CLAYTON COUNTY,
GEORGIA
AND INCORPORATED AREAS
Community
Name
CLAYTON COUNTY
(UNINCORPORATED AREAS)
FOREST PARK, CITY OF
JONESBORO, CITY OF
LAKE CITY, CITY OF
LOVEJOY, CITY OF
MORROW, CITY OF
RIVERDALE, CITY OF
Community
Number
130041
Clayton County
130042
130043
130044
130658
130045
130047
Effective: August 16, 2007
FLOOD INSURANCE STUDY NUMBER
13063CV000A
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 (FIS) report may not
contain all data available within the Community Map Repository. Please contact
the Community Map Repository for any additional data.
The Federal Emergency Management Agency (FEMA) may revise and republish
part or all of this FIS report at any time. In addition, FEMA may revise part of
this FIS report by the Letter of Map Revision process, which does not involve
republication or redistribution of the FIS report. Therefore, users should consult
with community officials and check the Community Map Repository to obtain
the most current FIS report components.
Initial Countywide FIS Effective Date: August 16, 2007
TABLE OF CONTENTS
VOLUME I
1.0
INTRODUCTION ...........................................................................................................1
1.1 Purpose of Study........................................................................................................1
1.2 Authority and Acknowledgments ..............................................................................1
1.3 Coordination ..............................................................................................................3
2.0
AREA STUDIED .............................................................................................................4
2.1 Scope of Study ...........................................................................................................4
2.2 Community Description.............................................................................................6
2.3 Principal Flood Problems...........................................................................................6
2.4 Flood Protection Measures ........................................................................................7
3.0
ENGINEERING METHODS .........................................................................................7
3.1 Hydrologic Analyses..................................................................................................8
3.2 Hydraulic Analyses..................................................................................................20
3.3 Vertical Datum.........................................................................................................22
4.0
FLOODPLAIN MANAGEMENT APPLICATIONS ................................................23
4.1 Floodplain Boundaries .............................................................................................24
4.2 Floodways ................................................................................................................25
5.0
INSURANCE APPLICATIONS ..................................................................................48
6.0
FLOOD INSURANCE RATE MAP ............................................................................48
7.0
OTHER STUDIES.........................................................................................................49
8.0
LOCATION OF DATA.................................................................................................49
9.0
BIBLIOGRAPHY AND REFERENCES ....................................................................49
i
TABLE OF CONTENTS (Continued)
VOLUME I
FIGURES
Figures 1A - 1F - Frequency-Discharge, Drainage Area Curves ..................................................14
Figure 2 - Floodway Schematic .....................................................................................................47
TABLES
Table 1 - Summary of Discharges .................................................................................................10
Table 2 - Summary of Stillwater Elevations..................................................................................13
Table 3 - Manning’s “n” Values ....................................................................................................21
Table 4 - Vertical Datum Conversion............................................................................................23
Table 5 - Floodway Data ...............................................................................................................26
Table 6 - Community Map History................................................................................................50
EXHIBITS
Exhibit 1 - Flood Profiles
Beaver Dam Creek
Big Cotton Indian Creek
Camp Creek
Camp Creek Tributary
Conine Creek
Conley Creek
Conley Creek Tributary
Duffey Tributary
East Tributary of Jester Creek
Flint River
Flint River Tributary
Hurricane Creek
Jester Creek
Mud Creek
North Fork Jester Creek
Panther Creek
Pates Creek
Pine Creek
Poole Creek
Poole Creek Tributary
Reeves Creek
Roberts Road Tributary
Shoal Creek
Stratford Tributary
Stream A
Stream B
Panels
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ii
01P-03P
04P-05P
06P-09P
10P-11P
12P
13P-14P
15P
16P
17P
18P-23P
24P-25P
26P-29P
30P-36P
37P-38P
39P-41P
42P-45P
46P-48P
49P
50P
51P
52P-54P
55P-56P
57P
58P-59P
60P-61P
62P-63P
TABLE OF CONTENTS (Continued)
Exhibit 1 - Flood Profiles (Continued)
Stream BT
Stream C
Stream CT
Stream CT-A
Stream D
Sullivan Creek
Swamp Creek
Tar Creek
Upton Creek
Wallis Creek
West Tributary of Jester Creek
York Tributary
Panel
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Panel
Panel
Exhibit 2 - Flood Insurance Rate Map Index
Flood Insurance Rate Map
iii
64P
65P-66P
67P-68P
69P
70P
71P-73P
74P-76P
77P
78P
79P-81P
82P
83P
FLOOD INSURANCE STUDY
CLAYTON COUNTY, GEORGIA AND INCORPORATED AREAS
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 Clayton
County, including the Cities of Forest Park, Jonesboro, Lake City, Lovejoy,
Morrow and Riverdale, and the unincorporated areas of Clayton County
(referred to collectively herein as Clayton 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 City of College Park is geographically located in both
Clayton County and Fulton County, and the flood hazard information is included
entirely in the Fulton County FIS report. Please see the Fulton County FIS
report for flood hazard information for the City of College Park.
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.
The Digital Flood Insurance Rate Map (DFIRM) and FIS report for this
countywide study have been produced in digital format. Flood hazard
information was converted to meet the Federal Emergency Management Agency
(FEMA) DFIRM database specifications and Geographic Information System
(GIS) format requirements. The flood hazard information was created and is
provided in a digital format so that it can be incorporated into a local GIS and be
accessed more easily by the community.
1.2
Authority and Acknowledgments
The sources of authority for this FIS are the National Flood Insurance Act of
1968 and the Flood Disaster Protection Act of 1973.
1
Information on the authority and acknowledgements for each jurisdiction
included in this countywide FIS report, as compiled from their previously
printed FIS reports, are shown below:
Clayton County
(Unincorporated Areas):
The hydrologic and hydraulic analyses
for the original FIS report dated
June 15, 1978 (Reference 1), were
prepared by the U.S. Army Corps of
Engineers (USACE), Savannah District,
for the Federal Insurance Administration
(FIA), under Inter-Agency Agreement
Nos. IAA-H-2-73 and IAA-H-16-75,
Project Order Nos. 1 and 2, respectively.
The work was completed in December
1975.
For the FIS report dated May 1, 1984
(Reference 2), the hydrologic and
hydraulic analyses were prepared by the
USACE,
Savannah
District,
and
additional information was obtained from
the Clayton County Commissioners,
Public Works Department.
For
the
FIS
report
dated
November 6, 1991 (Reference 3), the
hydrologic and hydraulic analyses were
prepared by the USACE, Mobile District,
for the Federal Emergency Management
Agency (FEMA), under Inter-Agency
Agreement
No.
EMW-88-E-2739,
Project Order No. 4, Amendment No. 1.
The work was completed in November
1989. The hydrologic and hydraulic
analyses for North Fork Jester Creek and
Conine Creek were taken from the FIS
for the City of Morrow, Georgia
(Reference 4).
For
the
FIS
report
dated
November 20, 2000 (Reference 5), no
hydrologic or hydraulic analyses were
performed.
