosion throughout the Inlet Zone and erosion of the remains
of the recurved spit.
03/2001 – 03/2003
Figure 43 H depicts the morphologic changes along Bear Inlet and Brown’s Island
shoulder from March 2001 to March 2003. The channel kept it’s orientation (165° azimuth) and
sediment that was on the ebb delta became available to Brown’s Inlet shoulder after the
breaching episode, taken by wave and tidal current to the inlet throat, leading to the development
73
of another recurved spit. The new position of the channel depleted the shoreline along zones I
and II, which eroded without exceptions (average of 24 m along Zone I and 19 m along Zone II).
The ebb tidal delta reached its smallest size as well as the inlet width (266 m) and the amount of
sediment within the inlet throat and flood tidal delta changed the configuration of the channels
that feed Bear Inlet with water from the estuary. The size of the marsh islands within the estuary
was increased by the more availability of sediment in the flood tidal basin of Bear Inlet.
03/2003 – 10/2006
Between March 2003 and October 2006 the ebb channel orientation changed from 165°
azimuth toward Bear Island to 218° azimuth toward Brown’s Island, probably due another ebb
delta breaching episode (Figure 44 I). This change in ebb channel orientation increased the size
of the spit formed between March 2001 and March 2003 and caused accretion on the shoreline
along the Inlet Zone (average of 117 m) and on the transects closer to the inlet of Zone I
(transects BR1 thru BR4). From transects BR5 thru BR7 on zone I to all transects along Zone II
erosion was predominant (average of 10 m along zone II). Deposition occurred closer to the inlet
because of the new configuration of the ebb channel and the sediment input brought by the
marginal flood channel (Figure 44 I). The configuration of the channels within the estuary was
changed again, becoming more like the configuration on previous periods investigated in this
study.
74
Figure 44. Bear Inlet morphologic and shoreline changes along Brown’s Island shoulder from March 2003 to
October 2006 (I) and from October 2006 to October 2008 (J). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars, and the yellow-colored arrow represents spit presence or
development. Photographic source: USACE Wilmington District Office.
These changes (erosion and deposition along the shoreline, ebb delta breaching episode,
sudden and drastic change in the ebb channel orientation, and change in the configuration of the
channels within the flood tidal basin) might have been caused by hurricane Ophelia, which made
landfall in North Carolina as a Category I hurricane in September 2005.
10/2006 – 10/2008
From October 2006 to October 2008 the ebb channel deflected 280 m to the southwest
toward Brown’s island, followed by the outer portion of the ebb channel, which orientation
ranged from 218° azimuth in October 2006 to 165° azimuth in October 2008 (Figure 43 J). This
new channel configuration caused the minimum width to increase, the size of the ebb tidal delta
decreased and the shoreline along the three zones eroded without exceptions (average 97 m along
Inlet Zone, 21 m along Zone I and 17 m along Zone II). The reason for the erosion trends along
Bear Inlet shoulder might be the new location of the ebb channel and the subsequent new
configuration of the ebb tidal delta. The recurved spit on Brown’s Island developed between
March 2001 and March 2003 became smaller, probably due to the proximity of the ebb channel.
75
Brown’s Inlet – Brown’s Island Shoulder
04/1938 – 01/1945
Figure 45 A depicts the morphologic changes that occurred along Brown’s Inlet and
Brown’s Island shoulder during the period between April 1938 and January 1945, characterized
by the occurrence of an ebb delta breaching episode. The ebb channel changed its orientation
from 235° azimuth toward Onslow Beach to 176° azimuth at an approximate shore-normal
position and deflected 144 m to the southwest toward Onslow Beach. This change in channel
configuration led to a change in the ebb tidal delta morphology (it became bigger and symmetric)
and caused deposition along two out of three transects of the Inlet Zone (average accretion of 14
m) and erosion on zones I and II without exceptions (average of 51 m on Zone I and 36 m on
Zone II). A marginal flood channel is developed along Brown’s Island shoulder; wave and tidal
currents transport the sediment available on the ebb zone of the inlet to the inlet throat toward
Brown’s Island, creating a possible recurved spit on Brown’s Island. Erosion occurred along the
transects farther from the inlet likely because of the ebb tidal delta is too far offshore to provide
protection for the shoreline along zones I and II.
Figure 45. Brown’s Inlet morphologic and shoreline changes along Brown’s Island shoulder from March 2003 to
October 2006 (I) and from October 2006 to October 2008 (J). The blue-colored arrows represent marginal flood
76
01/1945 – 04/1958
From January 1945 to April 1958 the inner portion of the ebb channel deflected 94 m to
the southwest and the outer portion of the ebb channel deflected to the northeast, toward Brown’s
Island (its channel orientation ranged from 176° azimuth in December 1945 to 165° azimuth in
April 1958) (Figure 45 B). The marginal flood channel is well developed in this period and
sediment is transported by wave and tidal currents to Brown’s Island shoulder, feeding the
recurved spit and creating an accretion bulge along transects BR1 thru BR3 along Zone I.
Accretion occurred along all transects of the Inlet Zone (average of 59 m) and along all transects
of zone I (average accretion of 33 m) except BR7 and BR8 (the easternmost transects of Zone I).
Hurricane Hazel made landfall near the North Carolina and South Carolina border in 1954.
Although it was a Category 4 hurricane, the photographs and the dataset were not able to identify
changes in erosion or deposition patterns on the inlet and adjacent shorelines caused by the
storm.
04/1958 – 03/1962
Figure 46 C depicts the morphologic changes on Brown’s Inlet and along the adjacent
shoreline on Brown’s Island during the period between April 1958 and March 1962. The channel
remained roughly at the same orientation whereas the inner portion of the ebb channel deflected
sometimes toward Brown’s Island and sometimes toward Onslow Beach. But although the ebb
channel hardly changed, the smallest changes in orientation and the changes of the location of
the inner portion of the ebb channel were enough to cause different responses of the shoreline,
depending on what happened to the ebb channel.
77
Figure 46. Brown’s Inlet morphologic and shoreline changes along Brown’s Island shoulder from May 1958 to
August 1959 (C) and from August 1959 to November 1960 (D). The blue-colored arrows represent marginal flood
Between April 1958 and August 1959 the inner portion of the ebb channel deflected 43 m
to the southwest and the outer portion bend slightly toward Brown’s Island, changing its
orientation from 165° azimuth in April 1958 to 150° azimuth in August 1959 (Figure 46 C). This
slight change in ebb channel configuration caused the ebb delta to decrease and erosion was
recorded in two out of three transects of the Inlet Zone and deposition on all transects of zones I
and II (averages of 45 m and 25 m respectively). The erosion along the Inlet Zone might be
explained by the apparent weakening of the marginal flood channel that was previously aiding
the deposition on the area. Accretion along Zones I and II was probably still caused by the shorenormal position of the ebb channel recorded in April 1958.
From August 1959 to November 1960 the channel came back to an azimuth of 165° and
the inner portion of the ebb channel deflected 36 m to the northeast, toward Brown’s Island
(Figure 46 D). The ebb tidal delta became smaller, the inlet became thinner and deposition
occurred along the Inlet Zone (average of 51 m). The recurved spit that began developing in
1945 became bigger, probably because of the strong marginal flood channel present adjacent to
Brown’s Island shoulder. Erosion was predominant along most of transects of zones I and II
78
(averages of 17 m on Zone I and 5 m on Zone II) probably due to the new configuration of the
inlet system, which did not provide protection or sediment to cause deposition along the zones
farther from the inlet.
In March 1962 the outer portion of the ebb channel went toward Brown’s Island once
more assuming an orientation of 152° azimuth (Figure 47 E). The inner portion of the ebb
channel deflected 26 m to the northeast, the ebb tidal delta became smaller but more symmetric
than in November 1960, and the inlet width decreased.
Figure 47. Brown’s Inlet morphologic and shoreline changes along Brown’s Island shoulder from November 1960
to March 1962 (E) and from March 1962 to December 1974 (F). The blue-colored arrows represent marginal flood
The position of the ebb channel along with the configuration of the ebb tidal delta
allowed the recurved spit on Brown’s Island shoulder to grow more but shoreline erosion
occurred along all three zones (average of 25 m at the Inlet Zone, 17 m at Zone I and 5 m at
Zone II. The erosion along all zones on Brown’s Island shoulder might be due to the Ash
Wednesday storm that hit the region in February 1962.
03/1962 – 12/1974
The period between March 1962 and December 1974 is characterized by a possible ebb
delta breaching episode (Figure 47 F). The ebb channel shifted from 152° to 199° azimuths, and
79
deflected 180 m to the southwest. The erosional trends along zones I and II continued (30 m
average along Zone I and 16 m average along Zone II. An opposite trend was recorded along the
Inlet Zone, which accreted an average of 190 m, probably due the sediment bypassing to the
northeast that occurred during the breaching episode.
12/1974 – 10/1993
During the period of December 1974 and October 1993, the ebb channel deflected several
times without signs of breaching episodes (Figures 48 and 49). These changes in the ebb channel
led to changes in the ebb tidal delta and the shoreline responded in different ways depending on
the ebb channel and ebb delta configurations.
In October 1983 the inner portion of the ebb channel deflected 73 m to the northeast and
the outer portion of the same channel changed its orientation from 199° to 183° azimuths,
assuming a shore-normal position (Figure 48 G). During the 9 year-period between December
1974 and October 1983 the shoreline accreted along all three zones (62 m at the Inlet Zone, 44 m
at Zone I and 37 m at Zone II). An accretion bulge was developed on Brown’s Island shoulder.
In October 1984 the inner portion of the ebb channel deflected 31 m toward Brown’s
Island shoulder and the outer portion of the same channel deflected to the southwest toward
Onslow Beach shoulder, changing its orientation from a shore-normal position in 1983 (183°
azimuth) to 205° azimuth in October 1984 (Figure 48 G).
80
Figure 48. Brown’s Inlet morphologic and shoreline changes along Brown’s Island shoulder from December 1974 to
October 1983 (E) and October 1983 to October 1984 (F). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars, and the pink-colored arrows represent linear bars. Black dashed
rectangles represent the presence of accretion bulges. Photographic source: USACE Wilmington District Office.
The advance of the inner portion of the ebb channel toward Brown’s Island caused the
transects along the Inlet Zone to retreat at an average of 64 m, erosion on the 4 transects closest
to the inlet, accretion along the remaining transects (average accretion for Zone I of 2 m), erosion
on the five transects closest to the inlet along Zone II (average erosion for Zone II of 2 m) and
accretion on the last two transects along Zone II (transects BR14 and BR15).
Swash bars deposited on the ebb section of Brown’s Inlet cause the outer portion of the
channel to deflect even more toward Onslow Beach in between October 1984 and January 1987
(215° azimuth) (Figure 49 I). The inner portion of the main channel went toward Onslow Beach
as well, deflecting 28 m to the southwest due to the creation of a horizontal spit on Brown’s
Island shoulder. All transects along Inlet Zone accreted at an average of 44 m but erosion was
recorded along zones I and II at averages of 28 m and 5 m due to the configuration of the ebb
channel and consequently the ebb tidal delta, which became more skewed to the southwest
following the new orientation of the ebb channel (Figure 49 I).
81
Figure 49. Brown’s Inlet morphologic and shoreline changes along Brown’s Island shoulder from October 1984 to
January 1987 (I) and January 1987 to October 1993 (J). The blue-colored arrows represent marginal flood channels,
the sand-colored arrows swash bars, and the pink-colored arrows represent linear bars. Photographic source:
USACE Wilmington District Office.
From January 1987 to October 1993 the ebb channel deflected to the northeast, changing
its orientation from 215° azimuth to 205° azimuth and migrating 15 m toward Brown’s Island
shoulder (Figure 49 J). The shoreline reach along Inlet Zone accreted (except transect I1 which
was eroded because of the deflection of the inner portion of the ebb channel toward Brown’s
Island shoulder) at an average of 8 m. Transects along Zone I eroded (except on transects farthest
from the inlet, BR6 thru BR8) at an average of 3 m. Transects along Zone II accreted at an
average of 10 m, probably because the changes in ebb channel orientation and consequently ebb
tidal delta configuration.
10/1993 – 06/2002
Figure 50 K depicts the changes in morphology along Brown’s Inlet and along Brown’s
Island shoulder between October 1993 and June 2002, characterized by an ebb delta breaching
episode. In this episode, the ebb channel shifted to a shore-normal orientation (180° azimuth) and
migrated 68 m to the northeast. This new configuration of the ebb channel led to erosion on all
zones (averages of 26 m for Zone I and 4 m for Zone II from June 1998 to June 2002). The inlet
82
became wider and the ebb tidal delta became smaller, more elongated and symmetric than its
previous configuration in October 1993.
Figure 50. Brown’s Inlet morphologic and shoreline changes along Brown’s Island shoulder from October 1993 to
June 2002 (K) and from June 2002 to March 2003 (L). The blue-colored arrows represent marginal flood channels,
the sand-colored arrows swash bars, and the pink-colored arrows represent linear bars. Black dashed rectangles
represent accretion bulges. Photographic source: USACE Wilmington District Office.
This period of time is also characterized by the incidence of several hurricanes such as
Fran (1996), Bertha (1996), Bonnie (1998) and Floyd (1999). The lack of good photographs and
therefore lack of data might be he reason why the impact of such strong storms could not be
noticed in this study.
06/2002 – 03/2003
The channel remained at a shore-normal position from June 2002 to March 2003 (Figure
50 L). This orientation of the ebb channel allowed the shoreline along all three zones to accrete
(average 5 m along Inlet Zone, 7 m along Zone I and 2 m along Zone II). The ebb tidal delta
became bigger, the inlet width decreased and an accretion bulge was formed on Brown’s Inlet
shoulder right at east of the Inlet Zone (Figure 50 L).
83
03/2003 – 10/2006
From March 2003 to October 2006 the inner portion of the ebb channel deflected 76 m to
the northeast while its outer portion bent slightly toward Onslow Beach going from a 170-degree
azimuth to 193-degree azimuth (Figure 51 M). The inlet became smaller and so did the ebb tidal
delta and erosion was dominant along most of the transects of Zone I (average erosion of 17 m),
along all transects of Zone II (average erosion of 20 m) and along all transects along the Inlet
Zone (average erosion of 7 m) except the Inlet Transect that accreted probably because of the
action of waves and tidal currents.
Hurricane Bertha made landfall close to the study area in 2005 and is probably the cause
of the changes in the ebb channel and erosion along all of the zones on Brown’s island shoulder.
Figure 51. Brown’s Inlet morphologic and shoreline changes along Brown’s Island shoulder from March 2003 to
October 2006 (M) and from October 2006 to October 2008 (N). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars, and the pink-colored arrows represent linear bars. Black dashed
rectangles represent accretion bulges. Photographic source: USACE Wilmington District Office.
10/2006 – 10/2008
From October 2006 to October 2008 the inner portion of the ebb channel migrated 117 m
to the southwest due to the development of a small horizontal spit on Brown’s Inlet shoulder
whereas the outer portion deflected to the northeast with azimuth of 170° in October 2008
(Figure 51 N). Overall accretion occurred along the shoreline studied on Brown’s Inlet shoulder
84
(average 38 m in the Inlet Zone, 3 m average along Zone I and 2 m average along Zone II).
Deposition right at east of the Inlet Zone is noted and an accretion bulge begins to develop on
Brown’s Island shoulder.
Brown’s Inlet – Onslow Beach Shoulder
04/1938 – 01/1945
The period between April 1938 and January 1945 is characterized by the occurrence of an
ebb delta breaching episode (Figure 52 A). The ebb channel changed its orientation from 235°
azimuth toward Onslow Beach to 176° azimuth (approximate shore-normal position) and
migrated 144 m to the southwest toward Onslow Beach.
Figure 52. Brown’s Inlet morphologic and shoreline changes along Onslow Beach shoulder from April 1938 to
January 1945 (A) and from January 1945 to May 1958 (B). The blue-colored arrows represent marginal flood
channels and the sand-colored arrows swash bars. Black dashed rectangles represent accretion bulges and the orange
ellipse represents a potential site for an ebb delta breaching episode. Photographic source: USACE Wilmington
District Office.
This change in channel configuration led to a change in the ebb tidal delta morphology (it
became bigger and symmetric) which caused deposition on zones I and II without exceptions
(average of 48 m on Zone I and 22 m on Zone II). The well-developed spit on Onslow Beach
shoulder present in the photograph of April 1938 is gone due to the breaching episode and
consequently erosion occurs in all transects along the Inlet Zone except transect OB3 which is
85
located where a accretion bulge is formed due to the bypassing of sediment to the southwest. The
new position of the ebb channel and the subsequent configuration of the ebb tidal delta provide
sediment and protection to the adjacent shoreline on Onslow Beach shoulder, explaining the
accretion pattern along the oceanfront shoreline zones (Zones I and II).
