CITY OF DESTIN, FLORIDA EAST PASS INLET STUDY

Transcription

CITY OF DESTIN, FLORIDA
EAST PASS INLET STUDY &
MANAGEMENT CONSIDERATIONS
PREPARED FOR:
CITY OF DESTIN
PREPARED BY:
COASTAL PLANNING & ENGINEERING, INC.
OCTOBER 2010
EAST PASS INLET STUDY & MANAGEMENT CONSIDERATIONS
TABLE OF CONTENTS
Background ........................................................................................................................................1
Evaluation of Erosional Patterns Near East Pass ...............................................................................4
Sediment Budgets ..............................................................................................................................46
Impacts of East Pass on Gulf-Front Erosion Patterns ........................................................................60
East Pass Inlet Management Alternatives ..........................................................................................68
Conclusions ........................................................................................................................................82
Recommendations ..............................................................................................................................83
References ..........................................................................................................................................85
List of Figures
Figure No.
1-1
1-2
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
2-13
2-14
2-15
2-16A
2-16B
2-17
2-18
3-1
3-2
Study Area Location ......................................................................................................2
East Pass February 2004 Aerial Photograph with Channel Locations ..........................2
August 1901 Nautical Chart of East Pass ......................................................................5
Shoreline and Volume Changes East of East Pass ........................................................23
Shoreline and Volume Changes West of East Pass .......................................................24
October 1991 Aerial Photograph of East Pass...............................................................26
February 1994 Aerial Photograph of East Pass .............................................................27
October 1995 Aerial Photograph of East Pass...............................................................28
East Pass Sediment Budget Cells ..................................................................................34
Bathymetry and Volume Change in the US Coast Guard Channel ...............................35
1995-1996 Bathymetry in the East Pass Channel, East Pass Ebb Shoal,
Old Pass, and the US Coast Guard Channel ..................................................................36
2007-2008 Bathymetry in the East Pass Channel, East Pass Ebb Shoal, and
Old Pass .........................................................................................................................37
1995/1996 to 2007/2008 Volume Changes in the East Pass Channel,
East Pass Ebb Shoal, and Old Pass ...............................................................................38
Bathymetry and Volume Change on Norriego Point.....................................................39
Bathymetry and Volume Change in the Western Sand Dike ........................................40
Bathymetry and Volume Change in the Eastern Sand Dike ..........................................41
March 2004 Channel Alignment ...................................................................................44
September 2009 Channel Alignment .............................................................................45
East Pass 1996-2007 Sediment Budget .........................................................................47
East Pass Sediment Budget 1990-1997 .........................................................................50
i
TABLE OF CONTENTS
(CONT'D)
List of Figures
Figure No.
3-3
3-4
3-5
3-6
3-7
4-1
4-2
4-3
4-4
4-5
4-6
5-1
5-2
5-3
Locations of 1983 and 2009 Current Measurements .....................................................51
1996-2007 Gulf-Front Sediment Budget .......................................................................53
Sediment Transport Rates ..............................................................................................58
Even-Odd Analysis for East Pass Based on the 1996-2007 Shoreline and
Volume Changes ............................................................................................................61
Even-Odd Analysis for East Pass Based on the 1969-1996
Shoreline Changes .........................................................................................................62
Impact of the Walton County/Destin Beach Restoration Project Borrow Area
Based on Shoreline Changes ..........................................................................................64
Impacts of the Walton County/Destin Beach Restoration Project Borrow
Area Based on Delft3D Numerical Model Simulations ................................................65
Eroded Beach at the Jetty East Condominium on January 3, 2006 ...............................66
Borrow Area for the Western Destin Beach Restoration Project,
Okaloosa Island Beach Restoration, and Eglin AFB Beach Restoration.......................67
Proposed Beach Restoration Projects near East Pass, Destin, FL .................................69
East Pass Inlet Management Alternatives .....................................................................71
Impact of Alternative 4 vs. Alternative 1 on Shoaling Rates ........................................77
List of Tables
Table No.
2-1
Recent Dredging Quantities...........................................................................................6
2-2A
Beach Survey Data Catalog ...........................................................................................7
2-2B
Additional Hydrographic and Topographic Surveys of East Pass .................................9
2-3
Aerial Photographs of East Pass ....................................................................................9
2-4
Storm Recovery and Beach Restoration Projects ..........................................................10
2-5
Surveyed Shoreline Changes .........................................................................................11
2-6
Volume Changes............................................................................................................15
2-7A&B Adjusted Shoreline and Volume Changes .....................................................................19
2-8
Volume Changes in East Pass .......................................................................................43
3-1
Sediment Transport on the Beach..................................................................................57
5-1
Beach and Ebb Shoal Surveys Required under Present Permits ...................................81
ii
TABLE OF CONTENTS
(CONT'D)
List of Appendices
Appendix No.
A
B
C
D
Delft3D Numerical Model
1996-2009 Volume Change Estimates and Beach Profiles
Permit Sketches for the East Pass Maintenance Dredging
Technical Advisory Committee Comments on Draft Report and Responses
iii
1.
BACKGROUND
1.1
Setting of East Pass
East Pass defines the western boundary for the city of Destin, FL. It is the sole inlet that
connects Gulf of Mexico to Destin Harbor and Choctawhatchee Bay (Figures 1-1 and 1-2),
which is approximately 28 miles long and 6 miles wide. The inlet channel is approximately
6,000 feet long, with a 1,400 foot long seaward segment running at a south-southwest to northnortheast orientation, and a 4,600 foot long landward segment running at a southeast to
northwest orientation. Destin Harbor adjoins East Pass near the landward end of the inlet, and is
approximately 2 miles long by ¼ miles wide, running from west-northwest to south-southeast.
Norriego Point separates Destin Harbor from East Pass. It adjoins Holiday Isle, which separates
Destin Harbor from the Gulf of Mexico.
The entrance of East Pass is protected by two rubble-mound jetties: a 3,860 foot long jetty on the
west side of the inlet running from northwest to southeast, and 1,210 foot long jetty on the east
side of the inlet running from north-northeast to south-southwest. The jetties were built between
1967 and 1969. The west jetty originally featured a 1,000 foot long weir section starting at the
shoreline. In 1985, the weir section was replaced with a conventional, rubble-mound crosssection. In 1977, a 330 foot long spur extension was adjoined to the landward tip of the east jetty
to divert flow away from the eastern bank of inlet (Morang, 1992). Additional structures along
East Pass include a seawall along the southern half of Norriego Point and adjacent
condominiums and two T-head groins near the northern half of Norriego Point, constructed in
2003.
1.2
Present Inlet Management Plan
The Florida Department of Environmental Protection (FDEP) issued the “East Pass Inlet
Management Study Implementation Plan – Certificate of Adoption” in June 2000, which
recommended a sediment management strategy for the inlet. The sediment management plan
was based on a report titled “Inlet Management Plan for East Pass to Choctawhatchee Bay”
dated June 1999, by Taylor Engineering, Inc. The requirements of the Inlet Management Plan
were the following:
1)
Continue to bypass sediment to the downdrift beaches.
As a first priority, place sand on downdrift beaches, west of the inlet, in areas of greatest
need as determined by the Department. As a minimum, bypassing of material shall meet
the average annual placement objective of 82,000 cubic yards as determined by the
sediment budget. The sediment budget contained in the study report is adopted as an
interim measure and shall be formally validated or redefined in subsequent revisions of
the plan based on a comprehensive monitoring plan by December 31, 2005.
1
EAST PASS STUDY AREA
FIGURE 1-1: Study Area Location.
NORRIEGO POINT
USCG STATION
DESTIN HARBOR
EAST
PASS
HOLIDAY ISLE
N
COORDINATES SHOWN HEREON ARE IN FEET BASED ON THE
FLORIDA STATE PLANE COORDINATE SYSTEM, NORTH ZONE,
NORTH AMERICAN DATUM OF 1983 (NAD83).
FIGURE 1-2: East Pass February 2004 Aerial Photograph
with Channel Locations (LABINS, 2004).
2
2)
Implement strategies for managing Norriego Point while meeting local government
objectives for land use goals that enable more material to be available for bypassing
to downdrift Gulf beaches.
Stabilization of Norriego Point will allow material dredged from the inlet, currently
being placed on the point, to be placed on downdrift beaches.
3)
Implement a comprehensive beach, inlet, and offshore monitoring program subject
to the approval of the Department.
The program will be used to identify beach placement locations for future bypassing
efforts and to revalidate the sediment budget.
Since the release of the 1999 Inlet Management Plan, the following events have taken place,
which merit a review of the present strategies to manage East Pass:
•
Approximately 896,000 c.y. (100,000 c.y./year) have dredged from East Pass (19992008), based on permitting documents from the U.S. Army Corps of Engineers Mobile
District (CESAM). A reported 396,000 c.y. (44,000 c.y./year) have been placed on the
beach west of the inlet, which is less than the recommended volume of 82,000 c.y./year.
•
Two T-head groins and a revetment were constructed along Norriego Point. However,
these structures were not able to stabilize the area completely. To address this concern,
the City of Destin has initiated the design of a project to completely stabilize Norriego
Point.
•
Regular surveys of the East Pass itself have been performed by CESAM. However, a
program of annual beach surveys on both sides of the inlet has not been instituted.
•
Several hurricanes have struck or passed the region, including Ivan (2004), Dennis
(2005), and Katrina (2005).
•
Severe erosion has occurred on gulf-front shoreline east of the inlet. In particular, the
shoreline near Destin Pointe (profile R18) retreated landward 282 feet between March
1996 and July 2007.
•
CESAM has completed a FDEP permit application to continue the maintenance dredging
of East Pass. Permits were granted in 2009. A dredging operation in early 2010 removed
181,141 c.y. from the inlet navigation channel and placed it on the beach on Santa Rosa
Island.
•
A total of 2,807,060 c.y. of material (February 2006 to June 2007) has been excavated
from the East Pass ebb shoal to construct the Walton County / Destin Beach Restoration
Project (Bridges, Trudnak, and Krecic, 2008, p. 22).
3
1.3
Objectives
The overall purpose of this inlet study is to update the 1999 Inlet Management Plan. To
accomplish this purpose, the study has the following objectives:
1. Evaluate the erosional patterns since the 1990s based on surveys, aerial photographs, and
dredging records.
2. Update the sediment budget presented in the 1999 Inlet Management Plan.
3. Develop potential alternatives to manage the material dredged from East Pass.
4. Evaluate the various alternatives using the Delft3D model (Appendix A).
5. Determine the effects caused by the excavation of the Walton County / Destin borrow
area in 2006 and 2007.
6. Develop an updated plan to manage East Pass.
2.
EVALUATION OF EROSIONAL PATTERNS NEAR EAST PASS
2.1
History of Inlet
The East Pass Federal navigation project is a 12 foot MLLW by 180 foot wide channel from the
Gulf of Mexico into Choctawhatchee Bay, with a 6 foot MLLW by 100 foot wide channel, 3,800
feet long from East Pass channel into Old Pass Lagoon, also known as Destin Harbor (USACE,
1997). The local sponsor of the navigation project is the Board of County Commissioners,
Okaloosa County, Florida.
East Pass has been used for navigation since the early 1800s (Morang, 1992, p. 1). At this time,
the inlet had a reputation for being dangerous to navigate, with numerous shoals (Morang, 1992).
The 1901 nautical chart documented a 3 mile inlet channel running between the gulf and the bay
along the present location of Destin Harbor (Figure 2-1). In April 1928, a severe storm and a
high tide partially breached Santa Rosa Island near the inlet’s present location. Local inhabitants
dug a pilot channel along the route of the 1928 breach to help augment the runoff of the bay
(Morang, 1992). Federal maintenance of East Pass began in 1931 (Morang, 1992). However,
the present Federal maintenance program was authorized in 1951 (USACE, 1997). Construction
of the inlet’s jetties took place between 1967 and 1969, with the addition of the spur feature to
the landward end of the east jetty in 1977 (see Figure 1-2) (Morang, 1992). The presently
authorized length of the Old Pass (Destin Harbor) Channel was established in 1981 (USACE,
1997).
When the jetties were first constructed, there were some investigations that concluded that the
net sediment transport was from west to east near East Pass (Morang, 1992). For this reason, the
west jetty originally featured a weir near its landward end to allow sand to fall into a deposition
basin. Nevertheless, in the early 1970s, local residents blamed the weir section for the high
4
erosion rates on Norriego Point (Morang, 1992). The weir was finally removed in 1985 and
replaced with a rubble mound groin section.
In addition to the inlet jetties, a number of structures were built to stabilize Norriego Point.
These structures included the seawalls along the East Pass Towers and Waterview Towers
condominiums and two small geotextile groins built in 1991 (CPE, 2009). In 2003, two T-head
groins and a rubble mound revetment were constructed to further stabilize Norriego Point. With
the addition of these structures in 2003, the inlet reached its present configuration.
FIGURE 2-1: August 1901 Nautical Chart of East Pass (NOAA 2001).
Since 1986, 2,352,600 cubic yards of material have been dredged from East Pass by the U.S.
Army Corps of Engineers (Table 2-1). Excavation of the borrow area for the Walton County /
Destin Beach Restoration Project (2006-2007) increases the total volume of dredged material to
5,159,704 cubic yards. The interval between dredging operations varies from 1 to 3 years.
Excluding the Walton County / Destin project, the average dredging rate East Pass is
approximately 98,000 c.y./year.
The FDEP permit (46276059) for the maintenance dredging of East Pass expired on July 14,
2008. Therefore, no dredging was conducted in 2009. However, the FDEP permits were
renewed under permit number 0288799-001-JC on October 28, 2009. The most recent dredging
operation removed 181,141 c.y. from the inlet in early 2010.
5
P:\Okaloosa\1050000 Destin IMP Update\ENGINEERING\Sediment_Budget\East_Pass_2009_Sediment_Budget_Revised.xls EPdredge 8/4/2010 4:15 PM
TABLE 2-1
RECENT DREDGING QUANTITIES, EAST PASS, DESTIN, FL
USACE (2008), BRIDGES, ET AL (2008)
EXCAVATED MATERIAL (cubic yards)
USCG
Channel
Old Pass
(Destin
Harbor)
Sand Dikes
(next to inlet
on land)
Scour Hole
(near spur
jetty)
Nearshore
Beach
(V619+435' to (V611+480' to
V622+357')
V619+435')
East Pass +
Outer Bar
TOTAL
141,745
173,745
241,914
248,615
150,935
298,474
161,485
165,244
123,427
70,663
240,385
243,116
53,500
181,141
32,000
90,591
63,750
35,590
45,526
121,485
165,244
42,083
122,426
141,745
241,914
210,793
139,435
293,554
108,754
165,244
103,783
70,663
207,000
228,395
51,000
181,141
896,613
37,359
2,143,421
89,309
2,352,644
98,027
646,875
26,953
584,684
24,362
190,084
7,920
353,747
14,739
577,254
24,052
YEAR
TOTAL
1986
1987
1988
1991
1993
1995
1999
2002
2003
2005
2006
2008
2010
173,745
241,914
248,615
150,935
298,474
161,485
165,244
123,427
70,663
240,385
243,116
53,500
181,141
TOTAL
ANNUAL
2,352,644
98,027
2006-2007
Walton
Co./Destin
Project
2,807,060
1996/1998
to 2004
359,334
11,002
8,642
181,059
158,631
339,690
359,334
207,327
0
0
0
152,007
1996/1998
to 2005
599,719
11,002
42,027
341,147
205,543
546,690
599,719
240,712
0
0
0
359,007
1996/1998
to 2007 &
2006-2007
Walton
Co./Destin
Project
3,649,895
11,002
56,748
478,253
3,103,892
775,085
842,835
(See Note 1)
(See Note 2)
0
0
396,113
2000 to
2010
912,232
11,002
59,248
495,384
346,598
841,982
912,232
92,689
242,289
0
0
577,254
NOTES:
East Pass
PLACED MATERIAL (cubic yards)
Norriego
Point
Outer Bar
(Ebb Shoal)
32,000
11,509
37,822
11,500
4,920
41,222
11,002
8,642
33,385
14,721
2,500
22,511
938
186,712
7,780
241,914
80,523
98,760
192,348
45,295
92,584
88,475
160,088
137,106
51,000
58,715
1,246,808
51,950
130,270
40,675
101,206
63,459
72,660
15,308
70,663
46,912
91,289
33,385
14,721
2,500
60,149
151,323
30,980
59,943
40,000
81,596
54,595
43,690
91,799
130,270
40,675
101,206
81,344
70,663
207,000
37,106
191,289
51,000
181,141
2,807,060
1. Erosion and deposition rates on Norriego Point from 1996 to 2007 were based on Oct.-Nov. 1995 and Nov. 2009 surveys.
Fill rates were based on the corresponding volume of 257,933 c.y. for the same time period.
2. Erosion and deposition rates in the Sand Dikes area from 1996 to 2007 were based on 1998 and 2005 surveys.
Fill rates were based on the corresponding volume of 0 c.y. for the same time period.
3. 2010 dredge quantities in East Pass
& the Outer Bar are approximate.
