CRAIGHEAD COUNTY, ARKANSAS

Transcription

CRAIGHEAD COUNTY,
ARKANSAS
AND INCORPORATED AREAS
COMMUNITY
NUMBER
COMMUNITY
NAME
BAY, CITY OF
* BLACK OAK, TOWN OF
BONO, CITY OF
BROOKLAND, TOWN OF
CARAWAY, CITY OF
CASH, TOWN OF
CRAIGHEAD COUNTY,
UNINCORPORATED AREAS
EGYPT, TOWN OF
JONESBORO, CITY OF
LAKE CITY, TOWN OF
MONETTE, CITY OF
050045
050389
050046
050047
050311
050396
050427
050585
050048
050049
050350
*NON-FLOODPRONE COMMUNITIES
PRELIMINARY
JAN. 29, 2009
Revised: ___________
Federal Emergency Management Agency
Flood Insurance Study Number 05031CV000A
NOTICE TO
FLOOD INSURANCE STUDY USERS
Communities participating in the National Flood Insurance Program have established repositories of flood
hazard data for floodplain management and flood insurance purposes. This Flood Insurance Study may not
contain all data available within the repository. It is advisable to contact the community repository for any
additional data.
Part or all of this Flood Insurance Study may be revised and republished at any time. In addition, part of this
Flood Insurance Study may be revised by the Letter of Map Revision process, which does not involve
republication or redistribution of the Flood Insurance Study. It is, therefore, the responsibility of the user to
consult with community officials and to check the community repository to obtain the most current Flood
Insurance Study components. A listing of the Community Map Repositories can be found on the Index Map.
Initial Countywide FIS Effective Date: September 27, 1991
First Revised Countywide FIS Revision Date: _________, 20__
i
TABLE OF CONTENTS
Page
1.0
INTRODUCTION.......................................................................................................................... 1
1.1
1.2
1.3
2.0
AREA STUDIED ........................................................................................................................... 3
2.1
2.2
2.3
2.4
3.0
Scope of Study .................................................................................................................... 3
Community Description...................................................................................................... 6
Principal Flood Problems.................................................................................................... 7
Flood Protection Measures ................................................................................................. 9
ENGINEERING METHODS ..................................................................................................... 10
3.1
3.2
3.3
4.0
Purpose of Study................................................................................................................. 1
Authority and Acknowledgments ....................................................................................... 1
Coordination ....................................................................................................................... 2
Hydrologic Analyses......................................................................................................... 10
Hydraulic Analyses........................................................................................................... 14
Vertical Datum.................................................................................................................. 16
FLOODPLAIN MANAGEMENT APPLICATIONS............................................................... 16
4.1
4.2
Floodplain Boundaries...................................................................................................... 17
Floodways......................................................................................................................... 17
5.0
INSURANCE APPLICATIONS................................................................................................. 19
6.0
FLOOD INSURANCE RATE MAP........................................................................................... 27
7.0
OTHER STUDIES ....................................................................................................................... 27
8.0
LOCATION OF DATA ............................................................................................................... 27
9.0
BIBLIOGRAPHY AND REFERENCES................................................................................... 29
ii
TABLE OF CONTENTS (Cont’d)
Page
FIGURES
Figure 1 – Floodway Schematic ................................................................................................................. 18
TABLES
Table 1 – Streams Studied by Detailed Methods. ......................................................................................... 4
Table 2 – Streams Studied by Approximate Methods ...................................................................................5
Table 3 – Stream Name Changes...................................................................................................................6
Table 4 – Summary of Discharges.............................................................................................................. 12
Table 5 – Summary of Roughness Coefficients.......................................................................................... 15
Table 6 – Floodway Data............................................................................................................................ 20
Table 7– Community Map History ............................................................................................................. 28
EXHIBITS
Exhibit 1 – Flood Profiles
Asher Ditch
Butlers Ditch
Christian Creek
Christian Creek Lateral
Gum Slough
Higginbottom Creek
Honey Cypress Ditch
Lateral No. 3
Lateral No. 5
Little Bay Ditch
Lost Creek
Maple Slough Ditch
Middle Drain
Moore's Ditch Lateral
Tributary to Maple Slough Ditch
Turtle Creek
Turtle Creek Lateral
Viney Slough
Whaley Slough Ditch
Whiteman's Creek
Panel
Panel
Panels
Panel
Panel
Panels
Panel
Panels
Panel
Panels
Panels
Panel
Panel
Panel
Panel
Panels
Panel
Panels
Panel
Panels
Exhibit 2 – Flood Insurance Rate Map Index
Flood Insurance Rate Maps
iii
01P
02P
03P - 05P
06P
07P
08P - 10P
11P
12P - 13P
14P
15P - 17P
18P - 20P
21P
22P
23P
24P
25P - 26P
27P
28P - 29P
30P
31P - 33P
FLOOD INSURANCE STUDY
CRAIGHEAD COUNTY AND INCORPORATED AREAS, ARKANSAS
1.0
INTRODUCTION
1.1
Purpose of Study
This Flood Insurance Study (FIS) revises and updates information on the existence and
severity of flood hazards in the geographic area of Craighead County, including the Cities of
Bay, Bono, Caraway, Jonesboro and Monette; and the Towns of Black Oak, Brookland,
Cash, Egypt, and Lake City; and the unincorporated areas of Craighead County (referred to
collectively herein as Craighead County), and aids in the administration of the National
Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. This study has
developed flood-risk data for various areas of the community that will be used to establish
actuarial flood insurance rates and to assist the community in its efforts to promote sound
floodplain management. Minimum floodplain management requirements for participation in
the National Flood Insurance Program (NFIP) are set forth in the Code of Federal
Regulations at 44 CFR, 60.3.
Please note that the Town of Black Oak is non-floodprone.
In some States or communities, floodplain management criteria or regulations may exist that
are more restrictive or comprehensive than the minimum Federal requirements. In such
cases, the more restrictive criteria take precedence, and the State (or other jurisdictional
agency) will be able to explain them.
1.2
Authority and Acknowledgments
The sources of authority for this FIS report are the National Flood Insurance Act of 1968 and
the Flood Disaster Protection Act of 1973.
This study was prepared to include incorporated areas within Craighead County in a
countywide FIS. This information was previously published in separate FIS documents for
these communities. Information on the authority and acknowledgments for each of the
previously printed FIS documents and Flood Insurance Rate Maps (FIRMs), compiled from
their effective FIS reports, is shown below.
City of Bono:
The hydrologic and hydraulic analyses for the study effective
December 4, 1985 were prepared by the Arkansas Soil and Water
Conservation Commission and the Soil Conservation Service (SCS)
during the preparation of the Flood Plain Management Study for
the City of Bono. This work was completed in December 1983.
Town of Brookland:
The hydrologic and hydraulic analyses for the FIS dated October
15, 1979 (FIRM dated April 15, 1980) were prepared by Carver &
Carver, Inc., for FEMA, under Contract No. 11–4594. This work
was completed in July 1978.
1
City of Caraway:
City of Jonesboro:
The hydrologic and hydraulic analyses for the FIS dated December
1979 (FIRM dated June 18, 1980) were prepared by Carver &
Carver, Inc., for FEMA, under Contract No. 11–4594. This work
was completed in July 1977.
The hydrologic and hydraulic analyses for the FIS dated December
5, 1980 (FIRM dated June 15, 1981) were prepared by the U.S.
Army Corps of Engineers (USACE) Memphis District for FEMA,
under Inter Agency Agreement No. IAA–Il–7–76, Project Order
No. 19. This work was completed in July 1979.
Authority and acknowledgements for the Cities of Bay and Monette and the Towns of Cash
and Lake City are not available because no FIS reports were ever published for these
communities.
In the original countywide study, the hydrologic and hydraulic analyses of flooding sources
within the unincorporated areas of Craighead County were prepared by the Memphis District
of the USACE for the Federal Emergency Management Agency (FEMA), under Inter–
Agency Agreement No. EMW–87–E–2509. This work was completed in July 1988. The
initial countywide study also incorporated an updated hydraulic analysis for Lateral No. 3,
within the City of Jonesboro. This work, prepared by Miller Newell Engineering, Ltd., was
completed in August 1989.
In this revision of the Craighead County FIS, analysis of flooding sources within the
corporate limits of the City of Jonesboro were prepared by the City of Jonesboro for FEMA
under Inter–Agency Agreement No. EMT-2004-CA-0123r (Reference 1). This work was
completed in May 2009. The Comprehensive Flood Risk Resources and Response (CF3R)
Joint Venture completed the updates for the remainder of the county under contract EMT2002-CO-0049.
1.3
Coordination
The dates of the initial and final Consultation Coordination Officer’s (CCO) meetings for the
first countywide FIS for Craighead County and the incorporated areas within its boundaries
are shown in the following tabulation.