01/1945 – 04/1958
From January 1945 to April 1958 (Figure 51 B) the inner portion of the ebb channel
migrated 94 m to the southwest and the outer portion of the ebb channel deflected to the
northeast, toward Brown’s Island (its channel orientation ranged from 176° azimuth in December
1945 to 165° azimuth in April 1958). The accretion bulge formed between April 1938 and
December 1945 eroded in April 1958, due to the advance of the channel toward Onslow Beach
and its new orientation and configuration of the ebb tidal delta. Erosion occurred on transects I3
and Inlet Transect (average erosion on Inlet Zone of 11 m) and along Zone I on transects OB1
and OB2. Accretion occurred along all transects of Zone II (average of 64 m) and on transects
OB3 thru OB8 along Zone I (total average of 26 m).
Hurricane Hazel made landfall near the North Carolina and South Carolina border in
1954. Although it was a Category 4 hurricane, the photographs and the dataset designed for this
study were not able to identify changes in erosion or deposition patterns on the inlet and adjacent
shorelines caused by the storm.
04/1958 – 03/1962
Figures 53 and 54 depict the morphologic changes that took place on Brown’s Inlet and
along the shoreline of Onslow Beach during the period between April 1958 and March 1962. The
ebb channel remained roughly at the same orientation whereas the inner portion of the ebb
86
channel sometimes migrated toward Brown’s Island and sometimes toward Onslow Beach. But
although the ebb channel hardly changed, the smallest changes in orientation and the changes of
the location of the inner portion of the ebb channel were enough to cause different responses of
the shoreline, depending on what happened to the ebb channel.
Between April 1958 and August 1959 the inner portion of the ebb channel migrated 43 m
to the southwest and the outer portion bent slightly toward Brown’s Island, changing its
orientation from 165° azimuth in April 1958 to 150° azimuth in August 1959 (Figure 53C).
Figure 53. Brown’s Inlet morphologic and shoreline changes along Onslow Beach shoulder from May 1958 to
August 1959 (C) and from August 1959 to November 1960 (D). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars and the pink-colored arrow represent linear bars. Photographic source:
This slight change in ebb channel configuration caused the ebb tidal delta to decrease in
size and erosion was recorded along all three zones (average of 33 m at the Inlet Zone, 47 m at
Zone I and 59 m at Zone II) The erosion along the shoreline of Onslow Beach shoulder can be
explained by the change in ebb delta configuration which became smaller and most of it at the
eastern side of the ebb channel: being smaller and less effective in protecting the shoreline reach
along Onslow Beach shoulder it helped to cause erosion throughout the shoulder combined with
the new location of the ebb channel.
87
From August 1959 to November 1960 the ebb channel was oriented with an azimuth of
165° and the inner portion of the ebb channel deflected 36 m to the northeast, toward Brown’s
Island (Figure 53D). The ebb tidal delta became smaller, the inlet became narrower and erosion
occurred again along all three zones (average of 53 m at Zone I, 13 m at Zone II and 12 m along
Zone II).
In March 1962 the outer portion of the ebb channel went toward Brown’s Island once
more assuming an orientation of 152° (Figure 54 E). The inner portion of the ebb channel
migrated 26 m to the northeast, the ebb tidal delta became smaller but more symmetric than in
November 1960, and the inlet width decreased. The position of the ebb channel along with the
configuration of the ebb tidal delta allowed erosion to occur along all three zones in all transects
but Inlet Transect (3 m average at Inlet Zone, 9 m average along Zone I and 13 m average along
Zone II). The erosion along all zones on Brown’s Island shoulder might be due to the Ash
Wednesday storm that hit the region in February 1962.
Figure 54. Brown’s Inlet morphologic and shoreline changes along Onslow Beach shoulder from November 1960 to
March 1962 (E) and from March 1962 to December 1974 (F). The blue-colored arrows represent marginal flood
channels, the sand-colored arrows swash bars and the pink-colored arrows represent linear bars. Photographic
88
03/1962 – 12/1974
The period between March 1962 and December 1974 is characterized by a possible ebb
delta breaching episode (Figure 54 F). The ebb channel shifted from 152° azimuth to 199°
azimuth, roughly at a shore-normal position and migrated 156 m to the southwest. The erosional
trend along the Inlet Zone continued (84 m average). Accretion was recorded along Zones I and
II, which accreted an average of 51 m along Zone I and an average of 22 m along Zone II,
probably due to the new configuration of the ebb delta and ebb channel favoring this section of
the shoreline.
12/1974 – 10/1993
Figures 55 and 56 depict the morphologic changes that took place along Brown’s Inlet
and Onslow Beach during the period of December 1974 and October 1993. The orientation of the
ebb channel was variable, and no signs of breaching were noticed. These changes in the ebb
channel led to changes in the ebb tidal delta and the shoreline responded in different ways
depending on the ebb channel and ebb delta configurations.
In October 1983 the inner portion of the ebb channel migrated 73 m to the northeast and
the outer portion of the same channel changed its orientation from 199° to 183° azimuths,
assuming a shore-normal position (Figure 55 G).
89
Figure 55. Brown’s Inlet morphologic and shoreline changes along Onslow Beach shoulder from December 1974 to
October 1983 (G) and from October 1983 to October 1984 (H). The blue-colored arrows represent marginal flood
During the 9 year-period between December 1974 and October 1983 the shoreline
accreted along the Inlet Zone and Zone II (70 m average at the Inlet Zone and 18 m average at
Zone II). The recurved spit on Onslow Beach that began developing in November 1960
advanced toward the flood area of the inlet, probably being the cause for the inner portion of the
ebb channel to deflect to the northeast. Zone I eroded at an average of 4 m probably because of
the action of wave and tidal currents transporting the sediment to the interior of the inlet.
In October 1984 the ebb channel migrated 31 m toward Brown’s Island shoulder and the
outer portion of the same channel deflected to the southwest toward Onslow Beach shoulder,
changing its orientation from a shore-normal position in 1983 (183° azimuth) to 205° azimuth in
October 1984 (Figure 55 H). The deflection of the ebb channel toward Onslow Beach shoulder
caused transects along the Inlet Zone to retreat at an average of 55 m and erosion at the vicinities
of transect OB1 of Zone I. The remaining transects of Zone I and all transects of Zone II
advanced seaward (average accretion for Zone I of 20 m and 31 m average accretion for Zone
II). The new configurations of the ebb channel and ebb tidal delta are the cause of accretion
along zones I and II.
90
Swash bars deposited on the ebb section of Brown’s Inlet cause the ebb channel to deflect
toward Onslow Beach in between October 1984 and January 1987 (215° azimuth), as depicted in
Figure 56 I. The inner portion of the main channel went toward Onslow Beach as well, deflecting
28 m to the southwest. All transects along Inlet Zone eroded (average erosion of 129 m) as well
as along zones I and II (average of 25 m along Zone I and 59 m along Zone II), except at the
vicinity of transect OB1 along Zone I, which lies where an accretion bulge formed on Onslow
Beach shoulder.
Figure 56. Brown’s Inlet morphologic and shoreline changes along Onslow Beach shoulder from October 1984 to
January 1987 (I) and from January 1987 to October 1993 (J). The blue-colored arrows represent marginal flood
From January 1987 to October 1993 the ebb channel migrated to the northeast, changing
its orientation from 215° to 205° azimuths and migrating 15 m toward Brown’s Island shoulder
(Figure 56 J). The shoreline reach along Inlet Zone retreated without exceptions (average erosion
of 53 m) but most of the transects along zones I and II accreted at an average of 41 m along Zone
I (except on transect OB1, the closest one to the inlet) and at an average of 48 m along Zone II
Accretion occurred along zones I and II are probably because of the changes in ebb channel
orientation and consequently ebb tidal delta configuration.
91
10/1993 – 06/2002
Figure 57 K depicts the period between October 1993 and June 2002, characterized by an
ebb delta breaching episode in which the channel assumed a shore-normal orientation (180°
azimuth) and migrated 68 m to the northeast. This new configuration of the ebb channel led to
accretion along the Inlet Zone and Zone I (averages of 28 m and 35 m respectively) due to
sediment that was bypassed to the southwest when the breaching occurred. Erosion was
dominant along most of transects of Zone II with exception of transect OB9 (average erosion for
Zone II of 4 m), probably because it was not favored either by sediment bypassing or by the new
ebb channel and ebb tidal delta configurations. Brown’s Inlet became wider and the ebb tidal
delta became smaller, more elongated and symmetric than its previous configuration in October
1993.
Figure 57. Brown’s Inlet morphologic and shoreline changes along Onslow Beach shoulder from October 1993 to
June 2002 (K) and June 2002 to March 2003 (J). The blue-colored arrows represent marginal flood channels and the
pink-colored arrows represent linear bars. Black dashed rectangles represent accretion bulges. Photographic source:
This period of time is also characterized by the incidence of several hurricanes such as
Fran (1996), Bertha (1996), Bonnie (1998) and Floyd (1999). The lack of good photographs
representing the years elapsed in this period and therefore lack of shoreline data might be he
reason why the impact of such strong storms could not be noticed in this study.
92
06/2002 – 03/2003
The channel remained at a shore-normal position from June 2002 to March 2003,
although it deflected to the southwest (orientation ranged from 180° azimuth in June 2002 to
170° in March 2003 and the inner portion of the ebb channel deflected 35 m toward Onslow
Beach shoulder) (Figure 57 L). This orientation of the ebb channel allowed the shoreline on
zones I and II to accrete (average of 22 m along Zone I and 23 m along Zone II). The deflection
of the ebb channel toward Onslow Beach shoulder might be the reason for erosion on most
transects of the Inlet Zone (average erosion of 3m), with exception of transect I3, farthest from
the inlet.
03/2003 – 10/2006
From March 2003 to October 2006 the ebb channel migrated 76 m to the northeast while
its outer portion bent slightly toward Onslow Beach going from a 170-degree orientation to 193degree orientation (Figure 58 M). The inlet became smaller and so did the ebb tidal delta and
erosion was dominant along all the zones except along the Inlet Zone, where a recurved spit was
developed. Zone I eroded 37 m average, along Zone II the average erosion was of 19 m and the
transects along the Inlet Zone accreted at an average of 119 m.
Hurricane Bertha made landfall close to the study in 2005 and is probably the cause of
the changes in the ebb channel and erosion along the oceanfront shoreline along Onslow Beach
shoulder.
93
Figure 58. Brown’s Inlet morphologic and shoreline changes along Onslow Beach shoulder from March 2003 to
October 2006 (M) and from October 2006 to October 2008 (N). The blue-colored arrows represent marginal flood
channels, the sand colored arrows represent swash bars and the pink-colored arrows represent linear bars.
10/2006 – 10/2008
From October 2006 to October 2008 the ebb channel migrated 117 m to the southwest
whereas the outer portion of the ebb channel deflected to the northeast with azimuth of 170° in
October 2008 (Figure 58 N). Overall accretion occurred along the shoreline reach of Zones I and
II (averages of 30 m and 19 m respectively). Deflection of the ebb channel toward Onslow Beach
is possibly the reason why erosion occurred along the Inlet Zone at an average of 62 m.
SUMMARY AND CONCLUSIONS
Bear and Brown’s Inlets from 1938 to 2008 had significant change in their ebb channel
orientation and this resulted in substantial changes in the ebb tidal delta configurations and
oceanfront shoreline erosion or accretion. Table 5 depicts a summary of the changes that
occurred in Bear and Brown’s Inlets and along their adjacent shorelines.
Although there is no data available from 1872 to April 1938, it is probable that Bear and
Brown’s Inlets were different before the dredging of the AIWW. The dredging of the AIWW
was probably the cause of the significant greater infilling of Bear Inlet’s tidal basin.
94
Table 5. Summary of changes that occurred in Bear and Brown’s Inlets and their adjacent shorelines.
Summary Data
Brown's Inlet
Onslow Beach
Brown's Island
Shortened 508 m
Lengthened 341 m
-301 m (IZ), 146 m (ZI),
381 m (IZ), -45 m (ZI),
95 m (ZII)
-42 m (ZII)
Migration Distance to the SW
355 m
Migration Rates
5 m/yr
Max. time channel deflection
30 yrs
Ebb delta breaching events
4
Bar bypassing direction
3 NE and 1 SW
Baseline Inlet Width
384 m
Bear Inlet
Brown's Island
Lengthened 31 m
- 3 m (IZ), -79 m (ZI),
-96 m (ZII)
Migration Distance to the SW
Migration Rates
Max. time channel deflection
Ebb delta breaching events
Bar bypassing direction
Baseline Inlet Width
Bear Island
Lengthened 261 m
163 m (IZ), -61 m (ZI),
-18 m (ZII)
592 m
8.5 m/yr
49
5
4 NE and 1 SW
592 m
However, Bear and Brown’s Inlets ebb channels did not change the same way at the same
time and their adjacent shorelines responded in a different way to these changes in a different
time frame. For both of them there is a time lag between the change in ebb channel orientation
and the shoreline response to such change, but this time lag is variable.
There were, at least, 5 ebb delta breaching episodes recorded in this study for Bear Inlet
(Table 5). Four of these episodes had sediment bypassing to the northeast while the fifth episode
had sediment bypassing to the southwest. The maximum time between two ebb delta breaching
episodes was 49 years.
There were 4 identified ebb delta breaching episodes on Brown’s Inlet system (Table 5),
with 3 of them causing bar bypassing to the northeast and one of them to the southwest. The
maximum time lag between breaching episodes was of 30 years.
Even though the nature and timing of ebb-delta breaching and the bar-bypassing events
are sometimes similar in Bear and Brown’s Inlets, the adjacent shorelines do not respond in a
similar manner all the time and sometimes their response is with different intensity (in some
95
cases one shoulder of one inlets responds more intensely to the breaching event than the other)
and other times is totally opposite.
The three inlet zones for both shoulders of Bear and Brown’s inlets responded differently
to the changes in the ebb channel orientation over the study period. However, the changes did not
regularly affect the same locations on the oceanfront shoreline. The length of shoreline that
these inlets control is variable and the region closer to the inlet is more affected by erosion and
deposition. The shoreline farther away from the inlet was less affected by changes in the ebb
channel orientation.
Although ebb delta breaching episodes caused drastic changes in erosion and accretion
patters along the shoulders on both inlets, they were not responsible for the greatest changes over
the time period studied. Most of times, the permanence of the channel roughly at the same
position for some time and changes in the ebb tidal delta size and symmetry were responsible for
the greatest and more consistent changes, specially along zones I and II .
AMBUR and DSAS proved to be an efficient tool to study shoreline change due to the
influence of tidal inlets. Although they have their discrepancies (DSAS only runs in data that are
in meters linear unities, while AMBUR can run in any linear unit; AMBUR runs using an
software package named R whose “language” is in prompt commands, while DSAS runs directly
through ESRI ArcMap; the output data provided by DSAS is more limited and cannot be used as
it is to perform studies like this one, needing to be treated, whereas AMBUR gives tables and
graphs that are useful to study shoreline change; although DSAS provides the data in a less
sophisticated way than AMBUR it is more “user friendly” than AMBUR and does not require
previous programming knowledge like AMBUR does) the data they provided was very similar.
So similar were the results that there was no need for displaying results acquired by both
96
programs during the analysis of Bear and Brown’s inlets and their adjacent shorelines in this
study.
To understand Bear and Brown’s inlets behavior and how and to what extent they
influence the adjacent shoreline, a future study using more datasets should be conducted,
including both older shorelines (between January 1872 and April 1938) and newer ones. Older
shorelines could be acquired using old maps and charts and more recent photographs along with
data collected using another remote sensing tools (LIDAR, ADCP, RTK, etc) will be able to
provide more recent data. Although the data provided by using DSAS and AMBUR were very
similar, both of them were inconsistent in interpreting the curved inlet zone configuration
(JACKSON et al, in press). This inconsistency may be alleviated when both GIS extensions are
updated in the future. With these corrections to the GIS extension, these areas should be studied
again so as to provide more accurate data and to comprehend these systems in more detail.
97
LITERATURE CITED
BENTON, S., BELLIS, C.J., OVERTON, M.F., FISCHER, J.S., HENCH, J.L. and DOLAN, R., 1997.
North Carolina average annual rates of shoreline change. Division of Coastal Management,
Raleigh, North Carolina.
BRUUN, P. and GERRITSEN, F., 1959. Natural bypassing of coastal inlets. Journal of waterways
and harbors division, pp. 75-107.
CLEARY, W.J., 1994. New topsail inlet, North Carolina. Mitigation and barrier realignment:
consequences for beach restoration and erosion control projects. Union Geographique
Internationale, Comission Sur de l’Environment Cotier C, Institute de Geographique, pp. 116130.