2
Forest Park, City of:
For
the
FIS
report
dated
November 16, 1976 (Reference 6), the
hydrologic and hydraulic analyses were
performed by the USACE, Mobile
District for the FIA, under Inter Agency
Agreement Nos. IAA-H-2-73 and
IAA-H-19-74, Project Order Nos. 13 and
15, respectively. The work, which was
completed in October 1974, covered all
flooding sources affecting the City of
Forest Park.
For the FIS report dated August 16, 1982
(Reference 4), the hydrologic and
hydraulic analyses were prepared by
Mayes, Sudderth and Etheredge, Inc., for
FEMA, under Contract No. H-6828. The
work was completed in October 1981.
Morrow, City of:
Riverdale, City of:
For
the
FIS
report
dated
November 6, 1991 (Reference 7), the
hydrologic and hydraulic analyses were
prepared by the USACE, Savannah
District, for the FIA, under Inter-Agency
Agreement No. IAA-H-7-76, Project
Order No. 6. The work was completed in
February 1977.
No previous FIS report was published for the Cities of Jonesboro, Lake City,
and Lovejoy.
1.3
Coordination
The initial and final meeting dates for the previous FIS reports for Clayton
County and its communities are listed in the following table:
Community
Clayton County
(Unincorporated Areas)
Forest Park, City of
Morrow, City of
Riverdale, City of
FIS Date
Initial Meeting
Final Meeting
June 15, 1978
May 1, 1984
November 6, 1991
November 20, 2000
November 1976
August 16, 1982
November 6, 1991
May 15, 1974
∗
∗
June 23, 19991
*
June 14, 1979
May 22, 1975
October 17, 1975
∗
November 27, 1990
∗
March 25, 1975
March 29, 1982
October 14, 1976
∗Data not available
Community was notified by letter that revision would be conducted
1
3
The meetings held for the unincorporated areas of Clayton County were attended
by representatives of FEMA, FIA, USACE, Clayton County, and Mayes,
Sudderth, and Etheredge, Inc.
For the City of Forest Park, a search for basic data was made at all levels of
government. The city provided a large scale city map from which the base maps
used in the report were taken. Contacts were made with city officials during the
study in order to minimize all possible conflicts.
The meetings held for the City of Morrow were attended by representatives of
FEMA, city officials and Mayes, Sudderth, and Etheredge, Inc.
The meetings held for the City of Riverdale were attended by representatives of
the USACE, FIA and community officials.
For this revision, a Scoping Meeting was held on October 28, 2004, and attended
by representatives of Clayton County, the cities of Jonesboro, Lake City,
Lovejoy, Morrow, and Riverdale, the Georgia Department of Natural Resources
(DNR), and Greenhorne & O’Mara. The purpose of the meeting was to discuss
the scope of the FIS. The final meeting was held on April 18, 2006, and was
attended by representatives of Clayton County, FEMA, the Georgia DNR,
PBS&J, and local communities.
2.0
AREA STUDIED
2.1
Scope of Study
This FIS covers the geographic area of Clayton County, Georgia, 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.
Precountywide Analyses
The following streams were studied by detailed methods for the June 15, 1978,
FIS report for Clayton County (Unincorporated Areas): Beaver Dam Creek, Big
Cotton Indian Creek, Camp Creek, Conley Creek, Flint River, Hurricane Creek,
Jester Creek, Mud Creek, Panther Creek, Pates Creek, Reeves Creek, Roberts
Road Tributary, Sullivan Creek, Swamp Creek, Tar Creek, Upton Creek and
Wallis Creek.
Portions of the following streams were restudied by detailed methods for the
May 1, 1984, revision for Clayton County (Unincorporated Areas): Conley
Creek and Big Cotton Indian Creek.
4
For the November 6, 1991, revision for Clayton County (Unincorporated Areas),
the following streams were either revised or newly restudied by detailed
methods: Camp Creek Tributary, Conine Creek, Flint River, Flint River
Tributary, Jester Creek, North Fork Jester Creek, Shoal Creek, Smith Reservoir,
Sullivan Creek.
For the November 20, 2000, revision for Clayton County (Unincorporated
Areas), the county boundary between Clayton County and Henry County was
updated and Little Cotton Indian Creek was renamed to Big Cotton Indian
Creek.
The following flooding sources were studied by detailed methods in the City of
Forest Park, November 16, 1976, FIS report: Conley Creek, Conley Creek
Tributary, East Tributary of Jester Creek, Jester Creek, Pine Creek, Poole Creek,
Poole Creek Tributary, and West Tributary of Jester Creek.
The following streams were studied by detailed methods for the August 16,
1982, FIS report for the City of Morrow: Conine Creek, Duffey Tributary, North
Fork Jester Creek, Stratford Tributary and York Tributary.
The following streams were studied by detailed methods for the
November 6, 1991, FIS report for the City of Riverdale: Camp Creek, Flint
River, Stream A, Stream B, Stream BT, Stream C, Stream CT, Stream CT-A and
Stream D.
Countywide Analyses
For this countywide analyses, the FIS report and FIRM were converted to
countywide format, and the flooding information for the entire county, including
both incorporated and unincorporated areas, is shown. Also, the vertical datum
was converted from the National Geodetic Vertical Datum of 1929 (NGVD29)
to the North American Vertical Datum of 1988 (NAVD88). In addition, the
Universal Transverse Mercator coordinates, previously referenced to the North
American Datum of 1927, are now referenced to the North American Datum of
1983.
As part of Letter of Map Revision Case No. 99-04-101P, dated October 29,
1999, a 1-percent-annual-chance floodplain along the unnamed tributary to
North Fork Jester Creek, between the Lake City corporate limits and the Norfolk
Southern Railway, was studied by detailed methods.
Approximate analyses were used to study those areas having low development
potential or minimal flood hazards. The scope and methods of study were
proposed to and agreed upon by FEMA and Clayton County.
5
2.2
Community Description
Clayton County is located immediately south of Atlanta, in the northwest portion
of Georgia. Clayton County is bordered by DeKalb County to the northeast,
Fulton County to the northwest, Fayette County to the southwest, Henry County
to the east, and Spaulding County to the south. Clayton County is the
southernmost of the seven counties that comprise the Atlanta Regional
Commission Planning Area. Administration of the county is performed by the
Board of County Commissioners, with Jonesboro serving as the county seat.
According to the U.S. Census Bureau, in 2000 the population for Clayton
County and incorporated areas was 236,517 (Reference 8).
The county has a land area of 146 square miles; approximately 37.4 percent of
the land area (54.6 square miles) lies in the Ocmulgee River drainage basin, and
the remaining 91.4 square miles lies in the Appalachicola River drainage basin.
The Norfolk Southern Railway runs essentially along the ridge that separates
these areas. The ridge between the Ocmulgee River basin and the Appalachicola
River basin divides Clayton County approximately east and west. The major
stream is the Flint River, which has its headwaters in the City of College Park,
and flows through the William B. Hartsfield Airport.