Community Name
City of Bono
Initial CCO Date
Final CCO Date
*
January 17, 1985
Town of Brookland
June 23, 1977
February 28, 1979
City of Caraway
June 23, 1977
February 28, 1979
City of Jonesboro
December 16, 1975
February 11, 1980
Craighead County
Unincorporated Areas
January 8, 1987
September 26, 1990
* Data not available
Both the initial and final CCO meetings for the first countywide FIS were attended by
representatives of FEMA, the communities, and the study contractors. The final CCO
meeting for the unincorporated areas of Craighead County also served as the final CCO
meeting for the initial countywide study and was open to representatives from all
2
communities within the county that were covered by the countywide study. All problems
raised at that meeting were addressed in the study.
The initial CCO meeting for this revision of the countywide FIS was held on September 24,
2004, and attended by representatives of FEMA, CF3R, Arkansas Geographic Information
Office, Craighead County, City of Bay, City of Bono, Town of Brookland, City of
Jonesboro, and Town of Lake City.
The results of the study were reviewed at the final CCO meeting held on
______________________________,
and
attended
by
representatives
of
_____________________________________________________________. All problems
raised at that meeting have been addressed in this study.
2.0
AREA STUDIED
2.1
Scope of Study
This FIS report covers the geographic area of Craighead County, Arkansas including the
incorporated communities listed in Section 1.1.
The areas studied by detailed methods were selected with priority given to all known flood
hazards and areas of projected development or proposed construction through December 16,
2008. Table 1, Streams Studied by Detailed Methods, lists the limits of study for the streams
studied by detailed methods.
Under Inter-Agency Agreement No. EMT-2004-CA-0123r (Reference 1), the City of
Jonesboro redelineated Butlers Ditch, Christian Creek, Christian Creek Lateral,
Higginbottom Creek, Lateral No. 3, Lateral No. 5, a portion of Little Bay Ditch, Lost Creek,
Moore’s Ditch Lateral, Turtle Creek, Turtle Creek Lateral, a portion of Viney Slough, and a
portion of Whiteman’s Creek. The mapping extents for several of the re-delineated areas
within the City of Jonesboro changed from the effective mapping extents. The differences
can be attributed to three main factors; (1) new topographic data, (2) change in the vertical
datum, and (3) channel centerline adjustments. Several mapping areas decreased in size
while others increased slightly. There were a few instances on Christian Creek Lateral,
Turtle Creek, and Lateral No. 5 where the channel centerlines were shifted to reflect their
current locations. Turtle Creek and Lateral No. 5 shifted at the upper end of their reaches
while Christian Creek Lateral was shifted along its entirety. All other changes to mapping
extents were minor in comparison to the effective study information (Reference 1).
The remaining streams in Craighead County were redelineated by CF3R, including Asher
Ditch, Gum Slough, Honey Cypress Ditch, a portion of Little Bay Ditch, Maple Slough
Ditch, Middle Drain, Tributary to Maple Slough Ditch, a portion of Viney Slough, Whaley
Slough Ditch and a portion of Whiteman’s Creek.
3
TABLE 1 – STREAM STUDIED BY DETAILED METHODS
Stream
Asher Ditch
Limits of Detailed Study
From State Highway 158 to a point approximately 449 feet
upstream of Missouri Street
Butlers Ditch
From its confluence with Little Bay Ditch to County
Road 910
From its confluence with Lost Creek to Neely Road
From its confluence with Christian Creek to Culberhouse
Street
From its confluence with Big Bay Ditch to County Road
673
From its confluence with Viney Slough at Ingels Road
to the downstream side of Parkview Street
From the St. Louis Southwestern Railway to a point
approximately 475 feet upstream of State Highway 158
From its confluence with Little Bay Ditch to the Union
Pacific Railroad
From its confluence with Turtle Creek to a point
approximately 158 feet upstream of the most upstream
Burlington Northern Railroad crossing
From the county boundary to County Road 910
From a point approximately 0.22 mile downstream of U.S.
Highway 63 to Peachtree Avenue
From its confluence with Gum Slough to a point
approximately 2 miles upstream of State Highway 18
From its confluence with Whaley Slough Ditch to a point
approximately 2,750 feet upstream of Main Street
From its confluence with Moore’s Ditch to a point
approximately 0.23 mile upstream of the Union Pacific
Railroad
From a point approximately 53 feet downstream of Rural
Road to a point approximately 0.4 mile upstream of
Stevens Street
From its confluence with Whiteman’s Creek to the
downstream site of U.S. Highway 49 at State Highway 1
From its confluence with Turtle Creek to Aggie Road
From the county boundary to the confluence of
Higginbottom Creek
From a point approximately 1,300 feet downstream of State
Highway 230 to the confluence of Middle Drain
From its confluence with Little Bay Ditch to Caraway Road
Christian Creek
Gum Slough
Higginbottom Creek
Honey Cypress Ditch
Lateral No. 3
Lateral No. 5
Little Bay Ditch
Lost Creek
Maple Slough Ditch
Middle Drain
Moore’s Ditch Lateral
Tributary to Maple
Slough Ditch
Turtle Creek
Viney Slough
Whaley Slough Ditch
Whiteman’s Creek
4
The following flooding sources were studied by approximate methods (Table 2).
TABLE 2 – STREAM STUDIED BY APPROXIMATE METHODS
Angle Ditch
Ark Slough Ditch
Asher Ditch
Big Bay Ditch
Big Creek
Big Creek Lateral No. 1
Big Slough Ditch
Black Fork Creek
Bohanan Slough Ditch
Bridger Creek
Cache River
Cache River Tributary 25
Cane Island Slough Ditch
Caney Ditch
Cockle Burr Slough Ditch
Deep Slough
Ditch No. 1
Ditch No. 2
Ditch No. 3
Ditch No. 4
Ditch No. 5
Ditch No. 7
Ditch No. 8
Ditch No. 10
Ditch No. 32
East Cache River
Emerson Ditch Lateral
Gum Slough
Gum Slough Ditch
Gunner Slough
Honey Cypress Ditch
Johnson Ditch
Lateral No. 3
Little Bay Ditch
Little Slough Ditch
Lost Creek
Maple Slough Ditch
Moore’s Ditch Lateral.
Mud Creek
Mud Slough Ditch
Podo Creek
Purcell Slough Ditch
Rogers Bayou
Saint Francis River
Thompson Creek
Tupelo Slough
Whaley Slough Ditch
Whistle Ditch
Whiteman’s Creek
Willow Ditch
Approximate analyses were used to study those areas having a low development potential or
minimal flood hazards. The scope and methods of study were proposed to, and agreed upon,
by FEMA and Craighead County.
Table 3, “Stream Name Changes” lists those streams whose name has changed or differs
from that published in the previous FIS or published Flood Insurance Rate Maps (FIRMs) for
Craighead County.
5
TABLE 3 - STREAM NAME CHANGES
Community
Bay, City of
Bay, City of
Jonesboro, City of
Jonesboro, City of
Jonesboro, City of
Lake City, Town of
Lake City, Town of
Lake City, Town of
Unincorporated areas of
Craighead County
Unincorporated areas of
Craighead County
2.2
Old Name
Ditch No. 6
Gum Slough Ditch
Big Creek Ditch
Davis Branch
Viney Slough Ditch
Purcell Slough Ditch No. 6
Ditch No. 7
Thompson Creek Ditch
Johnson Ditch Lateral No. 3
New Name
Ditch No. 3
Gum Slough
Big Creek
Rogers Bayou
Viney Slough
Purcell Slough Ditch
Ditch No. 9
Thompson Creek
Johnson Ditch
West Cache River
Cache River Tributary 25
Community Description
Craighead County encompasses an area of 713 square miles in northeastern Arkansas. It is
bordered by the unincorporated areas of Greene County to the north, the unincorporated
areas of Lawrence County to the northwest, the unincorporated areas of Jackson County to
the west, the unincorporated areas of Poinsett County the south, the unincorporated areas of
Mississippi County to the east, and the unincorporated areas of Dunklin County, Missouri, to
the northeast.
Crowley's Ridge, extends from Greene County to the north and crosses the west central
portion of Craighead County in a southerly direction. The lands on the ridge are gently
rolling, and gradually slope down to bottom-lands on either side. The bottom-lands are rich
delta land, used mainly for agricultural purposes. The portion of Craighead County lying
east of Crowley's Ridge is drained by the St. Francis River and its numerous tributaries.
Cache River enters from the north and flows in a southerly and southwesterly direction.
Cache River and its tributaries drain all that territory lying west of Crowley's Ridge.
The climate in the area of Craighead County is humid subtropical, with a mean annual
temperature of 61 degrees Fahrenheit (˚F). Temperature extremes range from –18 F to 116 F.
The average annual precipitation is 48 inches (Reference 2).
According to the U.S. Census Bureau 2000 census, Craighead County has a population of
82,148. The 2008 Census estimate shows the county increased in population to 92,640
people. The county has two county seats located in the City of Jonesboro and the Town of
Lake City (Reference 3).