CLEARY, W.J., 1996. Inlet induced shoreline changes: Cape Lookout – Cape Fear. In: CLEARY,
W.J. (ed.), Environmental Coastal Geology: Cape Lookout to Cape Fear, NC. Wilmington,
North Carolina: Carolina Geological Society, pp. 49-59.
CLEARY, W.J. and HOSIER, P.E., 1987. Onslow Beach, NC: morphology and stratigraphy.
Coastal Sediments’87, pp.1745-1749.
CLEARY, W.J and MARDEN, T.P. 1999. A pictorial atlas of North Carolina inlets : shifting
shorelines. Raleigh, NC : UNC Sea Grant, North Carolina State University.
CLEARY, W.J. and PILKEY, O.H., 1968. Sedimentation in Onslow Bay. In: Guidebook for field
excursion, Geological Society of America, Southeastern section, Durham, NC: Southeastern
Geology, Special Publication, (1), 1-17.
CLEARY, W.J. AND PILKEY, O.H., 1996, Environmental coastal geology: Cape Lookout to Cape
Fear, North Carolina regional overview. In: W.J. Cleary (ed.), CarolinaGeological Society
Field Trip Guidebook .p. 89-138.
CLEARY, W.J. and RIGGS, S.R., 1999. Beach Erosion and Hurricane Protection Plan for Onslow
Beach, Camp Lejeune, North Carolina. Camp Lejeune, North Carolina: United States Marine
Corps, Comprehensive Geologic Characteristics Report (unpublished), 137p.
CROWELL, M., LEATHERMAN, S.P., and BUCKLEY, M.K., 1991. Historical shoreline change:
Error analysis and mapping accuracy. Journal of Coastal Research, 7(3), p.839-852.
DAVIS, R.A., 1994. Geology of Holocene barrier island systems. New York: Springer-Verlag,
464p.
98
DAVIS, R.A. and FITZGERALD, D.M., 2004. Beaches and Coasts. Oxford: Blackwell Publishing,
419p.
FITZGERALD, D.M., 1988. Shoreline erosional-depositional processes associated with tidal inlets.
In: AUBREY, D.G. and WEISHAR, L. (eds.), Lecture and notes on coastal and estuarine
studies. Hydrodynamics and sediment dynamics of tidal inlets. New York: Spinger-Verlag, pp.
186-225.
FITZGERALD, D. M., KRAUS, N. C., and HANDS, E. B., 2001. Natural mechanisms of sediment
bypassing at tidal inlets. ERDC/CHL CHETN-IV-30, U.S. Army Engineer Research and
Development Center, Vicksburg, MS. (http://chl.wes.army.mil/library/publications/chetn)
HAYES, M.O., 1975. Morphology of sand accumulations in estuaries. In: CRONIN, L.E. (ed.),
Estuarine research. New York: Academic Press, pp. 3-22.
HAYES, M.O., 1980. General morphology and sediment patterns in tidal inlets. Sed. Geol., 26,
139-156.
HAYES, M.O., 1994. The Georgia Bight barrier system. In: DAVIS (ed.), Geology of Holocene
barrier islands systems. New York: Springer-Verlag, chapter 7, pp. 233-305.
JACKSON, C.W. Jr., 2004. Quantitative shoreline change analysis of an inlet-influenced
transgressive barrier system: Figure Eight Island, North Carolina. Wilmington, North Carolina:
University of North Carolina at Wilmington, Master’s thesis, 86p.
JACKSON, C.W. Jr., 2010. Spatio-temporal analysis of barrier island shoreline change. Atlanta,
Georgia: University of Georgia, PhD Dissertation.
JACKSON, C.W. et al. Application of the AMBUR R Package for Spatio-Temporal Analysis of
Shoreline Change: Jekyll Island, Georgia, U.S.A. Computers and Geoscience, in press.
LANGFELDER, J., FRENCH, T., MCDONALD, R. and LEDBETTER, R., 1974. A review of some North
Carolina’s coastal inlets. Center of Marine and Coastal Studies, NC State University, Raleigh,
N.C., 43p.
RIGGS, S.R., CLEARY, W.J. and SNYDER, S.W., 1995. Influence of inherited geologic framework
on barrier shoreface morphology and dynamics. Marine Geology, 126, pp. 213-234.
SAULT, M., 1999. A Historical and Morphologic Study of Contrasting Inlet Behavior: Browns
and New River Inlets, Onslow Bay, North Carolina. Wilmington, North Carolina: University of
North Carolina at Wilmington, Master’s thesis, 57p.
99
SNYDER, S.W.; HOFFMAN, C.W., and RIGGS, S.R., 1994. Seismic stratigraphy framework of the
inner continental shelf: Mason Inlet to New Inlet, North Carolina. North Carolina Geological
Survey Bulletin, 96, 59p.
UNITED STATES ARMY CORPS of ENGINEERS, (USACE) 1986. Detailed project report and
environmental assessment on improvement of navigation, New River Inlet, Onslow County,
North Carolina. Wilmington District, North Carolina, 38p.
UNITED STATES ARMY CORPS of ENGINEERS (USACE), 2004. Bogue Inlet Channel Erosion
Response Project: Final Environmental Impact Statement. Wilmington District, North
Carolina, 269p.
100
APPENDIX
Table A1. Compilation of data and time periods used to create the dataset of historical shorelines for the study of
Bear Inlet
Bear Inlet
Year
Source
Agency
Color? (Yes/No)
# GCP
RMS
Cell Size
1872 (-)
Shoreline.shp file
NC DCM
n/a
n/a
n/a
n/a
7.09
1938 (Apr)
aerial photo HWL
Coastal Geology Lab Archives
No
13
2.69
1949 (Oct)
aerial photo HWL
No
8
2.39
12
1959 (Aug)
aerial photo HWL
Yes
8
3.15
9.29
1962 (Mar)
aerial photo HWL
USACE
No
10
2.01
5.5
1974 (Nov)
aerial photo HWL
USACE
No
10
2.77
0.75
1983 (Oct)
aerial photo HWL
USACE
Yes
11
2.80
0.87
1984 (Feb)
aerial photo HWL
USACE
Yes
-
-
-
1985 (Dec)
aerial photo HWL
USACE
Yes
13
1.66
0.69
1986 (Sep)
aerial photo HWL
USACE
Yes
-
-
-
1987 (Jan)
aerial photo HWL
USACE
Yes
21
1.88
0.88
1989 (Mar)
aerial photo HWL
USACE
Yes
17
2.37
0.88
1990 (Aug)
aerial photo HWL
USACE
Yes
16
1.76
0.70
1993 (Oct)
aerial photo HWL
USACE
Yes
-
-
-
1994 (May)
aerial photo HWL
USACE
Yes
27
1.97
1.87
1996 (Sep)
aerial photo HWL
USACE
Yes
16
1.41
0.73
2001 (Mar)
aerial photo HWL
USACE
Yes
10
2.23
0.66
2002 (Jun)
aerial photo HWL
USACE
Yes
-
-
-
2003 (Mar)
aerial photo HWL
USACE
Yes
17
0.98
0.65
2006 (-)
orthophoto HWL
NC Department of Agriculture
Yes
n/a
n/a
n/a
2008 (-)
orthophoto HWL
Yes
n/a
n/a
n/a
101
Table A2. Compilation of data and time periods used to create the dataset of historical shorelines for the study of
Brown’s Inlet
Brown’s Inlet
Year
Source
Agency
Color? (Yes/No)
#GCP
RMS
Cell size
1872 (-)
Shoreline.shp file
NC DCM
n/a
n/a
n/a
n/a
1938 (Apr)
aerial photo HWL
No
11
2.24
0.09
1945 (Jan)
aerial photo HWL
USACE
No
12
2.23
1.50
1958 (May)
aerial photo HWL
USACE
Yes
11
1.19
2.92
1959 (Aug)
aerial photo HWL
No
12
2.56
1.48
1960 (Nov)
aerial photo HWL
No
12
2.28
0.89
1962 (Mar)
aerial photo HWL
USACE
Yes
11
2.83
3.35
1964 (Oct)
aerial photo HWL
USACE
Yes
9
2.5
0.86
1974 (Dec)
aerial photo HWL
USACE
Yes
10
0.70
2.17
1983 (Oct)
aerial photo HWL
USACE
Yes
26
1.52
1.35
1.48
1984 (Dec)
aerial photo HWL
USACE
Yes
9
3.24
1986 (Aug)
aerial photo HWL
Yes
10
2.81
1987 (Jan)
aerial photo HWL
USACE
Yes
10
2.69
1.41
1993 (Oct)
aerial photo HWL
USACE
Yes
14
1.87
1.47
1996 (Sep)
aerial photo HWL
USACE
Yes
-
-
-
2001 (Mar)
aerial photo HWL
USACE
Yes
12
2.76
1.39
2002 (Jun)
aerial photo HWL
USACE
Yes
15
1.56
0.74
2003 (Mar)
aerial photo HWL
USACE
Yes
14
1.77
0.67
2006 (-)
orthophoto HWL
Yes
n/a
n/a
n/a
2008 (-)
orthophoto HWL
Yes
n/a
n/a
n/a
102
Table A3. Bear Inlet Bear Island and Brown’s Island zone-wide net changes between the periods of 1872-1938 and
1938-2008.
Bear Inlet
Zones
Bear Island
Transects
Inlet Transect
Zone I
Zone II
Brown's Island
1872-1938 (m)
1938-2008 (m)
Transects
1872-1938 (m)
IT
468.7
BE1
171.5
BE2
BE3
1938-2008 (m)
185.5
IT
138
61
-26
BR1
79
-39
223
-75.6
BR2
50
-52
221.5
-83.5
BR3
11.4
-65
BE4
215.8
-77.1
BR4
-7
-77
BE5
218.2
-72.5
BR5
-14
-92
BE6
201.02
-66.3
BR6
-12
-98
BE7
187
-54.5
BR7
-13
-106
BE8
181.6
-46.7
BR8
-27
-104
BE9
161.3
-34.3
BR9
-25
-104.3
BE10
169.1
-35
BR10
-35
-99
BE11
163.7
-27.2
BR11
-29
-94
BE12
153.5
-23.3
BR12
-24
-92
BE13
148.8
-17.1
BR13
-17
-96
BE14
143.4
-13.2
BR14
-17
-94
BE15
132.5
-3.6
BR15
-17
-96
103
Table A4. Summary of Bear Inlet Bear Island and Brown’s Island zone-wide shoreline change by period.
Cumulative changes from April 1938 to October 2008 are listed in bold.
Bear Inlet
Bear Island
Period
Inlet Zone (IZ)
Change
(m)
04/25/1938 - 10/03/2008
161.7
Brown's Island
Inlet Zone (IZ)
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
Period
2.3
3.7
04/25/1938 - 10/03/2008
EPR
(m/yr)
LRR
(m/yr)
30.5
0.4
-1.4
4/25/1938 - 10/21/1949
-41.5
-3.8
-
4/25/1938 - 10/21/1949
176.4
16.0
-
10/21/1949 - 08/16/1959
127.6
12.8
-
10/21/1949 - 08/16/1959
-65.2
-6.5
-
08/16/1959 - 03/13/1962
-34.6
-11.5
-
08/16/1959 - 03/13/1962
-55.5
-18.5
-
03/13/1962 - 12/01/1974
74.8
24.9
-
03/13/1962 - 12/01/1974
135.1
11.3
-
12/01/1974 - 09/19/1984
94.6
9.5
-
12/01/1974 - 09/19/1984
-111.1
-11.1
-
09/19/1984 - 12/22/1985
-33.3
-33.3
-
09/19/1984 - 12/22/1985
43.4
43.4
-
12/22/1985 - 01/14/1987
24.1
12.1
-
12/22/1985 - 01/14/1987
-74.7
-37.3
-
01/14/1987 - 03/25/1989
74.6
37.3
-
01/14/1987 - 03/25/1989
-39.4
-19.7
-
09/19/1989 - 05/08/1990
-25.8
-25.8
-
09/19/1989 - 05/08/1990
-1.5
-1.5
-
05/08/1990 - 10/29/1993
-82.8
-27.6
-
05/08/1990 - 10/29/1993
11.3
3.8
-
10/29/1993 - 05/07/1994
30.5
30.5
-
10/29/1993 - 05/07/1994
42.2
42.2
-
05/07/1994 - 09/15/1996
-2.5
-1.2
-
05/07/1994 - 09/15/1996
-105.3
-52.6
-
09/15/1996 - 03/10/2001
-53.3
-10.7
-
09/15/1996 - 03/10/2001
-9.7
-1.9
-
03/10/2001 - 03/10/2003
130.6
65.3
-
03/10/2001 - 03/10/2003
64.4
32.2
-
03/10/2003 - 10/14/2006
-88.5
-29.5
-
03/10/2003 - 10/14/2006
116.8
38.9
-
10/14/2006 - 10/03/2008
-32.8
-16.4
-
10/14/2006 - 10/03/2008
-96.8
-48.4
-
EPR
(m/yr)
LRR
(m/yr)
Period
EPR
(m/yr)
LRR
(m/yr)
Period
Zone I
Change
(m)
Zone I
Change
(m)
04/25/1938 - 10/03/2008
-61.18
-0.9
0.04
04/25/1938 - 10/03/2008
-79.4
-1.13
-1.7
4/25/1938 - 10/21/1949
-73.6
-6.7
-
4/25/1938 - 10/21/1949
31.4
2.9
-
10/21/1949 - 08/16/1959
63.9
6.4
-
10/21/1949 - 08/16/1959
29.3
2.9
-
08/16/1959 - 03/13/1962
-71.5
-23.8
-
08/16/1959 - 03/13/1962
-61.1
-20.4
-
03/13/1962 - 12/01/1974
63.5
5.3
-
03/13/1962 - 12/01/1974
33.0
2.8
-
12/01/1974 - 09/19/1984
11.2
1.1
-
12/01/1974 - 09/19/1984
-63.8
-6.4
-
09/19/1984 - 12/22/1985
2.8
2.8
-
09/19/1984 - 12/22/1985
19.5
19.5
-
12/22/1985 - 01/14/1987
-33.0
-16.5
-
12/22/1985 - 01/14/1987
-9.1
-4.6
-
01/14/1987 - 03/25/1989
3.3
1.7
-
01/14/1987 - 03/25/1989
-16.5
-8.3
-
09/19/1989 - 05/08/1990
26.0
26.0
-
09/19/1989 - 05/08/1990
-2.0
-2.0
-
05/08/1990 - 10/29/1993
12.8
4.3
-
05/08/1990 - 10/29/1993
1.1
0.4
-
10/29/1993 - 05/07/1994
-1.1
-1.1
-
10/29/1993 - 05/07/1994
-23.5
-23.5
-
05/07/1994 - 09/15/1996
-55.6
-27.8
-
05/07/1994 - 09/15/1996
-26.2
-13.1
-
09/15/1996 - 03/10/2001
-11.4
-2.3
-
09/15/1996 - 03/10/2001
44.4
8.9
-
03/10/2001 - 03/10/2003
46.5
23.2
-
03/10/2001 - 03/10/2003
-24.5
-12.2
-
03/10/2003 - 10/14/2006
-7.6
-2.5
-
03/10/2003 - 10/14/2006
9.2
3.1
-
10/14/2006 - 10/03/2008
-37.5
-18.7
-
10/14/2006 - 10/03/2008
-20.5
-10.3
-
104
Table A4 Cont.
Period
Zone II
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
Period
04/25/1938 - 10/03/2008
04/25/1938 - 10/03/2008
-18.4
-0.3
0.13
Zone II
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
-96.6
-1.4
-1.3
-
4/25/1938 - 10/21/1949
-33.2
-3.0
-
4/25/1938 - 10/21/1949
-16.9
-1.5
10/21/1949 - 08/16/1959
29.8
3.0
-
10/21/1949 - 08/16/1959
51.9
5.2
-
08/16/1959 - 03/13/1962
-45.2
-15.1
-
08/16/1959 - 03/13/1962
-72.9
-24.3
-
03/13/1962 - 12/01/1974
71.5
6.0
-
03/13/1962 - 12/01/1974
65.5
5.5
-
12/01/1974 - 09/19/1984
-2.2
-0.2
-
12/01/1974 - 09/19/1984
-77.1
-7.7
-
09/19/1984 - 12/22/1985
-9.1
-9.1
-
09/19/1984 - 12/22/1985
27.8
27.8
-
12/22/1985 - 01/14/1987
-26.0
-13.0
-
12/22/1985 - 01/14/1987
-0.4
-0.2
-
01/14/1987 - 03/25/1989
2.8
1.4
-
01/14/1987 - 03/25/1989
-29.5
-14.8
-
09/19/1989 - 05/08/1990
14.7
14.7
-
09/19/1989 - 05/08/1990
12.1
12.1
-
05/08/1990 - 10/29/1993
5.4
1.8
-
05/08/1990 - 10/29/1993
6.6
2.2
-
10/29/1993 - 05/07/1994
0.0
0.0
-
10/29/1993 - 05/07/1994
-23.7
-23.7
-
05/07/1994 - 09/15/1996
-38.9
-19.5
-
05/07/1994 - 09/15/1996
-27.8
-13.9
-
09/15/1996 - 03/10/2001
4.5
0.9
-
09/15/1996 - 03/10/2001
33.1
6.6
-
03/10/2001 - 03/10/2003
27.6
13.8
-
03/10/2001 - 03/10/2003
-18.6
-9.3
-
03/10/2003 - 10/14/2006
-4.4
-1.5
-
03/10/2003 - 10/14/2006
-9.5
-3.2
-
10/14/2006 - 10/03/2008
-15.7
-7.8
-
10/14/2006 - 10/03/2008
-17.2
-8.6
-
105
Table A5. Summary of Brown’s Inlet Brown’s Island and Onslow Beach zone-wide shoreline change by period. Cumulative
changes from January 1934 to October 2008 are listed in bold.