Prior to the mid 1990s, beaches on the east side of East Pass were generally accretional, with
eroding beaches on the west side of the inlet. However, with the passage of Hurricane Opal in
1995, storm activity began to increase along the Florida Panhandle. Severe erosion occurred as a
result of these storms, particularly on the eastern side of the inlet. Following the 2005 hurricane
season, the 1.6 mile segment on the eastern side of East Pass was designated as a critically
eroded segment of shoreline (FDEP, 2009, p. 3). The erosional patterns since the 1990s, based
on aerial photographs and surveys, are detailed in the next part of this section.
2.2
Inventory of Survey Data and Aerial Photographs
Shoreline and volume changes along the beach since the 1990s were based on available beach
profile surveys and LIDAR surveys available from FDEP and NOAA. The surveys were taken
along the following profile lines in Table 2-2A:
TABLE 2-2A
BEACH SURVEY DATA CATALOG
DESTIN, FL
Approximate Date
November 1973
October 1975
March 1976
March 1978
May 1981
July 1984
April 1987
August 1987
November 1989
October 1993
July 1994
June 1995
August 1995
November 1995
March 1996
October 1996
January 1998
November 1998
April 2004
June 2004
August 2004
November 2004
July 2005
September 2005
November 2005
December 2006
July 2007
June 2008
Sept. 8, 2008
Sept. 22, 2008
July 2009
R- Lines
Surveyed?
All
R- Lines Below
Wading Depth?
V601 to V622
Surveyed?
V601 to V622
Below Wading
Depth?
CONVENTIONAL SURVEYS
rd
Every 3
All
Some
Every 3
rd
Every 3rd
Every 3rd
All
Every 3rd
Every 3rd
Every 3rd
All
All
Some
All
Every 3rd
All
All
All
All
Every 3rd
All
All
Some
Some
East
West
Some
All
Some
Some
Some
Some
Some
Some
East
Some
All
Some
Some
7
All
All
Some
All
All
Some
All
Some
Some
TABLE 2-2A (continued)
BEACH SURVEY DATA CATALOG
DESTIN, FL
Approximate Date
R- Lines
Surveyed?
October 1995
November 1995
November 1996
October 1997
November 1998
January 2000
May 2000
April 2004
November 2004
July 2005
November 2005
Near inlet
Near inlet
Near inlet
Near inlet
All
Near inlet
Near inlet
All
All
All
West
R- Lines Below
Wading Depth?
LIDAR SURVEYS:
Near inlet
Near inlet
Near inlet
Near inlet
Near inlet
Near inlet
All
East
All
West
V601 to V622
Surveyed?
Near inlet
Near inlet
Near inlet
Near inlet
All
Near inlet
Near inlet
All
All
All
All
V601 to V622
Below Wading
Depth?
Near inlet
Near inlet
Near inlet
Near inlet
Near inlet
Near inlet
All
All
All
FDEP beach profile line R1, also referred to as OKL-R1, is located at the west end of Fort
Walton Beach. Beach profile line R17 (or OKL-R17) is located at the east jetty of the pass.
Beach profile line V622 (or OKL-V622) is located at the west jetty and was established to
monitor performance of the Air Force property. Profile V601 (or OKL-V601) is located at the
western side of the Eglin Air Force property. FDEP beach profile R16 (or OKL-R16) is located
to the west of V601.
The first survey to cover the entire length between Fort Walton Beach (FDEP beach profile R1)
and the Okaloosa/Walton County line (R50) was taken in March 1996. This date coincided with
the recovery period following Hurricane Opal (1995). The most recent survey covering all of the
same area was taken in July 2007. Accordingly, the time period selected for the new analysis
was from March 1996 to July 2007. Shoreline and volume changes during this period were
based on the following surveys:
•
The March 1996 survey, with additional data points on the landward end of each profile
supplied by the November 1995 beach survey. On profiles V611 to V622, the offshore
portion of the profile was based on the November 1996 LIDAR survey of East Pass.
•
The April 2004 LIDAR survey, with additional data points on the landward end of each
profile supplied by the June 2004 FDEP survey.
•
The July 2005 combined LIDAR and conventional survey, with additional data points on
the landward end of the Fort Walton Beach profiles (R1-R16) supplied by the November
2005 FDEP survey.
•
The July 2007 survey.
Except for the March 1996 survey, all of the surveys above contained data both above and below
wading depth on every profile. To provide an accurate representation of changes near the dunes,
the March 1996, April 2004, and July 2005 surveys were merged with additional survey data as
8
described above. To evaluate changes within East Pass itself, additional hydrographic surveys
were provided by the U.S. Army Corps Mobile District (CESAM) and FDEP (Table 2-2B):
TABLE 2-2B
ADDITIONAL HYDROGRAPHIC AND TOPOGRAPHIC SURVEYS OF EAST PASS
Date
Source
Location
4/2009
1/2009
11/2008
8/2008
7/2008
1/2008
9/2007
7/2007
5/2006
2/2006
7/2005
3/2004
1995
CESAM
CPE
CESAM
CESAM
Morgan & Ecklund
CESAM
Morgan & Ecklund
CESAM
CESAM
Morgan & Ecklund
CESAM
CESAM
USGS
East Pass Channel
Norriego Point and East Pass
East Pass Channel
East Pass Channel
East Pass Ebb Shoal
East Pass Channel
East Pass Ebb Shoal
East Pass Channel and Destin Harbor
USCG Station Channel
East Pass Ebb Shoal
Land Digital Elevation Models (14) of Okaloosa and Walton Counties
In addition the various surveys above, aerial photographs were used to identify large-scale
changes at East Pass. Images used in the analysis are listed in Table 2-3:
TABLE 2-3
AERIAL PHOTOGRAPHS OF EAST PASS
Date
10/1991
1/1994
10/1995
1/1999
2/2004
2/2007
Source
Inlets Online
FDEP-LABINS
Inlets Online
FDEP-LABINS
FDEP-LABINS
FDEP
Original Geo-referencing
None
Florida Albers NAD83 meters
None
Florida State Plane North Zone, NAD83 feet
An extensive amount of beach fill, dune fill, and dredge spoil has been placed on the study area’s
beaches. The largest projects are the Walton County / Destin Beach Restoration and the
navigational dredging at East Pass (Table 2-1). However, there have also been a number of
storm recovery projects using trucked fill. The primary sources for information regarding beach
fill, dune fill, and dredge spoil are:
•
The responses for the first Request for Additional Information for the Destin East Pass
Maintenance Dredging and Disposal permit application filed with FDEP (0288799-001JC, Okaloosa County). This source tabulates the maintenance dredging volumes from
East Pass between 1986 and 2008 (see Table 2-1).
•
The Walton County / Destin Beach Restoration Project 2007 monitoring report (Bridges,
Trudnak, and Krecic, 2008).
9
•
The Strategic Beach Management Plan for the Panhandle Gulf Coast Region (FDEP,
2008). This source lists the approximate locations and volumes for the various beach
nourishment and storm recovery projects along the study area (Table 2-4).
•
Arnouil, D., and Trudnak, M., 2009. Walton County/Destin Beach Restoration Project,
Walton County and Okaloosa County, Florida, 2009 Two-Year Post-Construction
Monitoring Report, Taylor Engineering, Inc., 68 p. plus appendices.
TABLE 2-4
STORM RECOVERY AND
BEACH RESTORATION PROJECTS
FORT WALTON BEACH TO DESTIN, FL
(FDEP, 2008; BRIDGES, ET. AL, 2008)
PROJECT
Post-Georges, October 1998
Post-Georges, October 1998
Post-2004 Hurricane
FEMA Berm Repair
May 2005 Dune Construction
Spring 2006 Placement of Dredge
Spoil from East Pass
May 2006 FEMA Post Storm Berm
Repair and Dune Restoration
Walton County / Destin Beach
Restoration (1/23/2006 to 6/25/2007)
APPROX.
LOCATION
APPROX.
LENGTH
(feet)
VOLUME
(c.y.)
R1-R15
R39-R50
14,984
11,011
Unknown
Unknown
AVERAGE
FILL
DISTRIB.
(c.y./foot)
7*
7*
R1-R15
14,984
Unknown
7*
R1-R15
14,984
Unknown
7*
R17-R22
4,997
50,000
10.0
R39-R50
11,011
Unknown
7*
R39-R50
11,011
844,700
76.7
NOTES: *Volumes for these projects could not be located. The average fill distribution is based on typical values for
post-storm dune and berm repair projects in Florida.
For the majority of projects in Table 2-4, detailed fill volumes could not be located. In these
cases, a fill distribution of 7 c.y./foot was assumed. This value was an average value based on
the typical values for post-storm dune and berm repair projects in Florida.
2.3
Shoreline Changes
Gulf-front shoreline changes were estimated by locating the position of the mean high water line
(+0.84’ NAVD, NOAA, 2003) during each survey (Table 2-5). Over the 1996-2007 study
period, the largest retreat (189 to 282 feet) within the study area (R1-R50) occurred at profiles
R17 and R18 (Destin Pointe). The largest advances (128-138 feet) occurred at profiles R41
(Woodward Street), R41.5 (Hutchinson Street), and R43 (Barracuda Street), which were located
in the Walton County / Destin Beach Restoration project area. Aside from these locations, the
largest advance (126 feet) took place near profile V620, just west of the inlet. Although V620
was located inside the Nearshore Disposal Area for East Pass, no dredge spoil was placed in the
nearshore disposal area between 1996 and 2007 (see Table 2-1).
10
TABLE 2-5
SURVEYED SHORELINE CHANGES – FORT WALTON BEACH TO DESTIN, FL
(not adjusted for beach or dune fill)
Profile
Line
OKL-R1
OKL-R2
OKL-R3
OKL-R4
OKL-R5
OKL-R6
OKL-R7
OKL-R8
OKL-R9
OKL-R10
OKL-R11
OKL-R12
OKL-R13
OKL-R14
OKL-R15
OKL-R16
OKL-V601
OKL-V602
OKL-V603
OKL-V604
OKL-V605
OKL-V606
OKL-V607
OKL-V608
OKL-V609
OKL-V610
OKL-V611
OKL-V612
OKL-V613
OKL-V614
OKL-V615
OKL-V616
OKL-V617
OKL-V618
OKL-V619
OKL-V620
OKL-V621A
OKL-V622
AVG.
Beach
Length
(feet)
Shoreline Retreat (-feet) & Advance (+feet)
3/1996
4/2004
7/2005
3/1996
to
to
to
to
4/2004
7/2005
7/2007
7/2007
504
1,079
1,129
1,098
1,065
1,063
1,075
1,079
1,061
1,020
1,049
1,088
1,073
1,065
970
931
990
988
988
988
988
988
988
988
988
988
994
998
996
996
996
996
996
996
996
996
747
249
27.6
-34.4
29.3
-7.8
-4.5
31.6
11.4
-15.5
32.1
-12.7
-37.2
-2.9
11.2
-8.8
45.5
-9.3
-1.7
-0.4
-19.1
2.8
-39.8
6.9
-29.3
50.3
-48.3
14.9
-1.4
-66.3
19.4
-93.9
31.2
-1.4
3.3
-77.4
-23.2
41.7
-13.1
1.5
-83.9
-37.1
-81.4
-50.4
-32.5
-27.3
-38.9
-9.3
-35.6
8.6
-34.0
-23.3
-28.9
-19.1
-86.0
-39.9
-53.2
-102.2
-67.3
-86.3
-73.5
-65.4
-16.4
13.6
13.9
-27.3
6.0
4.5
-41.0
26.1
-131.6
-42.0
-17.4
78.6
114.3
22.5
-33.3
-4.6
-51.7
-54.8
4.0
-57.6
-37.6
-51.0
-67.8
-83.9
-58.5
-71.9
-11.8
-37.5
-3.9
14.4
-5.0
8.8
49.4
59.1
17.8
17.4
29.0
-52.1
-42.1
-48.5
-85.6
-43.2
-94.2
-51.0
16.9
-38.1
18.4
20.9
-25.0
-96.5
-74.2
61.6
44.0
72.0
-108.0
-126.3
-48.1
-115.8
-74.5
-46.8
-95.3
-108.7
-62.0
-76.0
-83.0
-63.7
-21.6
-13.4
-45.5
-40.5
-5.5
-43.5
-68.5
-66.1
-84.3
-110.7
-87.7
15.4
-120.0
-55.6
-89.6
-112.9
-4.8
-105.9
-82.1
-22.6
-39.1
-95.2
16.9
125.8
-2.5
68.9
37,188
-5.3
-28.8
-23.7
-57.9
11
TABLE 2-5 (continued)
Profile
Line
OKL-R17
OKL-R18
OKL-R19
OKL-R20
OKL-R21
OKL-R22
OKL-R23
OKL-R24
OKL-R25
OKL-R26
OKL-R27
OKL-R28
OKL-R29
OKL-R30
OKL-R31
OKL-R32
OKL-R33
OKL-R34
OKL-R35
OKL-R36
OKL-R37
OKL-R38
OKL-R39
Beach
Length
(feet)
357
911
1,033
1,064
1,109
1,008
915
1,070
1,148
1,073
1,034
997
1,156
1,163
961
957
1,013
976
963
1,022
1,073
1,096
680
3/1996
4/2004
7/2005
3/1996
to
to
to
to
4/2004
7/2005
7/2007
7/2007
-107.4
-77.1
45.5
-13.2
-16.9
-12.7
-25.0
-4.6
12.2
79.0
-23.7
3.7
16.4
12.5
18.9
14.1
-21.5
6.1
-71.6
-3.0
20.0
-15.3
-7.1
-153.1
-162.8
-74.5
-33.3
3.3
-22.3
2.7
-71.6
-20.4
-58.1
-14.2
-29.0
-16.9
-32.9
-8.9
-35.4
-35.0
-49.8
-27.4
-1.3
3.9
0.4
-9.1
12
71.1
-42.1
-62.5
-59.2
-47.0
-23.2
-40.0
33.7
-57.8
-47.1
-24.5
-37.8
-17.2
-18.0
-86.9
-10.8
-35.2
-10.5
6.2
-70.3
-27.1
-52.8
56.8
-189.4
-282.0
-91.5
-105.8
-60.7
-58.2
-62.3
-42.5
-65.9
-26.2
-62.4
-63.0
-17.7
-38.3
-76.9
-32.1
-91.7
-54.3
-92.9
-74.6
-3.2
-67.7
40.6
Profile
Line
OKL-R39.5
OKL-R40
OKL-R40.5
OKL-R41
OKL-R41.5
OKL-R42
OKL-R42.5
OKL-R43
OKL-R43.5
OKL-R44
OKL-R44.5
OKL-R45
OKL-R45.5
OKL-R46
OKL-R46.5
OKL-R47
OKL-R47.5
OKL-R48
OKL-R48.5
OKL-R49
OKL-R49.5
OKL-R50
R17-R50
AVG.
2.4
Beach
Length
(feet)
3/1996
4/2004
7/2005
3/1996
to
to
to
to
4/2004
7/2005
7/2007
7/2007
301
520
660
581
488
485
483
498
471
486
543
567
573
515
473
489
530
520
482
492
499
248
-19.9
-41.7
-13.5
42.9
28.9
19.9
9.0
16.8
6.2
-46.7
-45.2
4.9
-3.2
-3.2
-20.3
-3.5
-1.2
-7.0
22.6
29.0
9.6
-17.1
-6.6
2.2
-18.5
-15.0
-18.7
8.6
-18.7
4.3
-23.0
-43.6
-8.2
-33.5
-28.9
-28.9
-6.0
-1.9
12.3
5.2
-27.8
-52.1
-34.4
1.7
77.6
110.5
135.9
110.4
118.1
89.8
133.1
107.3
101.2
137.6
113.6
101.7
104.9
104.7
123.1
126.5
99.5
100.8
110.4
134.5
132.6
119.7
51.1
71.0
103.9
138.3
128.3
118.3
123.3
128.4
84.4
47.3
60.2
73.1
72.8
72.6
96.8
121.1
110.6
99.0
105.2
111.4
107.8
104.3
33,686
-2.7
-27.4
16.4
-13.7
Volume Changes along the Gulf-Front Beaches
Volume changes were evaluated using the following methods:
•
The April 2004 LIDAR survey was used in the volume change estimates. However,
when compared to other surveys, the April 2004 LIDAR survey exhibited closure
problems offshore. To correct this problem, the offshore section of each 2004 profile was
shifted upward, to bring it into consistency with March 1996, July 2005, and July 2007
surveys. The average shift was approximately 1 foot. The vertical accuracy of the other
beach and inlet surveys was assumed to be sufficient for volumetric change estimates.
13
•
On profiles V601 to V610, direct volume change estimates were calculated using BMAP
for the following periods: 2004-2005 and 2005-2007. Based on the sections of each
profile used for these estimates, the active profile depth along the V- profiles averaged
-24 feet NAVD. Berm elevations, based on the April 2004 survey, averaged +4 feet
NAVD. Since offshore profile data was not available, approximate volume changes
between 1996 and 2004 were then estimated using the average active profile depth (-24
feet NAVD), the average berm elevation (+4 feet), and the corresponding shoreline
changes in Table 2. The total volume change between 1996 and 2007 was then estimated
as the sum of the changes during the 3 shorter periods – 1996-2004, 2004-2005, and
2005-2007.