Clayton County’s mild climate consists of warm, humid summers and rather
warm winters. The average annual precipitation is 50.2 inches with March being
the wettest month. The mean temperatures range from a January low of 33
degrees Fahrenheit (ºF) to an July high of 89°F (Reference 9).
The topography and floodplains of the streams studied by detailed methods vary
from stream to stream and from the headwaters to the mouth of each stream. All
streams except the Flint River are generally characterized by narrow, steep
channels with narrow floodplains at the headwaters, but change to narrow
streams with broad floodplains near the mouth. The Flint River above Lee’s
Mill Road has a narrow floodplain. Downstream of Lee’s Mill Road, the
floodplain becomes broad and swampy. Channel banks are low and are
overtopped frequently.
2.3
Principal Flood Problems
The Flint River and its tributaries generally flow through flat, swampy areas.
The floodplains are covered with natural brush and undergrowth, except where
development has infringed on the floodplain. Such undergrowth tends to impede
flood-flows along these streams. Streams in the eastern portion of the county,
particularly Reeves and Pates Creeks, are very steep and rocky, and present a
velocity hazard during floods.
Flood damage in the past has mostly been sustained by roads, culverts, and
public utilities. Minor flooding is attributed to beaver dams on many streams.
6
The greatest flood for which data is available was the flood of November 10,
1966.
Other great floods occurred on streams in the metropolitan area of Atlanta on
December 7-10, 1919; April 30, 1963; and September 27, 2004. The 1919
floods resulted from a recorded 11.8 inches of rain on December 8 and 9, 1919.
Due to the short stream lengths and urban uses of the watersheds, floods may
occur on streams in Clayton County only a short time after intense rainfall
begins. Previous studies have shown that the streams normally recede within 24
hours. Flood-producing storms may occur at any time during the year, but are
more numerous in winter and spring. Winter storms are usually of the frontal
type, lasting from 2 to 4 days and covering large areas. Summer storms are
generally of a thunderstorm nature, with high rainfall intensities scattered over
small areas.
Within the City of Morrow, the restriction of North Fork Jester Creek caused by
Interstate Highway 75 results in major ponding that enhances substantial
mosquito infestation. In addition, siltation occurs in this area during significant
floods, which contributes to a reduction in channel capacity which may
ultimately raise future flood levels.
In the City of Riverdale, the floodplain along Stream C has been slightly
developed by residential housing, making some homes subject to flooding. The
concentration of upstream runoff into Stream C is a major cause of flash
flooding. Homes along Stream CT, upstream of Roundtree Road, and Stream B,
upstream of Voyles Drive, are subject to flooding from small culverts and storm
sewers beneath the streets and adjacent yards. Along Stream D, high velocity
flows and small culverts create a flood hazard. Shallow flooding at the
headwaters of Stream D is due to the fact that this area is relatively flat and there
is no well defined stream channel.
2.4
Flood Protection Measures
Although there is no flood protection structures located in Clayton County, the
floodplains along all streams within Clayton County are protected by the county
zoning laws and the Sediment Control Resolution adopted by the County
Commission in November 1973.
3.0
ENGINEERING METHODS
For the flooding sources studied by detailed methods in the community, standard
hydrologic and hydraulic study methods were used to determine the flood hazard data
required for this study. Flood events of a magnitude that are 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
7
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 (100-year) 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
community.
The peak discharge-frequency relationships estimated using the U.S. Geological
Survey (USGS) regression equations were adjusted to urbanization applying the
relationships in the USGS Water Resources Investigation (WRI) Report 77-57
(Reference 10).
Discharge-frequency relationships for Beaver Dam Creek, Big Cotton Indian
Creek, Conley Creek, Flint River Tributary, Hurricane Creek, Panther Creek,
Pates Creek, Reeves Creek, Roberts Road Tributary, Stream A, Stream B,
Stream BT, Stream C, Stream CT, Stream CT-A, Stream D, Swamp Creek, Tar
Creek, Upton Creek, and Wallis Creek were based on a statistical analysis for
data obtained at all stream gages in the Metropolitan Atlanta area. The
following tabulation lists gage records that were used in the log-Pearson Type III
analysis:
Gage Location
South River at East Point
Yellow River near Snellville
Peachtree Creek at Northside Drive at Atlanta
South Utoy Creek Tributary at East Point
North Fork Camp Creek at Atlanta
South River at Atlanta
South River near Atlanta
Snapfinger Creek near Decatur
South Fork Peachtree Creek at Atlanta
8
Length of Record
(years)
5
26
10
5
5
18
18
7
7
Peak discharge-frequency relationships along the Flint River were computed
using rainfall-runoff models formulated with the USACE HEC-1 computer
program (Reference 11) using the Soil Conservation Service (SCS)
dimensionless unit hydrograph methodology.
Peak discharge-frequency
relationships were also formulated using the USGS regional regression equations
(Reference 12).
Rainfall depth-duration-frequency data were taken from Technical Paper No. 40
(Reference 13) and Hydro 35 (Reference 14). The rainfall loss rates were
defined by the SCS curve number methodology. Storage-outflow relationships
were derived using a USACE HEC-2 backwater model (Reference 15) for
stream routings on the Flint River from the Hartsfield Airport boundary to the
Clayton County boundary. Muskingum routings were used for Camp Creek,
Flint River, Jester Creek, Mud Creek, and Sullivan Creek above the lower airport
boundary. The hydrologic models computed the discharge-frequency relations in
the basin for the 10-, 2-, 1-, and 0.2-percent-annual-chance floods.
Unit hydrograph parameters were developed for 39 sub-basins in the Flint River
basin for use in the USACE HEC-1 computer models (Reference 11). For areas
outside the Hartsfield Airport, the SCS lag parameter was determined using
stream length and land slope values measured from topographic maps. The SCS
lag equation used related lag to stream length, land slope, and curve number.
The point rainfall depth-duration relationship for the 0.2-percent-annual-chance
rainfall was graphically extrapolated from the 10-, 2-, and 1-percent-annualchance depth-duration data (References 13 and 14).
For the Hartsfield Airport, the SCS time lag was determined from the time of
concentration ,TC, for each airport sub-basin using the equation:
lag = 0.6 (TC)
The times of concentration for the airport subbasins were provided by the airport
engineers.
The SCS curve numbers were used in both the lag computation and in defining
the rainfall loss rate function. The SCS curve numbers for the sub-basins were
determined by integrating soil group and land use for the land cover type and
hydrologic conditions presented in Table 2-2 of Technical Release No. 55
(Reference 16). Soil group determinations were made from soil surveys
(References 17 and 18). Land use determinations for areas outside the airport
were made from aerial photos. Land use for the airport was taken from data
provided by the airport engineers giving impervious (pavement) and pervious
(grass) areas in each airport sub-basin.
Rainfall depth-drainage area
relationships were defined for a range of area sizes by applying area corrections
to the point rainfall amounts.