The City of Jonesboro is the largest city in northeast Arkansas and is the fifth most populous
city in the state. According to the 2008 U.S. Census Bureau estimates, Jonesboro’s
population is 63,960 with an area of 80 square miles. Over 75 percent of the county’s
residents live in Jonesboro. Nine smaller communities with populations ranging from 106 to
2,130 are located throughout the county (References 3 and 4).
The Town of Lake City is located about 10 miles east of Jonesboro. Lake City, the second
6
county seat, is the second most populous city in Craighead County with a 2008 population
estimate of 2,130 people and an aerial extent of 2.2 square miles (References 3 and 4).
The City of Bay comprises 3.4 square miles located south east of Jonesboro. The U.S.
Census Bureau estimates the 2008 population at 2,030 residents (References 3 and 4).
The Town of Black Oak has a 2008 population estimate of 300 within a 0.4 square mile area.
The Town is located approximately 15 miles east of Jonesboro (References 3 and 4).
The City of Bono has a 2008 population estimate of 1,599 within 1.4 square miles in the
north west portion of the County. Bono is located approximately 5 miles north west of
Jonesboro (References 3 and 4).
The Town of Brookland’s 2008 estimated population was 1,670 people. The Town has an
area of 1.4 square miles located approximately 5 miles north east of Jonesboro (References 3
and 4).
The City of Caraway is located in south east Craighead County. The City’s corporate
boundary encompasses 2.3 square miles and extends to the Craighead-Mississippi County
boundary. According to the U.S. Census Bureau, Caraway had an estimated 1,393 residents
in 2008 (References 3 and 4).
The Town of Cash is located about 10 miles west of Jonesboro. Cash’s corporate limits
extend 0.4 square miles. The 2008 population estimate is 318 (References 3 and 4).
The Town of Egypt is located in the western portion of the County, approximately 15 miles
west of Jonesboro. The Town has an aerial extent of 0.4 square miles and a population
estimate of 106 (References 3 and 4).
The City of Monette is located about 20 miles east of Jonesboro. The City has an area of 1.6
square miles and a 2008 population estimate of 1,229 (References 3 and 4).
2.3
Principal Flood Problems
The majority of floods in the Craighead County occur in the winter and spring. The flooding
is aggravated by roads and bridges in the floodplains that restrict flows and by urbanization
of the watersheds. In the City of Bono, flooding is from manmade ditches that provide
drainage from urban areas and upstream runoff from Crowley’s Ridge. Flood problems in
the City of Bono are aggravated by undersized road openings and excavated soil piled along
North Drain.
In March 1997, excessive rainfall combined with high water levels on the Mississippi River
caused flooding in portions of eastern Arkansas including Craighead County. Flooding
caused 18 bridges to be washed out in Poinsett County to the south of Craighead County.
Approximately 100 homes were flooded in the area. Property damage of $1.8 million dollars
was estimated for this flood event (Reference 5).
7
On October 5, 1998, flash flooding was reported in the eastern part of Craighead County
where over 3 inches of rain fell in a short period of time. Streets were flooded in the Towns
of Bay and Monette with two cars under water in Monette. The flash flooding forced people
to use sandbags in Bay (Reference 5).
On February 14, 2001, 4 inches of rain fell in a short period of time and caused flood waters
to reach many houses in the City of Jonesboro where about 100 residents were forced to
evacuate (Reference 5).
On August 13, 2002, 20 homes and several businesses flooded in Jonesboro (Reference 5).
A cold front moved into Arkansas during the afternoon and evening hours of September
26th, 2007. Showers and thunderstorms that developed ahead of the front dumped four to
five inches of rain south of Brookland and produced flash flooding on Bridger Creek. The
flood waters moved into the Windsor Landing and Sage Meadow Subdivisions in the
Farrville area. At least twenty-five homes were flooded. Two of the home's garages
exploded due to fumes from gasoline containers interacting with water heater pilot lights. A
few automobiles were also flooded (Reference 5).
Above normal rainfall across Northeast Arkansas brought the Black River to record-setting
levels in March 2008. The record setting levels put pressure on many levees in the area
causing a few breaks. Numerous roads were closed due to the flooding and many homes
were inundated. Heavy rain caused flooding along the Cache River and Big Creek Ditch.
The Windsor Landing Subdivision on U.S. Highway 49 at Farville was flooded as well as the
Cottonwood Subdivision near Jonesboro. Many streets in the City of Jonesboro were
flooded (Reference 5).
A semi-tropical low pressure system that tracked across the Mid-South during the late
afternoon and evening of May 24, 2009 produced heavy rainfall and flash flooding in the
northern parts of Jonesboro. Several homes were flooded along Burke Avenue and North
Patrick Street. Three fatalities were reported for this storm. A child was swept into a
drainage ditch near Burke Avenue and Vine Street in Jonesboro. In the Greensboro area, a
sport utility vehicle was pulling into a flooded driveway off County Road 785 and was swept
100 yards downstream, killing both passengers. At least 2 feet of water covered the bridge. A
portion of the bridge was washed out (Reference 5).
Four United States Geological Survey (USGS) stream flow gages are located in Craighead
County. The gages are located on the St. Francis River (Gage 07040450) in the Town of
Lake City, on the Cache River (Gage 07077380) in the Town of Egypt and on Lost Creek
(Gage 07077652) and Whiteman’s Creek (Gage 07047855) in the City of Jonesboro. The
two gages located in the City of Jonesboro are operated by the USGS in cooperation with the
City. These gages are real-time data sites that record gage height only. Data for these gages
are available on-line for only the past 60 days (Reference 6).
The gages located on St. Francis River and Cache River are operated by the USGS and
record daily gage height and stream flow along with peak observations. Peak stream flows
recorded for these gauging stations are listed below. The period of record for the gage on St.
Francis River extends from 1931 to present. The period of record for the gage on Cache
River extends from 1938 to present (Reference 6).
8
2.4
River
Gage
St. Francis
Cache
07040450
07077380
Date
Peak
Gage Height(ft)
April 2-3, 1979
January 6, 1966
14.37
21.88
Peak
Stream Flow
(cfs)
42,700
8,940
Flood Protection Measures
The Natural Resources Conservation Service (NRCS), formerly the Soil Conservation
Service (SCS) has constructed three flood control reservoirs in the upper reaches of the Lost
Creek watershed. The effects of these reservoirs were considered in the hydraulic analysis of
Lost Creek (Reference 7).
Several PL-566 flood retarding structures are located in the Big Creek watershed. Many of
the older PL-566 dams are nearing the end of their 50 year life span and have significant
rehabilitation needs. In fiscal year 2007, the NRCS developed rehabilitation plans for PL566 reservoir, Big Creek Site 6 in Craighead County (Reference 8).
Several levees are located along the St. Francis River in the eastern portion of the county.
The St. Francis West Levee, St. Francis East Levee and Thompson Creek Levee were
constructed by the USACE and operated by the Bay and St. Francis Drainage District No.
29. The St. Francis River Left Bank Levee, Cockle Burr Slough Levee and the Right Hand
Chute of the Little River Levee were constructed by the USACE and operated by the Buffalo
Island Drainage District No. 9. FEMA specifies that all levees must meet and continue to
meet, minimum design, operation, and maintenance standards consistent with the level of
protection sought through the comprehensive flood plain management criteria established by
44CFR65.10. The St. Francis East and West Levees and the Thompson Creek Levee were
certified by USACE and meet the requirement of 44CFR65.10.
Although a Provisionally Accredited Levee agreement was signed on March 14, 2007 for the
St. Francis River Left Bank Levee, Cockle Burr Slough Levee and the Right Hand Chute of
the Little River Levee, FEMA did not receive the documentation necessary to demonstrate
compliance with 44CFR65.10 within the 24-month period, so these levees are not shown as
providing protection from the 1-percent-annual-chance flood.
Several man-made channels have been constructed within the County to convey floodwaters
including Big Slough Ditch, Ditch No. 2, and Main Ditch. In 2004, the NRCS initiated an
improvement project for Segment No. 7 of the Main Ditch to provide flood prevention
benefits. The project included four miles of channel improvement for Segment No. 7 of
Main Ditch in the Poinsett watershed south of Jonesboro (Reference 9).
In the City of Bono, two man–made channels – Whaley Slough Ditch and Middle Drain –
convey floodwaters through the area (Reference 7).
In 1999, the Memphis District USACE initiated a channel maintenance project for Ditch No.
9 in the St. Francis River Basin (Reference 10). The Memphis District USACE also initiated
channel improvements for several streams in Craighead County in 1992. The improvements
consisted of 6.1 miles within the City of Jonesboro including channel enlargement of 2.95
miles of Higginbottom Creek, 0.72 miles of Moore’s Ditch, 0.92 miles of Turtle Creek and
9
1.5 miles of Whiteman’s Creek (Reference 11).
Most of the flood protection measures on the remaining streams in the county are limited to
cleaning and excavating the channels to promote drainage through the study area.