Brown's Inlet
Brown's Island
Period
Inlet Zone (IZ)
Change
(m)
Onslow Beach
EPR
(m/yr)
LRR
(m/yr)
Period
Inlet Zone (IZ)
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
01/01/1934 - 10/03/2008
381.1
5.2
5.1
01/01/1934 - 10/03/2008
-301.2
-4.1
-5.4
01/01/1934 - 04/25/1938
68.1
17.0
-
01/01/1934 - 04/25/1938
61.3
15.3
-
04/25/1938 - 01/24/1945
14.2
2.0
-
04/25/1938 - 01/24/1945
-90.7
-13.0
-
01/24/1945 - 05/04/1958
58.8
4.5
-
01/24/1945 - 05/04/1958
-11.4
-0.9
-
05/04/1958 - 08/16/1959
-3.4
-3.4
-
05/04/1958 - 08/16/1959
-33.4
-33.4
-
08/16/1959 - 11/20/1960
51.5
51.5
-
08/16/1959 - 11/20/1960
-53.4
-53.4
-
11/20/1960 - 03/13/1962
-25.2
-12.6
-
11/20/1960 - 03/13/1962
-3.5
-1.8
-
03/13/1962 - 12/01/1974
190.1
15.8
-
03/13/1962 - 12/01/1974
-84.4
-7.0
-
12/01/1974 - 10/03/1983
61.7
6.9
-
12/01/1974 - 10/03/1983
69.9
7.8
-
10/03/1983 - 10/03/1984
-64.5
-64.5
-
10/03/1983 - 10/03/1984
-55.4
-55.4
-
10/03/1984 - 01/13/1987
43.7
14.6
-
10/03/1984 - 01/13/1987
-129.1
-43.0
-
01/13/1987 - 10/29/1993
8.4
1.4
-
01/13/1987 - 10/29/1993
-52.8
-8.8
-
10/29/1993 - 06/26/1998
-64.5
-12.9
-
10/29/1993 - 06/26/1998
63.5
12.7
-
06/26/1998 - 06/05/2002
6.0
1.5
-
06/26/1998 - 06/05/2002
-35.5
-8.9
-
06/05/2002 - 03/10/2003
5.3
5.3
-
06/05/2002 - 03/10/2003
-3.3
-3.3
-
03/10/2003 - 10/14/2006
-7.4
-2.5
-
03/10/2003 - 10/14/2006
119.5
59.7
-
10/14/2006 - 10/03/2008
38.3
19.2
-
10/14/2006 - 10/03/2008
-62.5
-31.2
-
Period
Zone I
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
01/01/1934 - 10/03/2008
-44.8
-0.6
01/01/1934 - 04/25/1938
35.2
8.8
04/25/1938 - 01/24/1945
-51.6
01/24/1945 - 05/04/1958
Period
Zone I
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
-0.8
01/01/1934 - 10/03/2008
145.9
2.0
1.6
-
01/01/1934 - 04/25/1938
16.3
4.1
-
-7.4
-
04/25/1938 - 01/24/1945
48.2
6.9
-
32.9
2.5
-
01/24/1945 - 05/04/1958
26.0
2.0
-
05/04/1958 - 08/16/1959
30.6
30.6
-
05/04/1958 - 08/16/1959
-47.0
-47.0
-
08/16/1959 - 11/20/1960
-16.9
-16.9
-
08/16/1959 - 11/20/1960
-13.2
-13.2
-
11/20/1960 - 03/13/1962
-12.0
-6.0
-
11/20/1960 - 03/13/1962
-9.0
-3.0
-
03/13/1962 - 12/01/1974
-30.4
-2.5
-
03/13/1962 - 12/01/1974
51.0
4.3
-
12/01/1974 - 10/03/1983
43.8
4.9
-
12/01/1974 - 10/03/1983
-3.7
-0.4
-
10/03/1983 - 10/03/1984
2.5
2.5
-
10/03/1983 - 10/03/1984
19.9
19.9
-
10/03/1984 - 01/13/1987
-27.7
-9.2
-
10/03/1984 - 01/13/1987
-24.8
-8.3
-
01/13/1987 - 10/29/1993
-3.5
-0.6
-
01/13/1987 - 10/29/1993
41.1
6.8
-
10/29/1993 - 06/26/1998
-25.2
-5.0
-
10/29/1993 - 06/26/1998
9.4
1.9
-
06/26/1998 - 06/05/2002
-15.9
-4.0
-
06/26/1998 - 06/05/2002
16.7
4.2
-
06/05/2002 - 03/10/2003
6.8
6.8
-
06/05/2002 - 03/10/2003
21.6
21.6
-
03/10/2003 - 10/14/2006
-16.7
-5.6
-
03/10/2003 - 10/14/2006
-37.1
-12.4
-
10/14/2006 - 10/03/2008
3.2
1.6
-
10/14/2006 - 10/03/2008
30.4
15.2
-
106
Table A5 Cont.
Period
Zone II
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
Period
Zone II
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
01/01/1934 - 10/03/2008
-41.7
-0.6
01/01/1934 - 04/25/1938
36.6
9.2
-0.5
01/01/1934 - 10/03/2008
94.9
1.3
0.9
-
01/01/1934 - 04/25/1938
13.6
3.4
04/25/1938 - 01/24/1945
-36.0
-
-5.1
-
04/25/1938 - 01/24/1945
22.5
3.2
-
01/24/1945 - 05/04/1958
-24.4
-1.9
-
01/24/1945 - 05/04/1958
64.0
4.9
-
05/04/1958 - 08/16/1959
24.8
24.8
-
05/04/1958 - 08/16/1959
-58.6
-58.6
-
08/16/1959 - 11/20/1960
-4.8
-4.8
-
08/16/1959 - 11/20/1960
-12.2
-12.2
-
11/20/1960 - 03/13/1962
-13.8
-6.9
-
11/20/1960 - 03/13/1962
-12.8
-6.4
-
03/13/1962 - 12/01/1974
-16.3
-1.4
-
03/13/1962 - 12/01/1974
22.0
1.8
-
12/01/1974 - 10/03/1983
36.8
4.1
-
12/01/1974 - 10/03/1983
17.8
2.0
-
10/03/1983 - 10/03/1984
-1.9
-1.9
-
10/03/1983 - 10/03/1984
31.1
31.1
-
10/03/1984 - 01/13/1987
-4.7
-1.6
-
10/03/1984 - 01/13/1987
-59.4
-19.8
-
01/13/1987 - 10/29/1993
9.6
1.6
-
01/13/1987 - 10/29/1993
48.0
8.0
-
10/29/1993 - 06/26/1998
-27.8
-5.6
-
10/29/1993 - 06/26/1998
-4.8
-1.0
-
06/26/1998 - 06/05/2002
-4.3
-1.1
-
06/26/1998 - 06/05/2002
0.5
0.1
-
06/05/2002 - 03/10/2003
2.3
2.3
-
06/05/2002 - 03/10/2003
23.1
23.1
-
03/10/2003 - 10/14/2006
-19.5
-6.5
-
03/10/2003 - 10/14/2006
-18.8
-6.3
-
10/14/2006 - 10/03/2008
1.7
0.9
-
10/14/2006 - 10/03/2008
19.1
9.5
-
107
Table A6. Summary of Bear Inlet Bear Island and Brown’s Island zone-averaged cumulative
shoreline change from April 1938 to October 2008.
Bear Inlet
Bear Island
Date
Brown's Island
Cumulative Shoreline Change (m)
Inlet Zone (IZ)
Zone I
Zone II
I1, IT, I2
BE1-BE7 BE8-BE15
All
IZ to BE15
Inlet Zone (IZ)
Zone I
Zone II
All
I1, IT, I2
BR1-BR7 BR8-BR15 IZ to BR15
04/25/1938
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
11/01/1949
-41.5
-73.6
-33.2
-49.4
176.4
31.4
-16.9
63.6
08/16/1959
86.1
-9.6
-3.4
24.4
111.3
60.7
35.0
69.0
03/13/1962
51.5
-81.1
-48.6
-26.1
55.8
-0.4
-37.8
5.8
12/01/1974
126.3
-17.6
22.9
43.8
190.9
32.6
27.7
83.7
09/19/1984
220.9
-6.4
20.7
78.4
79.8
-31.2
-49.4
-0.3
12/22/1985
187.6
-3.6
11.6
65.2
123.2
-11.7
-21.7
29.9
01/14/1987
211.7
-36.6
-14.4
53.6
48.5
-20.8
-22.1
1.9
03/25/1989
286.3
-33.3
-11.6
80.5
9.1
-37.4
-51.6
-26.6
05/08/1990
260.5
-7.3
3.1
85.4
7.6
-39.4
-39.5
-23.8
10/29/1993
177.7
5.5
8.4
63.9
18.9
-38.3
-32.8
-17.4
05/07/1994
208.2
4.4
8.5
73.7
61.1
-61.8
-56.6
-19.1
09/15/1996
205.7
-51.2
-30.5
41.4
-44.2
-88.0
-84.4
-72.2
03/10/2001
152.4
-62.6
-25.9
21.3
-53.9
-43.6
-51.3
-49.6
03/10/2003
283.0
-16.1
1.6
89.5
10.5
-68.0
-69.9
-42.5
10/14/2006
194.5
-23.7
-2.8
56.0
127.3
-58.9
-79.4
-3.7
10/03/2008
161.7
-61.2
-18.4
27.4
30.5
-79.4
-96.6
-48.5
108
Table A7. Summary of Bear Inlet Bear Island and Brown’s Island zone-averaged cumulative shoreline change from
April 1938 to October 2008.
Brown's Inlet
Brown's Island
Date
Onslow Beach
Inlet Zone (IZ)
Zone I
Zone II
I1, IT, I2
BR1-BR7 BR8-BR15
All
IZ to BR15
Inlet Zone (IZ)
Zone I
Zone II
I1, IT, I2
OB1-OB7 OB8-OB15
All
IZ-OB15
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
04/25/1938
68.1
35.2
36.6
46.6
61.3
16.3
13.6
30.4
01/24/1945
82.3
-16.4
0.7
22.2
-29.3
64.5
36.1
23.8
05/04/1958
141.1
16.5
-23.8
44.6
-40.7
90.6
100.1
50.0
08/16/1959
137.7
47.1
1.0
61.9
-74.2
43.6
41.5
3.6
11/20/1960
189.2
30.3
-3.8
71.9
-127.6
30.4
29.2
-22.6
03/13/1962
164.0
18.3
-17.6
54.9
-131.1
21.4
16.4
-31.1
12/01/1974
354.1
-12.1
-33.9
102.7
-215.5
72.4
38.4
-34.9
10/03/1983
415.9
31.7
2.9
150.2
-145.6
68.7
56.2
-6.9
10/03/1984
351.4
34.2
1.0
128.9
-201.0
88.7
87.3
-8.4
01/13/1987
395.0
6.5
-3.7
132.6
-330.1
63.8
27.8
-79.5
10/29/1993
403.4
3.0
5.9
137.4
-382.9
104.9
75.8
-67.4
06/26/1998
338.9
-22.2
-22.0
98.3
-319.4
114.2
71.1
-44.7
06/05/2002
344.9
-38.1
-26.3
93.5
-354.9
131.0
71.6
-50.8
03/10/2003
350.2
-31.3
-24.0
98.3
-358.3
152.6
94.6
-37.0
10/14/2006
342.8
-48.0
-43.4
83.8
-238.8
115.5
75.8
-15.8
10/03/2008
381.1
-44.8
-41.7
98.2
-301.2
145.9
94.9
-20.2
109
Table A8a. Summary of Bear Inlet Bear Island cumulative shoreline change along transects I1 through BE3 from
Bear Inlet
Bear Island Cumulative Shoreline Change (m)
Date
I1
IT
I2
BE1
BE2
04/25/1938
0.0
0.0
0.0
0.0
0.0
BE3
0.0
11/01/1949
-28.0
-38.6
-57.9
-122.9
-124.5
-94.8
08/16/1959
78.3
106.2
73.9
18.3
-5.7
-17.1
03/13/1962
72.4
57.8
24.4
-87.0
-109.7
-88.4
12/01/1974
214.4
146.1
18.3
-91.5
-76.7
-36.1
09/19/1984
212.4
259.8
190.5
25.7
-12.9
-12.3
12/22/1985
191.1
205.7
165.8
33.8
-10.4
-7.3
01/14/1987
183.9
266.0
185.0
-13.1
-43.3
-46.3
03/25/1989
306.7
296.6
255.5
5.6
-45.2
-46.3
05/08/1990
225.6
288.2
267.6
55.8
-1.6
-5.7
10/29/1993
154.8
163.9
214.4
55.3
3.5
-10.3
05/07/1994
137.2
250.7
236.8
57.4
5.9
-3.4
09/15/1996
177.9
288.0
151.4
-38.1
-73.8
-63.3
03/10/2001
163.3
163.4
130.5
-38.7
-81.5
-66.5
03/10/2003
364.7
285.9
198.3
53.5
-17.7
-31.8
10/14/2006
147.9
184.7
250.8
23.5
-26.7
-38.4
10/03/2008
87.0
182.2
215.9
-25.0
-75.9
-81.0
Table A8b. Summary of Bear Inlet Bear Island cumulative shoreline change along transects BE4 through BE9 from
Bear Inlet
Date
BE4
BE5
BE6
BE7
BE8
04/25/1938
0.0
0.0
0.0
0.0
0.0
BE9
0.0
11/01/1949
-58.7
-49.9
-44.9
-46.5
-46.2
-37.1
08/16/1959
-17.0
-22.7
-14.6
-9.6
-8.4
-13.9
03/13/1962
-79.0
-84.6
-67.1
-61.0
-72.1
-62.6
12/01/1974
7.8
10.2
16.9
11.8
16.4
22.7
09/19/1984
-8.2
-6.3
-6.2
-18.6
-12.5
6.9
12/22/1985
-10.7
-20.1
-14.2
-2.4
2.5
12.2
01/14/1987
-45.4
-50.2
-39.9
-29.4
-24.9
-26.1
03/25/1989
-42.1
-47.2
-35.1
-31.4
-24.4
-22.0
05/08/1990
-12.1
-27.1
-26.3
-21.2
-20.2
-10.8
10/29/1993
0.4
-9.8
-1.7
2.5
4.1
7.8
05/07/1994
-11.6
-8.7
-5.1
-4.8
5.6
7.0
09/15/1996
-55.4
-58.7
-45.6
-39.5
-34.9
-33.5
03/10/2001
-74.3
-76.9
-66.8
-51.6
-44.6
-37.5
03/10/2003
-36.0
-37.4
-23.0
-18.6
-17.9
-14.9
10/14/2006
-41.1
-39.8
-26.8
-22.9
-17.5
-11.9
10/03/2008
-75.2
-73.7
-61.7
-52.5
-44.4
-32.0
110
Table A8c. Summary of Bear Inlet Bear Island cumulative shoreline change along transects BE10 through BE15
from April 1938 to October 2008.