9
The synthetic depth-duration-frequency rainfall data were used in the USACE
HEC-1 computer model (Reference 11) to define the peak flood frequency
relationships for streams in the Flint River study area. Peak discharges obtained
from the USACE HEC-1 model were compared to the USGS regional regression
equations to verify the reasonableness of the computed peak flood discharge
estimates.
Peak discharge-frequency relationships were computed for Camp Creek
Tributary, Shoal Creek, and Smith Reservoir, using the regional study
methodologies applied for the upper Flint River. The USGS methodology
presented in WRI 83-4203 (Reference 19) was used to adjust the regional
regression estimates for urbanized areas. The equations in WRI 83-4203 use
drainage area, percent impervious area, and stream slope as the independent
variables in estimating flood discharges.
Hydrologic analyses of North Fork Jester Creek and Conine Creek were based
on the USGS regional regression equations presented in WRI 78-137 (Reference
20) which relate discharge to drainage area for natural streams in various
physiographic provinces in Georgia. The WRI 78-137 regression equation
results were adjusted for urbanization.
For Duffey Tributary, Lake Spivey, Stratford Tributary, and York Tributary,
hydrologic analyses were based upon utilization of the regional regression
equations presented in WRI 78-137 (Reference 20) relating discharge to
drainage area for natural streams in various physiographic provinces in Georgia.
For Conley Creek, Conley Creek Tributary, East Tributary of Jester Creek, Jester
Creek, Pine Creek, Poole Creek, Poole Creek Tributary, and West Tributary of
Jester Creek, in the City of Forest Park flood-flow frequency data were taken
from regionalized frequency curves developed by the USACE for the Atlanta
Metropolitan Area.
Peak discharge-drainage area relationships for all streams studied by detailed
methods are shown in Table 1.
Table 1 - Summary of Discharges
Peak Discharges (cubic feet per second)
FLOODING SOURCE AND
LOCATION
DRAINAGE
AREA
(square miles)
BEAVER DAM CREEK
See Figures 1A
and 1B
BIG COTTON INDIAN CREEK
See Figures 1A
and 1B
10-PercentAnnualChance
10
2-PercentAnnualChance
1-PercentAnnualChance
0.2-PercentAnnualChance
Table 1 - Summary of Discharges (Continued)
Peak Discharges (cubic feet per second)
FLOODING SOURCE AND
LOCATION
CAMP CREEK
CAMP CREEK TRIBUTARY
At the confluence with Camp
Creek
At West Fayetteville Road / State
Highway 314
At Bethsaida Road
At upstream county boundary
CONINE CREEK
At the confluence with North
Fork Jester Creek
DRAINAGE
AREA
(square miles)
1,800
2,100
2,900
3.42
1,000
1,600
1,800
2,500
1.90
0.93
800
400
1,200
700
1,400
800
1,900
1,200
1.23
732
1,094
1,259
1,674
191
285
332
443
See Figure 1F
159.68
136.98
9,600
9,900
16,400
17,100
18,300
19,000
23,900
25,200
126.04
10,300
16,800
18,700
24,500
72.44
8,500
13,900
15,600
20,100
68.03
8,400
13,600
15,300
19,600
47.98
6,600
10,200
11,500
14,800
39.18
7,800
11,800
13,700
17,800
27.22
5,900
8,700
9,800
12,700
23.41
19.99
7,600
7,300
12,000
10,600
13,500
11,900
17,200
14,900
11.99
5,100
7,300
8,200
10,100
2.24
1.36
0.50
900
700
500
1,400
1,000
700
1,600
1,200
800
2,200
1,600
1,100
See Figure 1D
DUFFEY TRIBUTARY
At the confluence with York
Tributary
0.13
HURRICANE CREEK
0.2-PercentAnnualChance
1,200
CONLEY CREEK TRIBUTARY
FLINT RIVER TRIBUTARY
At the confluence with Flint River
At State Highway 85
Approximately 2,450 feet
upstream of West Lees Mill
Road
1-PercentAnnualChance
3.70
See Figure 1D
FLINT RIVER
At downstream county boundary
Just downstream of the
confluence of Shoal Creek
Just downstream of the
confluence of Hurricane Creek
Just downstream of the
confluence of Swamp Creek
Just downstream of the
confluence of Camp Creek
Just upstream of the confluence
of Camp Creek
Just downstream of the
confluence of Jester Creek
Just upstream of the confluence
of Jester Creek
At Upper Riverdale Road
Just downstream of the
confluence of Mud Creek
Just downstream of the
confluence of Sullivan Creek
2-PercentAnnualChance
See Figure 1C
CONLEY CREEK
EAST TRIBUTARY OF
JESTER CREEK
10-PercentAnnualChance
See Figure 1D
See Figures 1A
and 1B
11
Table 1 - Summary of Discharges (Continued)
Peak Discharges (cubic feet per second)
FLOODING SOURCE AND
LOCATION
JESTER CREEK
At the confluence with Flint River
At U.S. Interstate Highway 19 /
41/ State Highway 3C / Tara
Boulevard
Just downstream of the
confluence of North Fork Jester
Creek
Just upstream of the confluence
of North Fork Jester Creek
At Morrow Road
Just upstream of Windsor Drive
MUD CREEK
NORTH FORK JESTER CREEK
At Morrow Industrial Boulevard
Just downstream of Interstate
Highway 75 / State Highway
401
Just upstream of Morrow Road
DRAINAGE
AREA
(square miles)
10-PercentAnnualChance
11.96
11.62
3,100
3,100
8.61
1-PercentAnnualChance
0.2-PercentAnnualChance
4,600
4,500
5,200
5,200
6,800
6,700
2,700
3,900
4,500
5,800
3.57
1,500
2,300
2,600
3,400
2.21
1.48
1,200
1,000
1,800
1,400
2,000
1,700
2,700
2,200
4.27
2.46
1,691
1,218
2,462
1,780
2,799
2,030
3,636
2,649
1.59
939
1,377
1,574
2,061
9.13
1,600
2,600
3,000
4,200
0.34
333
493
570
756
0.22
205
305
354
473
See Figures 1A
and 1B
PANTHER CREEK
See Figures 1A
and 1B
PATES CREEK
See Figures 1A
and 1B
PINE CREEK
See Figure 1D
POOLE CREEK
See Figure 1D
POOLE CREEK TRIBUTARY
See Figure 1D
REEVES CREEK
See Figures 1A
and 1B
ROBERTS ROAD TRIBUTARY
See Figures 1A
and 1B
SHOAL CREEK
At the confluence with Flint River
STRATFORD TRIBUTARY
Approximately 200 feet
downstream of Harbin Wood
Drive
Approximately 625 feet
downstream of Mural Circle
2-PercentAnnualChance
STREAM A
See Figure 1E
STREAM B
See Figure 1E
STREAM BT
See Figure 1E
12
Table 1 - Summary of Discharges (Continued)
Peak Discharges (cubic feet per second)
DRAINAGE
AREA
(square miles)
FLOODING SOURCE AND
LOCATION
STREAM C
See Figure 1C
STREAM CT
See Figure 1C
STREAM CT-A
See Figure 1F
STREAM D
See Figure 1F
SULLIVAN CREEK
At the confluence with Flint River
Just downstream of Interstate
Highway 285 / State Highway
407
6.01
4.17
2-PercentAnnualChance
1-PercentAnnualChance
0.2-PercentAnnualChance
2,200
2,100
3,300
3,000
3,800
3,400
4,800
4,500
0.31
338
501
579
767
0.13
159
237
276
369
SWAMP CREEK
See Figures 1A
and 1B
TAR CREEK
See Figures 1A
and 1B
UPTON CREEK
See Figures 1A
and 1B
WALLIS CREEK
See Figures 1A
and 1B
WEST TRIBUTARY OF
JESTER CREEK
See Figure 1D
YORK TRIBUTARY
Approximately 250 feet
downstream of Meadowbrook
Lane
Approximately 260 feet upstream
of Meadowbrook Lane
10-PercentAnnualChance
Stillwater elevations for lakes studied in detail within Clayton County are shown in Table 2.