3.0
ENGINEERING METHODS
For the flooding sources studied by detailed methods in the communities, standard hydrologic and
hydraulic study methods were used to determine the flood-hazard data required for this study. Flood
events of a magnitude that is expected to be equaled or exceeded once on the average during any 10–,
50–, 100–, or 500–year period (recurrence interval) have been selected as having special significance
for floodplain management and for flood insurance rates. These events, commonly termed the 10–,
50–, 100–, and 500–year floods, have a 10–, 2–, 1–, and 0.2–percent chance, respectively, of being
equaled or exceeded during any year. Although the recurrence interval represents the long-term,
average period between floods of a specific magnitude, rare floods could occur at short intervals or
even within the same year. The risk of experiencing a rare flood increases when periods greater than
1 year are considered. For example, the risk of having a flood that equals or exceeds the
1-percent-annual-chance flood in any 50–year period is approximately 40 percent (4 in 10); for any
90–year period, the risk increases to approximately 60 percent (6 in 10). The analyses reported
herein reflect flooding potentials based on conditions existing in the community at the time of
completion of this study. Maps and flood elevations will be amended periodically to reflect future
changes.
3.1
Hydrologic Analyses
Hydrologic analyses were carried out to establish peak discharge-frequency relationships for
each flooding source studied by detailed methods affecting the communities. Peak
discharge–frequency relationships for Little Bay Ditch, Viney Slough, and Whiteman’s
Creek (from its confluence with Little Bay Ditch to a point approximately 0.5 mile upstream
of the Union Pacific Railroad), were determined using USACE HEC–1 hydrographs
(Reference 12). Peak discharges for Butlers Ditch were based on the HEC–1 analysis of
Little Bay Ditch, because Butlers Ditch is a sub–basin area of Little Bay Ditch. Peak
discharges for Gum Slough and Maple Slough Ditch were determined from drainage area–
discharge relationships.
Information on the methods used to determine peak discharge– frequency relationships for
the streams studied by detailed methods is shown below. The incorporated communities are
listed in alphabetical order; methodologies are described for each community. For streams
that flow through two or more communities, each methodology described applies only to that
portion of the stream studied by detailed methods within that particular community.
The original FIS for the City of Bono considered Whaley Slough Ditch and Middle Drain
(Reference 13). In that study, peak discharges were determined using the SCS Technical
Release 20 computer program (Reference 14). Variables included factors such as soil
moisture condition, watershed land use, precipitation amount and time distribution, and
channel characteristics that influence water flow.
10
The original FIS for the Town of Brookland considered Tributary to Maple Slough Ditch
(Reference 15). In that study, synthetic storms were computed to define the discharge–
frequency data. Rainfall distribution for the 10–, 2–, and 1–percent-annual-chance
frequencies were computed from rainfall–frequency data contained in the National Weather
Service Technical Paper No. 40 (Reference 16). Unit hydrographs were computed for the
stream using Snyder’s coefficients. The hydrographs and rainfall distributions were used to
compute synthetic storms of the desired frequencies from which the peak discharges were
obtained. A log–probability relationship of the lower frequency peak discharges was used to
compute each of the 0.2-percent-annual-chance peak discharges.
The original FIS for the City of Caraway considered Honey Cypress Ditch and Asher Ditch
(Reference 17). In that study, synthetic storms were computed to define the discharge–
frequency data. Rainfall distribution for the 10–, 2–, and 1-percent-annual-chance
frequencies were computed from rainfall–frequency data contained in the National Weather
Service Technical Paper No. 40 (Reference 16). Unit hydrographs were computed for the
stream using Snyder’s coefficients. The hydrographs and rainfall distributions were used to
compute synthetic storms of the desired frequencies from which the peak discharges were
obtained. A log–probability relationship of the lower frequency peak discharges was used to
compute each of the 0.2-percent-annual-chance peak discharge.
The original FIS for the City of Jonesboro considered the following streams: Christian
Creek, Christian Creek Lateral, Lateral No. 3, Lost Creek, Moore’s Ditch Lateral,
Higginbottom Creek, Whiteman’s Creek (from a point approximately 1.2 miles downstream
of U.S. Highway 63 to the downstream side of Highland Drive), Turtle Creek, Turtle Creek
Lateral, and Lateral No. 5 (Reference 18). In that study, because there are no stream flow
records for these streams, peak discharges were obtained by applying various rainfall–
duration amounts to unit hydrographs developed along the streams. Rainfall frequency
values were determined from Technical Paper No. 40 (Reference 16). Unit hydrographs were
developed using Snyder’s method with coefficients taken from regional curves developed by
the Memphis District USACE from previous studies of basins with similar characteristics.
Storage routing models were developed for all streams using standard procedures.
A summary of the drainage area–peak discharge relationships for the streams studied by
detailed methods is shown in Table 4, Summary of Discharges.
11
TABLE 4 – SUMMARY OF DISCHARGES
DRAINAGE
AREA
(sq. miles)
FLOODING SOURCE AND
LOCATION
Asher Ditch
At State Highway 158
Butlers Ditch
At confluence with Little Bay Ditch
Christian Creek
At County Road
At Matthew's Avenue
At West Nettleton Avenue
At Woodsprings Road
At U.S. Route 63 Bypass
At confluence with Christian Creek
Gum Slough
At confluence with Big Bay Ditch
Higginbottom Creek
At Caraway Road
At State Highway 1 Bypass
At Stroud Street
At Parkview Street
Honey Cypress Ditch
Approximately 0.2 mile above the mouth
Lateral No. 3
At confluence with Moore's Ditch
At Burlington Northern Railroad
Lateral No. 5 **
At mile 1.58
Little Bay Ditch
At mouth
Lost Creek
Approximately 1,125 feet downstream of
U.S. Highway 63
At Culberhouse Street
At cross section L
At Peachtree Avenue (cross section M)
Maple Slough Ditch
At confluence with Gum Slough Ditch
PEAK DISCHARGES (cfs)
10%
2%
1%
0.2%
Annual Annual Annual Annual
Chance Chance Chance Chance
7.31
851
1,148
1,270
1,580
6.00
*
*
1,016
*
4.65
3.59
2.78
1.67
1.39
3,485
3,170
2,465
1,100
1,100
4,385
4,120
3,375
1,335
1,360
4,790
4,540
3,750
1,455
1,470
5,725
5,490
4,580
1,735
1,720
0.52
340
480
540
670
30.75
*
*
8,100
*
7.27
5.13
1.29
0.47
3,400
2,835
1,725
690
4,615
3,910
2,410
965
5,210
4,375
2,710
1,085
6,600
5,655
3,370
1,360
7.05
655
888
984
1,230
5.42
0.26
1,155
275
1,580
385
1,890
435
2,555
545
1.68
1.46
1,145
1,555
1,675
2,180
1,905
2,455
2,395
3,070
70.78
*
*
10,025
*
27.56
20.63
18.99
15.66
9.41
7,360
4,310
4,250
3,140
2,220
9,560
5,790
5,715
4,050
3,105
10,515
6,450
6,330
4,445
3,500
12,765
7,995
7,650
5,435
4,375
16.93
*
*
6,375
*
* Data not computed
**Discharges decrease downstream in some cases because of valley storage effects
12
TABLE 4 – SUMMARY OF DISCHARGES (continued)
DRAINAGE
AREA
(sq. miles)
FLOODING SOURCE AND
LOCATION
Middle Drain
At North Kathleen Street
At St. Louis Southwestern Railway
Bridge
At Stevens Street
Turtle Creek **
At Union Pacific Railroad
At Nettleton Avenue
At confluence of Lateral No. 5
At confluence of Turtle Creek Lateral
At State Highway 1
At Aggie Road
Viney Slough
Upstream of County Road 616
Whaley Slough Ditch
Approximately 1,300 feet downstream of
State Highway 230
Whiteman's Creek
At confluence with Little Bay Ditch
At County Road 604 (mile 2.42)
At Ingels Road (mile 3.5)
At Highway 63 Bypass
At confluence of Turtle Creek
At Mo-Pac Railroad
At Highway No. 1 Bypass
At Highland Drive
PEAK DISCHARGES (cfs)
10%
2%
1%
0.2%
Annual Annual Annual Annual
Chance Chance Chance Chance
1.81
683
*
1,026
*
1.29
805
1,025
1,125
1,340
3.04
2,060
2,650
2,930
3,530
2.72
2,000
2,590
2,870
3,440
6.30
4.76
4.68
2.69
0.45
3,475
3,328
3,015
2,540
730
4,050
4,080
3,930
3,315
1,025
4,270
4,360
4,350
3,670
1,155
5,120
5,295
5,360
4,505
1,445
0.24
255
360
405
505
21.56
*
*
4,080
*
2.39
1,265
*
1,888
*
15.50
12.43
10.42
9.03
7.98
1.72
1.37
0.56
*
3,685
3,680
3,450
3,280
740
845
440
*
4,845
4,675
4,370
4,370
1,045
1,155
620
5,001
5,360
5,120
4,800
4,865
1,150
1,295
695
*
6,600
6,330
5,955
5,900
1,365
1,590
870
* Data not computed
**Discharges decrease downstream in some cases because of valley storage effects
13
3.2
Hydraulic Analyses
Analyses of the hydraulic characteristics of flooding from the sources studied were carried
out to provide estimates of the elevations of floods of the selected recurrence intervals. Users
should be aware that flood elevations shown on the FIRM represent rounded whole-foot
elevations and may not exactly reflect the elevations shown on the Flood Profiles or in the
Floodway Data tables in the FIS report. Flood elevations shown on the FIRM are primarily
intended for flood insurance rating purposes. For construction and/or floodplain
management purposes, users are cautioned to use the flood elevation data presented in this
FIS in conjunction with the data shown on the FIRM.