Bear Inlet
Date
BE10
BE11
BE12
BE13
BE14
04/25/1938
0.0
0.0
0.0
0.0
0.0
BE15
0.0
11/01/1949
-42.0
-42.9
-40.2
-28.4
-23.6
-18.4
08/16/1959
-13.2
-8.1
-6.1
3.7
-0.5
14.4
03/13/1962
-69.4
-42.7
-44.1
-44.8
-56.1
-20.8
12/01/1974
18.5
23.3
23.0
23.3
22.2
27.2
09/19/1984
8.9
18.2
27.1
30.9
21.1
31.7
12/22/1985
-3.1
1.4
11.1
13.2
22.2
24.2
01/14/1987
-25.3
-18.6
-14.8
-12.2
-6.8
2.9
03/25/1989
-28.0
-16.9
-9.4
-7.5
-4.3
6.6
05/08/1990
-10.2
-4.1
2.1
7.3
12.6
24.7
10/29/1993
1.6
4.6
9.5
10.4
10.5
14.7
05/07/1994
-2.0
5.4
12.8
9.1
9.2
17.8
09/15/1996
-38.6
-35.8
-32.5
-30.7
-26.4
-15.8
03/10/2001
-39.1
-31.8
-26.1
-21.5
-18.6
-7.0
03/10/2003
-13.4
-4.1
4.5
8.1
11.5
19.8
10/14/2006
-20.3
-7.7
-2.5
7.2
2.7
13.1
10/03/2008
-31.1
-22.2
-18.3
-13.7
-10.8
-0.8
Table A8d: Summary of Bear Inlet Brown’s Island cumulative shoreline change along transects I1 through BR3
from April 1938 to October 2008
Bear Inlet
Brown's Island Cumulative Shoreline Change (m)
Date
I1
IT
I2
BR1
BR2
BR3
04/25/1938
0.0
0.0
0.0
0.0
0.0
0.0
11/01/1949
197.9
193.5
137.9
32.8
82.8
79.9
08/16/1959
125.3
120.7
87.7
33.8
43.3
90.9
03/13/1962
120.2
46.0
1.1
38.2
43.1
36.8
12/01/1974
257.9
206.1
108.6
48.1
50.7
44.2
09/19/1984
89.9
87.5
62.0
-8.1
-4.8
-20.1
12/22/1985
147.8
150.6
71.1
6.4
4.3
-2.7
01/14/1987
51.6
50.2
43.6
-3.7
-8.1
-9.3
03/25/1989
37.9
20.8
-31.4
-27.8
-31.2
-16.8
05/08/1990
-12.6
59.2
-23.8
-27.9
-19.7
-28.3
10/29/1993
64.4
4.6
-12.3
-25.5
-25.4
-30.1
05/07/1994
91.1
102.2
-10.0
-58.9
-49.6
-54.7
09/15/1996
-8.6
-49.6
-74.3
-81.7
-82.7
-84.4
03/10/2001
-28.9
-62.0
-70.8
-42.7
-26.0
-26.4
03/10/2003
53.3
15.7
-37.5
-60.0
-56.9
-56.8
10/14/2006
192.7
162.1
27.0
-23.2
-34.6
-39.3
10/03/2008
60.8
34.1
-3.4
-38.9
-51.9
-66.0
111
Table A8e. Summary of Bear Inlet Brown’s Island cumulative shoreline change along transects BR4 through BR9
from April 1938 to October 2008.
Bear Inlet
Date
BR4
BR5
BR6
BR7
BR8
04/25/1938
0.0
0.0
0.0
0.0
0.0
BR9
0.0
11/01/1949
43.0
30.8
9.3
-10.1
-17.5
-20.9
08/16/1959
73.7
47.1
83.8
69.6
43.5
49.1
03/13/1962
-0.6
-15.0
-22.8
-39.2
-43.8
-37.6
12/01/1974
37.1
31.2
25.0
15.9
8.5
14.8
09/19/1984
-36.2
-35.6
-35.1
-54.0
-55.9
-52.7
12/22/1985
-7.2
-24.8
-26.2
-22.8
-20.5
-24.0
01/14/1987
-18.9
-28.1
-26.1
-32.8
-39.4
-23.7
03/25/1989
-40.1
-31.5
-42.6
-53.7
-55.1
-52.0
05/08/1990
-41.6
-48.2
-44.1
-49.4
-55.9
-52.0
10/29/1993
-36.1
-43.3
-47.6
-47.8
-50.6
-41.7
05/07/1994
-61.7
-67.3
-68.5
-68.2
-65.4
-62.1
09/15/1996
-85.9
-89.2
-91.6
-96.0
-92.1
-91.4
03/10/2001
-36.4
-47.2
-54.2
-58.0
-57.6
-52.9
03/10/2003
-64.8
-71.1
-75.4
-79.0
-80.2
-72.3
10/14/2006
-51.3
-80.2
-75.8
-82.4
-84.0
-83.4
10/03/2008
-77.3
-92.4
-97.8
-106.5
-104.1
-104.4
Table A8f. Summary of Bear Inlet Brown’s Island cumulative shoreline change along transects BR10 through
BR15 from April 1938 to October 2008.
Bear Inlet
Date
BR10
BR11
BR12
BR13
BR14
BR15
04/25/1938
0.0
0.0
0.0
0.0
0.0
0.0
-26.3
11/01/1949
-21.0
-9.2
-6.5
-16.4
-18.1
08/16/1959
50.3
40.1
29.3
29.1
26.2
21.3
03/13/1962
-36.5
-37.8
-41.4
-38.3
-33.3
-40.0
12/01/1974
12.7
21.9
30.3
31.4
40.5
42.0
09/19/1984
-50.1
-47.0
-47.6
-49.9
-47.2
-51.8
12/22/1985
-24.2
-20.6
-19.4
-22.5
-23.5
-17.4
01/14/1987
-17.1
-25.7
-21.5
-22.3
-20.1
-24.3
03/25/1989
-49.8
-47.8
-49.1
-52.6
-52.0
-58.1
05/08/1990
-41.9
-33.5
-34.3
-36.3
-38.5
-40.0
10/29/1993
-33.8
-33.8
-31.5
-26.8
-25.3
-37.1
05/07/1994
-59.4
-53.4
-53.3
-55.8
-57.9
-54.3
09/15/1996
-91.5
-81.2
-77.5
-82.7
-80.4
-86.4
03/10/2001
-49.8
-51.0
-49.1
-47.7
-50.6
-57.9
03/10/2003
-71.9
-69.0
-68.2
-70.0
-66.0
-71.6
10/14/2006
-77.5
-70.6
-76.8
-77.0
-83.4
-87.1
10/03/2008
-99.6
-94.2
-92.1
-96.1
-93.9
-96.2
112
Table A9a. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along transects I1 through BR3
from January 1934 to October 2008.
Brown's Inlet
Date
I1
BR1
BR2
01/01/1934
0.0
IT
0.0
I2
0.0
0.0
0.0
BR3
0.0
04/25/1938
39.4
74.4
90.6
31.5
34.8
32.3
01/24/1945
93.4
86.7
66.9
-28.3
-24.9
-24.0
05/04/1958
235.7
110.8
76.9
49.5
49.8
38.7
08/16/1959
202.5
107.2
103.5
80.0
65.4
55.9
11/20/1960
113.0
244.9
209.6
37.2
34.6
30.1
03/13/1962
268.6
131.6
91.8
56.9
45.9
33.2
12/01/1974
359.3
396.2
306.9
-4.5
-8.0
-15.3
10/03/1983
380.0
440.0
427.7
74.3
57.6
30.0
10/03/1984
386.1
355.5
312.6
64.3
43.6
23.6
01/13/1987
396.0
455.2
334.0
22.2
14.0
0.4
10/29/1993
377.5
483.3
349.5
8.4
4.1
-2.4
06/26/1998
315.7
411.1
290.0
-12.8
-19.3
-29.0
06/05/2002
438.5
355.9
240.3
-32.5
-41.3
-46.0
03/10/2003
417.4
354.4
278.8
-25.3
-38.2
-42.8
10/14/2006
383.9
391.2
253.4
-24.4
-34.5
-52.6
10/03/2008
404.8
416.5
322.1
-34.6
-44.8
-55.5
Table A9b. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along transects BR4 through
BR9 from January 1934 to October 2008.
Brown's Inlet
Date
BR4
BR5
BR6
BR7
BR8
BR9
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
34.1
04/25/1938
33.2
35.8
38.7
39.6
35.5
01/24/1945
-14.3
-11.7
-12.6
-7.5
-7.9
-4.1
05/04/1958
26.3
3.7
-3.4
-12.1
-20.3
-17.2
08/16/1959
53.0
45.7
28.3
24.4
24.3
15.5
11/20/1960
34.7
40.7
35.7
21.7
7.3
-1.1
03/13/1962
10.1
3.2
7.8
1.8
-12.5
-13.7
12/01/1974
-14.5
-13.5
-12.5
-12.3
-16.2
-20.4
10/03/1983
21.4
25.5
18.1
12.6
14.2
11.7
10/03/1984
20.5
32.3
43.3
26.3
20.0
9.3
01/13/1987
1.4
3.8
3.1
4.3
3.2
1.1
10/29/1993
-5.9
-5.3
4.3
11.0
9.8
7.9
06/26/1998
-28.1
-24.2
-24.6
-19.0
-20.6
-21.2
06/05/2002
-45.3
-38.1
-35.3
-33.9
-32.5
-32.6
03/10/2003
-34.1
-27.7
-29.1
-27.6
-25.4
-27.9
10/14/2006
-60.3
-59.6
-50.1
-50.0
-52.3
-47.2
10/03/2008
-52.4
-49.8
-46.0
-38.5
-36.9
-36.1
113
Table A9c. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along transects BR10 through
BR15 from January 1934 to October 2008.
Brown's Inlet
Date
BR10
BR11
BR12
BR13
BR14
01/01/1934
0.0
0.0
0.0
0.0
0.0
BR15
0.0
04/25/1938
34.1
33.1
34.2
41.6
39.4
39.9
01/24/1945
-1.3
-2.3
2.8
3.3
2.0
4.3
05/04/1958
-19.5
-24.4
-25.6
-27.4
-25.4
-26.7
08/16/1959
5.7
3.0
-4.9
-1.5
-4.6
-6.2
11/20/1960
-1.8
-2.2
-3.9
-3.5
-8.5
-5.8
03/13/1962
-11.3
-19.3
-19.5
-20.5
-15.1
-23.4
12/01/1974
-24.6
-28.8
-33.0
-36.8
-42.6
-51.1
-9.6
10/03/1983
9.1
6.5
3.8
1.6
-2.6
10/03/1984
6.7
-0.8
-6.8
-2.6
3.6
-2.2
01/13/1987
-0.3
-4.2
-0.9
-3.5
-6.3
-11.8
10/29/1993
3.9
5.6
6.5
8.3
6.3
2.7
06/26/1998
-23.0
-26.6
-23.5
-21.4
-19.3
-18.7
06/05/2002
-30.2
-27.8
-25.4
-22.4
-21.7
-23.6
03/10/2003
-23.5
-23.9
-22.9
-18.8
-19.2
-31.7
10/14/2006
-44.6
-45.6
-45.7
-41.4
-39.5
-40.1
10/03/2008
-34.6
-36.2
-37.9
-33.8
-57.0
-56.2
Table A9d. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along transects I1 through OB3
from January 1934 to October 2008.
Brown's Inlet
Onslow Beach Cumulative Shoreline Change (m)
Date
I1
IT
I2
OB1
OB2
OB3
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
04/25/1938
158.4
61.3
-35.7
51.5
27.8
13.6
01/24/1945
-111.1
-66.8
89.9
74.5
68.6
68.0
05/04/1958
34.8
-139.8
-17.2
47.6
51.6
88.0
08/16/1959
13.0
-158.3
-77.2
41.2
43.0
42.4
11/20/1960
15.8
-245.4
-153.1
18.1
22.6
32.9
03/13/1962
9.0
-237.8
-164.5
7.8
14.2
16.4
12/01/1974
-85.7
-327.9
-232.8
70.0
74.3
83.8
10/03/1983
22.6
-253.8
-205.5
66.4
73.6
69.3
10/03/1984
-62.6
-322.0
-218.4
54.9
92.6
94.9
01/13/1987
-201.7
-456.5
-332.1
59.0
86.0
86.8
10/29/1993
-244.5
-516.5
-387.9
34.4
101.2
117.9
06/26/1998
-126.1
-468.4
-363.8
47.3
96.6
111.9
06/05/2002
-248.0
-486.7
-330.1
108.9
126.5
142.6
03/10/2003
-272.1
-506.2
-296.4
137.2
150.8
173.8
10/14/2006
-126.4
-361.6
-228.4
91.7
109.9
122.8
10/03/2008
-224.1
-422.0
-257.6
108.7
144.4
158.3
114
Table A9e. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along transects OB4 through
OB9 from January 1934 to October 2008.
Brown's Inlet
Date
OB4
OB5
OB6
OB7
OB8
OB9
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
04/25/1938
9.8
6.9
7.9
6.6
6.3
7.2
01/24/1945
70.8
68.0
62.4
55.7
48.2
41.8
05/04/1958
110.2
112.0
105.4
98.4
111.2
98.6
08/16/1959
44.4
45.1
42.0
48.1
42.6
32.5
11/20/1960
34.4
36.2
33.9
32.5
33.1
32.9
03/13/1962
27.8
31.0
28.8
25.6
19.7
19.0
12/01/1974
78.6
76.2
70.9
65.8
59.7
55.7
10/03/1983
65.1
67.6
67.5
69.5
70.9
68.4
10/03/1984
103.9
92.1
81.5
96.7
92.9
98.3
01/13/1987
72.5
61.4
54.2
48.3
42.4
29.9
10/29/1993
132.8
127.6
116.6
107.2
101.5
90.9
06/26/1998
120.8
126.9
139.5
136.3
134.7
120.0
06/05/2002
132.8
148.9
140.0
129.0
119.2
98.9
03/10/2003
170.0
164.3
154.8
142.4
127.5
115.1
10/14/2006
122.2
125.1
120.4
118.7
113.2
93.5
10/03/2008
158.4
156.8
153.4
147.3
139.7
130.9
Table A9f. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along transects OB10 through
OB15 from January 1934 to October 2008.
Brown's Inlet
Date
OB10
OB11
OB12
OB13
OB14
OB15
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
21.2
04/25/1938
7.7
9.7
13.3
14.6
21.4
01/24/1945
36.8
36.7
36.5
37.5
34.4
29.2
05/04/1958
95.8
93.0
99.5
102.0
102.8
108.9
08/16/1959
47.4
42.5
43.5
42.5
41.5
40.4
11/20/1960
32.5
30.2
27.4
27.3
27.2
27.1
03/13/1962
16.2
15.3
14.7
13.5
16.0
20.5
12/01/1974
44.8
40.6
36.6
33.6
30.5
27.2
10/03/1983
64.4
60.4
56.4
52.3
48.0
43.4
10/03/1984
93.5
88.1
86.9
79.7
85.6
78.9
01/13/1987
28.4
36.7
27.4
31.8
21.4
19.2
10/29/1993
84.7
79.2
75.5
68.5
65.3
66.7
06/26/1998
92.6
71.7
58.9
55.7
52.9
45.8
06/05/2002
82.4
77.4
73.7
57.4
52.4
58.6
03/10/2003
108.7
96.5
89.2
93.1
83.4
76.4
10/14/2006
86.8
83.6
79.3
71.3
61.7
54.3
10/03/2008
116.2
103.3
89.9
81.7
72.8
69.2
115
Table A10. Summary of Bear Inlet Bear Island and Brown’s Island zone-wide shoreline change by period using
AMBUR Cumulative changes from April 1938 to October 2008 are listed in bold.