Table 2 - Summary of Stillwater Elevations
1
Water Surface Elevations (Feet NAVD88 )
Flooding Source
10-PercentAnnual-Chance
SMITH RESERVOIR
805.8
LAKE SPIVEY
784.7
1
2
2-PercentAnnual-Chance
806.3
2
785.5
1-PercentAnnual-Chance
806.5
2
786.1
0.2-PercentAnnual-Chance
806.9
2
786.7
2
North American Vertical Datum of 1988
Elevations for Lake Spivey were taken from the Henry County, Georgia profile for Rum Creek.
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 Table 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 report in conjunction with the data shown on the FIRM.
Cross sections for all flooding sources studied by detailed methods were
obtained from field surveys. All bridges, dams, and culverts were field
surveyed to obtain elevation data and structural geometry. Cross sections for
the backwater analyses were field surveyed at selected intervals to model
conveyance of the valley; they were also field surveyed just upstream and
downstream of bridges and culverts in order to compute the significant
backwater effects of such structures. Four-foot contour interval topographic
mapping was photogrammetrically derived from aerial surveys (Reference 21)
and are utilized to supplement the surveyed cross sections for select flooding
sources.
For the May 1, 1984, FIS report for the unincorporated areas of Clayton
County, the USACE, Savannah District, provided HEC-2 computer printouts
(Reference 15) revising the water surface profiles and correcting the flood
delineations for Conley Creek. The analysis supersedes the information
presented in the USACE, Savannah District, Flood Plain Information report
completed in 1968 (Reference 22).
For the restudy of Big Cotton Indian Creek included in the May 1, 1984, FIS
report for the unincorporated areas of Clayton County, the Clayton County
Commissioners, Public Works Department surveyed the Mill Pond Dam and
found the elevation to be approximately 7 feet lower than was previously
reported in the June 15, 1978, FIS report for the unincorporated areas of
Clayton County. A review of the HEC-2 program used for Big Cotton Indian
Creek revealed that data for the dam had not been included in the model.
Instead, input data held the WSELs upstream and downstream of the dam at a
constant value. Since detailed channel cross sections were not available in the
area of the dam, calculations of weir flow were used with the correct dam
elevation to revise the water surface profiles for the stream reach.
Starting WSELs for Big Cotton Indian Creek, Camp Creek, Conine Creek,
Duffey Tributary, Flint River, Flint River Tributary, Hurricane Creek, North
Fork Jester Creek, Panther Creek, Stratford Tributary, Stream C, Stream CT,
Tar Creek, Upton Creek and York Tributary were developed by the slope-area
20
method. Water-surface profiles for Pates Creek, Stream B and Stream D were
started at critical depth. Starting WSELs for Beaver Dam Creek, Roberts Road
Tributary, Sullivan Creek, Swamp Creek, and Wallis Creek were taken from
computed profile elevations of the Flint River. Starting WSELs for Stream A
and Stream BT were taken from the computed profile elevations of Camp
Creek and Stream B, respectively. Starting WSELs for Reeves Creek were
taken from a USACE Floodplain Information Report in adjacent Henry County
(Reference 23). Starting elevations for Conley Creek were taken from the
Floodplain Information Report completed in 1968 by the USACE, Savannah
District (Reference 22). Starting WSELs for Mud Creek and Jester Creek were
obtained from a Floodplain Information Report completed in 1969 by the
USACE, Mobile District (Reference 24).
Channel roughness factors (Manning’s “n”) used in the hydraulic computations
were chosen by engineering judgment and based on field observations of the
stream channels and overbank floodplain areas. The channel and overbank “n”
values for all streams studied by detailed methods are shown Table 3.
Table 3 - Manning’s “n” Values
Stream
Beaver Dam Creek
Big Cotton Indian Creek
Camp Creek
Camp Creek Tributary
Conine Creek
Conley Creek
Conley Creek Tributary
Duffey Tributary
East Tributary of Jester Creek
Flint River
Flint River Tributary
Hurricane Creek
Jester Creek
Mud Creek
North Fork Jester Creek
Panther Creek
Pates Creek
Pine Creek
Poole Creek
Poole Creek Tributary
Reeves Creek
Roberts Road Tributary
Shoal Creek
Stratford Tributary
Stream A
Stream B
* Data not available
21
Channel “n”
Overbank “n”
0.045-0.070
0.045-0.070
0.045-0.055
0.045-0.055
0.045-0.055
0.045-0.070
*
0.055
*
0.045-0.055
0.045-0.055
0.045-0.070
0.045-0.055
0.045-0.070
0.045-0.055
0.045-0.070
0.045-0.070
*
*
*
0.045-0.070
0.045-0.070
0.045-0.055
0.055
0.045-0.055
0.045-0.055
0.055-0.150
0.055-0.150
0.10-0.12
0.075-0.120
0.075-0.120
0.055-0.150
*
0.075-0.11
*
0.10-0.12
0.10-0.12
0.055-0.150
0.075-0.120
0.055-0.150
0.075-0.120
0.055-0.150
0.055-0.150
*
*
*
0.055-0.150
0.055-0.150
0.075-0.120
0.075-0.11
0.06-0.15
0.06-0.15
Table 3 - Manning’s “n” Values (Continued)
Stream
Stream BT
Stream C
Stream CT
Stream CT-A
Stream D
Sullivan Creek
Swamp Creek
Tar Creek
Upton Creek
Wallis Creek
West Tributary of Jester Creek
York Tributary
Channel “n”
Overbank “n”
0.045-0.055
0.045-0.055
0.045-0.055
0.045-0.055
0.045-0.055
0.045-0.055
0.045-0.070
0.045-0.070
0.045-0.070
0.045-0.070
*
0.055
0.06-0.15
0.06-0.15
0.06-0.15
0.06-0.15
0.06-0.15
0.075-0.120
0.055-0.150
0.055-0.150
0.055-0.150
0.055-0.150
*
0.075-0.11
* Data not available
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 this study 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.
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 in use for newly created or revised FIS reports and
FIRMs was the NGVD29. With the finalization of the NAVD88, many FIS
reports and FIRMs are being prepared using NAVD88 as the referenced
vertical datum.