Cross section data for the streams studied by detailed methods were obtained by field
inspection. All bridges and culverts were field surveyed to obtain elevation data and
structural geometry. Cross sections were located at close intervals above and below bridges
and culverts in order to compute the significant backwater effects of these structures.
Locations of selected cross sections used in the hydraulic analyses are shown on the Flood
Profiles (Exhibit 1). For stream segments for which a floodway was computed (Section 4.2),
selected cross-section locations are also shown on the FIRM (Exhibit 2).
The hydraulic analyses for the FIS studies were based on unobstructed flow. The flood
elevations shown on the Flood Profiles (Exhibit 1) are thus considered valid only if hydraulic
structures remain unobstructed, operate properly, and do not fail.
Water–surface elevations for floods of the selected recurrence intervals on Little Bay Ditch,
Whiteman’s Creek, Gum Slough, Maple Slough Ditch, and Viney Slough were determined
using the USACE HEC–2 step–backwater computer program (Reference 19).
Information on the methods used to determine the water–surface elevations for floods of the
selected recurrence intervals on the streams studied by detailed methods within the
incorporated areas of the county, compiled from the previously printed narratives for those
communities, is shown below. The listing of streams considered in each FIS includes only
those streams or portions of streams whose hydraulic analyses were taken from that
particular study.
The original FIS for the City of Bono considered Whaley Slough Ditch and Middle Drain
(Reference 13). In that study, water–surface elevations were computed using the SCS WSP–
2 computer program (Reference 20). Starting water–surface elevations were taken at critical
depth.
The original FIS for the Town of Brookland considered Tributary to Maple Slough Ditch
(Reference 15). In that study, water–surface elevations were computed using the USACE
HEC–2 step– backwater computer program (Reference 19). Starting water–surface elevations
were determined using the conveyance water–surface elevation curves constructed for the
downstream sections of the streams.
The original FIS for the City of Caraway considered Honey Cypress Ditch and Asher Ditch
HEC–2 step–backwater computer program (Reference 19). Starting water–surface elevations
14
were determined using the conveyance water–surface elevation curves constructed for the
downstream sections of the streams.
The original FIS for the City of Jonesboro considered the following streams: Christian
Creek, Christian Creek Lateral, Higginbottom Creek, Lateral No. 3, Lateral No. 5, Lost
Creek, Moore’s Ditch Lateral, Turtle Creek, Turtle Creek Lateral and Whiteman’s Creek
HEC–2 step–backwater computer program (Reference 19). Starting water–surface elevations
were obtained by the slope/area method and from previous studies performed by the
USACE.
Letter of Map Revisions (LOMRs) that affect the studied stream reaches were evaluated and
incorporated, as necessary.
Flood profiles were drawn showing computed water–surface elevations for floods of the
selected recurrence intervals.
Channel roughness factors (Manning’s “n”) used in the hydraulic computations were
assigned on the basis of field inspections. Table 5, Summary of Roughness Coefficients,
shows the ranges of channel and overbank “n” values for the streams studied by detailed
methods.
TABLE 5 – SUMMARY OF ROUGHNESS COEFFICIENTS
Channel “n”
0.040 - 0.045
--- 1
0.050 2
0.050 2
--- 1
0.050 2
0.040 - 0.045
0.050 2
0.050 2
--- 1
0.050 2
--- 1
--- 1
0.050 2
0.035 - 0.050
0.050 2
0.050 2
--- 1
--- 1
--- 1
Stream
Asher Ditch
Butler's Ditch
Christian Creek
Gum Slough
Higginbottom Creek
Honey Cypress Ditch
Lateral No. 3
Lateral No. 5
Little Bay Ditch
Lost Creek
Maple Slough Ditch
Middle Drain
Turtle Creek
Viney Slough
Whaley Slough Ditch
Whiteman's Creek
1
2
Data not available
Average value
15
Overbank "n"
0.070
--- 1
0.090 2
0.090 2
--- 1
0.090 2
0.070
0.090 2
0.090 2
--- 1
0.090 2
--- 1
--- 1
0.090 2
0.070 - 0.090
0.090 2
0.090 2
--- 1
--- 1
--- 1
3.3
Vertical Datum
All FIS reports and FIRMs are referenced to a specific vertical datum. The vertical datum
provides a starting point against which flood, ground, and structure elevations can be
referenced and compared. Until recently, the standard vertical datum used for newly created
or revised FIS reports and FIRMs was the National Geodetic Vertical Datum of 1929
(NGVD). With the completion of the North American Vertical Datum of 1988 (NAVD),
many FIS reports and FIRMs are now prepared using NAVD as the referenced vertical
datum.
Flood elevations shown in this FIS report and on the FIRM are referenced to the NAVD.
These flood elevations must be compared to structure and ground elevations referenced to
the same vertical datum. Some of the data used in this revision were taken from the prior
effective FIS reports and FIRMs and adjusted to NAVD88. The datum conversion factor
from NGVD29 to NAVD88 in Craighead County is +0.21 feet.
For additional information regarding conversion between the NGVD and NAVD, visit the
National Geodetic Survey website at www.ngs.noaa.gov, or contact the National Geodetic
Survey at the following address:
Vertical Network Branch, N/CG13
National Geodetic Survey, NOAA
Silver Spring Metro Center 3
1315 East-West Highway
Silver Spring, Maryland 20910
(301) 713-3191
Temporary vertical monuments are often established during the preparation of a flood hazard
analysis for the purpose of establishing local vertical control. Although these monuments are
not shown on the FIRM, they may be found in the Technical Support Data Notebook
associated with the FIS report and FIRM for this community. Interested individuals may
contact FEMA to access these data.
To obtain current elevation, description, and/or location information for benchmarks shown
on this map, please contact the Information Services Branch of the NGS at (301) 713 3242,
or visit their website at www.ngs.noaa.gov.
4.0
FLOODPLAIN MANAGEMENT APPLICATIONS
The NFIP encourages State and local governments to adopt sound floodplain management programs.
To assist in this endeavor, each FIS report provides 1-percent-annual-chance floodplain data, which
may include a combination of the following: 10-, 2-, 1-, and 0.2-percent-annual-chance flood
elevations; delineations of the 1- and 0.2-percent-annual-chance floodplains; and a
1-percent-annual-chance floodway. This information is presented on the FIRM and in many
components of the FIS report, including Flood Profiles and Floodway Data tables. Users should
reference the data presented in the FIS report as well as additional information that may be available
at the local community map repository before making flood elevation and/or floodplain boundary
determinations.
16
4.1
Floodplain Boundaries
To provide a national standard without regional discrimination, the 1-percent-annual-chance
flood has been adopted by FEMA as the base flood for floodplain management purposes.
The 0.2-percent-annual-chance flood is employed to indicate additional areas of flood risk in
the county.
Within the City of Jonesboro, the 1- and 2- percent annual chance flood hazard boundaries
were digitally mapped using the flooding sources listed in the 1991 FIS for Craighead
County within the City of Jonesboro using water surface elevations, lettered cross-sections,
and floodway information included in the effective study data, including LOMRs. This data
was geo-referenced, the datum shifted from NGVD 29 to NAVD 88, and the Base Flood
Elevations (BFEs) re-delineated using 2005 LlDAR 2-foot contours (Reference 1). All
floodway data was reproduced from the existing 1991 FIS and adjusted slightly for
smoothing purposes. The effective delineations were used at any location where the new redelineation boundaries extended beyond the effective delineations. In areas where the
floodplains fell within the effective boundaries, the redelineated boundaries were used. Zone
A hazard areas were reproduced from the effective data and adjusted to fit revised channel
locations and new topographic information (Reference 1).
For detail study streams outside of Jonesboro, the 1- and 0.2-percent-annual-chance
floodplain boundaries have been redelineated using the flood elevations determined at each
cross section. Between cross sections, the boundaries were interpolated using topographic
maps at a scale of 1:24,000 with a contour interval of 5 feet (Reference 21).