•
On all other profiles, direct volume change estimates were calculated using Beach
Morphology Analysis Package (BMAP, Sommerfeld, et al., 1994) for the following
periods: 1996-2004, 2005-2007, 1996-2007, and 2007-2009 (V611 to V621, see
Appendix A). Volume changes between 2004 and 2005 were calculated based on the
other 3 estimates. The visual plotting capabilities in BMAP were used to identify the
changes that were representative of the erosion and accretion patterns on the beach.
Changes due to survey uncertainty were excluded, along with anomalous changes in the
deeper sections of the profile (i.e. below -45 to -55 feet NAVD). Based on the sections of
each profile used for these estimates (Attachment A), the active profile depth averaged 36 feet NAVD along Fort Walton Beach (R1 to R16), -24 feet NAVD on profiles V611
to V621, -44 feet NAVD along western Destin (R17 to R38), and -51 feet NAVD in the
Walton County / Destin Beach Restoration project area (R39 to R50).
Further details regarding the volumetric change estimates appear in Appendix B.
Except along Eglin Air Force Base (V601 to V622), estimates for the active profile depth, or
depth of closure, were generally deeper than previous estimates (-31 feet NAVD, Taylor, 2007,
p. 49). This finding was probably due to the influence of the Hurricanes Earl (1998), Georges
(1998), Ivan (2004), Dennis (2005), and Katrina (2005), along with other storm events. These
storms brought higher waves to the region than earlier storm events. In particular, a 52 foot
wave was observed south of Mobile, AL (NOAA Buoy 42040) during Hurricane Ivan. Along
Eglin Air Force Base (V601 to V622), the depth of closure (-24 feet NAVD) was shallower than
the other estimates, most likely due to the presence of the extensive East Pass ebb shoal.
Volume changes by profile line appear in Table 2-6.
Along the majority of the study area, the shoreline changes between April 2004 and July 2005
were characterized by retreat, but the volume changes appeared to be characterized by accretion,
even with the adjustments described above. This finding was somewhat unexpected, and
occurred on both the R- profiles and the V- profiles. It was certainly plausible that during Ivan,
the onshore-offshore movement of sediment was the primary sediment transport process. In that
case, one would expect retreat in most locations accompanied by a volume change near 0.0
c.y./foot. However, on the majority of the profiles, there appeared to be accretion between April
2004 and July 2005. This result could have been due to either a natural process or offshore
closure survey problems.
14
TABLE 2-6
VOLUME CHANGES (not adjusted for beach or dune fill)
Profile
Line
OKL-R1
OKL-R2
OKL-R3
OKL-R4
OKL-R5
OKL-R6
OKL-R7
OKL-R8
OKL-R9
OKL-R10
OKL-R11
OKL-R12
OKL-R13
OKL-R14
OKL-R15
OKL-R16
OKL-V601
OKL-V602
OKL-V603
OKL-V604
OKL-V605
OKL-V606
OKL-V607
OKL-V608
OKL-V609
OKL-V610
OKL-V611
OKL-V612
OKL-V613
OKL-V614
OKL-V615
OKL-V616
OKL-V617
OKL-V618
OKL-V619
OKL-V620
OKL-V621A
OKL-V622
AVG.
Beach
Length
(feet)
Erosion (-c.y./foot) & Accretion (+c.y./foot)
3/1996
4/2004
7/2005
3/1996
to
to
to
to
4/2004
7/2005
7/2007
7/2007
504
1,079
1,129
1,098
1,065
1,063
1,075
1,079
1,061
1,020
1,049
1,088
1,073
1,065
970
931
990
988
988
988
988
988
988
988
988
988
994
998
996
996
996
996
996
996
996
996
747
249
24.7
-52.6
-12.5
-35.1
-15.0
14.2
-10.3
-9.1
-6.5
-26.7
-11.4
-6.5
-20.7
-17.5
77.1
-0.6
-1.8
-0.4
-19.8
2.9
-41.3
7.1
-30.3
52.2
-50.0
15.4
-7.5
-20.4
23.6
-19.3
23.8
-11.6
23.5
-34.5
7.2
92.3
29.9
-66.4
-30.9
2.2
8.4
7.9
12.3
29.3
-6.9
44.7
12.2
66.3
25.5
77.3
14.1
55.0
-69.8
24.7
-29.3
-29.0
-29.2
-28.0
-26.8
-25.5
-25.6
-25.8
-24.9
-17.2
0.5
61.0
1.0
57.7
-11.5
76.1
19.4
23.9
64.5
42.4
46.0
62.6
14.5
1.4
18.3
-5.4
21.2
24.0
-31.4
-51.7
-20.4
-31.9
-4.3
-35.9
10.9
13.9
-3.9
-12.1
21.4
-6.6
-31.9
42.2
9.2
-41.3
4.0
11.9
-40.5
23.8
-33.6
-5.7
4.6
-41.6
2.1
-9.3
-10.5
-22.2
-30.5
78.3
-10.8
78.3
8.3
-49.0
14.2
-32.6
18.6
67.5
-48.6
-16.2
-14.7
7.7
9.8
34.8
4.4
51.4
3.3
11.9
-9.7
-36.0
-80.9
17.1
-58.9
-59.7
-52.0
38.3
-115.4
22.0
-40.6
35.0
29.1
-3.2
14.4
55.2
32.3
-32.8
41.2
212.9
65.2
74.5
37,188
-3.3
11.7
-4.5
3.9
15
VOLUME CHANGES
Profile
Line
OKL-R17
OKL-R18
OKL-R19
OKL-R20
OKL-R21
OKL-R22
OKL-R23
OKL-R24
OKL-R25
OKL-R26
OKL-R27
OKL-R28
OKL-R29
OKL-R30
OKL-R31
OKL-R32
OKL-R33
OKL-R34
OKL-R35
OKL-R36
OKL-R37
OKL-R38
OKL-R39
Beach
Length
(feet)
357
911
1,033
1,064
1,109
1,008
915
1,070
1,148
1,073
1,034
997
1,156
1,163
961
957
1,013
976
963
1,022
1,073
1,096
680
3/1996
4/2004
7/2005
3/1996
to
to
to
to
4/2004
7/2005
7/2007
7/2007
-93.9
-60.8
-67.4
-60.4
-50.5
-33.3
-45.8
-62.0
-31.1
21.7
11.2
-46.5
19.8
-49.3
23.9
-59.3
-6.6
-30.3
-79.2
-16.1
-10.2
-8.5
7.5
-49.8
-150.5
-17.8
13.5
47.7
22.1
50.1
7.2
11.5
-22.3
74.9
43.9
24.7
29.8
8.0
60.7
23.8
24.5
47.4
62.9
18.9
38.8
-46.0
16
43.0
-67.4
-51.5
-21.8
6.3
-25.9
-1.4
26.9
-11.1
-9.9
-11.0
-6.1
33.5
3.3
-16.0
-17.4
-2.1
13.8
7.4
-30.9
10.7
-28.1
55.2
-100.7
-278.6
-136.8
-68.7
3.5
-37.2
2.9
-27.8
-30.7
-10.5
75.1
-8.7
78.0
-16.2
15.8
-16.0
15.1
8.0
-24.5
15.9
19.4
2.2
16.7
VOLUME CHANGES
Profile
Line
OKL-R39.5
OKL-R40
OKL-R40.5
OKL-R41
OKL-R41.5
OKL-R42
OKL-R42.5
OKL-R43
OKL-R43.5
OKL-R44
OKL-R44.5
OKL-R45
OKL-R45.5
OKL-R46
OKL-R46.5
OKL-R47
OKL-R47.5
OKL-R48
OKL-R48.5
OKL-R49
OKL-R49.5
OKL-R50
R17-R50
AVG.
Beach
Length
(feet)
3/1996
4/2004
7/2005
3/1996
to
to
to
to
4/2004
7/2005
7/2007
7/2007
301
520
660
581
488
485
483
498
471
486
543
567
573
515
473
489
530
520
482
492
499
248
-58.9
-94.9
-56.0
55.5
2.3
-51.0
-22.2
6.8
-22.1
-46.4
-34.2
-21.8
-22.7
-23.5
-42.0
-60.5
-31.0
1.6
3.5
5.3
-15.7
-36.4
7.8
19.7
31.2
-27.5
11.8
51.3
33.5
15.5
16.0
16.5
36.7
57.0
26.4
-2.4
37.4
77.4
67.2
55.9
19.1
-17.6
1.8
21.0
58.6
65.1
67.3
69.6
50.3
31.0
50.9
71.0
68.2
65.8
59.3
52.7
72.4
91.0
82.2
73.4
60.4
46.1
58.9
71.8
92.5
113.0
7.5
-10.1
42.5
97.6
64.5
31.3
62.2
93.2
62.1
35.9
61.8
87.9
76.2
65.1
77.7
90.4
96.6
103.6
81.5
59.5
78.7
97.7
33,686
-28.2
20.2
17.2
9.2
17
VOLUME CHANGES
Profile
Line
OKL-R39.5
OKL-R40
OKL-R40.5
OKL-R41
OKL-R41.5
OKL-R42
OKL-R42.5
OKL-R43
OKL-R43.5
OKL-R44
OKL-R44.5
OKL-R45
OKL-R45.5
OKL-R46
OKL-R46.5
OKL-R47
OKL-R47.5
OKL-R48
OKL-R48.5
OKL-R49
OKL-R49.5
OKL-R50
R17-R50
AVG.
Beach
Length
(feet)
3/1996
4/2004
7/2005
3/1996
to
to
to
to
4/2004
7/2005
7/2007
7/2007
301
520
660
581
488
485
483
498
471
486
543
567
573
515
473
489
530
520
482
492
499
248
-58.9
-94.9
-56.0
55.5
2.3
-51.0
-22.2
6.8
-22.1
-46.4
-34.2
-21.8
-22.7
-23.5
-42.0
-60.5
-31.0
1.6
3.5
5.3
-15.7
-36.4
7.8
19.7
31.2
-27.5
11.8
51.3
33.5
15.5
16.0
16.5
36.7
57.0
26.4
-2.4
37.4
77.4
67.2
55.9
19.1
-17.6
1.8
21.0
58.6
65.1
67.3
69.6
50.3
31.0
50.9
71.0
68.2
65.8
59.3
52.7
72.4
91.0
82.2
73.4
60.4
46.1
58.9
71.8
92.5
113.0
7.5
-10.1
42.5
97.6
64.5
31.3
62.2
93.2
62.1
35.9
61.8
87.9
76.2
65.1
77.7
90.4
96.6
103.6
81.5
59.5
78.7
97.7
33,686
-28.2
20.2
17.2
9.2
Due to the unexpected results for the volume changes between 2004 and 2005, the primary focus
of this analysis was the volume changes between 1996 and 2007. Closure between surveys on
the R- profiles was more reasonable using the 1996 and 2007 profiles. On the V- profiles, the 11
year study period was long enough to reduce offshore closure problems regarding the 2004 and
2005 surveys.
To determine adjusted rates of volume change, the dredged and trucked fill distributions in
Tables 2-1 and 2-4 were subtracted from the volume changes in Table 3. For example, the
surveyed volume change on profile R20 was -69 c.y./foot between 1996 and 2007. By removing
the approximately 10 c.y./foot of dredge spoil placed in 2006, the total adjusted volume change
become -79 c.y./foot. The resulting volume changes appear in Figures 2-2 and 2-3 and Table 27.
18
\\CPE-GIS\Projects\Okaloosa\1050000 Destin IMP Update\ENGINEERING\Beach_Profiles\Destin_1996_to_2007_Shoreline_and_Volume_Changes.xls SUM2007 12/9/2009 11:28 AM
TABLE 2-7
ADJUSTED SHORELINE AND VOLUME CHANGES
Profile
Line
Beach
Length
(feet)
3/1996 to 7/2007
Surveyed Changes
Shorelines
Volumes
(feet)
(c.y./foot)
3/1996 to 7/2007
Fill & Dredge Spoil
Volumes
Equiv. Width
(feet)
(c.y./foot)
3/1996 to 7/2007
Adjusted Changes
Shorelines
Volumes
(feet)
(c.y./foot)
Profile
Lines
Beach
Length
(feet)
March 1996 to June 2007 Volume Changes
(cubic yards)
Surveyed
Fill & Dredge
Adjusted
Spoil
OKL-R1
OKL-R2
OKL-R3
OKL-R4
OKL-R5
OKL-R6
OKL-R7
OKL-R8
OKL-R9
504
1,079
1,129
1,098
1,065
1,063
1,075
1,079
1,061
-108.0
-126.3
-48.1
-115.8
-74.5
-46.8
-95.3
-108.7
-62.0
8.3
-49.0
14.2
-32.6
18.6
67.5
-48.6
-16.2
-14.7
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
21.0
21.0
21.0
21.0
21.0
21.0
21.0
21.0
21.0
-122.2
-140.5
-62.3
-129.9
-88.7
-60.9
-109.5
-122.9
-76.1
-12.7
-70.0
-6.8
-53.6
-2.4
46.5
-69.6
-37.2
-35.7
R1 to R2
R2 to R3
R3 to R4
R4 to R5
R5 to R6
R6 to R7
R7 to R8
R8 to R9
R9 to R10
1,008
1,150
1,109
1,088
1,043
1,083
1,068
1,091
1,030
-20,500
-20,000
-10,200
-7,600
44,900
10,200
-34,600
-16,900
-3,600
21,200
24,200
23,300
22,800
21,900
22,700
22,400
22,900
21,600
-41,700
-44,200
-33,500
-30,400
23,000
-12,500
-57,000
-39,800
-25,200
OKL-R10
OKL-R11
OKL-R12
OKL-R13
OKL-R14
OKL-R15
1,020
1,049
1,088
1,073
1,065
970
-76.0
-83.0
-63.7
-21.6
-13.4
-45.5
7.7
9.8
34.8
4.4
51.4
3.3
14.2
14.2
14.2
14.2
14.2
14.2
21.0
21.0
21.0
21.0
21.0
21.0
-90.2
-97.1
-77.8
-35.7
-27.6
-59.7
-13.3
-11.2
13.8
-16.6
30.4
-17.7
R10 to R11
R11 to R12
R12 to R13
R13 to R14
R14 to R15
R15 to R16
1,010
1,089
1,087
1,060
1,069
871
8,800
24,200
21,300
29,600
29,300
6,600
21,200
22,900
22,800
22,300
22,400
0
-12,400
1,300
-1,500
7,300
6,900
6,600
931
990
988
988
988
988
988
988
988
988
988
734
-40.5
-5.5
-43.5
-68.5
-66.1
-84.3
-110.7
-87.7
15.4
-120.0
-55.6
-89.6
11.9
-9.7
-36.0
-80.9
17.1
-58.9
-59.7
-52.0
38.3
-115.4
22.0
-40.6
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
-40.5
-5.5
-43.5
-68.5
-66.1
-84.3
-110.7
-87.7
15.4
-120.0
-55.6
-89.6
11.9
-9.7
-36.0
-80.9
17.1
-58.9
-59.7
-52.0
38.3
-115.4
22.0
-40.6
R16 to V601
V601 to V602
V602 to V603
V603 to V604
V604 to V605
V605 to V606
V606 to V607
V607 to V608
V608 to V609
V609 to V610
V610 to V611
V611 to V611+480
992
988
988
988
988
988
988
988
988
988
988
480
1,100
-22,600
-57,700
-31,500
-20,600
-58,500
-55,100
-6,700
-38,100
-46,100
-9,200
-10,800
0
0
0
0
0
0
0
0
0
0
0
0
1,100
-22,600
-57,700
-31,500
-20,600
-58,500
-55,100
-6,700
-38,100
-46,100
-9,200
-10,800
OKL-R16
OKL-V601
OKL-V602
OKL-V603
OKL-V604
OKL-V605
OKL-V606
OKL-V607
OKL-V608
OKL-V609
OKL-V610
OKL-V611
P:\Okaloosa\1050000 Destin IMP Update\ENGINEERING\Beach_Profiles\Destin_1996_to_2007_Shoreline_and_Volume_Changes.xls SUM2007 1/20/2010 2:09 PM
Profile
Line
Beach
Length
(feet)
3/1996 to 7/2007
Surveyed Changes
Shorelines
Volumes
(feet)
(c.y./foot)
3/1996 to 7/2007
Fill & Dredge Spoil
Volumes
Equiv. Width
(feet)
(c.y./foot)
3/1996 to 7/2007
Adjusted Changes
Shorelines
Volumes
(feet)
(c.y./foot)
Profile
Lines
Beach
Length
(feet)
(cubic yards)
Surveyed
Fill & Dredge
Adjusted
Spoil
V611+480
OKL-V612
OKL-V613
OKL-V614
OKL-V615
OKL-V616
OKL-V617
OKL-V618
OKL-V619
500
758
996
996
996
996
996
996
716
-100.8
-112.9
-4.8
-105.9
-82.1
-22.6
-39.1
-95.2
16.9
-4.3
35.0
29.1
-3.2
14.4
55.2
32.3
-32.8
41.2
48.2
48.2
48.2
48.2
48.2
48.2
48.2
48.2
48.2
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
50.0
-149.0
-161.1
-53.0
-154.0
-130.2
-70.7
-87.3
-143.4
-31.3
-54.3
-15.0
-20.9
-53.2
-35.5
5.2
-17.6
-82.8
-8.8
V611+480 to V612
V612 to V613
V613 to V614
V614 to V615
V615 to V616
V616 to V617
V617 to V618
V618 to V619
V619 to V619+435
520
996
996
996
996
996
996
996
435
8,000
31,900
12,900
5,600
34,700
43,600
-300
4,200
34,200
26,000
49,800
49,800
49,800
49,800
49,800
49,800
49,800
21,700
-18,000
-17,900
-36,900
-44,200
-15,100
-6,200
-50,100
-45,600
12,500
V619+435
OKL-V620
OKL-V621A
OKL-V622
498
779
747
249
64.4
125.8
-2.5
68.9
116.2
212.9
65.2
74.5
48.2
0.0
0.0
0.0
50.0
0.0
0.0
0.0
16.3
125.8
-2.5
68.9
66.2
212.9
65.2
74.5
V619+435 to V620
V620 to V621A
V621A to V622
561
996
499
92,300
138,500
34,800
0
0
0
92,300
138,500
34,800
AVERAGE /
TOTAL
37,188
-57.9
3.9
16.8
20.1
-74.7
-16.1
TOTAL
37,188
146,100
710,900
-564,800
Profile
Line
Beach
Length
(feet)
3/1996 to 7/2007
Surveyed Changes
Shorelines
Volumes
(feet)
(c.y./foot)
3/1996 to 7/2007
Fill & Dredge Spoil
Volumes
Equiv. Width
(feet)
(c.y./foot)
3/1996 to 7/2007
Adjusted Changes
Shorelines
Volumes
(feet)
(c.y./foot)
Profile
Lines
Beach
Length
(feet)
(cubic yards)
Surveyed
Fill & Dredge
Adjusted
Spoil
OKL-R17
OKL-R18
OKL-R19
OKL-R20
OKL-R21
OKL-R22
OKL-R23
OKL-R24
OKL-R25
OKL-R26
357
911
1,033
1,064
1,109
1,008
915
1,070
1,148
1,073
-189.4
-282.0
-91.5
-105.8
-60.7
-58.2
-62.3
-42.5
-65.9
-26.2
-100.7
-278.6
-136.8
-68.7
3.5
-37.2
2.9
-27.8
-30.7
-10.5
5.6
5.6
5.6
5.6
5.6
5.6
0.0
0.0
0.0
0.0
10.0
10.0
10.0
10.0
10.0
10.0
0.0
0.0
0.0
0.0
-195.0
-287.6
-97.1
-111.4
-66.3
-63.8
-62.3
-42.5
-65.9
-26.2
-110.7
-288.6
-146.8
-78.7
-6.5
-47.2
2.9
-27.8
-30.7
-10.5
R17 to R18
R18 to R19
R19 to R20
R20 to R21
R21 to R22
R22 to R23
R23 to R24
R24 to R25
R25 to R26