Bear Inlet
Bear Island
Period
Brown's Island
Inlet Transect (IT)
Change
EPR
(m)
(m/yr)
LRR
(m/yr)
Period
Inlet Transect (IT)
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
-1.2
04/25/1938 - 10/03/2008
291.4
4.1
4.3
04/25/1938 - 10/03/2008
38.2
0.5
4/25/1938 - 10/21/1949
-40.2
-3.7
-
4/25/1938 - 10/21/1949
185.9
16.9
-
10/21/1949 - 08/16/1959
144.6
14.5
-
10/21/1949 - 08/16/1959
-69.2
-6.9
-
08/16/1959 - 03/13/1962
-51.3
-17.1
-
08/16/1959 - 03/13/1962
-64.1
-21.4
-
03/13/1962 - 12/01/1974
67.0
5.6
-
03/13/1962 - 12/01/1974
141.5
11.8
-
12/01/1974 - 09/19/1984
123.3
12.3
-
12/01/1974 - 09/19/1984
-111.9
-11.2
-
09/19/1984 - 12/22/1985
-41.4
-41.4
-
09/19/1984 - 12/22/1985
62.4
62.4
-
12/22/1985 - 01/14/1987
59.5
29.8
-
12/22/1985 - 01/14/1987
-99.1
-49.6
-
01/14/1987 - 03/25/1989
7.6
3.8
-
01/14/1987 - 03/25/1989
-24.0
-12.0
-
09/19/1989 - 05/08/1990
20.8
20.8
-
09/19/1989 - 05/08/1990
-46.4
-46.4
-
05/08/1990 - 10/29/1993
-122.2
-40.7
-
05/08/1990 - 10/29/1993
46.2
15.4
-
10/29/1993 - 05/07/1994
83.0
83.0
-
10/29/1993 - 05/07/1994
79.4
79.4
-
05/07/1994 - 09/15/1996
21.5
10.8
-
05/07/1994 - 09/15/1996
-138.6
-69.3
09/15/1996 - 03/10/2001
-110.2
-22.0
-
09/15/1996 - 03/10/2001
-13.6
-2.7
-
03/10/2001 - 03/10/2003
94.0
47.0
-
03/10/2001 - 03/10/2003
88.6
44.3
-
03/10/2003 - 10/14/2006
-68.2
-22.7
-
03/10/2003 - 10/14/2006
116.0
38.7
-
10/14/2006 - 10/03/2008
103.4
51.7
-
10/14/2006 - 10/03/2008
-115.1
-57.6
-
Period
Zone I
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
Period
Zone I
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
04/25/1938 - 10/03/2008
-60.0
-0.9
-0.02
04/25/1938 - 10/03/2008
-86.3
-1.2
-1.7
4/25/1938 - 10/21/1949
-71.2
-6.5
-
4/25/1938 - 10/21/1949
38.6
3.5
-
10/21/1949 - 08/16/1959
62.7
6.3
-
10/21/1949 - 08/16/1959
26.0
2.6
-
08/16/1959 - 03/13/1962
-69.4
-23.1
-
08/16/1959 - 03/13/1962
-67.4
-22.5
-
03/13/1962 - 12/01/1974
60.8
5.1
-
03/13/1962 - 12/01/1974
43.3
3.6
-
12/01/1974 - 09/19/1984
11.8
1.2
-
12/01/1974 - 09/19/1984
-66.8
-6.7
-
09/19/1984 - 12/22/1985
3.2
3.2
-
09/19/1984 - 12/22/1985
21.2
21.2
-
12/22/1985 - 01/14/1987
-32.3
-16.1
-
12/22/1985 - 01/14/1987
-13.6
-6.8
-
01/14/1987 - 03/25/1989
2.8
1.4
-
01/14/1987 - 03/25/1989
-17.4
-8.7
-
09/19/1989 - 05/08/1990
24.7
24.7
-
09/19/1989 - 05/08/1990
-4.5
-4.5
-
05/08/1990 - 10/29/1993
14.3
4.8
-
05/08/1990 - 10/29/1993
3.8
1.3
-
10/29/1993 - 05/07/1994
-0.6
-0.6
-
10/29/1993 - 05/07/1994
-15.6
-15.6
-
05/07/1994 - 09/15/1996
-56.3
-28.2
-
05/07/1994 - 09/15/1996
-34.0
-17.0
-
09/15/1996 - 03/10/2001
-11.7
-2.3
-
09/15/1996 - 03/10/2001
41.5
8.3
-
03/10/2001 - 03/10/2003
47.1
23.6
-
03/10/2001 - 03/10/2003
-17.7
-8.9
03/10/2003 - 10/14/2006
-8.0
-2.7
-
03/10/2003 - 10/14/2006
12.6
4.2
-
10/14/2006 - 10/03/2008
-38.0
-19.0
-
10/14/2006 - 10/03/2008
-27.3
-13.6
-
116
Table A10 Cont.
Zone II
Zone II
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
Period
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
04/25/1938 - 10/03/2008
-18.9
-0.270221
0.13
04/25/1938 - 10/03/2008
-96.0
-1.4
-1.3
4/25/1938 - 10/21/1949
-33.7
-3.1
-
4/25/1938 - 10/21/1949
-17.8
-1.6
-
10/21/1949 - 08/16/1959
31.1
3.1
-
10/21/1949 - 08/16/1959
49.5
5.0
-
Period
08/16/1959 - 03/13/1962
-46.7
-15.6
-
08/16/1959 - 03/13/1962
-70.7
-23.6
-
03/13/1962 - 12/01/1974
72.1
6.0
-
03/13/1962 - 12/01/1974
69.4
5.8
-
12/01/1974 - 09/19/1984
-2.1
-0.2
-
12/01/1974 - 09/19/1984
-79.7
-8.0
-
09/19/1984 - 12/22/1985
-9.3
-9.3
-
09/19/1984 - 12/22/1985
27.9
27.9
-
12/22/1985 - 01/14/1987
-25.5
-12.8
-
12/22/1985 - 01/14/1987
-0.5
-0.2
-
01/14/1987 - 03/25/1989
2.5
1.2
-
01/14/1987 - 03/25/1989
-30.7
-15.4
-
09/19/1989 - 05/08/1990
14.6
14.6
-
09/19/1989 - 05/08/1990
14.4
14.4
-
05/08/1990 - 10/29/1993
5.6
1.9
-
05/08/1990 - 10/29/1993
6.6
2.2
-
10/29/1993 - 05/07/1994
-0.3
-0.3
-
10/29/1993 - 05/07/1994
-24.8
-24.8
-
05/07/1994 - 09/15/1996
-38.7
-19.4
-
05/07/1994 - 09/15/1996
-26.9
-13.5
-
09/15/1996 - 03/10/2001
3.5
0.7
-
09/15/1996 - 03/10/2001
31.4
6.3
-
03/10/2001 - 03/10/2003
28.8
14.4
-
03/10/2001 - 03/10/2003
-17.3
-8.7
-
03/10/2003 - 10/14/2006
-4.9
-1.6
-
03/10/2003 - 10/14/2006
-10.6
-3.5
-
10/14/2006 - 10/03/2008
-16.0
-8.0
-
10/14/2006 - 10/03/2008
-16.1
-8.0
-
117
Table A11. Summary of Brown’s Inlet Brown’s Island and Onslow Beach zone-wide shoreline change by period
using AMBUR. Cumulative changes from January 1934 to October 2008 are listed in bold.
Brown's Inlet
Brown's Island
Period
Onslow Beach
Inlet Transect (IT)
Change
EPR
(m)
(m/yr)
LRR
(m/yr)
Period
Inlet Transect (IT)
Change
EPR
(m)
(m/yr)
LRR
(m/yr)
01/01/1934 - 10/03/2008
347.7
4.7
5.0
01/01/1934 - 10/03/2008
No Data
No Data
No Data
01/01/1934 - 04/25/1938
68.6
17.1
-
01/01/1934 - 04/25/1938
No Data
No Data
-
04/25/1938 - 01/24/1945
7.9
1.1
-
04/25/1938 - 01/24/1945
No Data
No Data
-
01/24/1945 - 05/04/1958
9.1
0.7
-
01/24/1945 - 05/04/1958
-96.6
-7.4
-
05/04/1958 - 08/16/1959
12.9
12.9
-
05/04/1958 - 08/16/1959
-17.9
-17.9
-
08/16/1959 - 11/20/1960
123.7
123.7
-
08/16/1959 - 11/20/1960
-38.7
-38.7
-
11/20/1960 - 03/13/1962
-114.1
-57.0
-
11/20/1960 - 03/13/1962
-5.5
-2.7
-
03/13/1962 - 12/01/1974
247.9
20.7
-
03/13/1962 - 12/01/1974
-88.6
-7.4
-
12/01/1974 - 10/03/1983
67.1
7.5
-
12/01/1974 - 10/03/1983
109.8
12.2
-
10/03/1983 - 10/03/1984
-142.9
-142.9
-
10/03/1983 - 10/03/1984
-95.1
-95.1
-
10/03/1984 - 01/13/1987
116.7
38.9
-
10/03/1984 - 01/13/1987
-143.8
-47.9
-
01/13/1987 - 10/29/1993
38.7
6.5
-
01/13/1987 - 10/29/1993
-51.6
-8.6
-
10/29/1993 - 06/26/1998
-83.2
-16.6
-
10/29/1993 - 06/26/1998
82.2
16.4
-
06/26/1998 - 06/05/2002
-43.1
-10.8
-
06/26/1998 - 06/05/2002
-70.2
-17.5
-
06/05/2002 - 03/10/2003
-20.4
-20.4
-
06/05/2002 - 03/10/2003
-14.8
-14.8
-
03/10/2003 - 10/14/2006
54.4
18.1
-
03/10/2003 - 10/14/2006
139.0
46.3
-
10/14/2006 - 10/03/2008
4.4
2.2
-
10/14/2006 - 10/03/2008
-71.4
-14.3
-
Period
Zone I
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
Period
Zone I
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
01/01/1934 - 10/03/2008
-44.9
-0.6
-0.7
01/01/1934 - 10/03/2008
147.8
2.0
1.7
01/01/1934 - 04/25/1938
35.5
8.9
-
01/01/1934 - 04/25/1938
13.8
3.4
-
04/25/1938 - 01/24/1945
-51.6
-7.4
-
04/25/1938 - 01/24/1945
49.3
7.0
-
01/24/1945 - 05/04/1958
31.9
2.5
-
01/24/1945 - 05/04/1958
30.5
2.3
-
05/04/1958 - 08/16/1959
29.6
29.6
-
05/04/1958 - 08/16/1959
-49.1
-49.1
08/16/1959 - 11/20/1960
-15.7
-15.7
-
08/16/1959 - 11/20/1960
-13.4
-13.4
-
11/20/1960 - 03/13/1962
-12.3
-6.2
-
11/20/1960 - 03/13/1962
-8.9
-4.5
-
03/13/1962 - 12/01/1974
-29.3
-2.4
-
03/13/1962 - 12/01/1974
49.6
4.1
-
12/01/1974 - 10/03/1983
42.4
4.7
-
12/01/1974 - 10/03/1983
-2.2
-0.2
-
10/03/1983 - 10/03/1984
2.3
2.3
-
10/03/1983 - 10/03/1984
21.9
21.9
-
10/03/1984 - 01/13/1987
-27.1
-9.0
-
10/03/1984 - 01/13/1987
-28.4
-9.5
-
01/13/1987 - 10/29/1993
-2.2
-0.4
-
01/13/1987 - 10/29/1993
44.7
7.4
-
10/29/1993 - 06/26/1998
-25.7
-5.1
-
10/29/1993 - 06/26/1998
10.4
2.1
-
06/26/1998 - 06/05/2002
-15.5
-3.9
-
06/26/1998 - 06/05/2002
13.3
3.3
-
06/05/2002 - 03/10/2003
6.3
6.3
-
06/05/2002 - 03/10/2003
20.9
20.9
-
03/10/2003 - 10/14/2006
-16.6
-5.5
-
03/10/2003 - 10/14/2006
-36.1
-12.0
-
10/14/2006 - 10/03/2008
3.4
1.7
-
10/14/2006 - 10/03/2008
31.5
15.8
-
118
Table A11 Cont.
Period
Zone II
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
Period
Zone II
Change
(m)
EPR
(m/yr)
LRR
(m/yr)
01/01/1934 - 10/03/2008
-40.7
-0.6
01/01/1934 - 04/25/1938
36.6
9.2
-0.5
01/01/1934 - 10/03/2008
92.4
1.2
0.9
-
01/01/1934 - 04/25/1938
14.6
3.7
-
04/25/1938 - 01/24/1945
-35.6
-5.1
-
04/25/1938 - 01/24/1945
21.5
3.1
-
01/24/1945 - 05/04/1958
-25.2
-1.9
-
01/24/1945 - 05/04/1958
63.9
4.9
-
05/04/1958 - 08/16/1959
24.8
24.8
-
05/04/1958 - 08/16/1959
-59.0
-59.0
-
08/16/1959 - 11/20/1960
-4.4
-4.4
-
08/16/1959 - 11/20/1960
-12.0
-12.0
-
11/20/1960 - 03/13/1962
-13.8
-6.9
-
11/20/1960 - 03/13/1962
-13.0
-6.5
-
03/13/1962 - 12/01/1974
-17.2
-1.4
-
03/13/1962 - 12/01/1974
21.1
1.8
-
12/01/1974 - 10/03/1983
37.1
4.1
-
12/01/1974 - 10/03/1983
18.0
2.0
-
10/03/1983 - 10/03/1984
-1.1
-1.1
-
10/03/1983 - 10/03/1984
30.0
30.0
-
10/03/1984 - 01/13/1987
-5.4
-1.8
-
10/03/1984 - 01/13/1987
-57.7
-19.2
-
01/13/1987 - 10/29/1993
9.9
1.7
-
01/13/1987 - 10/29/1993
47.2
7.9
-
10/29/1993 - 06/26/1998
-27.5
-5.5
-
10/29/1993 - 06/26/1998
-6.6
-1.3
-
06/26/1998 - 06/05/2002
-4.3
-1.1
-
06/26/1998 - 06/05/2002
2.0
0.5
-
06/05/2002 - 03/10/2003
2.3
2.3
-
06/05/2002 - 03/10/2003
24.0
24.0
-
03/10/2003 - 10/14/2006
-19.7
-6.6
-
03/10/2003 - 10/14/2006
-20.1
-6.7
-
10/14/2006 - 10/03/2008
3.0
1.5
-
10/14/2006 - 10/03/2008
18.6
9.3
-
Table A12. Summary of Bear Inlet Bear Island and Brown’s Island average shoreline cumulative changes for each
zone using AMBUR
Bear Inlet
Bear Island
Brown's Island
Cumulative Shoreline Change
Date
Inlet Transect (IT)
Zone I
Zone II
All
Inlet Transect (IT)
Zone I
Zone II
04/25/1938
0.0
0.0
0.0
0.0
0.0
0.0
0.0
All
0.0
11/01/1949
-27.9
-71.2
-33.7
-44.3
185.9
38.6
-17.8
68.9
71.0
08/16/1959
81.9
-8.5
-2.6
23.6
116.7
64.6
31.7
03/13/1962
68.0
-77.9
-49.3
-19.7
52.6
-2.8
-38.9
3.6
12/01/1974
195.3
-17.1
22.8
67.0
194.2
40.5
30.5
88.4
09/19/1984
258.3
-5.3
20.7
91.2
82.2
-26.3
-49.3
2.2
12/22/1985
01/14/1987
03/25/1989
196.1
261.7
334.2
-2.1
-34.3
-31.5
11.4
-14.2
-11.7
68.5
71.1
97.0
144.7
45.5
21.5
-5.1
-18.8
-36.2
-21.3
-21.8
-52.6
39.4
1.6
-22.4
05/08/1990
279.0
-6.8
2.9
91.7
-24.8
-40.7
-38.2
-34.6
10/29/1993
154.2
7.5
8.6
56.8
21.3
-36.9
-31.6
-15.7
05/07/1994
141.5
7.0
8.3
52.2
100.8
-52.5
-56.4
-2.7
09/15/1996
213.0
-49.4
-30.4
44.4
-37.8
-86.5
-83.3
-69.2
03/10/2001
171.4
-61.1
-26.9
27.8
-51.4
-45.0
-52.0
-49.4
03/10/2003
326.7
-13.9
2.0
104.9
37.3
-62.7
-69.3
-31.6
10/14/2006
174.2
-22.0
-2.9
49.8
153.3
-50.1
-79.9
7.8
10/03/2008
104.3
-60.0
-18.9
8.5
38.2
-77.4
-96.0
-45.1
119
Table A13. Summary of Brown’s Inlet Brown’s Island and Onslow Beach average shoreline cumulative changes for
each zone using AMBUR
Brown's Inlet
Brown's Island
Date
Inlet Transect
(IT)
Onslow Beach
Zone I
Zone II
All
BR1-BR16 BR17-BR30 IT, BR1-BR30
Zone I
Zone II
Inlet Transect (IT) OB1-OB16 OB17-OB30
All
OB1-OB30
01/01/1934
0.0
0.0
0.0
0.0
No Data
0.0
0.0
0.0
04/25/1938
68.6
35.5
36.6
46.9
No Data
13.8
34.8
24.3
01/24/1945
76.4
-16.2
1.1
20.4
No Data
63.0
49.4
56.2
05/04/1958
85.5
15.7
-24.1
25.7
No Data
93.6
70.8
82.2
08/16/1959
98.4
45.2
0.7
48.1
No Data
44.4
134.8
89.6
11/20/1960
222.1
29.6
-3.7
82.7
No Data
31.1
75.8
53.4
03/13/1962
108.0
17.2
-17.6
35.9
No Data
22.1
63.9
43.0
12/01/1974
356.0
-12.1
-34.7
103.0
No Data
71.8
50.9
61.3
10/03/1983
423.1
30.3
2.3
151.9
No Data
69.5
72.0
70.8
10/03/1984
280.2
32.6
1.2
104.7
No Data
91.5
89.9
90.7
01/13/1987
396.9
5.5
-4.2
132.7
No Data
63.1
119.9
91.5
10/29/1993
435.6
3.3
5.8
148.2
No Data
107.7
62.2
85.0
06/26/1998
352.4
-22.4
-21.7
102.7
No Data
118.1
109.4
113.8
06/05/2002
309.3
-38.0
-26.1
81.8
No Data
131.5
102.7
117.1
03/10/2003
288.9
-31.7
-23.7
77.8
No Data
152.4
104.7
128.5
10/14/2006
343.3
-48.3
-43.4
83.9
No Data
116.3
128.7
122.5
10/03/2008
347.7
-44.9
-40.7
87.4
No Data
147.8
108.6
128.2
120
Table A14a. Summary of Bear Inlet Bear Island shoulder cumulative shoreline change from Inlet transect (IT) to
transect BE5 from April 1938 to October 2008 using AMBUR
Bear Inlet
Date
IT
BE1
BE2
BE3
BE4
04/25/1938
0.0
0.0
0.0
0.0
0.0
BE5
0.0
11/01/1949
-27.9
-120.7
-119.7
-124.9
-109.5
-97.9
08/16/1959
81.9
34.5
11.3
1.9
-7.6
-14.5
03/13/1962
68.0
-70.8
-94.0
-109.0
-101.3
-87.9
12/01/1974
195.3
-76.9
-98.3
-111.0
-56.5
-45.0
09/19/1984
258.3
44.4
13.5
-5.2
-14.2
-11.3
12/22/1985
196.1
58.5
18.0
-6.1
-7.6
-5.7
01/14/1987
261.7
13.9
-20.7
-37.9
-44.3
-45.0
03/25/1989
334.2
32.9
-10.1
-38.0
-42.9
-44.4
05/08/1990
279.0
84.4
38.3
6.9
-4.0
-4.3
10/29/1993
154.2
74.7
41.5
12.9
-3.1
-5.4
05/07/1994
141.5
85.6
42.3
15.4
4.2
-0.3
09/15/1996
213.0
-16.2
-50.2
-69.7
-67.6
-63.6
03/10/2001
171.4
-19.9
-52.9
-75.4
-77.6
-58.4
03/10/2003
326.7
81.3
35.9
-5.2
-24.2
-30.0
10/14/2006
174.2
46.2
9.9
-18.4
-30.6
-35.6
10/03/2008
104.3
0.8
-42.5
-66.6
-78.6
-80.1
Table A14b. Summary of Bear Inlet Bear Island cumulative shoreline change along transects BE6 through BE11
from April 1938 to October 2008 using AMBUR.