The 1-and 0.2-percent-annual-chance floodplain boundaries are shown on the Flood
Insurance Rate Map (Exhibit 2). On this map, the 1–percent-annual-chance floodplain
boundary corresponds to the boundary of the areas of special flood hazards (Zones A and
AE), and the 0.2-percent-annual-chance floodplain boundary corresponds to the boundary of
areas of moderate flood hazards. In cases where the 1-and 0.2-percent-annual-chance
floodplain boundaries are close together, only the 1–percent-annual-chance floodplain
boundary has been shown. Small areas within the floodplain boundaries may lie above the
flood elevations but cannot be shown due to limitations of the map scale and/or lack of
detailed topographic data.
For the streams studied by approximate methods, the 1–percent-annual-chance floodplains
were delineated using the Flood Hazard Boundary Map for the unincorporated areas of
Craighead County (References 7 and 22).
4.2
Floodways
Encroachment on floodplains, such as structures and fill, reduces flood-carrying capacity,
increases flood heights and velocities, and increases flood hazards in areas beyond the
encroachment itself. One aspect of floodplain management involves balancing the economic
gain from floodplain development against the resulting increase in flood hazard. For
purposes of the NFIP, a floodway is used as a tool to assist local communities in this aspect
of floodplain management. Under this concept, the area of the 1-percent-annual-chance
floodplain is divided into a floodway and a floodway fringe. The floodway is the channel of
a stream, plus any adjacent floodplain areas, that must be kept free of encroachment so that
17
the base flood can be carried without substantial increases in flood heights. Minimum
Federal standards limit such increases to 1 foot, provided that hazardous velocities are not
produced. The floodways in this study are presented to local agencies as minimum standards
that can be adopted directly or that can be used as a basis for additional floodway studies.
The floodways presented in this study for Christian Creek, Christian Creek Lateral, Lateral
No. 3, Lateral No. 5, Lost Creek, Moore’s Ditch Lateral, Higginbottom Creek, Turtle Creek,
Turtle Creek Lateral, and Whiteman’s Creek were taken from the FIS for the City of
Jonesboro (Reference 18). The floodway for Tributary to Maple Slough Ditch was taken
from the FIS for the Town of Brookland (Reference 15).
The floodways presented in this study were computed for certain stream segments on the
basis of equal-conveyance reduction from each side of the floodplain. Floodway widths
were computed at cross sections. Between cross sections, the floodway boundaries were
interpolated. The results of the floodway computations are tabulated for selected cross
sections (see Table 6, Floodway Data).
In cases where the floodway and
1-percent-annual-chance floodplain boundaries are either close together or collinear, only the
floodway boundary is shown.
The area between the floodway and 1-percent-annual-chance floodplain boundaries is termed
the floodway fringe. The floodway fringe encompasses the portion of the floodplain that
could be completely obstructed without increasing the water-surface elevation (WSEL) of
the base flood more than 1 foot at any point. Typical relationships between the floodway
and the floodway fringe and their significance to floodplain development are shown in
Figure 1.
Figure 1 - Floodway Schematic
18
Near the mouths of streams studied in detail, floodway computations are made without
regard to flood elevations on the receiving water body. Therefore, “Without Floodway”
elevations presented in Table 6 for certain downstream cross sections of Christian Creek
Lateral, Turtle Creek Lateral, Lateral No. 3, and Lateral No. 5 are lower than the regulatory
flood elevations in that area, which must take into account the 1–percent-annual-chance
flooding due to backwater from other sources.
Because of the scope of this study, floodways were not calculated for Asher Ditch, Gum
Slough, Honey Cypress Ditch, Little Bay Ditch, Maple Slough Ditch, Middle Drain, Viney
Slough, and Whaley Slough Ditch. Although floodways were not calculated for the streams
within the City of Caraway, sufficient right–of–way should be provided for maintenance of
the channels.
5.0
INSURANCE APPLICATION
For flood insurance rating purposes, flood insurance zone designations are assigned to a community
based on the results of the engineering analyses. These zones are as follows:
Zone A
Zone A is the flood insurance rate zone that corresponds to the 1-percent-annual-chance floodplains
that are determined in the FIS report by approximate methods. Because detailed hydraulic analyses
are not performed for such areas, no base (1-percent-annual-chance) flood elevations (BFEs) or
depths are shown within this zone.
Zone AE
Zone AE is the flood insurance rate zone that corresponds to the 1-percent-annual-chance floodplains
that are determined in the FIS report by detailed methods. Whole-foot BFEs derived from the
detailed hydraulic analyses are shown at selected intervals within this zone.
Zone X
Zone X is the flood insurance rate zone that corresponds to areas outside the
0.2-percent-annual-chance floodplain, areas within the 0.2-percent-annual-chance floodplain, areas of
1-percent-annual-chance flooding where average depths are less than 1 foot, areas of
1-percent-annual-chance flooding where the contributing drainage area is less than 1 square mile
(sq. mi.), and areas protected from the base flood by levees. No BFEs or depths are shown within
this zone.
19
FLOODING SOURCE
CROSS SECTION
Butlers Ditch
A
B
C
D
E
2
3
WIDTH (FEET)
SECTION AREA
(SQUARE FEET)
MEAN VELOCITY
(FEET PER SECOND)
REGULATORY
WITHOUT FLOODWAY
WITH FLOODWAY
INCREASE
0.33
0.83
1.74
2.85
2.91
62
51
104
99
40
450
931
2,167
3,674
8,681
2.3
2.8
1.4
1.4
3.0
232.2
232.9
233.7
234.2
234.4
231.2 2
232.9
233.7
234.2
234.4
232.1 2
233.4
234.7
235.1
235.3
0.9
0.5
1.0
0.9
0.9
0.42
0.51
0.52
0.73
0.84
0.91
1.11
1.27
1.55
1.85
2.02
2.10
2.44
2.69
3.02
3.33
3.57
3.62
447
275
270
136
73
92
367
46
399
55
58
62
45
48
45
98
291
122
1,470
1,216
983
776
796
781
1,542
558
1,540
632
647
643
498
291
366
308
692
265
3.12
3.77
4.48
5.68
5.53
5.64
2.86
7.90
2.57
6.26
5.07
5.10
6.60
5.03
3.99
4.92
2.19
5.71
287.7
288.5
288.5
292.0
294.2
295.4
297.0
298.6
303.5
306.4
308.8
309.5
314.5
320.5
329.1
333.9
340.3
341.9
287.7
288.5
288.5
292.0
294.2
295.4
297.0
298.6
303.5
306.4
308.8
309.5
314.5
320.5
329.1
333.9
340.3
341.9
288.7
289.5
289.5
292.8
295.1
295.8
297.9
299.6
304.5
306.5
308.9
309.6
315.3
320.5
329.3
334.9
341.3
342.9
1.0
1.0
1.0
0.8
0.9
0.4
0.9
1.0
1.0
0.1
0.1
0.1
0.8
0.0
0.2
1.0
1.0
1.0
1,3
DISTANCE
1
Christian Creek 3
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
1
BASE FLOOD
WATER SURFACE ELEVATION
FLOODWAY
Miles above confluence with Little Bay Ditch
Elevation computed without consideration of backwater effects from Little Bay Ditch
Miles above confluence with Lost Creek