R26 to R27
714
1,108
958
1,170
1,047
968
862
1,278
1,018
1,128
-135,400
-230,000
-98,400
-38,100
-17,600
-16,600
-10,700
-37,400
-20,900
36,500
7,100
11,100
9,600
11,700
10,500
0
0
0
0
0
-142,500
-241,100
-108,000
-49,800
-28,100
-16,600
-10,700
-37,400
-20,900
36,500
OKL-R27
OKL-R28
OKL-R29
OKL-R30
OKL-R31
OKL-R32
1,034
997
1,156
1,163
961
957
-62.4
-63.0
-17.7
-38.3
-76.9
-32.1
75.1
-8.7
78.0
-16.2
15.8
-16.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
-62.4
-63.0
-17.7
-38.3
-76.9
-32.1
75.1
-8.7
78.0
-16.2
15.8
-16.0
R27 to R28
R28 to R29
R29 to R30
R30 to R31
R31 to R32
R32 to R33
939
1,054
1,258
1,069
854
1,061
31,200
36,600
38,900
-200
-100
-500
0
0
0
0
0
0
31,200
36,600
38,900
-200
-100
-500
OKL-R33
OKL-R34
OKL-R35
OKL-R36
OKL-R37
OKL-R38
1,013
976
963
1,022
1,073
1,096
-91.7
-54.3
-92.9
-74.6
-3.2
-67.7
15.1
8.0
-24.5
15.9
19.4
2.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
-91.7
-54.3
-92.9
-74.6
-3.2
-67.7
15.1
8.0
-24.5
15.9
19.4
2.2
R33 to R34
R34 to R35
R35 to R36
R36 to R37
R37 to R38
R38 to R39
966
986
939
1,106
1,039
1,153
11,200
-8,100
-4,000
19,500
11,200
10,900
0
0
0
0
0
0
11,200
-8,100
-4,000
19,500
11,200
10,900
Profile
Line
Beach
Length
(feet)
3/1996 to 7/2007
Surveyed Changes
Shorelines
Volumes
(feet)
(c.y./foot)
3/1996 to 7/2007
Fill & Dredge Spoil
Volumes
Equiv. Width
(feet)
(c.y./foot)
3/1996 to 7/2007
Adjusted Changes
Shorelines
Volumes
(feet)
(c.y./foot)
Profile
Lines
Beach
Length
(feet)
(cubic yards)
Surveyed
Fill & Dredge
Adjusted
Spoil
OKL-R39
OKL-R39.5
OKL-R40
OKL-R40.5
OKL-R41
OKL-R41.5
OKL-R42
OKL-R42.5
OKL-R43
OKL-R43.5
OKL-R44
OKL-R44.5
680
301
520
660
581
488
485
483
498
471
486
543
40.6
51.1
71.0
103.9
138.3
128.3
118.3
123.3
128.4
84.4
47.3
60.2
16.7
7.5
-10.1
42.5
97.6
64.5
31.3
62.2
93.2
62.1
35.9
61.8
68.3
68.8
69.3
76.9
84.5
51.8
19.1
28.3
37.6
36.0
34.3
29.8
139.0
140.1
141.2
156.6
172.1
105.5
38.9
57.7
76.6
73.2
69.9
60.7
-27.7
-17.7
1.7
27.0
53.8
76.5
99.2
95.0
90.8
48.4
13.0
30.4
-122.3
-132.7
-151.4
-114.1
-74.5
-41.0
-7.6
4.4
16.7
-11.2
-34.1
1.1
R39 to R39.5
R39.5 to R40
R40 to R40.5
R40.5 to R41
R41 to R41.5
R41.5 to R42
R42 to R42.5
R42.5 to R43
R43 to R43.5
R43.5 to R44
R44 to R44.5
R44.5 to R45
207
395
646
675
487
489
481
484
512
430
542
545
2,500
-500
10,500
47,300
39,500
23,400
22,500
37,600
39,700
21,100
26,400
40,800
28,900
55,500
96,200
110,900
67,600
35,300
23,300
32,500
38,300
30,800
35,400
30,600
-26,400
-56,000
-85,700
-63,600
-28,100
-11,900
-800
5,100
1,400
-9,700
-9,000
10,200
OKL-R45
OKL-R45.5
OKL-R46
OKL-R46.5
OKL-R47
OKL-R47.5
OKL-R48
OKL-R48.5
OKL-R49
OKL-R49.5
OKL-R50
567
573
515
473
489
530
520
482
492
499
248
73.1
72.8
72.6
96.8
121.1
110.6
99.0
105.2
111.4
107.8
104.3
87.9
76.2
65.1
77.7
90.4
96.6
103.6
81.5
59.5
78.7
97.7
25.3
37.5
49.7
44.8
39.9
34.7
29.5
34.5
39.5
47.9
56.2
51.4
76.4
101.3
91.3
81.3
70.7
60.1
70.3
80.4
97.5
114.6
47.8
35.3
22.9
52.0
81.2
75.9
69.5
70.7
71.9
60.0
48.1
36.4
-0.2
-36.2
-13.6
9.0
25.9
43.5
11.3
-20.9
-18.8
-16.9
R45 to R45.5
R45.5 to R46
R46 to R46.5
R46.5 to R47
R47 to R47.5
R47.5 to R48
R48 to R48.5
R48.5 to R49
R49 to R49.5
R49.5 to R50
589
558
473
474
503
557
483
482
502
496
48,300
39,400
33,800
39,800
47,100
55,800
44,700
34,000
34,700
43,700
37,700
49,600
45,500
40,900
38,300
36,400
31,500
36,300
44,600
52,500
10,600
-10,200
-11,700
-1,100
8,800
19,400
13,200
-2,300
-9,900
-8,800
33,686
-13.7
9.2
16.6
33.7
-30.3
-24.5
TOTAL
33,686
310,100
1,048,600
-738,500
AVERAGE /
TOTAL
0
10,000
-300
+ ADVANCE /
ACCRETION
− RETREAT / EROSION
5,000
15,000
R31
R29
R27
R25
-250
-200
-150
-100
-50
0
50
100
Shoreline Changes (feet)
25,000
30,000
Changes have been adjusted to exclude beach & dune fill
placed between 1996 and 2007.
20,000
Distance from East Pass (feet)
N
P:\Okaloosa\1050000 Destin IMP Update\ENGINEERING\Beach_Profiles\Destin_1996_to_2007_Shoreline_and_Volume_Changes.xls plots_final 8/3/2010 5:23 PM
R43
R41
R39
R37
Volume Changes (c.y./foot)
R49
R47
R45
R35
R33
R23
R21
R19
R17
150
FIGURE 2-2: Shoreline and Volume Changes East of East Pass, Destin, FL.
N
35,000
-200
-150
-100
-50
0
50
100
− RETREAT / EROSION
25,000
20,000
150
V601
R15
R13
R11
200
FIGURE 2-3: Shoreline and Volume Changes West of East Pass, Destin, FL.
Shoreline Changes (feet)
15,000
10,000
+ ADVANCE / ACCRETION
Changes have been adjusted to exclude dredge spoil & dune
fill placed between 1996 and 2007.
30,000
V615
V613
V611
V609
Volume Changes (c.y./foot)
5,000
0
P:\Okaloosa\1050000 Destin IMP Update\ENGINEERING\Beach_Profiles\Destin_1996_to_2007_Shoreline_and_Volume_Changes.xls plots_final 8/3/2010 5:23 PM
V621A
V619
V617
V607
V605
V603
R9
R7
R5
R3
R1
250
After accounting for the projects in Tables 2-1 and 2-4, the highest erosion rates near East Pass
between 1996 and 2007 occurred on the east side of the inlet. Volume changes on the east side
of the inlet were characterized primarily by erosion, with the highest adjusted loss in the county
occurring near Destin Pointe (R18, 289 c.y./foot). Volume changes on the west side of the inlet
were also characterized by erosion at most locations, except at profiles V-620 to V-622. These
profiles located immediately west of the pass, experienced the highest adjusted gains in the
county, ranging from 65 to 213 c.y./foot.
2.5
Recent Evolution of Inlet
Changes to the East Pass Inlet complex itself are based on the aerial photographs and surveys in
Tables 2-2 through 2-3.
In October 1991, East Pass was characterized by healthy beaches on the eastern side of the inlet,
as shown in Figure 2-4. The large offset between the shorelines on the eastern and western sides
of the inlet was indicative of sediment transport from east to west along the Gulf-front shoreline.
The ebb shoal exhibited an elliptical shape, with the major axis oriented from north to south and
centered on the seaward tip of the west jetty. A slight bulge in the shoreline was located near
R17, close to the point at which the ebb shoal adjoined the beach east of the inlet. Bar and
trough systems were visible on both sides of the inlet, beginning 2,600 feet from the east jetty
3,500 feet from the west jetty. West of the inlet, a bar and trough system was visible, starting
approximately 3,500 feet from the west jetty. Within the inlet and the bay, the small groin fillets
on Norriego Point and the visible shoals suggested sediment transport in both the landward and
seaward directions.
The characteristics of East Pass in February 1994 were similar to those in 1991 (Figure 2-5).
However, small bulge in the shoreline had begun to develop near the point at which the ebb shoal
adjoined the beach west of the inlet. In addition, the bar and trough system on the both sides of
the inlet began at the ebb shoal, rather than a few thousand feet upcoast or downcoast.
In October 1995, Hurricane Opal made landfall near Pensacola. The conditions after this storm
appear in Figure 2-6. Opal’s most visible impact was the breach in Norriego Point, which
removed almost half the land area north of the East Pass Towers condominium. The other major
impact was a large amount of shoreline retreat. At profiles R17 to R19, approximately 135 to
166 feet of retreat occurred between February 1994 and November 1995. The shoreline bulges
visible in 1994 were gone. In addition, the ebb shoal began to assume a more triangular shape,
rather than elliptical shape visible in the 1991 and 1994 aerials.
Between October 1995 and January 1999, Tropical Storm Josephine (Oct. 1996), Hurricane
Danny (July 1997), Hurricane Earl (Sep. 1998) and Hurricane Georges (Sep. 1998) struck the
region. The conditions after these storms (Nov. 1998 to January 1999) appear in Figure 2-7. By
January 1999, the breach in Norriego Point had been closed, with the placement of 121,500 cubic
yards of dredge spoil from East Pass (Table 2-1). However, the northern end of Norriego Point
25
FIGURE 2-4: October 1991 Aerial Photograph of East Pass (Inlets Online, USACE, 1999).
26
FIGURE 2-5: February 1994 Aerial Photograph of East Pass (LABINS, 2004).
27
FIGURE 2-6: October 1995 Aerial Photograph of East Pass (Inlets Online, USACE, 1999).
28
was still narrow. West of the inlet, the November 1998 shoreline was characterized by a number
of small shoreline undulations. These undulations were concentrated between the west jetty and
profile V-617, and appeared to be transient, since they were not visible on the January 1999
aerial photograph. Typical lengths were on the order of 500 feet, with widths on the order of 80
feet. Given their locations, these undulations were probably associated with the transfer of
material from the ebb shoal into the bar and trough system beginning near profile V-617. East of
the inlet, the October 1995 to November 1998 shoreline changes on the Gulf-front beach were
small. The exception was an indentation in the November 1998 shoreline between the east jetty
and profile R17. This indentation also appeared to be a transient feature, since it was not visible
on the January 1999 aerial photograph. It may have been caused by the swash channel along the
same area, which was still visible in the January 1999 aerial photograph. Within East Pass itself,
the deepest part of the channel was located along the eastern side of the inlet.
The period between January 1999 and February-April 2004 was characterized by a number of
tropical storms and distant hurricanes. The most visible change between these dates (Figures 2-7
and 2-8) was the widening of Norriego Point, primarily through the placement of two T-head
groins, a rubble mound revetment, and 207,300 cubic yards of dredge spoil from East Pass
(Table 2-1). The other major change was a re-orientation of the shoreline east of the inlet.
Between profiles R17 and R18, the shore-parallel direction was from east to west, rather than
following the east-northeast to west-southwest orientation visible in the 1995 and 1999 aerials.
The reorientation of the shoreline led to a slight protrusion in the shoreline near profile R18.5.
Between 2004 and 2007, the Destin area experienced intense storm activity, which included
Hurricanes Ivan (2004), Dennis (2005), and Katrina (2005). During this period, the ebb shoal
became slightly longer (in the longshore direction) and slightly narrower (in the cross-shore
direction). However, the most visible change was the severe shoreline retreat east of the inlet,
which exhibited a maximum value of 205 feet profile R18 (Table 2-5). Much of this shoreline
retreat was associated with changes in the shoreline orientation (Figure 2-9). Between the east
jetty and profile R18, the shore-parallel direction changed from an east to west orientation to an
east-northeast to west-southwest orientation. Conversely, the shore-parallel direction between
profiles R18 and R23 began to change from an east-northeast to west-southwest orientation to
east to west orientation, flatting the shoreline protrusion near profile R18.5. As detailed in
Appendix A, these changes were partly due to the presence of a swash channel running between
East Pass and profile R19. West of the inlet, shoreline changes were characterized by advancing
shorelines between the west jetty and profile V-619. Shorelines in this area were due to the
filling of a slight indentation in the shoreline. Elsewhere, shoreline changes west of the inlet
were characterized by retreat. On Norriego Point, a large loss of land area occurred north of the
T-head groins.
Overall, the inlet’s changes since the 1990s were dominated by a slow reshaping of the ebb
shoal, hurricane-driven erosion on Norriego Point, the formation of swash channel east of the
inlet, and ongoing changes to the shoreline orientation, most notably along Holiday Isle (R17 to
R27). The ongoing changes to the shoreline orientation east of the inlet are responsible for the
severe retreat along that area. The primary cause of those changes appeared by the swash
channel east of the inlet and the extensive storm activity in 1995, 2004, and 2005.
29
30
31
FIGURE 2-9: February 2007 Aerial Photograph of East Pass (FDEP, 2009).
32
2.6
Volume Changes in East Pass
Volume changes in East Pass are based on the surveys in Tables 2-2A and 2-2B. To facilitate
the volume change estimates and the sediment budget development, East Pass is divided into 6
inlet cells, which appear in Figure 2-10. The cell boundaries are generally based on the disposal
area and the dredge cut boundaries in the permit sketches for the Destin East Pass Maintenance
Dredging and Disposal. The East Pass Ebb shoal cell encompasses the borrow area for the
Destin/Walton County Beach Restoration project, along with the area surveyed as part of the
project’s monitoring plan. The general time period for analysis was from March 1996 to July
2007. To evaluate changes within the 6 cells, grid surfaces with a grid spacing of 20 feet were
generated using the following surveys, based on the availability of survey data within each:
•
U.S Coast Guard Channel: November 1995 LIDAR survey and May 2006 hydrographic
survey (Figure 2-11).