All flood elevations shown in this FIS report and on the FIRM are referenced to
NAVD88. Structure and ground elevations in the community must, therefore,
be referenced to NAVD88. It is important to note that adjacent communities
may be referenced to NGVD29. This may result in differences in Base Flood
Elevations (BFEs) across the corporate limits between the communities. The
average conversion factor that was used to convert the data in this FIS report to
NAVD88 was calculated using the National Geodetic Survey’s VERTCON
online utility (Reference 25). The data points used to determine the conversion
factor are listed in Table 4, “Vertical Datum Conversion”.
22
Table 4 - Vertical Datum Conversion
Quad
Name
Riverdale
Riverdale
Jonesboro
Jonesboro
Riverdale
Hampton
Corner
Latitude
NW
NE
NE
SE
SE
SW
33.63
33.63
33.63
33.50
33.50
33.38
Longitude
Conversion
from NGVD29
to NAVD88
-84.50
-84.38
-84.25
-84.25
-84.38
-84.38
0.164 feet
0.203 feet
0.177 feet
0.095 feet
0.102 feet
0.046 feet
AVERAGE
0.131 feet
For more information on NAVD88, see the FEMA publication entitled
Converting the National Flood Insurance Program to the North American
Vertical Datum of 1988 (FEMA, June 1992), or contact the Vertical Network
Branch, National Geodetic Survey, Coast and Geodetic Survey, National
Oceanic and Atmospheric Administration, Silver Spring, Maryland 20910
(Internet address http://www.ngs.noaa.gov).
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.
4.0
FLOODPLAIN MANAGEMENT APPLICATIONS
The NFIP encourages State and local governments to adopt sound floodplain
management programs. Therefore, each FIS provides 1-percent-annual-chance
(100-year) flood elevations and delineations of the 1- and 0.2-percent-annual-chance
(500-year) floodplain boundaries and 1-percent-annual-chance floodway to assist
communities in developing floodplain management measures. This information is
presented on the FIRM and in many components of the FIS report, including Flood
Profiles, Floodway Data Table, and Summary of Stillwater Elevations Table. Users
should reference the data presented in the FIS report as well as additional information
that may be available at the local map repository before making flood elevation and/or
floodplain boundary determinations.
23
4.1
Floodplain Boundaries
To provide a national standard without regional discrimination, the 1-percentannual-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 community. For each
stream studied by detailed methods, the 1- and 0.2-percent-annual-chance
floodplain boundaries have been delineated using the flood elevations
determined at each cross section.
For Camp Creek, Camp Creek Tributary, Flint River, Flint River Tributary,
Jester Creek, Shoal Creek, and Sullivan Creek the boundaries between cross
sections were interpolated using topographic maps at a scale of 1:4,800, with a
contour interval of 4 feet (Reference 21). For Conine Creek, Duffey Tributary,
North Fork Jester Creek, Stratford Tributary and York Tributary, the
boundaries between cross sections were interpolated using topographic maps at
a scale of 1:2,400, with a contour interval of 5 feet (Reference 4). Between
cross sections for Conley Creek Tributary, East Tributary of Jester Creek, Pine
Creek, Poole Creek, Poole Creek Tributary, West Tributary of Jester Creek,
and the portions of Conley Creek and Jester Creek within the City of Forest
Park corporate limits, the boundaries were interpolated using topographic maps
at a scale of 1:24,000, with a contour interval of 10 feet (Reference 26). For
Stream A, Stream B, Stream BT, Stream C, Stream CT, Stream CT-A, Stream
D and the portions of Flint River and Flint River Tributary that are within the
corporate limits of the City of Riverdale, the boundaries between cross sections
were interpolated using USGS quadrangle maps enlarged to a scale of 1:7,200,
with a contour interval of 10 feet (Reference 27). For Beaver Dam Creek, Big
Cotton Indian Creek, Conley Creek, Hurricane Creek, Mud Creek, Panther
Creek, Pates Creek, Reeves Creek, Roberts Road Tributary, Swamp Creek, Tar
Creek, Upton Creek and Wallis Creek the boundaries between cross sections
were interpolated using topographic maps at a scale of 1:12,000, with a contour
interval of 10 feet (Reference 28).
The 1- and 0.2-percent-annual-chance floodplain boundaries are shown on the
FIRM (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, AE, and AO), 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, only the 1-percent-annualchance floodplain boundary is shown on the FIRM (Exhibit 2).
24
For streams studied by approximate methods within the unincorporated areas of
Clayton County the floodplain boundaries were determined using Flood Prone
Area Maps furnished by SCS and USGS maps (References 29-32). The Flood
Prone Area Maps were prepared by several methods. Floodplain boundaries
along some streams depict the inundation of past floods as estimated from
photographs and/or high-water marks. Other floodplain boundaries were
estimated from regional relations between drainage area and depth of a
relatively large flood.
For streams studied by approximate methods within the City of Morrow, the
flood boundaries were determined from Flood Hazard Boundary Maps prepared
by Gannett-Fleming for FEMA dated May 24, 1974, and revised July 30, 1976
(Reference 33).
For streams studied by approximate methods within the City of Riverdale, the
flood boundaries were determined through field observation and the use of
USGS topographic maps at a scale of 1:24,000, with a contour interval of 10
feet (Reference 27).