TABLE 6
FLOODWAY DATA
FEDERAL EMERGENCY MANAGEMENT AGENCY
CRAIGHEAD COUNTY, AR
BUTLERS DITCH - CHRISTIAN CREEK
20
FLOODING SOURCE
CROSS SECTION
1
2
3
BASE FLOOD
FLOODWAY
1,3
DISTANCE
WIDTH (FEET)
SECTION AREA
(SQUARE FEET)
MEAN VELOCITY
(FEET PER SECOND)
REGULATORY
WITHOUT FLOODWAY
WITH FLOODWAY
INCREASE
Christian Creek
Lateral1
A
B
C
D
E
0.27
0.52
0.65
0.73
1.06
50
50
40
40
30
163
158
102
85
89
3.31
3.40
0.77
0.92
0.88
292.1
292.4
292.5
292.8
294.0
285.8 2
289.1 2
290.1 2
290.2 2
290.7 2
285.8
289.1
290.1
290.2
290.7
0.0
0.0
0.0
0.0
0.0
Higginbottom Creek 3
A
B
C
D
E
F
G
H
I
J
K
L
0.64
1.08
1.78
2.32
2.99
3.19
3.23
3.69
3.90
4.13
4.21
4.34
157
110
74
750
340
440
265
80
70
80
230
150
1,441
1,195
482
1,879
1,451
1,690
1,546
458
490
301
755
528
3.51
4.20
10.50
2.26
2.92
1.36
2.57
5.03
2.92
4.74
1.89
2.71
254.0
257.8
260.8
272.2
280.5
282.0
285.3
289.1
291.1
297.8
299.2
301.9
254.0
257.8
260.8
272.2
280.5
282.0
285.3
289.1
291.1
297.8
299.2
301.9
255.0
258.6
260.8
272.3
281.5
283.0
285.4
290.1
292.1
298.8
300.2
302.9
1.0
0.8
0.0
0.1
1.0
1.0
0.1
1.0
1.0
1.0
1.0
1.0
Miles above confluence with Christian Creek
Elevation computed without consideration of backwater effects from Christian Creek
Miles above confluence with Viney Slough Ditch
TABLE 6
FLOODWAY DATA
CHRISTIAN CREEK LATERAL - HIGGINBOTTOM CREEK
21
FLOODING SOURCE
CROSS SECTION
Lateral No. 3
A
B
C
D
E
F
G
H
I
J
K
L
2
3
WIDTH (FEET)
SECTION AREA
(SQUARE FEET)
MEAN VELOCITY
(FEET PER SECOND)
REGULATORY
WITHOUT FLOODWAY
WITH FLOODWAY
INCREASE
0.26
1.74
1.98
2.23
2.25
2.33
2.52
3.11
3.24
3.55
3.57
3.82
911
1,088
985
1,548
1,549
1,512
205
38
100
78
78
51
1,542
1,817
2,209
1,522
1,421
652
342
144
244
137
154
42
1.25
1.06
0.86
0.36
0.40
0.90
1.69
4.00
2.40
1.60
1.41
5.20
232.2
234.6
235.5
236.1
236.1
236.3
237.5
240.7
242.9
246.7
247.0
249.9
231.5 2
234.6
235.5
236.1
236.1
236.3
237.5
240.7
242.9
246.7
247.0
249.9
232.5
235.5
236.4
237.1
237.1
237.3
238.5
241.2
243.2
246.8
247.0
249.9
1.0
0.9
0.9
1.0
1.0
1.0
1.0
0.5
0.3
0.1
0.0
0.0
0.03
0.09
0.26
0.41
0.83
1.33
1.74
40
30
80
100
400
120
70
335
279
749
492
1,398
403
141
5.47
6.56
2.44
3.72
1.56
5.41
6.18
263.9
264.2
267.0
268.4
274.8
278.9
288.7
262.5 4
264.2
267.0
268.4
274.8
278.9
288.7
262.7
264.2
267.1
269.4
274.8
279.7
289.6
0.2
0.0
0.1
1.0
0.0
0.8
0.9
1,3
DISTANCE
1
Lateral No. 5 3
A
B
C
D
E
F
G
1
BASE FLOOD
FLOODWAY
4
Elevation computed without consideration of backwater effects from Little Bay Ditch
Miles above confluence with Turtle Creek
Elevation computed witout consideration of backwater effects from Turtle Creek
TABLE 6
FLOODWAY DATA
LATERAL NO. 3 - LATERAL NO. 5
22
FLOODING SOURCE
CROSS SECTION
Lost Creek
A
B
C
D
E
F
G
H
I
J
K
L
M
2
WIDTH (FEET)
SECTION AREA
(SQUARE FEET)
MEAN VELOCITY
(FEET PER SECOND)
REGULATORY
WITHOUT FLOODWAY
WITH FLOODWAY
INCREASE
0.11
0.32
0.75
1.81
2.33
2.83
3.28
3.33
4.21
4.82
5.74
6.26
6.73
680
89
1,827
93
138
641
350
480
429
72
643
176
105
2,725
1,293
10,887
846
1,323
2,011
1,490
1,321
1,631
771
1,634
958
1,024
3.75
7.90
0.94
7.40
4.70
3.10
3.19
3.60
2.92
5.34
2.19
3.73
3.49
283.5
285.3
287.2
289.3
292.1
293.7
297.0
297.6
302.1
305.3
315.0
319.6
323.0
283.5
285.3
287.2
289.3
292.1
293.7
297.0
297.6
302.1
305.3
315.0
319.6
323.0
284.5
286.3
288.1
290.1
292.8
294.7
297.9
298.1
303.1
306.3
315.9
320.6
324.0
1.0
1.0
0.9
0.8
0.7
1.0
0.9
0.5
1.0
1.0
0.9
1.0
1.0
0.02
0.25
0.78
1.25
1.27
1.53
489
850
590
100
40
90
1,023
1,733
871
347
238
465
1.08
0.64
1.27
3.02
4.41
2.25
237.0
238.1
243.1
249.7
250.3
252.1
237.0
238.1
243.1
249.7
250.3
252.1
238.0
239.1
243.6
249.7
250.3
253.1
1.0
1.0
0.5
0.0
0.0
1.0
1,2
DISTANCE
1
Moore's Ditch Lateral 2
A
B
C
D
E
F
1
BASE FLOOD
FLOODWAY
Miles above confluence with Big Creek
Miles above confluence with Moore's Ditch
TABLE 6
FLOODWAY DATA
LOST CREEK - MOORE'S DITCH LATERAL
23
FLOODING SOURCE
CROSS SECTION
Tributary to
Maple Slough
Ditch1
A-B
C
D
E
F
G
H
I
J
1
2
DISTANCE
BASE FLOOD
FLOODWAY
1,3
WIDTH (FEET)
SECTION AREA
(SQUARE FEET)
MEAN VELOCITY
(FEET PER SECOND)
REGULATORY
WITHOUT FLOODWAY
WITH FLOODWAY
INCREASE
271
275
70
65
200
425
350
300
829
824
521
462
929
1,463
927
831
3.60
3.60
5.60
6.30
3.20
2.00
3.10
3.40
252.9
253.8
259.8
260.6
262.3
264.8
266.0
270.7
252.9
253.8
259.8
260.6
262.3
264.8
266.0
270.7
253.8
254.5
260.8
261.4
262.9
265.6
266.7
271.4
0.9
0.7
1.0
0.8
0.6
0.8
0.7
0.7
300
280
600
370
80
90
90
70
60
250
60
310
150
1,358
1,259
1,431
2,570
1,206
746
611
693
563
1,028
640
1,573
467
3.56
4.84
6.77
2.38
3.69
5.93
7.35
6.27
6.28
3.44
5.52
1.19
4.01
-- 2
0.94
1.00
1.46
1.50
1.62
1.90
2.00
2.30
Turtle Creek 3
A
0.05
B
0.23
C
0.33
D
0.68
E
0.97
F
1.21
G
1.62
H
1.71
I
1.87
J
1.94
2.09
K
2.13
L
M
2.36
Miles above confluence with Maple Slough Ditch
No floodway data computed
3
4
248.2
248.7
0.9
247.8 4
250.4
0.9
250.4
249.5 4
250.9
0.6
251.2
250.3 4
252.3
252.3
253.1
0.8
252.9
252.9
253.7
0.8
254.8
254.8
255.3
0.5
260.8
260.8
261.0
0.3
262.5
262.5
263.5
1.0
264.6
264.6
265.2
0.6
266.1
266.1
266.1
0.0
268.4
268.4
269.4
1.0
269.6
269.6
270.4
0.8
270.0
270.0
270.7
0.7
Miles above confluence with Whiteman's Creek
Elevation computed without consideration of backwater effects from Whiteman's Creek
TABLE 6
FLOODWAY DATA
TRIBUTARY TO MAPLE SLOUGH DITCH - TURTLE CREEK
24
FLOODING SOURCE
CROSS SECTION
Turtle Creek (cont)
N
O
P
Q
R
2
WIDTH (FEET)
SECTION AREA
(SQUARE FEET)
MEAN VELOCITY
(FEET PER SECOND)
REGULATORY
WITHOUT FLOODWAY
WITH FLOODWAY
INCREASE
2.58
2.76
3.06
3.63
3.72
60
180
50
50
20
613
911
234
291
69
3.05
2.05
7.99
4.11
10.07
275.4
276.2
279.0
293.3
296.5
275.4
276.2
279.0
293.3
296.5
276.4
277.1
279.3
293.3
296.5
1.0
0.9
0.3
0.0
0.0
0.03
0.15
0.72
1.09
1.16
1.32
40
70
40
60
60
40
237
419
219
226
189
117
4.67
2.64
5.06
1.80
2.15
3.50
268.9
269.1
277.2
282.5
282.9
286.8
266.6 3
268.7 3
277.2
282.5
282.9
286.8
267.0
269.4
277.2
283.5
283.9
286.8
0.4
0.7
0.0
1.0
1.0
0.0
DISTANCE
1,2
1
Turtle Creek Lateral 2
A
B
C
D
E
F
1
BASE FLOOD
FLOODWAY
3
Miles above confluence with Whiteman's Creek
Miles above confluence with Turtle Creek
Elevation computed without consideration of backwater effects from Turtle Creek
TABLE 6
FLOODWAY DATA
TURTLE CREEK - TURTLE CREEK LATERAL
25
FLOODING SOURCE
1
CROSS SECTION
DISTANCE
Whiteman's Creek
A
B
C
D
E
F
G
H
I
J
K
3.50
4.33
4.72
4.84
5.39
5.67
5.85
6.01
6.58
6.98
7.57
BASE FLOOD
FLOODWAY
1
WIDTH (FEET)
SECTION AREA
(SQUARE FEET)
MEAN VELOCITY
(FEET PER SECOND)
REGULATORY
WITHOUT FLOODWAY
WITH FLOODWAY
INCREASE
1,790
1,120
110
140
300
30
320
301
139
89
123
4,915
3,989
673
933
1,358
180
1,004
569
569
182
138
1.04
1.24
6.97
5.03
3.56
4.57
1.22
2.10
2.10
3.50
4.60
236.1
239.1
242.4
244.6
248.2
250.4
251.7
252.3
260.2
261.0
267.2
236.1
239.1
242.4
244.6
248.2
250.4
251.7
252.3
260.2
261.0
267.2
237.1
240.1
243.4
245.4
248.7
250.6
252.7
252.9
260.6
261.5
267.4
1.0
1.0
1.0
0.8
0.5
0.2
1.0
0.6
0.4
0.5
0.2
TABLE 6
FLOODWAY DATA
WHITEMAN'S CREEK
26
6.0
FLOOD INSURANCE RATE MAP
The FIRM is designed for flood insurance and floodplain management applications.