•
Old Pass (Destin Harbor Channel): November 1995 LIDAR survey and July 2007
hydrographic survey (Figures 2-12, 2-13, and 2-14).
•
East Pass Channel (Figures 2-12, 2-13, and 2-14):
o October and November 1995 LIDAR surveys, combined with the October 1996
LIDAR survey ¼ mile north of the US 98 bridge.
o July 2007 hydrographic survey, combined with the January 2008 hydrographic
survey north of the US 98 bridge.
•
East Pass Ebb shoal (Figures 2-12, 2-13, and 2-14):
o October and November 1995 LIDAR surveys, combined with the October 1996
LIDAR survey on the eastern and western fringes of the ebb shoal and the 1979
hydrographic survey on the southern fringe of the ebb shoal.
o The July 2007 beach and hydrographic surveys, combined with the September
2007 survey of the Walton County / Destin borrow area.
•
Norriego Point: November 1995 LIDAR survey and January 2009 topographic and
hydrographic survey (Figure 2-15).
•
Western Sand Dikes: USGS 1995 digital elevation model and November 2005 LIDAR
survey (Figure 2-16A).
•
Eastern Sand Dikes: 1995-1996 combined LIDAR surveys (see above) and July 2005
LIDAR survey (Figure 2-16B).
33
Old Pass (Destin Harbor Channel)
US Coast Guard Channel
Norriego Point
Sand Dikes
Beach Disposal Area
Nearshore
Disposal Area
East
Pass
Channel
Sand Dikes
R17-R27, Holiday Isle
East Pass Ebb Shoal
(Outer Bar)
DATE OF AERIAL PHOTOGRAPH: FEBRUARY 2004 (LABINS, 2004).
FIGURE 2-10: East Pass Sediment Budget Cells.
34
FIGURE 2-11: Bathymetry and Volume Change in the U.S. Coast Guard Channel.
35
FIGURE 2-12: 1995-1996 Bathymetry in the East Pass Channel, East Pass Ebb Shoal,
Old Pass, and the U.S. Coast Guard Channel.
36
Swash Channel
FIGURE 2-13: 2007-2008 Bathymetry in the East Pass Channel,
East Pass Ebb Shoal, and Old Pass.
37
FIGURE 2-14: 1995/1996 to 2007/2008 Volume Changes (cubic yards) in the
East Pass Channel, East Pass Ebb Shoal, and Old Pass.
38
FIGURE 2-15: Bathymetry and Volume Change (cubic yards) on Norriego Point.
39
FIGURE 2-16A: Bathymetry and Volume Change (cubic yards) in the Western Sand Dike.
40
FIGURE 2-16B: Bathymetry and Volume Change (cubic yards)
in the Eastern Sand Dike.
41
Volume changes based on the surveys above appear in Table 2-8. Since the mid 1990s, the
dredged areas within East Pass and its ebb shoal have gained a net volume of 22,000 c.y./year.
Approximately 331,000 c.y./year were removed by dredging. Of this amount, 20,000 c.y./year
were placed on Norriego Point. The remainder was placed in the Beach Disposal Area
(V611+480' to V619+435') west of the inlet, the Sand Dikes on either side of the inlet, and the
Walton / County Destin project area (R39 to Walton County profile R23.8).
In general, volume changes within East Pass are characterized by shoaling in the interior of the
inlet and slow losses on the ebb shoal. Changes in the U.S. Coast Guard Channel are relatively
small, although shoaling can occur along the part of the channel due to the encroachment of the
flood shoal. Major scour at the east end of the channel and minor scour in the western half are
largely responsible for the net volume change, which is a -4,000 c.y./year loss. The Destin
Harbor Channel is a relatively small area that shoals 4,000 c.y./year. Most of these gains occur
at the western end of the channel due to the shifting of Norriego Point and the minor shoals
under the US98 Bridge. Changes in the eastern section of the Destin Harbor Channel are small,
as the currents are not large enough to transport sediments in or out of this section. The East
Pass Channel shoals approximately 60,000 c.y./year. Depositional areas within the East Pass
Channel include the areas on either side of the US98 Bridge, another depositional area
approximately ¼ mile to the north, and a shallow area in the middle of the inlet facing the spur
jetty on the eastern side. Excluding the dredging that took place during the Walton-Destin
Project, the East Pass Ebb Shoal naturally loses 38,000 c.y./year. The primary scouring area
within the East Pass Ebb shoal extends approximately 2,000 feet south from the tip of the west
jetty. Scouring in this area has led to changes in the maintained channel location across the ebb
shoal. In 1995 and 2004, the maintained channel generally ran from north-to-south (Figure 217). The present channel runs from north-northeast to south-southwest (Figure 2-18).
The Sand Dikes on either side of the inlet are occasionally used for the placement of dredged
material. The combined volume of material placed in these two areas between 1996 and 2007 is
191,000 c.y. Based on the 1995 digital elevation model and the 2005 LIDAR survey, the
Western Sand Dike appears to have received approximately 10,000 c.y./year of dredge spoil.
However, since the net volume gain is only 9,000 c.y./year, the natural change is a 1,000
c.y./year loss, which occurs primarily due to overwash and wind-blow sand transport. The
Eastern Sand Dike has received an average of 10,000 c.y./year of dredge spoil. Since the net
volume gain is only 4,000 c.y., the natural change is a 6,000 c.y./year loss into the inlet.
Based on observed volume changes, Norriego Point might appear to gain 11,000 c.y./year.
However, this area receives an average of 20,000 c.y./year of fill. When fill is accounted for, the
effective rate of erosion from Norriego Point is 9,000 c.y./year.
42
TABLE 2-8
VOLUME CHANGES IN EAST PASS
MID-1990s TO MID-2000s
Sediment
Budget Cell
Observed Changes*
c.y.
c.y./year
Dredge (-) & Fill (+)**
c.y.
c.y./year
Observed − (Dredge & Fill)
c.y.
c.y./year
Time Period
Used
DREDGED AREAS:
U.S. Coast Guard Channel
Old Pass (Destin Harbor Channel)
East Pass Channel
East Pass Ebb Shoal (Outer Bar)
-48,205
-11,183
185,196
-3,519,869
Total
-5,000
-1,000
17,000
-320,000
-11,002
-56,748
-478,253
-3,103,892
-309,000
-1,000
-5,000
-43,000
-282,000
-37,203
45,565
663,449
-415,977
-331,000
-4,000
4,000
60,000
-38,000
11/1995 - 5/2006
11/1995 - 7/2007
1996 - 2007
1996 - 2007
22,000
DISPOSAL AREAS IN INLET:
Norriego Point
Western Sand Dike
Eastern Sand Dike
Total
142,341
93,986
37,773
11,000
9,000
4,000
257,933
101,380
89,909
24,000
20,000
10,000
10,000
40,000
NOTES: * See Figures 2-11 to 2-16B.
** See Table 2-1.
43
-115,592
-7,394
-52,136
-9,000
-1,000
-6,000
-16,000
11/1995 - 1/2009
Late 1995 - 2005
1996 - 2005
FIGURE 2-17: March 2004 Channel Alignment.
44
FIGURE 2-18: September 2009 Channel Alignment.
45
3.0
SEDIMENT BUDGETS
To evaluate sediment transport near East Pass, sediment budgets were delineated for the inlet and
the beaches of Okaloosa County. The sediment budgets were based on the annualized volume
changes in Tables 2-7 and 2-8, the dredging volumes in Table 2-1, the fill volumes in Table 2-4,
and the Delft3D modeling results in Appendix A. The sediment budget cells used for the inlet
appear in Figure 2-10. The selected sediment budget cells along the Gulf-front beaches were:
•
•
•
•
•
R1 to R10, West Fort Walton Beach
R10 to R16, East Fort Walton Beach
R16 to V611+480', Eglin AFB
V611+480' to V619+435', Beach Disposal Area
V619+435' to V622+357', Nearshore Disposal Area
•
•
•
•
•
R17 to R27, Holiday Isle
R27 to R33, Holiday Inn to Silver Beach
R33 to R39, Henderson Beach State Park
R39 to R45, Matthew Blvd. to Sunfish St.
R45 to R50, Four Prong Lake
The sediment budget cells along the Gulf-front beaches were delineated based on the disposal
area boundaries for the Destin East Pass Maintenance Dredging and Disposal, the approximate
limits of Holiday Isle and Henderson Beach State Park, and the project area for the FDEP
Destin/Walton County Beach Restoration. During the development of the sediment budgets,
sediment transport across the southern boundaries of the East Pass Ebb Shoal cell and the cells
along the Gulf Beaches were assumed to be negligible.
3.1
East Pass Sediment Budget
The East Pass sediment budget appears in Figure 3-1. Volume changes, fill placement (P) rates,
and dredging (R) rates were based on the volume changes in Table 2-8 and the dredging volumes
in Table 2-1. Sediment transport rates across the inland boundaries of East Pass Channel, Old
Pass, and U.S. Coast Guard Channel cells were based on the Delft3D model results in Appendix
A. Sediment transport rates across the boundaries were extracted from the two dimensional, net
sediment transport mapping in Appendix A based on the following formula:
Q = ∫ q x p dL = ∫ (−qxcosφ + qysinφ) dL
where
Q = sediment transport across the boundary in c.y./year.
46
NET VOLUME LOSS (C.Y./YEAR)
NET VOLUME GAIN (C.Y./YEAR)
R = REMOVAL (C.Y./YEAR)
P = PLACEMENT (C.Y./YEAR)
SEDIMENT TRANSPORT
(C.Y./YEAR)
FIGURE 3-1: East Pass 1996-2007 Sediment Budget.
47
q = two dimensional sediment transport vector in c.y./year/foot, specified by east (+) /
west (−) component qx and north (+) /south (−) component qy.
p = unit vector running parallel to the cell boundary, specified by east/west component
sinφ and north/south component cosφ, where φ is the direction parallel to the cell
boundary in compass degrees.
dL = incremental length along the cell boundary
In the U.S. Coast Guard channel, the net transport into the cell across the northern boundary is
approximately 1,000 c.y./year. Transport out of the cell across the southern and eastern
boundaries averages 3,000 and 2,000 c.y./year, respectively. When combined with occasional
dredging, which is equivalent to 1,000 c.y./year, the observed volume change is equal to a loss of
5,000 c.y./year.
In the Destin Harbor Channel, approximately 6,000 c.y./year enters the western end of the
channel from the north. This transport is primarily associated with ebb currents along the eastern
part of the main channel and a small shoal near the US98 Bridge. Another 1,000 c.y./year enters
the channel through the shifting of Norriego Point. Approximately 3,000 c.y./year leave the
Destin Harbor Channel across the open, southwestern boundary that faces the main channel.
This transport is also associated with ebb currents along the eastern part of the main channel.
Overall, natural sediment transport brings a net volume of 4,000 c.y./year into the channel.
When combined with 5,000 c.y./year of maintenance dredging, the observed volume change is
equal to a loss of 1,000 c.y./year.
Norriego Point typically receives 20,000 c.y./year of fill from maintenance dredging operations.
Of this amount, 9,000 c.y./year slides off the northern tip, with remaining 11,000 c.y./year
remaining in the cell. Based on the Delft3D model results in Appendix A, approximately 1,000
c.y./year of eroded material goes into the Destin Harbor Channel, with rest (8,000 c.y./year)
going into the East Pass Channel.
In the East Pass Channel, approximately 12,000 c.y./year enters across the northwestern
boundary, primarily during flood. Although this amount is high, the source of the material
appears to be a broad scour zone adjacent to the boundary, which is visible on the aerial
photograph in Figure 2-10. A small amount (1,000 c.y./year) of material enters the channel
across the northern boundary, with a larger amount (6,000 c.y./year) coming across the
northeastern boundary. The source of this material also appears to be a broad scour zone that is
visible on aerial photographs (Figures 2-10). However, ebb currents are the primary transport
mechanism, rather than flood currents. Where the U.S. Coast Guard Channel adjoins the East
Pass Channel, the incoming transport is 2,000 c.y./year. Incoming transport from the Destin
Harbor Channel is 3,000 c.y./year. On the southern side of the US98 Bridge, a natural channel is
forming between the U.S. Coast Guard station and the East Pass Channel (see Figure 2-10). The
scour associated with the channel’s formation appears to be bringing 8,000 c.y./year into the East
Pass channel, based on the model results in Appendix A. The natural transport out of the East
Pass Channel is small. Approximately 8,000 c.y./year has entered from the Sand Dikes on either
side of the inlet. The lone mechanism for sediment transport out of the East Pass channel is
48
maintenance dredging, which averages 43,000 c.y./year. Overall, the observed 1996-2007
volume change in the East Pass Channel is 17,000 c.y./year. Based on a balance of the material
coming into the channel and the material removed, approximately 12,000 c.y./year of material
enters the channel from the south.
The East Pass Ebb Shoal has lost a considerable amount of material since 1996. The bulk of the
loss is the removal of 2,807,060 cubic yards for the construction of the Walton County / Destin
Beach Restoration Project (Table 2-1). However, the 1996-2007 total includes an additional
296,832 cubic yards of navigational maintenance dredging (Table 2-1). The combined total is
equivalent to 282,000 c.y./year. In addition to this amount, 12,000 c.y./year of material has gone
into the East Pass Channel. Based on the Gulf-front sediment budget discussed in the next
section, there is 37,000 c.y./year of material coming in from the east. Given the observed
volume loss of 320,000 c.y./year from the ebb shoal, the amount of dredged material, the littoral
drift into the East Pass Channel, and the amount coming in from the east, transport out of the ebb
shoal towards the west is approximately 63,000 c.y./year.
Overall, the 1996-2007 sediment budget suggests that the sediment transport is from north to
south in the inlet interior, and from south to north between the jetties. These results differ from
the earlier sediment budgets in the 1999 Inlet Management Plan (pp. 129-131), which assert the
opposite (i.e.: Figure 3-2). There are two primary reasons for these differences:
1. The earlier sediment budgets do not enjoy the benefit of a sediment transport model that
incorporates “wave action, inlet tidal currents, sediment physical characteristics, [and]
mechanical bypassing” (Taylor, 1999, p. 124). The Delft3D model in Appendix A
incorporates these processes.
2. The earlier sediment budgets do not examine changes on the flood shoal (Taylor, 1999, p.
125), due to the availability of data in that area in the late 1990s. In contrast, the 19962007 sediment budget accounts for processes on the flood shoal.
In general, the 1996-2007 sediment budget (Figure 3-1) depicts the interior of East Pass to be a
sediment sink, rather than the sediment source shown in Figure 3-2. There are two
considerations that make the sediment transport directions in Figure 3-1 more reasonable than
those in Figure 3-2:
1. Navigational dredging in the East Pass Channel averaged 52,000 c.y./year between 1986
and 2010 (Table 2-1, column 5). If the transport patterns inside the inlet were similar to
those in Figure 3-2, natural scour would have eliminated the need for maintenance
dredging.
49
NOTE: Sediment transport rates across the northern and southern boundaries of Cell 4 appear to be speculative.
FIGURE 3-2: East Pass Sediment Budget 1990 to 1997 (Taylor, 1999, p. 131).
50
NOTE: The location of the 1983 gages is approximate.
FIGURE 3-3: Locations of 1983 and 2009 Current Measurements.
51
2. The sediment transport directions in Figure 3-1 were consistent with current
measurements taken in 1983 (Morang, 1992) and 2009 (Appendix A). The 1983 current
measurements were taken close to the US98 Bridge (Figure 3-3), and were generally ebb
dominated (Morang, 1992, pp. 49-52). The 2009 current measurements, detailed in
Appendix A, were taken close to the jetties. These currents were generally flood
dominated.
The sediment transport rates in Figure 3-1 also differed from the 2004-2009 sediment budget
prepared for Norriego Point (CPE, 2009, p. 11). The two sediment budgets showed the same
amount of material eroding from Norriego Point into the Destin Harbor Channel. However, the
2004-2009 sediment budget indicated a larger amount of material eroding into the East Pass
Channel (20,700 c.y./year). The 2004-2009 sediment budget also assumed that the sediment
transport direction in the East Pass Channel was from south to north, while the sediment budget
in Figure 3-1 suggested that the direction of transport varied with position. The differences
between the sediment budget in Figure 3-1 and the Norriego Point sediment budget by CPE
(2009) were primarily due to:
•
The longer time period examined in Figure 3-1.
•
The larger area under examination in Figure 3-1.
•
The use of grid surfaces to directly determine volume changes (Figure 2-15), rather than
indirect estimates based on shoreline changes (CPE, 2009, p. 9).
Despite the differences between the sediment budget in Figure 3-1 and earlier estimates (CPE,
2009; Taylor, 1999), the 1996-2007 sediment budget provides a reasonable description of the
processes occurring in the interior of East Pass. The 1996-2007 sediment budget demonstrates
the need for dredging to maintain the navigability of the East Pass Channel. It shows why the
U.S. Coast Guard channel is not dredged frequently. The sources and sinks generally match
trends that are visible in the aerial photograph of the flood shoal and the US98 Bridge (Figure 210). Finally, the directions of transport are consistent with current measurements taken at
different locations within the inlet.