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 the 1-percent-annual-chance 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 FIS report and on the FIRM 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 have been tabulated for selected cross
sections (Table 5). In cases where the floodway and 1-percent-annual-chance
25
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
1
CROSS SECTION
DISTANCE
BEAVER DAM CREEK
A
B
C
D
E
F
G
H
I
J
K
L
M
5,000
7,000
7,525
8,025
8,625
9,100
9,600
10,075
11,118
11,618
12,368
13,368
15,568
WIDTH
(FEET)
140
65
25
215
80
50
80
16
25
20
35
15
12
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
536
140
165
516
401
90
202
71
104
52
130
45
33
1.8
6.6
5.0
1.6
1.9
8.6
3.2
8.0
5.1
9.0
3.4
7.0
1.5
REGULATORY
(FEET NAVD)
802.7
812.7
814.8
818.2
818.4
819.2
821.9
822.6
829.7
832.9
836.6
842.8
856.7
WITHOUT
FLOODWAY
(FEET NAVD)
802.7
812.7
814.8
818.2
818.4
819.2
821.9
822.6
829.7
832.9
836.6
842.8
856.7
WITH
FLOODWAY
(FEET NAVD)
803.7
813.0
815.8
819.2
819.3
819.6
822.9
823.6
829.7
832.9
837.6
843.1
857.7
1
Feet above confluence with Flint River
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
BEAVER DAM CREEK
INCREASE
(FEET)
1.0
0.3
1.0
1.0
0.9
0.4
1.0
1.0
0.0
0.0
1.0
0.3
1.0
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
CROSS SECTION
DISTANCE
WIDTH
(FEET)
BIG COTTON INDIAN
CREEK
A
B
C
D
E
F
G
H
I
101,700
103,620
106,220
109,145
111,220
113,620
114,760
116,920
118,820
175
175
160
540
425
265
605
170
330
1
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
1,302
1,252
1,088
4,389
3,445
696
2,241
738
1,478
4.0
4.3
4.8
1.2
1.2
5.8
1.7
3.0
1.5
REGULATORY
(FEET NAVD)
749.6
757.1
769.8
785.3
790.1
792.1
796.2
808.4
810.5
WITHOUT
FLOODWAY
(FEET NAVD)
749.6
757.1
769.8
785.3
790.1
792.1
796.2
808.4
810.5
WITH
FLOODWAY
(FEET NAVD)
750.6
758.1
770.6
786.3
791.1
793.1
797.2
808.7
811.5
1
Feet above confluence with South River
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
BIG COTTON INDIAN CREEK
INCREASE
(FEET)
1.0
1.0
0.8
1.0
1.0
1.0
1.0
0.3
1.0
FLOODING SOURCE
CROSS SECTION
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
1
DISTANCE
CAMP CREEK
A
944
B
3,564
C
7,364
D
10,514
E
15,660
F
17,130
G
19,632
H
21,160
I
23,600
J
26,200
K
28,300
L
29,100
M
31,630
N
33,622
O
35,464
P
37,370
Q
39,430
R
41,600
S
43,700
T
44,400
U
45,845
V
48,000
1
Feet above confluence with Flint River
2
Total width/width within county
WIDTH
(FEET)
2
856/380
2
182/95
372
467
2
146/100
2
310/266
2
300/130
2
620/302
2
270/190
2
400/225
2
360/12
50
160
330
50
180
230
150
80
40
40
40
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
11,024
1,829
3,456
3,059
918
2,198
1,586
4,406
892
2,090
1,476
339
902
1,279
242
480
1,081
516
314
212
204
146
0.5
3.3
1.7
2.0
5.3
2.2
2.9
1.1
4.9
1.9
2.6
11.4
3.3
2.3
10.9
5.5
2.0
4.5
5.9
8.8
7.9
9.2
REGULATORY
(FEET NAVD)
794.6
795.6
802.8
807.4
813.8
814.8
816.3
820.6
821.5
826.7
828.8
831.0
836.9
840.5
847.8
849.0
854.3
858.5
864.0
865.1
871.1
873.6
WITHOUT
FLOODWAY
(FEET NAVD)
WITH
FLOODWAY
(FEET NAVD)
N/A
N/A
802.8
807.4
813.8
814.8
816.3
820.6
821.5
826.7
828.8
831.0
836.9
840.5
847.8
849.0
854.3
858.5
864.0
865.1
871.1
873.6
N/A
N/A
803.8
808.3
814.8
815.8
817.2
820.8
822.0
827.7
829.8
831.7
837.8
841.5
847.8
849.1
855.3
859.2
865.0
866.1
872.1
874.4
FLOODWAY DATA
CAMP CREEK
INCREASE
(FEET)
N/A
N/A
1.0
0.9
1.0
1.0
0.9
0.2
0.5
1.0
1.0
0.7
0.9
1.0
0.0
0.1
1.0
0.7
1.0
1.0
1.0
0.8
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
CROSS SECTION
DISTANCE
WIDTH
(FEET)
CAMP CREEK
TRIBUTARY
A
B
C
D
E
F
G
H
I
J
K
L
M
N
585
1,532
2,170
2,920
3,525
3,950
4,800
5,520
6,730
7,830
8,170
9,380
9,700
10,330
118
197
127
38
95
176
146
63
145
132
232
73
61
117
1
SECTION
AREA
(SQUARE
FEET)
419
1,375
909
307
720
740
860
215
676
360
1,136
225
197
787
MEAN
VELOCITY
(FEET PER
SECOND)
5.0
1.5
2.3
5.9
2.5
2.4
2.1
8.4
2.1
3.9
1.2
6.2
7.1
1.0
REGULATORY
(FEET NAVD)
835.6
841.2
841.6
842.1
844.0
844.5
845.8
849.0
854.7
865.6
866.6
868.2
871.8
873.9
WITHOUT
FLOODWAY
(FEET NAVD)
2
833.3
841.2
841.6
842.1
844.0
844.5
845.8
849.0
854.7
865.6
866.6
868.2
871.8
873.9
WITH
FLOODWAY
(FEET NAVD)
834.3
842.1
842.5
842.9
844.5
845.0
846.5
849.4
855.3
866.3
867.5
868.7
871.8
874.3
1
Feet above confluence with Camp Creek
Elevation computed without consideration of backwater effects from Camp Creek
2
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
CAMP CREEK TRIBUTARY
INCREASE
(FEET)
1.0
0.9
0.9
0.8
0.5
0.5
0.7
0.4
0.6
0.7
0.9
0.5
0.0
0.4
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
CROSS SECTION
DISTANCE
CONINE CREEK
A
B
C
D
E
F
G
210
1
520
1
875
1
1,800
1
2,560
1
3,490
1
3,800
1
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
49
161
411
388
207
141
135
331
1,004
1,859
4,427
2,226
639
752
3.8
1.3
0.7
0.3
0.6
2.0
1.7
REGULATORY
(FEET NAVD)
862.2
862.2
869.5
869.5
869.5
869.6
870.0
WITHOUT
FLOODWAY
(FEET NAVD)
2
859.1
2
859.6
869.5
869.5
869.5
869.6
870.0
WITH
FLOODWAY
(FEET NAVD)
INCREASE
(FEET)
860.1
860.5
870.5
870.5
870.5
870.5
870.9
CONLEY CREEK
3
4
A
29,680
917
5,132
0.9
793.0
793.0
793.7
3
4
B
30,760
300
1,643
2.8
793.8
793.8
794.3
3
5
C
32,295
700/420
2,937
1.6
796.4
796.4
797.4
3
5
D
34,175
540/210
1,177
3.9