Bear Inlet
Date
BE6
BE7
BE8
BE9
BE10
BE11
04/25/1938
0.0
0.0
0.0
0.0
0.0
0.0
11/01/1949
-84.4
-62.8
-51.0
-45.6
-47.3
-42.5
08/16/1959
-18.9
-17.7
-24.4
-19.4
-21.0
-11.9
03/13/1962
-87.1
-82.1
-79.1
-72.6
-72.0
-68.4
12/01/1974
-19.0
6.5
4.5
16.0
14.5
20.5
09/19/1984
-11.3
-7.9
-8.5
-1.5
-2.3
-1.7
12/22/1985
-7.6
-8.4
-21.3
-18.4
-18.7
-14.0
01/14/1987
-45.8
-43.7
-51.3
-44.6
-46.2
-38.8
03/25/1989
-43.9
-42.2
-46.9
-44.1
-45.9
-33.9
05/08/1990
-7.9
-8.9
-29.5
-26.9
-28.5
-25.5
10/29/1993
-6.7
-3.0
-13.6
0.1
-0.8
1.4
05/07/1994
-8.9
-11.2
-10.6
-1.4
-2.9
-0.9
09/15/1996
-62.0
-55.7
-59.7
-53.6
-54.9
-44.5
03/10/2001
-67.8
-72.6
-78.1
-72.0
-72.2
-66.4
03/10/2003
-33.9
-34.1
-41.4
-32.9
-34.7
-22.8
10/14/2006
-41.8
-42.0
-42.3
-33.1
-33.8
-25.3
10/03/2008
-81.6
-77.9
-79.6
-66.9
-69.4
-61.3
121
Table A14c. Summary of Bear Inlet Bear Island cumulative shoreline change along transects BE12 through BE17
Bear Inlet
Date
BE12
BE13
BE14
BE15
BE16
04/25/1938
0.0
0.0
0.0
0.0
0.0
BE17
0.0
11/01/1949
-46.1
-46.3
-51.3
-50.7
-38.1
-35.0
08/16/1959
-13.8
-10.7
-12.1
-11.4
0.1
0.7
03/13/1962
-68.2
-55.7
-62.7
-77.8
-57.9
-53.6
12/01/1974
11.8
11.7
11.1
12.5
23.2
23.9
09/19/1984
-11.4
-17.9
-26.3
-21.8
-1.4
7.4
12/22/1985
-3.6
-1.9
-5.7
-4.8
13.7
16.9
01/14/1987
-36.8
-30.4
-30.6
-28.6
-18.9
-21.6
-18.9
03/25/1989
-34.8
-32.3
-30.4
-29.6
-17.9
05/08/1990
-24.3
-20.5
-23.2
-23.8
-10.9
-9.4
10/29/1993
-1.0
2.0
3.3
6.7
11.6
10.2
05/07/1994
-9.1
-6.0
0.8
1.0
13.4
12.5
09/15/1996
-43.8
-40.0
-41.4
-39.1
-27.8
-30.4
03/10/2001
-62.6
-55.8
-55.1
-48.3
-41.9
-38.2
03/10/2003
-20.9
-15.5
-18.5
-19.0
-7.4
-11.1
10/14/2006
-26.1
-23.3
-23.6
-22.1
-9.6
-8.2
10/03/2008
-58.4
-55.2
-53.4
-52.3
-36.5
-31.4
Table A14d. Summary of Bear Inlet Bear Island cumulative shoreline change along transects BE18 through BE23
Bear Inlet
Date
BE18
BE19
BE20
BE21
BE22
BE23
04/25/1938
0.0
0.0
0.0
0.0
0.0
0.0
-40.1
11/01/1949
-39.4
-42.2
-42.4
-42.9
-43.6
08/16/1959
-14.3
-14.7
-9.7
-8.4
-7.7
-6.2
03/13/1962
-64.4
-68.5
-65.3
-44.2
-50.4
-44.9
12/01/1974
18.1
17.4
21.3
23.3
20.4
23.7
09/19/1984
9.8
7.9
12.4
16.5
22.8
22.7
12/22/1985
3.8
-3.2
-2.1
-0.1
6.1
10.6
01/14/1987
-27.2
-27.0
-19.9
-18.9
-18.6
-15.5
03/25/1989
-24.9
-29.1
-23.6
-18.1
-12.7
-8.8
05/08/1990
-10.6
-10.9
-8.2
-4.6
-0.9
2.7
10/29/1993
3.4
-0.1
4.7
5.3
7.0
9.1
05/07/1994
-0.1
-2.9
0.6
4.5
8.6
12.7
09/15/1996
-34.6
-39.4
-32.9
-35.9
-36.6
-32.6
03/10/2001
-44.4
-36.8
-35.6
-33.3
-33.1
-25.8
03/10/2003
-14.7
-15.2
-10.5
-4.5
-1.3
3.4
10/14/2006
-18.1
-20.9
-12.1
-7.6
-11.5
-5.0
10/03/2008
-32.3
-33.7
-27.3
-24.0
-22.5
-18.7
122
Table A14e. Summary of Bear Inlet Bear Island cumulative shoreline change along transects BE24 through BE30
Bear Inlet
Date
BE24
BE25
BE26
BE27
BE28
BE29
BE30
04/25/1938
0.0
0.0
0.0
0.0
0.0
0.0
0.0
11/01/1949
-40.2
-37.7
-28.4
-21.5
-23.6
-17.1
-18.0
08/16/1959
-6.1
-3.5
3.7
5.1
-0.6
10.7
14.6
03/13/1962
-44.1
-43.5
-44.7
-42.6
-55.9
-48.8
-19.7
12/01/1974
23.0
22.2
23.3
24.8
22.2
27.8
27.6
09/19/1984
27.1
27.5
30.9
23.3
21.1
28.4
32.0
12/22/1985
11.1
9.6
13.2
17.9
22.1
28.6
24.6
01/14/1987
-14.8
-13.5
-12.2
-4.5
-6.8
-1.0
3.2
03/25/1989
-9.4
-11.2
-7.5
-4.8
-4.3
2.8
6.9
05/08/1990
2.1
0.6
7.3
13.1
12.5
22.9
24.8
10/29/1993
9.5
3.3
10.4
13.3
10.6
18.6
14.8
05/07/1994
12.8
6.2
9.1
10.8
9.2
14.1
18.1
09/15/1996
-32.5
-33.9
-30.7
-26.9
-26.4
-17.7
-15.3
03/10/2001
-26.1
-26.3
-21.5
-20.1
-18.7
-9.7
-6.5
03/10/2003
4.5
2.6
8.1
14.6
11.4
20.1
20.1
10/14/2006
-2.5
3.5
7.2
6.6
2.7
11.2
13.5
10/03/2008
-18.3
-19.9
-13.7
-9.2
-10.8
-2.6
-0.5
Table A15a. Summary of Bear Inlet Brown’s Island cumulative shoreline change along transects IT through BR5
Bear Inlet
Date
IT
BR1
BR2
BR3
BR4
04/25/1938
0.0
0.0
0.0
0.0
0.0
BR5
0.0
11/01/1949
185.9
185.9
59.6
82.8
88.8
79.9
08/16/1959
116.7
116.7
34.2
43.3
101.3
90.9
03/13/1962
52.6
52.6
42.3
43.1
49.1
36.8
12/01/1974
194.2
194.2
50.9
50.7
51.8
44.2
09/19/1984
82.2
82.2
-7.1
-4.8
-6.9
-20.1
12/22/1985
144.7
144.7
2.2
4.3
-1.9
-2.7
01/14/1987
45.5
45.5
-8.1
-8.1
-8.9
-9.3
03/25/1989
21.5
21.5
-30.4
-31.2
-21.4
-16.8
05/08/1990
-24.8
-24.8
-23.4
-19.7
-20.7
-28.3
10/29/1993
21.3
21.3
-23.5
-25.4
-25.0
-30.1
05/07/1994
100.8
100.8
-49.0
-49.6
-53.7
-54.7
09/15/1996
-37.8
-37.8
-80.4
-82.7
-84.0
-84.4
03/10/2001
-51.4
-51.4
-30.5
-26.0
-22.6
-26.4
-56.8
03/10/2003
37.3
37.3
-56.9
-56.9
-52.9
10/14/2006
153.3
153.3
-24.5
-34.6
-33.3
-39.3
10/03/2008
38.2
38.2
-45.5
-51.9
-55.1
-66.0
123
Table A15b. Summary of Bear Inlet Brown’s Island cumulative shoreline change along transects BR6 through BR11
Bear Inlet
Date
BR6
BR7
BR8
BR9
BR10
BR11
0.0
04/25/1938
0.0
0.0
0.0
0.0
0.0
11/01/1949
57.5
43.1
33.9
30.8
14.8
9.3
08/16/1959
75.6
73.9
57.9
47.1
32.1
83.8
03/13/1962
8.9
-0.6
-8.0
-15.0
-22.4
-22.8
12/01/1974
33.2
37.2
39.3
31.2
24.2
25.0
09/19/1984
-28.7
-36.2
-29.2
-35.6
-31.7
-35.1
12/22/1985
-15.1
-7.3
-17.5
-24.8
-29.8
-26.2
01/14/1987
-18.5
-18.9
-21.8
-28.1
-25.1
-26.1
03/25/1989
-42.7
-40.1
-35.3
-31.5
-37.2
-42.6
05/08/1990
-43.0
-41.6
-44.7
-48.2
-50.4
-44.1
10/29/1993
-38.9
-36.1
-41.6
-43.3
-52.0
-47.6
05/07/1994
-64.3
-61.7
-62.9
-67.3
-71.2
-68.5
09/15/1996
-94.6
-86.0
-83.9
-89.2
-93.4
-91.6
03/10/2001
-38.4
-36.4
-41.0
-47.2
-52.6
-54.2
03/10/2003
-65.2
-64.8
-66.0
-71.1
-77.4
-75.4
10/14/2006
-48.3
-51.3
-63.2
-80.2
-89.5
-75.8
10/03/2008
-79.0
-77.3
-82.6
-92.4
-100.5
-97.8
Table A15c. Summary of Bear Inlet Brown’s Island cumulative shoreline change along transects BR12 through
BR17 from April 1938 to October 2008 using AMBUR.
Bear Inlet
Date
BR12
BR13
BR14
BR15
BR16
04/25/1938
0.0
0.0
0.0
0.0
0.0
BR17
0.0
11/01/1949
-2.3
-10.1
-18.8
-17.5
-19.9
-22.0
08/16/1959
70.3
69.6
60.4
43.5
33.1
42.3
03/13/1962
-38.1
-39.2
-47.0
-43.8
-41.3
-37.2
12/01/1974
20.2
15.9
11.0
8.5
10.5
13.0
09/19/1984
-43.1
-54.0
-57.7
-55.9
-56.7
-50.4
12/22/1985
-21.8
-22.8
-23.4
-20.5
-19.2
-25.4
01/14/1987
-28.9
-32.8
-36.9
-39.4
-34.6
-12.6
03/25/1989
-50.6
-53.7
-58.6
-55.1
-53.5
-52.2
05/08/1990
-45.5
-49.4
-55.0
-55.9
-56.1
-48.7
10/29/1993
-52.2
-47.8
-49.7
-50.6
-47.7
-38.6
05/07/1994
-68.8
-68.2
-68.8
-65.4
-66.6
-61.7
09/15/1996
-97.8
-96.0
-96.4
-92.1
-92.9
-94.0
03/10/2001
-56.7
-58.0
-62.7
-57.6
-58.1
-53.1
03/10/2003
-76.9
-79.0
-82.4
-80.2
-78.5
-72.9
10/14/2006
-80.0
-82.4
-83.3
-84.0
-85.3
-85.5
10/03/2008
-102.7
-106.5
-107.7
-104.1
-107.3
-103.4
124
Table A15d. Summary of Bear Inlet Brown’s Island cumulative shoreline change along transects BR18 through
Bear Inlet
Date
BR18
BR19
BR20
BR21
BR22
BR23
04/25/1938
0.0
0.0
0.0
0.0
0.0
0.0
11/01/1949
-21.0
-14.9
-9.2
-5.7
-6.5
-9.7
08/16/1959
50.2
42.3
40.0
35.8
29.3
28.7
03/13/1962
-36.5
-37.1
-37.8
-37.2
-41.4
-40.0
12/01/1974
12.7
16.7
22.0
28.6
30.3
30.9
09/19/1984
-50.1
-48.0
-47.0
-47.7
-47.6
-47.7
12/22/1985
-24.2
-22.1
-20.7
-15.6
-19.4
-19.8
01/14/1987
-17.1
-22.3
-25.7
-25.2
-21.5
-11.4
03/25/1989
-49.8
-48.2
-47.8
-46.8
-49.1
-49.6
05/08/1990
-41.9
-36.3
-33.5
-31.7
-34.3
-34.1
10/29/1993
-33.8
-30.6
-33.9
-31.2
-31.5
-29.6
05/07/1994
-59.4
-57.5
-53.4
-54.3
-53.3
-51.3
09/15/1996
-91.5
-85.4
-81.2
-76.1
-77.5
-77.5
03/10/2001
-49.8
-50.2
-51.0
-49.2
-49.1
-48.5
03/10/2003
-71.9
-72.1
-69.0
-67.7
-68.2
-66.1
10/14/2006
-77.5
-74.1
-70.6
-70.4
-76.8
-75.9
10/03/2008
-99.6
-95.5
-94.2
-92.7
-92.1
-92.8
Table A15e. Summary of Bear Inlet Brown’s Island cumulative shoreline change along transects BR24 through
Bear Inlet
Date
BR24
BR25
BR26
BR27
BR28
BR29
04/25/1938
0.0
0.0
0.0
0.0
0.0
0.0
BR30
0.0
11/01/1949
-16.4
-19.2
-18.0
-22.5
-26.3
-28.3
-29.2
08/16/1959
29.1
29.6
26.2
24.2
21.3
22.9
22.5
03/13/1962
-38.3
-35.7
-33.3
-35.6
-40.0
-45.9
-48.9
12/01/1974
31.4
34.6
40.5
40.0
42.0
42.0
41.8
09/19/1984
-49.9
-50.1
-47.1
-49.2
-51.8
-52.0
-51.3
12/22/1985
-22.5
-25.5
-23.5
-23.9
-17.4
-19.7
-18.8
01/14/1987
-22.3
-30.4
-20.1
-22.8
-24.3
-25.1
-24.6
03/25/1989
-52.6
-54.0
-52.0
-55.6
-58.1
-59.8
-60.2
05/08/1990
-36.3
-39.3
-38.5
-42.1
-40.0
-39.5
-38.7
10/29/1993
-26.8
-26.8
-25.3
-31.1
-37.1
-34.6
-32.1
05/07/1994
-55.8
-60.3
-57.8
-57.8
-54.3
-55.3
-57.7
09/15/1996
-82.7
-84.3
-80.3
-83.9
-86.4
-84.3
-81.7
03/10/2001
-47.7
-53.2
-50.6
-54.4
-57.9
-57.8
-55.2
03/10/2003
-70.0
-67.7
-66.0
-69.3
-71.6
-69.1
-68.3
10/14/2006
-77.0
-85.2
-83.4
-88.2
-87.1
-84.8
-82.2
10/03/2008
-96.1
-97.7
-93.9
-94.3
-96.2
-97.6
-97.4
125
Table A16a. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along transects IT through
BR5 from January 1934 to October 2008 using AMBUR.