Based on the detailed sediment budget in Figure 3-1, the 4 submerged cells were combined with
Norriego Point for use in a larger sediment budget covering the Gulf-front beaches of Okaloosa
County. Sediment transport rates developed as part of that sediment budget are detailed in the
next section.
3.2
Gulf-Front Sediment Budget
The Gulf-front sediment budget for Okaloosa County appears in Figures 3-4, 3-5, and 3-6.
Volume changes, placed fill (P) rates, and dredging (R) rates were based on the volume changes
in Table 2-7, the dredging volumes in Table 2-1, and the fill volumes in Table 2-4. Sediment
transport rates into and out the East Pass inlet complex were based on the Delft3D model results
as described in the previous section.
52
FIGURE 3-4: 1996-2007 Gulf-Front Sediment Budget,
Okaloosa/Walton County Line to Holiday Isle.
53
R27
R33
R39
R45
R50
SEDIMENT TRANSPORT (C.Y./YEAR)
Holiday Isle to East Pass Beach Disposal Area.
54
V611
+480’
V619
+435’
V622
+357’
R17
R27
Eglin Air Force Base to Fort Walton Beach.
55
R1
R10
R16
V611
+480’
Sediment transport estimates along the beach began with the volume changes and fill volumes in
Table 2-7, specifically the values in c.y./foot (columns 4 and 6). Each set of values was
integrated over the length of each cell to provide the total quantities in the 2nd and 3rd column of
Table 3-1. The resulting values in cubic yards were then annualized over the 11.3 year period
between March 1996 and July 2007 (columns 4 and 5 of Table 3-1). Wind-driven transport from
the beach into the dune was then calculated assuming an average value of 0.5 c.y./year/foot
based on Taylor (2007). Changes in the longshore transport rate along each cell from west to
east were then calculating by:
•
•
•
Subtracting the surveyed volume change.
Subtracting the wind-driven transport.
Adding the beach or dune fill.
For example, at the Four Prong Lake cell (R45 to R50), the longshore transport value was
approximately +15,000 c.y./year (west to east) at the west end of the cell. After subtracting the
observed change of +37,000 c.y./year (accretion) and the 3,000 c.y./year of aeolian transport,
36,000 c.y./year of fill were added to the sediment transport at the west end of the cell. The
resulting value at the east end of the cell was a net transport of +11,000 c.y./year (west to east).
This procedure was applied using two different methods – a spreadsheet estimate and the
Sediment Budget Analysis System (SBAS 5.1, Rosati, 2007). While both methods produced
consistent results, both required a known longshore transport value at a given location in order to
determine the longshore transport elsewhere.
To provide a known longshore transport value somewhere along the study area, sediment
transport values along the City of Destin (Figure 3-7) were determined using the Delft3D model
results in Appendix A. Near profile R33 (Silver Beach), the simulated longshore transport was
zero. This location was characterized by mild accretion (see Figure 2-2). By assuming the
longshore transport to be equal to zero at R33, a good fit between the sediment budget and the
simulated transport was achieved between profiles R22 (Moreno Point Road) and R39
(Henderson Park Inn). East of R39, the model results and the sediment budget diverged due to
an unusual offshore loss at profiles R38 to R40. West of R22, the differences between the model
results and the sediment budget were due to the more complex, two-dimensional sediment
transport patterns near the inlet.
At East Pass, the various cells in Figure 3-1 were collapsed into a single unit representing the
inlet complex as whole, with a net loss of 298,000 c.y./year and a net removal rate (dredging –
fill) of 311,000 c.y./year. These values were then combined with the other transport rates along
the combined cell boundaries to determine the longshore transport rates west of the inlet.
Prior to the mid 1990s, (Figure 3-2), the sediment transport along the beach was generally from
east to west. West of the inlet, this trend continued after 1996 (Table 3-1, Figures 3-5 and 3-6).
However, east of the inlet, the sediment transport switched direction at a number of locations.
56
TABLE 3-1
SEDIMENT TRANSPORT ON THE BEACH − FORT WALTON BEACH TO DESTIN, FL
Beach Segment
R1 to R10, West Fort Walton Beach
R10 to R16, East Fort Walton Beach
R16 to V611+480', Eglin AFB
V611+480' to V619+435', Beach Disposal Area
V619+435' to V622+357', Nearshore Disposal Area
R17 to R27, Holiday Isle
R27 to R33, Holiday Inn to Silver Beach
March 1996 - Sept. 2007
Surveyed
Beach &
Volume
Dune
Change
Fills
(c.y.)
(c.y.)
-58,283
203,062
March 1996 - Sept. 2007
Surveyed
Beach &
WindVolume
Dune
Driven
Change
Fills
Transp.
(c.y./year)
(c.y./year)
(c.y./year)
-5,000
18,000
111,596
11,000
10,000
3,000
-355,884
0
-31,000
0
6,000
292,285
396,113
0
15,000
26,000
35,000
0
50,000
-50,000
4,000
5,000
105,903
0
9,000
0
3,000
40,572
0
4,000
0
3,000
R39 to R45, Matthew Blvd. to Sunfish St.
310,774
585,441
27,000
52,000
3,000
413,366
37,000
57
36,000
R10
-73,000
R16
-77,000
V611+480'
-52,000
V619+435'
-36,000
V622+357'
-63,000
R17
-37,000
R27
12,000
R33
0
R39
-7,000
R45
15,000
R50
11,000
1,000
-568,846
421,201
-91,000
4,000
R33 to R39, Henderson Beach State Park
R45 to R50, Four Prong Lake
R1
5,000
119,777
174,770
Longshore
Transport
( -W / +E)
(c.y./year)
3,000
P:\Okaloosa\1050000 Destin IMP Update\ENGINEERING\D3D\Destin_D3D_Morphology_Calibration_1996_to_2005.xls plots2005 12/17/2009 9:27 AM
40,000
30,000
3
20,000
10,000
10
0
-10,000
-1
-20,000 -30
-30,000 -40,000
Net Longshore T
Transport (+W to E
E, -E to W, c.y./year)
COASTAL PLANNI
NING & ENGINEERIN
NG, INC.
FIGURE 3
3-7: Sediment Transport
T
Rates
es, East Pass to Okaloosa/Walto
on County Line
e.
N
0
5,000
10,000
15,000
20,000
25,000
1996-2007 Sediment Budget
Delft3D Calibration #35
30,000
Near profiles R18 and R19 (Lands End Drive), a split in the sediment transport (nodal point)
occurred. These profiles experienced the highest erosion rates in Okaloosa County between
1996 and 2007. Between profiles R19 and R32, the net sediment transport was from west to
east, rather than from east to west. Between profiles R33 and R39, the sediment transport
assumed its usual direction from east to west; however, the rates were generally small. This may
have been due to end losses off the west terminus of the Walton-Destin project. East of profile
R40, the sediment transport appeared to be from west to east. The nodal point near profiles R39
and R40 appeared to be generated by an unusual loss offshore. This loss was visible on the
profile plot for R40 in Appendix B, and occurred on both the shallow water portion of the profile
(above -20 feet NAVD) and the deep water portion (-20 feet NAVD).
The unusual sediment transport regime was most likely due to the high amount of storm activity
between 1996 and 2007. During the period depicted in Figure 3-2, 8 notable storms occurred –
Andrew (1992 offshore), Alberto (1994), Beryl (1994), Allison (1995), Erin (1995), Opal (1995),
Josephine (1996), and Danny (1997). However, only one was a major hurricane – Opal.
Between March 1996 and July 2007, 23 notable storms occurred – Josephine (1996), Danny
(1997), Earl (1998), Georges (1998), Helene (2000), Allison (2001), Barry (2001), Hanna
(2002), Isidore (2002), Lili (2002), Bill (2003), Bonnie (2004), Charley (2004), Frances (2004),
Ivan (2004), Jeanne (2004), Matthew (2004), Arlene (2005), Cindy (2005), Dennis (2005),
Katrina (2005), Rita (2005 offshore), and Alberto (2006). Several of these were major
hurricanes, including Ivan and Dennis. As noted in Appendix A, the principal, offshore wave
direction between 1999 and 2008 was from the south-southeast, which would generate sediment
transport from east to west. However, the largest waves generally came from the southsouthwest, which would generate sediment transport in the opposite direction. Given these wave
characteristics, it would be unclear whether one direction of transport would be favored over
another, since the higher waves occurred less often than the lower waves. Under such a wave
climate, transport in both directions could be likely. Based on Figures 3-5 to 3-7, this was indeed
the case between 1996 and 2007.
The 1996-2007 sediment transport rates west of the inlet varied differently than those between
1990 and 1997 (see Figures 3-2 and 3-6). This was due to several factors. First, the wave
climate after 1996 was characterized by a higher level of storm activity. Second, the shape of the
ebb shoal in the early 1990s was different than the present shape (see Figures 2-4 to 2-9). Third,
dredge spoil from East Pass was placed closer to the inlet in the early 1990s than it was after
1996. Further west of the inlet (R16), the 1996-2007 sediment transport estimates were in the
73,000 to 91,000 c.y./year range. This range was somewhat higher than values shown in Figure
3-2. However, it was comparable to earlier estimates presented by Morang (1992, p. 23), which
varied from 52,000 to 78,500 c.y./year.
Overall, the 1996-2007 sediment budget along the Gulf-front (Figures 3-4 to 3-6, Table 3-1)
presents a reasonable description of the sediment transport processes along Okaloosa County.
The sediment budget explains why the Holiday Isle area is experiencing severe erosion.
Nevertheless, it also represents an atypical period dominated by a high level of storm activity. If
storm activity reverts to its levels prior to Hurricane Opal, the direction of transport will probably
be from east to west on both sides of the East Pass.
59
4.0
IMPACTS OF EAST PASS ON GULF-FRONT EROSION PATTERNS
4.1
Area of Influence
A method for assessing the impact of an inlet is the Even-Odd analysis. The purpose of the
Even-Odd analysis is to separate the shoreline and volume changes which occur symmetrically
about the inlet (e.g., storm erosion, erosion and accretion due to relative sea level change) from
changes which are anti-symmetric (e.g., updrift impoundment at jetties and groins, downdrift
erosion) (Rosati and Kraus, 1997):
f(x) = fe(x) + sign(x)fo(x)
where
f(x) = observed shoreline or volume change
fe(x) = even function = [f(x) + f(-x)]/2
fo(x) = odd function = [f(x) - f(-x)]/2
x = distance from the distance from the inlet (-west, +east)
The Even-Odd analysis based on the 1996-2007 shoreline and volume changes appears in Figure
4-1. Based on the “odd” shoreline and volume changes, the inlet’s immediate impact zone over
the 11 year study period appears to lie with 6,000 feet of East Pass, extending from profiles
V615 to R23 (Oceania Condominium). However, the net transport direction at East Pass is not
the same on both sides of the inlet (Figures 3-1 and 3-5). For this reason, inlet-related impacts
may also be present within the “even” shoreline and volume changes. The “even” changes that
appear to be inlet-related lie within 10,000 feet of East Pass, extending from profiles V611 to
R27 (Holiday Inn). It is important to note that the 1996-2007 erosional patterns were a departure
from the preceding period (1969-1996), during which the “odd” erosional area was on the
western side of the inlet (Figure 4-2).
Taylor’s (1999) Even-Odd analysis of the 1969-1996 shoreline changes appears in Figure 4-2.
Based on the “odd” erosion patterns during the 27 year period, the major impacts of East Pass
occurred within 11,000 feet (2.1 miles) of the inlet (V610.5 to R28 / Gulf Terrace Drive). The
minor impacts occurred within 19,000 feet (3.6 miles) of the inlet (V602 to R36 / Comfort Inn).
Given the recent (1996-2007) and historical (1969-1996) erosion patterns, the area influenced by
East Pass over short-term and intermediate time scales (< 11 years) lies within 10,000 feet of the
inlet (V611 to R27). This reach includes all of Holiday Isle (R17 to R27). The area influenced
by East Pass over long-term time scales (> 27 years) lies with 3 to 4 miles of the inlet (V602 to
R36).
60
FIGURE 4-1: Even-Odd Analysis for East Pass Based on the
1996-2007 Shoreline and Volume Changes.
61
+ Advance
− Retreat
FIGURE 4-2: Even-Odd Analysis for East Pass Based on the
1969-1996 Shoreline Changes (adapted from Taylor, 1999, p. 27).
62
4.2
Impact of the Walton County / Destin Beach Restoration Project Borrow Area
The Walton County / Destin Beach Restoration Project removed 2,807,060 cubic yards of
material from the seaward fringe of the East Pass ebb shoal. The project was constructed over a
17 month period in 3 phases: February – May 2006 (R6 to R23.8 in Walton County), December
– January 2007 (R1 to R6 in Walton County), and May – June 2007 (R39 to R50 in Okaloosa
County) (Bridges, et al, 2008, p. 1). Pre-construction depths at the borrow area ranged from -13
to -45 feet NAVD. Due to the size and location of the borrow area (Figure 4-3), there were
concerns regarding potential impacts to beach erosion rates during the permitting process.
Shoreline positions before the project (Nov. 2005) appear in Figure 4-3, along with the
November 1998 and September 2008 shoreline positions. The September 2008 beach surveys
were the last profile surveys that were taken on both sides of East Pass (Table 2-2A). Between
November 1998 and November 2005, a large amount of shoreline retreat occurred on the eastern
side of the inlet. The maximum retreat was 279 feet, occurring midway between profiles R17
and R18. West of the inlet, shoreline changes between 1998 and 2005 were characterized by a
shoreline undulation pattern, with advancing shorelines at profile V620 and retreating shorelines
near profile V615. Between November 2005 and September 2008, very little shoreline change
occurred on the eastern side of the inlet. The maximum shoreline retreat, occurring at profile
R19.5, was only 37 feet during this period. Aside from this area, shoreline retreat east of the
inlet was minimal between 2005 and 2008. West of the inlet, the shoreline changes between
2005 and 2008 were characterized by shoreline advance near East Pass (V621 to V622, 95 feet),
shoreline retreat at profile V617 (84 feet), and shoreline advance near profile V615 (88 feet).
Since the September 2008 survey was taken only at profile lines spaced approximately 1,000 feet
apart, it was not possible to determine if the undulation pattern continued through September
2008.
East of the inlet, the Walton County / Destin borrow area had little impact on the beach erosion
patterns. Very little erosion occurred along Holiday Isle (R17 to R27) between the start of the
project and the most recent beach surveys, as shown in Figure 4-3. In addition, the Delft3D
modeling results in Appendix A and Figure 4-4 suggested that that the borrow area had only a
minor impact on the erosion rates between the post-construction survey (July 2007) and July
2009. Finally, photographs taken along Holiday Isle (Coastal Tech, 2006) showed that the area
was severely eroded prior to the start of the project in February 2006 (Figure 4-5). West of the
inlet, the September 2008 surveys were not able to resolve the true shoreline shape. Therefore, it
was not possible to conclusively assess the impacts of the borrow area based on shoreline
changes (Figure 4-3). However, the modeling results in Appendix A and Figure 4-4 suggested
that the erosional impacts of the borrow area were minor on the west side of inlet, as well as the
east side. Overall, based on surveys, site visits (Coastal Tech, 2006), and numerical modeling,
the erosional impacts of the Walton County / Destin borrow area, if any, have appeared to be
minor.
63
FIGURE 4-3: Impact of the Walton County/Destin Beach Restoration Project Borrow Area
Based on Shoreline Changes.
64
See Appendix A for details regarding the two
simulations upon which this map is based.
FIGURE 4-4: Impacts and Benefits of the Walton County/Destin Beach Restoration Project
Borrow Area Based on Delft3D Numerical Model Simulations.
65
FIGURE 4-5: Eroded Beach at the Jetty East Condominium (R18.5) on January 3, 2006
(Coastal Tech, 2006).
4.3
Impact of the Borrow Area for the Western Destin Beach Restoration Project,
Okaloosa Island Beach Restoration, and Eglin AFB Beach Restoration
Permit efforts for the Western Destin Beach Restoration Project, Okaloosa Island Beach
Restoration, and Eglin AFB Beach Restoration are in progress. These 3 projects use a common
borrow area, which is located offshore between profiles V601 to V610 (Figure 4-6). The
existing depth at the proposed borrow area varies from -43 to -54 feet NAVD. The borrow
area’s design depth is -49.5 feet NAVD. The potential impact of the borrow area on the nearby
erosional patterns is detailed in Appendix A. Overall, the erosion impacts of the borrow area
given its full excavation are expected to be minor.
66
Borrow Area Location and Bathymetry through September 2009 (feet NAVD)
FIGURE 4-6: Borrow Area for the Western Destin Beach Restoration Project,
Okaloosa Island Beach Restoration, and Eglin AFB Beach Restoration.
67
5.0
EAST PASS INLET MANAGEMENT ALTERNATIVES
To adapt the management of East Pass to present and future conditions, several alternatives for
the management of the inlet have been developed. These alternatives primarily address the
management of dredged material from the periodic maintenance of East Pass. Changes to the
sizes or alignments of the inlet’s Federally authorized channels are not being proposed, nor are
changes to the jetties at the inlet. However, it should be noted that the U.S. Army Corps of
Engineers has changed the channel alignment in the past to follow the contours of the ebb shoal
(Figures 2-17 and 2-18).