For flood insurance applications, the map designates flood insurance rate zones as described in
Section 5.0 and, in the 1-percent-annual-chance floodplains that were studied by detailed methods,
shows selected whole-foot BFEs or average depths. Insurance agents use zones and BFEs in
conjunction with information on structures and their contents to assign premium rates for flood
insurance policies.
For floodplain management applications, the map shows by tints, screens, and symbols, the 1- and
0.2-percent-annual-chance floodplains, floodways, and the locations of selected cross sections used in
the hydraulic analyses and floodway computations.
The countywide FIRM presents flooding information for the entire geographic area of Craighead
County. Previously, FIRMs were prepared for each incorporated community and the unincorporated
areas of the County identified as flood-prone. This countywide FIRM also includes flood-hazard
information that was presented separately on Flood Boundary and Floodway Maps (FBFMs), where
applicable. Historical data relating to the maps prepared for each community are presented in Table
7, Community Map History.
7.0
OTHER STUDIES
Previously printed FIS documents were prepared for the City of Bono (Reference 13), the Town of
Brookland (Reference 15), the City of Caraway (Reference 17), and the City of Jonesboro (Reference
18).
The original countywide FIS was prepared by the Memphis District of the USACE for the Federal
Emergency Management Agency (FEMA), under Inter–Agency Agreement No. EMW–87–E–2509
(Reference 7).
In this revision of the Craighead County FIS, analysis of flooding sources within the corporate limits
of the City of Jonesboro were prepared by the City of Jonesboro for FEMA under Inter–Agency
Agreement No. EMT-2004-CA-0123r (Reference 1). The CF3R Joint Venture completed the updates
for the remainder of the county under contract EMT-2002-CO-0049.
This FIS report either supersedes or is compatible with all previous studies published on streams
studied in this report and should be considered authoritative for the purposes of the NFIP.
8.0
LOCATION OF DATA
Information concerning the pertinent data used in the preparation of this study can be obtained by
contacting FEMA Region VI, Federal Insurance and Mitigation Division, 800 North Loop 288,
Denton, Texas 76209.
27
COMMUNITY
NAME
Bay, City of
INITIAL
IDENTIFICATION
FLOOD HAZARD
BOUNDARY MAP
REVISIONS DATE
FIRM EFFECTIVE DATE
FIRM
REVISIONS DATES
October 12, 1973
None
January 3, 1986
None
None
None
None
None
Bono, City of
August 30, 1974
October 3, 1975
December 4, 1985
None
Brookland, Town of
August 23, 1974
January 9, 1976
April 15, 1980
None
Caraway, City of
January 10, 1975
None
June 18, 1980
None
Cash, Town of
April 18, 1975
None
September 21, 1982
None
Craighead County,
Unincorporated Areas
November 15, 1977
None
September 27, 1991
None
Egypt, Town of
September 27, 1991
None
September 27, 1991
None
Jonesboro, City of
October 26, 1973
October 8, 1976
June 15, 1981
None
Lake City, Town of
May 24, 1974
October 10, 1975
April 15, 1986
None
September 27, 1991
None
September 27, 1991
None
* Black Oak, Town of
Monette, City of
* Non-floodprone
TABLE 7
COMMUNITY MAP HISTORY
CRAIGHEAD COUNTY, ARKANSAS
28
9.0
BIBLIOGRAPHY AND REFERENCES
1.
City of Jonesboro, Technical Support Data Notebook: Flood Insurance Study/Map Revision,
prepared by the City of Jonesboro, Craighead County, Arkansas, EMT-2004-CA-0123r, May
2009.
2.
U.S. Department of Agriculture, Soil Conservation Service, and the Arkansas Soil and Water
Conservation Commission, Bono Flood Plain Management Study, Craighead County,
Arkansas, Little Rock, Arkansas, December 1983.
3.
U.S. Census Bureau, 2008 Population Estimates, Census 2000, 1990 Census, Population
Division. Retrieved on November 23, 2009.
4.
Arkansas Municipal League, 2009. Local Government Portal. County and Municipal
Information and Services, http://local.arkansas.gov/index.php.
5.
National Oceanic and Atmospheric Association, Satellite and Information Service, National
Climatic Data Center, Extreme Weather and Climate Events, web site,
http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwevent~storms, accessed December 12,
2009.
6.
United States Geological Survey, National Water Information System: Web Interface, USGS
Water-Data Site Information for Arkansas, http://waterdata.usgs.gov/ar/nwis/si, accessed
December 12, 2009.
7.
Federal Emergency Management Agency, Federal Insurance Administration, Flood
Insurance Study, Craighead County, Arkansas and Incorporated Areas, Washington, D.C.,
September 27, 1991.
8.
Federal Register, Volume 71, Number 225, November 22, 2006, page 67543.
9.
Federal Register, Volume 69, Number 213, November 4, 2004, pages 64270 – 64273.
10.
U.S. Army Corps of Engineers, Memphis District, Ditch 9 and Below Ditch 9 Channel
Cleanout St. Francis Basin Project – Maintenance, Invitation for Bid No. DACW66-99-T0149, August 1999.
11.
U.S. Army Corps of Engineers, Memphis District, District Projects, Whiteman’s Creek,
Arkansas,
web
site
accessed
December
12,
2009,
http://www.mvm.usace.army.mil/projects/whiteman/home.asp
12.
U.S. Army Corps of Engineers, Hydrologic Engineering Center, HEC–1 Flood Hydrograph
Package, Davis, California, October 1970.
13.
Federal Emergency Management Agency, Flood Insurance Study, City of Bono, Craighead
County, Arkansas, Washington, D.C., December 4, 1985.
14.
U.S. Department of Agriculture, Soil Conservation Service, Technical Release No. 20,
Computer Program, Project Formulation, Hydrology, Washington, D.C. 1965.
29
15.
Insurance Study, City of Brookland, Craighead County, Arkansas, Washington, D.C., April
15, 1980.
16.
U.S. Department of Commerce, Weather Bureau, Technical Paper No. 40, Rainfall
Frequency Atlas of the United States, Washington D.C., 1961, Revised 1963.
17.
Insurance Study, City of Caraway, Craighead County, Arkansas, Washington, D.C., June 18,
1980.
18.
Insurance Study, City of Jonesboro, Craighead County, Arkansas, Washington, D.C., June
15,1981.
19.
U.S. Army Corps of Engineers, Hydrologic Engineering Center, HEC–2 Water Surface
Profiles, Generalized Computer Program, Davis, California, April 1984.
20.
U.S. Department of Agriculture, Soil Conservation Service, Technical Release No. 61,
WSP–2 Computer Program, Washington, D.C., May 1976.
21.
U.S. Department of the Interior, Geological Survey, 7.5–Minute Series Topographic Maps,
Scale 1:24,000, Contour Interval 5 Feet: Alicia, Arkansas, 1980; Bono, Arkansas, 1994;
Brookland, Arkansas, 1994; Caraway, Arkansas, 1994; Cash, Arkansas, 1994; Dixie,
Arkansas 1994; Greenfield, Arkansas, 1994; Grubbs, Arkansas, 1980; Hatchie Coon,
Arkansas, 1994; Herman, Arkansas, 1994; Jonesboro, Arkansas, 1994; Lake City, Arkansas,
1994; Leachville, Arkansas, 1994; Lorado, Arkansas, 1994; Needham, Arkansas, 1994;
Otwell, Arkansas, 1994; Podo Creek, Arkansas, 1994; Risher, Arkansas, 1994; Rivervale,
Arkansas, 1994; Swifton East, Arkansas, 1980; Trumann, Arkansas, 1994.
22.
U.S. Department of Housing and Urban Development, Federal Insurance Administration,
Flood Hazard Boundary Map, Unincorporated Areas of Craighead County, Arkansas,
November 15, 1977.
30

CRAIGHEAD COUNTY, ARKANSAS

Transcription

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