Brown's Inlet
Date
IT
BR1
BR2
BR3
BR4
BR5
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
04/25/1938
68.6
31.8
33.9
35.0
35.2
34.2
01/24/1945
76.4
-32.6
-24.7
-24.5
-25.3
-23.0
05/04/1958
85.5
45.0
57.0
51.6
45.9
40.1
08/16/1959
98.4
86.7
68.9
65.6
61.9
57.8
11/20/1960
222.1
37.5
36.8
34.6
33.3
31.2
03/13/1962
108.0
59.8
54.1
46.8
40.0
35.6
12/01/1974
356.0
-1.8
-3.9
-7.4
-10.9
-14.4
10/03/1983
423.1
80.1
63.7
58.1
49.8
29.8
10/03/1984
280.2
71.0
55.9
44.7
37.7
28.6
01/13/1987
396.9
23.7
19.1
15.1
8.5
1.7
10/29/1993
435.6
13.3
6.1
4.1
2.7
-0.8
06/26/1998
352.4
-10.8
-18.4
-19.9
-23.0
-27.7
06/05/2002
309.3
-30.6
-37.4
-40.9
-42.9
-45.1
03/10/2003
288.9
-25.2
-34.8
-37.9
-40.9
-41.0
10/14/2006
343.3
-23.8
-27.1
-33.8
-41.1
-49.3
10/03/2008
347.7
-31.8
-38.8
-44.3
-49.5
-54.2
Table A16b. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along transects BR6 through
Brown's Inlet
Date
BR6
BR7
BR8
BR9
BR10
01/01/1934
0.0
0.0
0.0
0.0
0.0
BR11
0.0
04/25/1938
31.3
32.8
33.6
36.0
36.6
38.0
01/24/1945
-21.6
-15.3
-14.4
-12.0
-12.8
-13.1
05/04/1958
33.7
28.4
14.9
4.2
2.4
-1.8
08/16/1959
53.5
53.2
48.3
46.9
36.1
29.3
11/20/1960
32.6
34.5
36.5
40.4
41.1
37.0
03/13/1962
26.4
5.3
12.7
4.2
6.6
11.5
12/01/1974
-15.1
-14.6
-14.1
-13.6
-13.1
-12.6
10/03/1983
26.9
22.3
22.3
25.9
21.3
18.4
44.2
10/03/1984
23.0
21.0
19.4
29.1
39.8
01/13/1987
-1.4
0.7
0.3
3.7
-1.0
1.5
10/29/1993
-3.6
-5.8
-6.6
-5.5
-2.6
1.8
06/26/1998
-27.5
-28.6
-26.2
-24.5
-23.9
-24.5
06/05/2002
-46.0
-45.9
-43.8
-38.5
-35.0
-34.8
03/10/2003
-40.6
-35.2
-31.0
-28.0
-29.6
-29.7
10/14/2006
-51.2
-58.4
-63.9
-60.6
-58.1
-51.5
10/03/2008
-54.1
-51.5
-54.6
-51.0
-47.7
-45.8
126
Table A16c. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along transects BR12 through
Brown's Inlet
Date
BR12
BR13
BR14
BR15
BR16
BR17
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
04/25/1938
41.7
40.8
35.3
35.6
35.4
31.7
01/24/1945
-11.9
-8.4
-6.9
-7.6
-4.9
-4.3
05/04/1958
-8.5
-11.0
-13.6
-20.2
-17.0
-17.9
08/16/1959
24.7
23.4
25.4
24.1
18.3
16.9
11/20/1960
28.6
22.7
14.0
8.0
4.3
-0.8
03/13/1962
-0.9
6.0
-2.2
-14.7
-15.8
-13.9
12/01/1974
-12.1
-11.9
-14.0
-15.9
-18.0
-20.0
10/03/1983
14.6
12.4
11.5
14.5
13.1
12.0
10/03/1984
29.3
26.1
19.8
20.2
11.8
8.5
01/13/1987
2.5
3.7
6.9
3.7
-0.6
1.5
10/29/1993
9.1
10.9
10.6
9.1
10.0
8.1
06/26/1998
-23.6
-19.2
-19.9
-21.0
-20.4
-21.3
06/05/2002
-33.1
-33.4
-32.9
-33.3
-34.0
-32.9
03/10/2003
-27.0
-26.5
-26.2
-25.6
-27.8
-27.3
10/14/2006
-48.2
-49.9
-51.4
-51.7
-52.9
-47.4
10/03/2008
-44.3
-39.5
-37.0
-37.4
-36.9
-36.7
Table A16d. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along transects BR18 through
Brown's Inlet
Date
BR18
BR19
BR20
BR21
BR22
01/01/1934
0.0
0.0
0.0
0.0
0.0
BR23
0.0
04/25/1938
33.7
33.9
33.6
32.5
36.5
33.9
01/24/1945
-3.7
-1.6
0.0
-2.1
0.4
3.5
05/04/1958
-16.4
-18.9
-21.0
-24.5
-24.2
-25.7
08/16/1959
12.7
7.1
4.3
3.0
1.5
-4.3
11/20/1960
1.1
-1.4
-1.3
-1.8
-3.6
-4.2
03/13/1962
-15.9
-11.2
-12.9
-19.6
-17.5
-18.7
12/01/1974
-22.1
-24.2
-26.3
-28.4
-30.5
-32.6
10/03/1983
10.6
9.3
8.0
6.7
5.4
4.1
10/03/1984
6.6
8.8
9.2
1.0
-6.4
-6.5
01/13/1987
0.2
0.1
-2.3
-3.9
-2.9
-0.7
10/29/1993
5.6
4.0
4.6
5.9
6.2
6.1
06/26/1998
-20.2
-22.0
-24.1
-26.3
-25.4
-23.8
06/05/2002
-31.7
-30.4
-29.2
-28.0
-26.8
-25.6
03/10/2003
-27.0
-24.6
-23.0
-24.0
-20.5
-22.5
10/14/2006
-46.9
-44.5
-45.7
-45.3
-46.7
-45.9
10/03/2008
-34.3
-34.0
-34.8
-36.9
-35.5
-36.5
127
Table A16e. Summary of Brown’s Inlet Brown’s Island cumulative shoreline change along transects BR24 through
Brown's Inlet
Date
BR24
BR25
BR26
BR27
BR28
BR29
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
BR30
0.0
04/25/1938
35.7
41.5
41.6
39.8
41.3
40.5
36.5
01/24/1945
2.1
2.3
7.4
1.9
0.8
4.3
4.0
05/04/1958
-26.4
-27.2
-27.3
-26.2
-24.3
-26.9
-31.2
08/16/1959
-4.3
-1.7
-2.5
-4.6
-4.4
-5.5
-8.4
11/20/1960
-3.3
-3.2
-5.0
-8.5
-7.0
-5.5
-7.7
03/13/1962
-20.9
-16.5
-18.3
-14.6
-22.5
-23.1
-20.2
12/01/1974
-34.7
-36.5
-38.0
-42.1
-46.1
-50.3
-54.6
-12.4
10/03/1983
2.8
1.7
1.0
-2.3
-5.5
-8.9
10/03/1984
-6.2
-5.4
2.6
4.1
1.3
-2.2
1.9
01/13/1987
-3.4
-3.5
-3.5
-6.0
-8.5
-11.2
-14.0
10/29/1993
7.9
8.7
7.2
6.4
6.0
3.1
1.0
06/26/1998
-22.8
-21.6
-20.4
-19.2
-19.2
-18.3
-19.9
06/05/2002
-24.4
-22.7
-20.9
-21.7
-22.5
-23.4
-24.4
03/10/2003
-18.3
-18.1
-16.7
-18.9
-24.3
-31.9
-34.8
10/14/2006
-44.2
-41.9
-39.4
-39.6
-39.7
-40.0
-40.4
10/03/2008
-36.1
-33.5
-40.2
-57.5
-56.6
-55.9
N/A
Table A17a. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along transects IT through OB5
from January 1934 to October 2008 using AMBUR.
Brown's Inlet
Date
IT
OB1
OB2
OB3
OB4
OB5
01/01/1934
No Data
0.0
0.0
0.0
0.0
0.0
04/25/1938
No Data
38.5
38.0
27.8
17.1
13.7
01/24/1945
No Data
72.8
71.5
68.6
67.2
68.0
05/04/1958
No Data
50.7
54.3
51.6
64.4
88.0
08/16/1959
No Data
44.9
46.3
43.0
42.2
42.4
11/20/1960
No Data
19.6
22.0
22.6
26.9
32.9
03/13/1962
No Data
10.1
12.7
14.2
14.6
16.4
12/01/1974
No Data
70.4
71.4
74.3
77.2
83.8
10/03/1983
No Data
70.8
70.6
73.6
77.0
69.3
10/03/1984
No Data
66.8
85.0
92.6
92.0
94.9
01/13/1987
No Data
65.9
73.9
86.0
88.8
86.8
10/29/1993
No Data
51.1
64.4
101.2
108.7
117.8
06/26/1998
No Data
65.3
78.6
96.6
102.8
111.9
06/05/2002
No Data
116.1
118.9
126.5
140.0
142.6
03/10/2003
No Data
145.6
145.6
150.8
159.6
173.8
10/14/2006
No Data
97.0
99.7
109.9
117.0
122.8
10/03/2008
No Data
124.2
128.8
144.4
154.1
158.3
128
Table A17b. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along transects OB6 through
OB11 from January 1934 to October 2008 using AMBUR.
Brown's Inlet
Date
OB6
OB7
OB8
OB9
OB10
OB11
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
04/25/1938
10.8
9.8
5.6
6.9
7.0
7.9
01/24/1945
70.3
70.8
68.9
68.0
63.0
62.4
05/04/1958
109.3
110.2
110.0
112.1
102.7
105.3
08/16/1959
42.1
44.4
46.5
45.1
46.6
41.9
11/20/1960
34.3
34.4
36.8
36.2
35.2
33.9
03/13/1962
23.5
27.8
29.7
31.0
33.3
28.8
12/01/1974
83.0
78.6
75.1
76.2
73.8
70.9
10/03/1983
68.9
65.1
67.7
67.6
65.0
67.5
10/03/1984
100.2
103.9
96.1
92.1
87.6
81.4
01/13/1987
74.5
72.5
65.6
61.4
55.8
54.2
10/29/1993
127.6
132.8
135.8
127.6
119.2
116.6
06/26/1998
115.1
120.8
125.2
126.9
133.0
139.5
06/05/2002
140.2
132.8
137.6
149.0
144.7
139.9
03/10/2003
173.4
170.0
168.7
164.3
157.0
154.8
10/14/2006
124.0
122.2
125.2
125.1
122.6
120.4
10/03/2008
159.3
158.4
158.2
156.8
154.3
153.4
Table A17c. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along transects OB12 through
Brown's Inlet
Date
OB12
OB13
OB14
OB15
OB16
OB17
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
04/25/1938
7.9
6.6
7.6
6.3
8.8
7.2
01/24/1945
58.3
55.7
52.3
48.2
42.5
41.8
05/04/1958
107.2
98.4
113.6
111.2
108.5
98.6
08/16/1959
45.3
48.1
48.6
42.6
40.9
32.5
11/20/1960
31.4
32.5
31.0
33.1
34.5
32.9
03/13/1962
27.5
25.6
20.9
19.7
18.6
19.0
12/01/1974
69.9
65.8
60.5
59.7
57.9
55.7
10/03/1983
68.7
69.5
70.2
70.9
70.4
68.4
10/03/1984
94.4
96.7
93.5
92.9
93.6
98.2
01/13/1987
49.1
48.3
44.8
42.4
39.2
29.9
10/29/1993
114.2
107.2
101.7
101.5
96.7
90.9
06/26/1998
137.7
136.3
135.9
134.7
130.0
120.0
06/05/2002
134.5
129.0
124.8
119.2
107.7
98.9
03/10/2003
148.2
142.4
134.1
127.5
121.8
115.1
10/14/2006
119.2
118.7
118.6
113.1
105.0
93.6
10/03/2008
149.7
147.3
142.4
139.7
135.8
130.9
129
Table A17d. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along transects OB18 through
Brown's Inlet
Date
OB18
OB19
OB20
OB21
OB22
OB23
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
04/25/1938
9.4
7.7
9.2
9.7
13.6
13.3
01/24/1945
40.6
36.8
34.7
36.7
38.5
36.7
05/04/1958
100.2
95.8
99.0
93.0
100.6
99.9
08/16/1959
34.0
47.4
40.3
42.5
43.9
43.5
11/20/1960
32.7
32.5
33.4
30.2
27.4
27.4
03/13/1962
16.3
16.2
15.2
15.3
15.4
14.7
12/01/1974
49.7
44.8
41.7
40.6
38.7
36.6
10/03/1983
66.4
64.4
62.5
60.4
58.3
56.5
10/03/1984
101.8
93.5
85.3
88.1
81.5
87.2
01/13/1987
28.6
28.4
34.0
36.7
32.2
27.5
10/29/1993
86.9
84.7
84.7
79.2
76.1
75.5
06/26/1998
105.0
92.6
81.8
71.7
63.4
58.9
06/05/2002
97.4
82.4
83.2
77.4
78.2
73.9
03/10/2003
111.9
108.7
101.8
96.5
96.4
89.2
10/14/2006
87.2
86.8
84.2
83.6
80.9
79.4
10/03/2008
122.2
116.2
109.3
103.3
96.2
90.2
Table A17e. Summary of Brown’s Inlet Onslow Beach cumulative shoreline change along transects OB24 through
Brown's Inlet
Date
OB24
OB25
OB26
OB27
OB28
OB29
01/01/1934
0.0
0.0
0.0
0.0
0.0
0.0
OB30
0.0
04/25/1938
15.3
14.6
18.0
21.4
21.5
21.2
22.6
01/24/1945
35.7
37.5
36.6
34.4
35.9
29.2
29.7
05/04/1958
93.8
102.1
97.7
103.0
102.9
108.9
104.8
08/16/1959
43.0
42.5
42.0
41.5
40.9
40.4
39.9
11/20/1960
27.4
27.3
27.3
27.2
27.2
27.1
27.1
03/13/1962
13.8
13.6
16.3
16.0
15.2
20.5
18.2
12/01/1974
35.1
33.5
32.0
30.5
28.7
27.2
25.7
10/03/1983
54.4
52.3
50.2
48.1
45.5
43.4
41.3
10/03/1984
87.6
79.7
83.3
85.6
79.1
78.9
62.3
01/13/1987
26.8
31.8
23.8
21.4
20.3
19.2
23.7
10/29/1993
73.0
68.5
66.4
65.3
61.5
66.7
65.2
06/26/1998
58.5
55.6
54.6
52.9
48.8
45.8
42.0
06/05/2002
68.6
57.4
56.7
52.3
49.5
58.6
44.7
03/10/2003
87.5
93.1
92.7
83.5
84.5
76.4
77.6
10/14/2006
78.8
71.3
65.6
61.8
56.3
54.3
49.8
10/03/2008
85.4
81.7
77.7
72.8
71.1
69.2
67.8
130

Thesis Prospectus Draft - iLumina Digital Collection | UNCW

Transcription

Similar documents

SHUTTLE VALVE “SHV”

KENNE BELL MAMMOTH TWIN SCREW vs TVS 2.3 KITS* KENNE

OB-30 Oxygen Booster For Charter and Commercial Aircraft

Model TM-550 Multi-Turn Anti-Siphon Frost

Westfalia Syncro Multivan

Phase 5 $8000000 - Town of North Topsail Beach

30351_Nakskov Fjord_u.cykelsti_UK.indd

tools needed start - Global Industrial

The Most Dangerous Game

Chapter XIV. In C,onclusion - Man-O