At Norriego Point, some alternatives recommend that fill placement be discontinued. The City
of Destin has initiated a project to stabilize the shoreline. However, aside from such a
recommendation, the management of Norriego Point is not discussed. Alternatives to stabilize
Norriego Point are discussed in the City of Destin, Florida Norriego Point Stabilization Project
Feasibility Study (CPE, 2009).
5.1
Projects in the Permitting or Design Phase near East Pass
A number of coastal projects are presently in the permitting or design phase near East Pass.
These include the
•
•
•
•
Norriego Point Stabilization Project.
Western Destin Beach Restoration Project.
Okaloosa Island Beach Restoration.
Eglin AFB Beach Restoration.
The locations of these projects, along with the Walton County / Destin Beach Restoration, appear
in Figure 5-1.
5.2
Present Dredging Requirements
Estimated dredging requirements based on the permit sketches and the most recent surveys
(primarily June 2010) appear in Appendix C. The dredging requirements in the permitted cuts
are approximately 186,700 cubic yards.
68
N
Okaloosa
Island Beach
Restoration
Western Destin
Beach
Restoration
Project
Walton County / Destin
Beach Restoration
Eglin AFB Beach Restoration
FIGURE 5-1: Proposed Beach Restoration Projects near East Pass, Destin, FL.
69
5.3
Inlet Management Alternatives
No Channel Maintenance (Alternative “0”)
This alternative discontinues the historical maintenance dredging of East Pass, with no further
maintenance or stabilization of Norriego Point. If channel maintenance were discontinued, the
main channel would begin to accumulate sediment (see Figure 3-1), especially between the
jetties and the US98 Bridge. The accumulation would occur in specific areas. Based on Figure
2-14 and Delft3D modeling results in Appendix A, the primary deposition areas would occur
along the authorized channel centerline near the spur extension of the east jetty and the north end
of Norriego Point. Additional deposition would occur near the west end of the authorized Destin
Harbor Channel. Under these shoaling patterns, a large vessel entering East Pass would need to
steer close to the east jetty and the south end of Norriego Point, and then drift into the middle of
the inlet further north. Entering Destin Harbor would be difficult, since shoaling would occur
along the authorized Destin Harbor Channel. This alternative is unlikely, since East Pass is a
Federal navigation project. However, it provides the basis for evaluating the impacts and
benefits of the other alternatives.
Alternative 1 - Present Inlet Management Practice
Alternative 1 continues the present dredge disposal practices, summarized by Figure 5-2 of the
permit sketches in Appendix C. These include:
•
Placement of dredged material from the Destin Harbor Channel and the northern half of
the main East Pass Channel on Norriego Point. As noted in CESAM’s response to
FDEP’s second “Request for Additional Information” on January 8, 2009, the placement
of material on Norriego Point would continue for two reasons:
o “Dredging within Old Pass Lagoon [or Destin Harbor Channel] potentially will
utilize a small dredge (8” dredge previously used), which would be unable to
pump directly to the beach due to distances….The channel located north of the
U.S. Highway 98 bridge would also likely utilize Norriego Point due to distance
limitations from the [Gulf] front beach”.
o “To date, only a portion of Norriego Point has been hardened with structures”.
•
Dredging in the U.S. Coast Guard Channel, with placement of the dredged material on
Norriego Point. Even though the U.S. Coast Guard Channel is not in the present permit
(0288799-001-JC), this area was dredged in 1995 and 2002 (Table 2-1). A permit
modification to allow dredging in the U.S. Coast Guard Channel would be possible. The
modeling study in Appendix A assumes that the U.S. Coast Guard Channel will be
dredged in the future. Based on this assumption, the Delft3D modeling results in
Appendix A predict a one-time dredging event in the U.S. Coast Guard Channel, with a
quantity similar to the 1995 and 2002 dredging events in Table 2-1.
70
FIGURE 5-2: East Pass Inlet Management Alternatives.
71
ALTERNATIVE 2 DISPOSAL AREA
ALTERNATIVE 1 DISPOSAL AREAS
ALTERNATIVE 3 DISPOSAL AREA
ALTERNATIVE 4 DISPOSAL AREAS
N
•
Placement of the remaining dredge spoil in the Beach Disposal Area (V611+480’ to
V619+435’) west of the inlet. Placement of dredge spoil in the Nearshore Disposal Area
(V619+435’ to V622+357’) is unlikely. This disposal area has not been used since 1993
(Table 2-1), and it appears to be full, based on the beach profiles in Appendix B (V620V622) and the design cross-sections in Appendix C.
•
A prohibition of dredge spoil placement along Holiday Isle. Placement of dredge spoil
on Holiday Isle (R17-R27) has been explicitly prohibited by Special Condition 8 of
Permit 0288799-001-JC as part of the settlement to OGC Case No. 09-3649.
•
Occasional placement of dredged material in the Sand Dike areas east and west of the
inlet. The purpose of sand placement in these two sites is to maintain the structural
integrity of the inlet’s jetties.
Alternative 1 departs from the June 2000 Certificate of Adoption (in Section 1.2) in the
following ways:
•
It does not place the 82,000 c.y./year of material on the beaches west of the inlet. Based
on Table 2-1 and the Delft3D modeling results in Appendix A, the total dredging in East
Pass will probably range from 85,000 to 99,000 c.y./year over the next 5 years.
However, only 63 to 70 percent of that material would be placed on the beaches west of
the inlet.
•
It assumes that the Norriego Point Stabilization Project is unlikely to be completed over
the next 5 years.
The primary advantages of Alternative 1 are the following:
•
It provides for the maintenance of Norriego Point if the stabilization project is not able to
be constructed.
•
It is the least expensive option for U.S. Army Corps of Engineers.
•
It provides for bypassing to the beach segment which is downdrift of the inlet most of the
time (see Figures 3-2 and 3-5).
The primary disadvantages of Alternative 1 are the following:
•
It does not place any dredge spoil along Holiday Isle (R17-R27), which is the most
severely eroded area in Okaloosa County. Given the present sediment transport patterns
(Figures 3-5), Holiday Isle can also be considered a downdrift beach, in addition to the
area west of the inlet.
•
Since Norriego Point is not stabilized, approximately 45% of dredge spoil placed on
Norriego Point goes back into the inlet (see Figure 3-1). It should be noted that much of
the dredging in the Destin Harbor Channel (Old Pass) is driven by incoming material
72
from the north (see Figure 3-1), not just the material eroding from Norriego Point.
Nevertheless, the dredged material that erodes from Norriego Point is material that
remains trapped within the inlet, outside the littoral system on the Gulf beaches, and
unable to address the inlet’s impact on the adjacent Gulf shorelines. Based on Table 2-1,
646,900 c.y. of dredge spoil has been placed on Norriego Point since 1986. The 45% that
has eroded back into the inlet is equal to 291,100 c.y.
•
By diverting some of the dredge spoil to Norriego Point, it effectively keeps sediment in
the inlet and restricts the amount of material available for bypassing to the downdrift
beach. Since the quantities placed on the beach are smaller, the western end of the Beach
Disposal Area (i.e.: V611+480’ to V614) may not receive dredged material.
•
It may not be able to satisfy local interests east of the inlet.
Alternative 2 - June 2000 Certificate of Adoption
Alternative 2 follows the June 2000 Certificate of Adoption by armoring Norriego Point and
placing all dredged material in the Beach Disposal Area. Similar to Alternative 1, this
alternative assumes that limited dredging may occur in the U.S. Coast Guard Channel.
•
It satisfies the present inlet management plan.
•
Excluding the U.S. Coast Guard Channel, it is allowed under the present permits (see
Appendix C).
•
It bypasses more material to the beach segment which is downdrift of the inlet most of
the time (see Figures 3-2 and 3-5). The larger quantities involved:
o Increase the likelihood of the dredge spoil placement on the western end of the
Beach Disposal Area (V611+480’ to V614).
o Provide more material to better satisfy the local interests west of the inlet.
•
By eliminating the placement of material on Norriego Point, it reduces the amount of
dredged material that returns into the inlet (see Figure 3-1) and frees up more material for
placement on the downdrift beach.
•
It will be more expensive to implement than Alternative 1, since a different set of
equipment would be required to move material to the disposal site from the Destin
Harbor Channel, the U.S. Coast Guard Channel, and the northern section of the main
channel.
73
•
It does not place any dredge spoil along the critically eroded beaches east of the inlet
(R17-R27).
•
It may not be able to satisfy local interests east of the inlet.
Alternative 3 – Placement of All Dredge Spoil East of Inlet
Alternative 3 places all dredge spoil from East Pass along the critically eroded section of Holiday
Isle (R17-R26). Similar to Alternative 1, this alternative assumes that a one-time dredging event
may occur in the U.S. Coast Guard Channel. It also assumes that Norriego Point will be
armored.
•
It can partially address the critical erosion problem east of the inlet if the Western Destin
project is not constructed. If the Western Destin project is constructed, it will lengthen
the life of that project and reduce the volumes and costs associated with its
renourishment.
•
placement on the severely eroded beach east of the inlet.
•
It satisfies the local interests east of the inlet.
•
It is not allowed under the present permits or consistent with FDEP policy to bypass
dredged materials to the downdrift beaches.
Obtaining the necessary permit
modifications would be more difficult than the efforts required for Alternatives 1 or 2.
•
It does not provide any material for the beach segment west of the inlet, which is
downdrift of the inlet most of the time (see Figures 3-2 and 3-5).
•
It is not able to satisfy the local interests west of the inlet.
•
It will be more expensive to implement than Alternative 1.
Alternative 4 – Split Dredge Spoil between Both Sides of East Pass
Alternative 4 splits the dredge spoil between the critically eroded section of Holiday Isle (R17R26) and the Beach Disposal Area (V611+480' to V619+435') west of the inlet. The Delft3D
modeling results in Appendix A assume that both sides of the inlet receive equal amounts of
material. However, the amounts of material could be adjusted based on the observed erosional
patterns and the conditions of the beaches on either side of the inlet. Similar to Alternative 1,
74
this alternative assumes that a one-time dredging event may occur in the U.S. Coast Guard
Channel. It also assumes that Norriego Point will be armored.
•
It provides material for both sides of East Pass, both of which can be considered
downdrift of the inlet at the present time (Figure 3-5).
•
It can partially address the critical erosion problem along Holiday Isle or lengthen the life
of the Western Destin Beach Restoration, if constructed.
•
placement on the downdrift beach west of the inlet and the severely eroded beach east of
the inlet.
•
Alternative 4 may be able to satisfy the local interests on both sides of East Pass.
However, if it is not, the permit modifications required for Alternative 4 would be less
difficult to secure than those required for Alternative 3. If the permit modifications were
contested, they would be more likely to withstand the challenge than those of Alternative
3.
•
It is not allowed under the present permits. Obtaining the necessary permit modifications
would be more difficult than the efforts required for Alternatives 1 or 2.
•
The quantities to be placed on each side of the inlet would be less than those under
Alternatives 2 or 3.
•
If the percentage allotments of dredge spoil were adjusted with each dredging operation,
there is the risk that various local interests would contest the allotments
(theDESTINlog.com, December 4, 2009).
•
It will be more expensive to implement than Alternatives 1, 2 or 3.
5.4
Performance and Impact
The benefits and impacts of each Alternative based on the Delft3D numerical model are
summarized below and detailed in Appendix A. The model simulations for each alternative were
conducted for a 5 year period. Because the present sediment transport patterns appeared to be
atypical (Figures 3-2 and 3-5), two sets of waves were used as input to the model:
•
The 1996-2005, high-energy wave climate used in the model’s calibration.
75
•
A moderate wave climate based on the 1980-1984 waves. During this 5 year period, the
simulated sediment transport was clearly from east to west on both sides of the inlet.
The general findings from the model study in Appendix A are the following:
5.5
•
If navigational maintenance of East Pass is discontinued, shoaling along the main channel
would occur opposite the north end of the east jetty and the T-head groins along Norriego
Point. Shoaling would also occur near the west end of the Destin Harbor Channel, the
east end of the U.S. Coast Guard Channel, and the southern edge of the ebb shoal
approximately 2,000 feet from the tips of the jetties.
•
High rates of beachfront erosion will continue to occur on the east side of the inlet (R17R18) due to the swash channel running along the beach. These will be accompanied by
high shoreline retreat rates, especially near the west end of Lands End Drive (R17.8), the
Jetty East condominium (R18.5), the Inlet Reef Club (R19), and the Destin on the Gulf
condominium (R20.5).
•
Dredging requirements under a moderate wave climate (1980-1984) are approximately 9
percent higher than those under a high-energy (1996-2005) wave climate.
•
West of the inlet, the immediate benefits of dredge spoil placement over a 5 year period
are confined to the placement area and a 1,000 foot zone adjoining its western limit.
Very minor benefits occur over an additional 4,000 feet to the west. Minor impacts (3 to
4 c.y./year/foot of less accretion or more erosion) occur between the eastern limit of the
placement and west jetty.
•
East of the inlet, the immediate benefits of dredge spoil placement over a 5 year period
cover the placement area and a 3,000 to 5,000 foot zone adjoining its eastern limit.
•
If dredge spoil were placed east of the inlet, the dredging requirement on the East Pass
Ebb Shoal would change very little. As shown in Figure 5-3, the 5 year impact of
Alternative 4 versus Alternative 1 is 6,900 c.y. of additional shoaling on the ebb shoal
(1,400 c.y./year), with elevation differentials of 1.3 feet or less. It should be noted that
the 6,900 c.y. is spread out over an area that is several times larger than the designated
dredge cut over the ebb shoal. This is the primary reason why the model results do not
suggest a large change in dredging requirements when dredge spoil is placed east of the
inlet.
Recommended Alternative
The recommended alternative is Alternative 4. Although Alternative 4 has some disadvantages,
it provides the greatest flexibility for the management of dredged material from East Pass. It
allows dredge spoil to be placed in the area of greatest need, and balances the needs of local
interests on both sides of the inlet.
76
FIGURE 5-3: Impact of Alternative 4 vs. Alternative 1 on Shoaling Rates.
77
5.5.1
Rationale for Recommendation
Alternatives 1 and 2 are both viable under present permits. However, neither alternative is able
to address the inlet induced erosion east of the inlet. Instead, both place all or some of the
dredged material from East Pass along the largely undeveloped Beach Disposal Area
(V611+480' to V619+435') west of the inlet. The only upland building that directly benefits
from dredge spoil placement is the Eglin Air Force Base Beach Club (V618). As discussed in
Appendix A, material placed in the Beach Disposal Area will take well over 5 years to reach Fort
Walton Beach (R1-R16). For this reason, neither alternative provides any measureable economic
benefit to Fort Walton Beach over a 5 year period. While Alternative 3 does address the critical
erosion problem east of East Pass, it does not provide any material to the western downdrift
beach. For this reason, it is not acceptable.
5.5.2
Legal Issues
Alternative 4 does have some challenges. First, the placement of dredged material on the eastern
side of East Pass may prompt a challenge by local interests west of the inlet. However, it should
be noted that FS§161.141(1) requires that “All construction and maintenance dredging of beachquality sand are placed on the adjacent eroding beaches unless, if placed elsewhere, an
equivalent quality and quantity of sand from an alternate location is placed on the adjacent
eroding beaches.” Fort Walton Beach, which is the nearest developed community west of the
inlet, is located over 4 miles from East Pass. It would probably not qualify as an “adjacent
eroding beach”.
It should also be noted that the erosional trends change at East Pass. Prior to 1996, the “adjacent
eroding beaches” were located on the western side of the inlet. However, since 1996, the
“adjacent eroding beaches” have been on the eastern side of the inlet (see Figures 2-2 and 4-6).
Since there is no disposal site on the “adjacent eroding beaches” east of the inlet, the present inlet
management practice is in conflict with current State law. Allowing the placement of material
on either side of the inlet ensures that the inlet management plan remains in compliance with
State law even if erosional trends change.
Adding a disposal site east of the inlet would require construction easements from upland
property owners. However, dune fill has previously been placed along this area (see Table 2-4).
In addition, the City of Destin has recently constructed the Holiday Isle Emergency Beach Fill
Project along the same reach. Since construction easements have been secured at least twice in
the recent past, it should be possible to secure them in the future to allow the placement of
dredged material on the beaches east of the inlet.
5.5.3
Economic Issues
The implementation of Alternative 4 affects the cost of maintaining East Pass in two ways. First,
dredge spoil will be discontinued at Norriego Point, which increases the pumping distances for
the areas north of the bridge. Second, there will be additional costs with the placement of
material in a newly defined spoil site on the eastern side of the inlet.
78
As stated earlier, the June 2000 Certificate of Adoption, which is the present inlet management
plan, recommends that Norriego Point be fully stabilized, with the discontinuing of dredge spoil
placement there. The City of Destin is presently pursuing plans to completely stabilize Norriego
Point. Furthermore, since 1999, the amount of dredge spoil placed on Norriego Point has been
declining. During the last dredging operation in 2010, no material was placed on Norriego Point
(see Table 2-1). Given these considerations, the placement of dredge spoil on Norriego Point is
likely to end regardless of whether Alternative 4 is adopted as a new inlet management plan.
There may be additional costs associated with introducing a new spoil area east of the inlet. The
securing of construction easements will introduce administrative costs. In addition, there may be
an increase in the bird monitoring costs when a dredging operation places material on both sides
of the inlet (see FDEP Permit 0288799-001-JC, Special Condition 28b). Finally, there may be
costs associated with additional piping required for placement of dredge spoil east of the inlet.
5.5.4
Experience with Similar Plans at Other Inlets in Florida
Disposal of dredged material from Federal navigation channels on both sides of an inlet is
successful for other navigational dredging projects in Florida, such as New Pass in Sarasota
County (USACE, 2000). The New Pass navigation project balances the need for erosion
mitigation along the updrift, but developed, side while bypassing material to the downdrift, but
largely undeveloped, side. A similar plan is recommended for sediment management at East
Pass using a flexible split of dredged material between both sides of the inlet.
5.6
Physical Monitoring
The June 2000 Certificate of Adoption for East Pass requires the implementation of “a
comprehensive beach, inlet, and offshore monitoring program subject to the approval of the
[Florida] Department [of Environmental Protection]”. However, comprehensive monitoring has
not been conducted. While the U.S. Army Corps of Engineers surveys East Pass on a regular
basis (http://navigation.sam.usace.army.mil/surveys/detail.asp?code=DE), annual beach surveys
on both sides of the inlet have not been conducted (see Table 2-2A). The most recent survey on
the west side of the inlet was conducted in July 2009. However, the most recent survey on the
eastern side was taken in September 2008, and it did not go below the water line. The present
monitoring programs, at best, provide only a partial depiction of the changes occurring at East
Pass.
A comprehensive beach, inlet, and offshore monitoring program could be optimized using the
required monitoring for the projects in Figure 5-1 and the present survey program by the U.S.
Army Corps of Engineers. If those projects are completed, various portions of the county’s
beaches will be surveyed on a regular basis to comply with the various permits in Table 5-1.
However, dependence on these surveys to monitor the inlet has the following disadvantages:
•
If all projects in Table 5-1 are constructed as scheduled, the first set of beach surveys that
covers both sides of East Pass will not occur until 2012.
79
•
If the any of the projects are delayed or cancelled, beach surveys along Holiday Isle, Fort
Walton Beach, or Eglin Air Force Base could be delayed indefinitely.
•
After 2014, the profiles west of the Beach Disposal Area (V611+480' to V619+435')
might be surveyed in different years than the others, making it difficult to assess how
quickly material is spreading.
•
The required monitoring of ebb shoal and the beaches on the western side of the inlet will
be discontinued between 2016 and 2017.
80
TABLE 5-1
BEACH AND EBB SHOAL SURVEYS
REQUIRED UNDER PRESENT PERMITS
Profiles
Project
FDEP Permit
Condition
Sponsor
Scheduled Surveys
V503 to V527
Eglin AFB Beach Restoration*
0289154-001-JC
Special Condition 26a
USAF
2012, 2013, 2014, 2015, 2017, 2019, 2021
V542 to V553
0289154-001-JC
USAF
2012, 2013, 2014, 2015, 2017, 2019, 2021
R1 to R15
Okaloosa Island Beach Restoration*
0286020-001-JC
Application Attachment K
Okaloosa Co.
2012, 2013, 2014, 2015, 2017, 2019, 2021
V601 to V617
0289154-001-JC
USAF
2012, 2013, 2014, 2015, 2017, 2019, 2021
V611 to V621
Walton Co. / Destin Beach Restoration
0218419-001-JC
City of Destin
2010, 2012, 2014, 2016
R17 to R38
Western Destin Beach Restoration**
0286575-001-JC
Application Attachment M
Okaloosa Co.
2011, 2012, 2013, 2014, 2016, 2018, 2020
R34 to R50
0218419-001-JC
City of Destin
2010, 2012, 2014, 2016
#
#
#
Ebb Shoal
0218419-001-JC
City of Destin
2010, 2012, 2014, 2016
NOTES: The information in this table applies to areas in Okaloosa County only.
* Survey dates based on project completion in 2012 (istockanalyst.com, December 7, 2009).
# Walton County is the project sponsor of the Walton County segment.
** Survey dates based on project construction beginning in late 2010 and ending in early 2011 (Northwest Florida Daily News, September 2, 2009).
81
A more comprehensive monitoring plan for the East Pass appears below:
1. Beginning in 2010, survey all beach profiles from V601 to R33 around July on an annual
basis, along with the Walton Co. / Destin borrow area. The area to be surveyed
corresponds to the area influenced by the inlet over long term time scales. The prime
sponsor for this survey could be the City of Destin, which is the sponsor of this study, or
the City and Okaloosa County, who is a co-sponsor for the Walton County / Destin Beach
Restoration project.
2. Coordinate the scheduling of the annual survey above with the periodic surveys
conducted in East Pass by the U.S. Army Corps of Engineers.
3. Add the other beach profiles in Table 5-1 to the survey above as required by the permits
for the other projects in Okaloosa and Walton Counties. Coordinate with the U.S Air
Force, Okaloosa County, and Walton County to cost share the additional survey work.
4. Include the annual beach survey above as a special permit condition for modification or
renewal of the FDEP permit for the Destin East Pass Maintenance Dredging and Disposal
(0288799-001-JC).
6.0
CONCLUSIONS
In 1999, an Inlet Management Plan was developed for East Pass. The plan was adopted by the
State in June 2000, requiring that:
1. At least 82,000 c.y./year of dredged material be placed on the beach west of the inlet.
2. Norriego Point be stabilized.
3. A comprehensive beach, inlet, and offshore monitoring program be implemented.
The first part of the plan was not met. Sand bypassing to the west has averaged 58,000 c.y./year
between 2000 and 2010 (Table 2-1, last row & column). The second part of the plan was
partially accomplished with the construction of two T-head groins and a revetment in 2003.
However, further stabilization efforts were required, leading to present design effort for the
Norriego Point Stabilization Project. The third part of the plan was not met. No systematic
program to regularly survey East Pass and the surrounding beaches was developed.
Since the adoption of the 1999 Inlet Management Plan, a large number of hurricanes and tropical
storms have affected the Destin area, including Hurricanes Ivan (2004), Dennis (2005), and
Katrina (2005). Due to these storms, East Pass has been subject to unusual sediment transport
conditions that are causing severe beach erosion on the east side of the inlet and accreting
beaches immediately west of the inlet. While the dominant sediment transport direction is from
east to west on the western side of the inlet, the dominant sediment transport direction on the
eastern side of the inlet is presently from west to east.
82
Within the inlet itself, the dominant sediment transport direction is from south to north near the
inlet entrance and from north to south near the US98 bridge. This converging transport is
consistent with recent and past current measurements, and it is the primary reason that dredging
is required to maintain the inlet’s navigability. Additional findings are as follows:
7.0
•
The Corps of Engineers has successfully maintained the East Pass navigation channel by
dredging approximately 99,600 cubic yards of material annually between 1999 and 2008.
•
East Pass has significantly influenced the coastline for a distance of approximately
10,000 ft. east and west of the inlet during the 1996 to 2007 study period.
•
Inlet management procedures should be modified to be able to accommodate both east
and west sediment transport scenarios and variable dredge quantities.
•
The Walton Co. / Destin Beach Project ebb shoal borrow area appears to have caused
some minor erosional impact to the adjacent beaches.
•
An ebb shoal swash channel near the east jetty may be partially responsible for the high
beach erosion rate east of the inlet.
•
The potential impacts of the proposed Western Destin Borrow Area are predicted to be
minor.
•
Dredge spoil material placed in the beach disposal area west of the inlet will take several
years to reach Fort Walton Beach under typical wave climates.
RECOMMENDATIONS
As stated in Chapter 161 of Florida Statutes (see Section 161.142 "Declaration of public policy
relating to improved navigation inlets"). "All construction and maintenance dredgings of beach
quality sand are placed on the adjacent eroding beaches unless, if placed elsewhere, an
equivalent quality and quantity of sand from an alternate location is placed on the adjacent
eroding beaches."
To address the conditions that presently exist, a flexible plan to manage the dredged material
from East Pass is recommended. Placing dredged material on Norriego Point, material west of
the inlet, and no material to the east is no longer a suitable plan for East Pass. Norriego Point is
likely to be completely armored within the next few years. Holiday Isle is presently the most
severely eroded area adjacent to East Pass. To better address these conditions, this study
proposes the following Inlet Management Plan modifications for East Pass:
1.
The inlet management plan should be modified to respond to sediment transport in both
east and west directions.
2.
The volume of sand to be transferred from the inlet channel to the adjacent beaches will
vary with each maintenance dredging event based on availability and federal funding.
83
3.
Prior to future channel dredging operations, analyze beach profile surveys on both sides
of the pass to determine the volume of erosion along the adjacent beaches 10,000 ft. east
and west of the pass.
4.
Place the dredge spoil material on the adjacent beaches accordingly to address the recent
measured erosion. If the available dredge volume is less than the total measured erosion,
the material placed on each side of the inlet should be pro-rated based on erosion.
5.
The City of Destin should complete the ongoing design, permitting and construction
effort to armor Norriego Point. This will allow for additional material to be available for
placement on adjacent beaches.
6.
Allow for a limited volume of dredge spoil from East Pass to be used prior to the
completion of the armoring project of Norriego Point.
7.
Discontinue the placement of dredged material from the main navigation channel on
Norriego Point once the armoring project has been completed.
8.
Conduct a survey of beach profiles V601 to R33 annually. The annual surveys should
extend to the depth of closure, take place around July, and be coordinated with required
surveys of the adjacent beach nourishment projects. This survey, combined the other
surveys required by existing permits shown in Table 5-1, will provide a comprehensive
county-wide data set to evaluate the impact of East Pass along the Gulf-front beaches.
9.
Continue the periodic surveys of the East Pass channel, the Destin Harbor Channel, and
the U.S. Coast Guard Channel by the U.S. Army Corps of Engineers.
10.
Communicate with Senators and Congressional Representatives to ensure that the East
Pass Federal navigation project can continue into the future
84
8.0
REFERENCES
Arnouil, D., and Trudnak, M., 2009. Walton County/Destin Beach Restoration Project, Walton
County and Okaloosa County, Florida, 2009 Two-Year Post-Construction Monitoring
Report, Taylor Engineering, Inc., 68 p. plus appendices.
Bridges, Allison, Trudnak, Michael, Krecic, Michael, 2008. Walton County / Destin Beach
Restoration Project, Walton County and Okaloosa County, Florida, 2007 Monitoring
Report, Taylor Engineering, Jacksonville, FL.
Coastal Technology, 2006. Coastal Assessment for Destin Pointe, Destin, Okaloosa County,
Florida, Coastal Technology, Vero Beach, FL.
Coastal Planning & Engineering, Inc., 2009. City of Destin, Florida Norriego Point Stabilization
Project Feasibility Study, Coastal Planning & Engineering, Inc., Boca Raton, FL.
Florida Department of Environmental Protection, 2000. East Pass Inlet Management Study
Implementation Plan, Certificate of Adoption,
http://bcs.dep.state.fl.us/bchmngmt/eastpass.pdf.
Florida Department of Environmental Protection, 2008. Strategic Beach Management Plan for
the Panhandle Gulf Coast Region,
http://www.dep.state.fl.us/beaches/publications/pdf/SBMP/Panhandle%20Gulf%20Coast
%20Region.pdf.
Florida Department of Environmental Protection, 2009. Historic Shoreline Database,
http://www.dep.state.fl.us/beaches/data/his-shore.htm.
Florida Department of Environmental Protection, 2009. Okaloosa County Permits,
http://www.dep.state.fl.us/beaches/permitting/okaloosa.htm.
Google, 2009. Google Earth 4.3.7284.3916, http://earth.google.com/.
istockanalyst.com, 2009. Construction projects to protect Okaloosa Island from storms begins:
Proposals came because 3 major hurricanes washed away roads and beaches in 10 years,
http://www.istockanalyst.com/article/viewiStockNews/articleid/3692061, December 7,
2009.
LABINS, 2004. 2004 Digital Orthographic Quarter-Quad, State Plane - NAD83 – MrSID,
http://data.labins.org/2003/MappingData/DOQQ/doqq_04_stpl_sid.cfm.
Microsoft, 2006. Microsoft Streets and Trips 2007, Microsoft, Redmond, WA.
Morang, Andrew, 1992. A Study of Geologic and Hydraulic Processes at East Pass, Destin,
Florida, U.S. Army Corps of Engineers, Washington, DC.
85
National Oceanographic and Atmospheric Administration, 2001. Office of Coast Survey
Historical Map & Chart Project,
http://historicalcharts.noaa.gov/historicals/historical_zoom.asp.
National Oceanographic and Atmospheric Administration, 2006. National Ocean Service (NOS)
Hydrographic Data Base (NOSHDB),
http://www.ngdc.noaa.gov/mgg/gdas/ims/hyd_cri.html.
National Oceanographic and Atmospheric Administration, 2008. Digital Coast: Data Access
Viewer, http://maps.csc.noaa.gov/dataviewer/viewer.html.
Northwest Florida Daily News, 2009. Okaloosa keeps beach MSBU intact,
http://www.nwfdailynews.com/common/printer/view.php?db=nwfdn&id=20243,
September 2, 2009.
Rosati, J. D. 2007. Sediment Budget Analysis System (SBAS),
http://cirp.usace.army.mil/products/index.html.
Rosati, Julie Dean, Kraus, Nicholas C., 1997. Even-Odd Function Analysis of Shoreline
Position and Volume Change, Coastal Engineering Technical Note IV-10, Coastal and
Hydraulics Laboratory, Vicksburg,
http://chl.erdc.usace.army.mil/library/publications/chetn/pdf/cetn-iv-10.pdf
Sommerfeld, Barry G., Mason, John M., Kraus, Nicholas C., Larson, Magnus, 1994. BFM:
Beach Fill Module, Report 1, Beach Morphology Analysis Package, (BMAP) – User’s
Guide, US Army Corps of Engineers, Vicksburg, MS.
Taylor Engineering, 1999. Investigation of Physical Processes, Inlet Management Plan for East
Pass to Choctawhatchee Bay, Okaloosa County, Florida, Taylor Engineering,
Jacksonville, FL.
Taylor Engineering, 2007. Okaloosa Island Beach Management Feasibility Study, Okaloosa
County, Florida, Taylor Engineering, Jacksonville, FL.
Taylor Engineering, 2008. Attachment C, Permit Drawings, Eglin AFB Beach Restoration
Project, Itemized Responses to the Request for Additional Information #2, Eglin AFB
Beach Restoration Project, Taylor Engineering, Jacksonville, FL.
Taylor Engineering, 2008. Attachment C, Permit Drawings, Okaloosa Island Beach Restoration
Project, Itemized Responses to the Request for Additional Information #2, Okaloosa
Island Beach Restoration Project, Taylor Engineering, Jacksonville, FL.
Taylor Engineering, 2009. Attachment B, Permit Drawings, Western Destin Beach Restoration
Project, Itemized Responses to the Request for Additional Information #3, Western
Destin Beach Restoration Project, Taylor Engineering, Jacksonville, FL.
86
U.S. Army Corps of Engineers, 1997. East Pass Channel, from the Gulf of Mexico into
Choctawhatchee Bay, Florida, Condition of Improvement on 30 September 1997,
http://navigation.sam.usace.army.mil/docs/document-download.asp?file=663.
U.S. Army Corps of Engineers, 1999. Inlets Online, http://www.oceanscience.net/inletsonline/.
U.S. Army Corps of Engineers, 2000. New Pass, Florida Plans for Maintenance Dredging, 8
Foot Project, U.S. Army Corps of Engineers, Jacksonville, FL.
U.S. Army Corps of Engineers, 2008. Request for Join Coastal Permit for Continued
Maintenance and Disposal Activities within East Pass Federal Navigation Project,
Destin, Okaloosa County, Florida, http://bcs.dep.state.fl.us/envprmt/okaloosa/pending/0288799_Destin_East_Pass_Maintenance_Dredging_%26_Dispo
sal/.
U.S. Army Corps of Engineers, 2008. Joint Airborne LIDAR Bathymetry Technical Center of
Expertise, East Pass Data CD-ROM, U.S. Army Corps of Engineers, Mobile, AL.
U.S. Army Corps of Engineers, 2009. Hydrographic Survey Detail & Download, East Pass,
http://navigation.sam.usace.army.mil/surveys/detail.asp?code=DE.
U.S. Army Corps of Engineers, 2009. East Pass, Florida Maintenance Dredging Stamped
Drawings, http://bcs.dep.state.fl.us/envprmt/okaloosa/issued/0288799_Destin_East_Pass_Maintenance_Dredging/001_JC/FINA
L%20ORDER%2010-28-2009/Stamped%20Drawings.pdf
WL | Delft (Waterloopkundig Labaratorium│Delft Hydraulics), 2005. Delft3D-FLOW,
Simulation of multi-dimensional hydrodynamic flows and transport phenomena,
including sediments, User manual. WL │ Delft Hydraulics, Delft, The Netherlands.
White, Mark L., 2009. East Pass Hydrographic Surveys (delivered via e-mail to Christopher M.
Day, P.E., August 12, 2009).
P:\Okaloosa\1050000 Destin IMP Update\_Deliverables\Inlet Management Plan Report DRAFT\East_Pass_Inlet_Mgmt_Plan_2010.doc
87

CITY OF DESTIN, FLORIDA EAST PASS INLET STUDY

Transcription

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