798.8
798.8
799.7
3
5
E
34,933
500/360
1,992
2.2
807.3
807.3
807.3
3
F
36,870
55
395
8.9
812.6
812.6
813.1
3
G
38,500
300
919
2.9
822.9
822.9
823.0
3
H
41,250
40
292
8.2
833.5
833.5
834.4
3
I
42,200
75
324
7.1
837.0
837.0
837.6
3
J
42,660
105
469
4.9
838.7
838.7
838.7
3
K
43,310
95
352
6.1
842.3
842.3
843.2
3
L
43,620
95
422
1.8
844.2
844.2
845.2
3
M
44,700
185
813
2.5
847.5
847.5
848.5
1
4
Feet above confluence with North Fork Jester Creek
This width is beyond county boundary
2
5
Elevation computed without consideration of backwater effects from North Fork Jester Creek
Total width/width within county
3
Feet above confluence with South River
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
CONINE CREEK - CONLEY CREEK
1.0
0.9
1.0
1.0
1.0
0.9
0.9
0.7
0.5
1.0
0.9
0.0
0.5
0.1
0.9
0.6
0.0
0.9
1.0
1.0
FLOODING SOURCE
CROSS SECTION
DUFFEY TRIBUTARY
A
B
C
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
DISTANCE
1
325
1
715
1
1,055
WIDTH
(FEET)
22
12
53
FLINT RIVER
2
3
A
3,100
345 / 270
2
3
B
4,320
287 / 175
2
3
C
5,060
266 / 125
2
3
D
7,440
571 / 320
2
3
E
10,160
1,027 / 935
2
3
F
13,280
933 / 130
2
3
G
15,360
966 / 65
2
3
H
17,470
756 / 455
2
3
I
18,980
362 / 155
2
3
J
19,080
541 / 150
2
3
K
21,950
2,224 / 780
2
3
L
24,601
1,325 / 1,060
2
3
M
30,320
1,061 / 460
2
3
N
32,181
312 / 0
2
O
35,800
399
2
P
35,934
374
2
Q
36,900
396
1
Feet above confluence with York Tributary
2
Feet above county boundary
3
Total width / width within county
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED ARES
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
REGULATORY
(FEET NAVD)
WITHOUT
FLOODWAY
(FEET NAVD)
WITH
FLOODWAY
(FEET NAVD)
INCREASE
(FEET)
65
35
76
5.1
9.5
4.4
850.1
857.0
866.1
850.1
857.0
866.1
851.1
857.2
867.0
1.0
0.2
0.9
3,155
3,201
3,357
8,139
11,803
11,199
11,297
8,559
4,622
6,055
26,120
12,367
9,360
3,199
5,435
3,485
6,367
5.8
5.7
5.5
2.2
1.6
1.6
1.6
2.1
4.0
3.0
0.7
1.5
2.0
5.9
3.5
5.5
3.0
757.7
760.7
761.8
764.3
765.2
765.9
766.4
766.9
768.2
768.9
769.9
770.4
773.0
775.2
779.4
779.9
781.1
757.7
760.7
761.8
764.3
765.2
765.9
766.4
766.9
768.2
768.9
769.9
770.4
773.0
775.2
779.4
779.9
781.1
758.3
761.7
762.7
765.2
766.2
766.9
767.4
767.8
769.2
769.9
770.9
771.3
773.9
775.9
780.3
780.9
782.0
0.6
1.0
0.9
0.9
1.0
1.0
1.0
0.9
1.0
1.0
1.0
0.9
0.9
0.7
0.9
1.0
0.9
FLOODWAY DATA
DUFFEY TRIBUTARY - FLINT RIVER
FLOODING SOURCE
CROSS SECTION
1
DISTANCE
FLINT RIVER
(CONTINUED)
R
38,640
S
40,130
42,061
T
45,545
U
V
48,240
W
54,070
X
56,625
Y
59,330
Z
61,100
AA
63,581
AB
69,130
AC
70,580
AD
71,500
AE
73,830
AF
75,300
AG
78,000
AH
78,285
AI
80,520
AJ
82,710
AK
84,330
AL
86,100
1
Feet above county boundary
2
Total width / width within county
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
452
1,173
300
1,832
1,809
2
1,638 / 1,210
2
547 / 147
2
311 / 285
2
1,620 / 60
2
1,650 / 455
2
401 / 310
2
1,265 / 1,175
2
1,074 / 600
802
406
1,263
1,148
647
663
636
843
7,047
17,453
4,193
27,974
25,469
21,438
7,005
3,353
12,967
17,555
3,954
10,484
8,877
9,525
4,744
15,622
13,573
5,407
6,532
5,614
6,605
2.7
1.1
4.5
0.7
0.7
0.9
2.7
5.6
1.5
1.1
3.9
1.5
1.7
1.2
2.4
0.7
0.8
2.1
1.8
2.0
1.7
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
REGULATORY
(FEET NAVD)
781.8
782.4
782.7
783.9
784.0
784.2
784.7
785.8
787.2
788.2
790.4
791.6
792.3
795.6
796.0
796.6
796.7
797.3
798.9
800.0
801.1
WITHOUT
FLOODWAY
(FEET NAVD)
WITH
FLOODWAY
781.8
782.4
782.7
783.9
784.0
784.2
784.7
785.8
787.2
788.2
790.4
791.6
792.3
795.6
796.0
796.6
796.7
797.3
798.9
800.0
801.1
(FEET NAVD)
782.7
783.4
783.6
784.9
785.0
785.2
785.7
786.8
788.1
789.1
791.2
792.5
793.1
796.3
796.7
797.4
797.5
798.0
799.7
800.8
801.9
FLOODWAY DATA
FLINT RIVER
INCREASE
(FEET)
0.9
1.0
0.9
1.0
1.0
1.0
1.0
1.0
0.9
0.9
0.8
0.9
0.8
0.7
0.7
0.8
0.8
0.7
0.8
0.8
0.8
FLOODING SOURCE
CROSS SECTION
1
DISTANCE
FLINT RIVER
(CONTINUED)
AM
86,630
AN
87,780
AO
89,255
AP
90,580
AQ
93,360
AR
94,500
AS
95,530
AT
96,490
AU
97,571
AV
99,175
AW
100,370
AX
101,500
AY
102,710
AZ
104,370
BA
104,860
BB
106,760
BC
107,940
BD
109,050
BE
110,670
BF
111,650
BG
113,110
1
Feet above county boundary
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
REGULATORY
259
1,042
1,114
1,057
388
447
146
634
209
699
238
751
444
537
154
753
1,195
753
748
1,169
531
1,571
7,673
8,384
7,211
3,028
3,683
1,355
6,214
2,415
7,006
2,049
7,613
4,199
4,550
1,217
7,747
11,847
7,617
4,259
6,690
3,110
7.3
1.5
1.4
1.6
3.8
3.1
0.1
2.2
4.1
1.4
4.8
1.3
2.3
2.2
8.1
1.3
0.8
1.3
2.3
1.5
4.3
801.4
804.4
804.9
805.4
807.2
808.5
810.7
815.5
816.3
817.2
817.9
819.5
820.0
821.5
822.0
824.8
825.1
825.4
826.6
828.3
831.4
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
(FEET NAVD)
WITHOUT
FLOODWAY
(FEET NAVD)
WITH
FLOODWAY
801.4
804.4
804.9
805.4
807.2
808.5
810.7
815.5
816.3
817.2
817.9
819.5
820.0
821.5
822.0
824.8
825.1
825.4
826.6
828.3
831.4
(FEET NAVD)
802.2
804.8
805.4
806.0
808.0
809.3
811.6
815.9
816.8
817.7
818.4
820.1
820.9
822.3
822.8
825.3
825.7
825.9
827.2
828.9
832.0
FLOODWAY DATA
FLINT RIVER
INCREASE
(FEET)
0.8
0.4
0.5
0.6
0.8
0.8
0.9
0.4
0.5
0.5
0.5
0.6
0.9
0.8
0.8
0.5
0.6
0.5
0.6
0.6
0.6
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
CROSS SECTION
DISTANCE
WIDTH
(FEET)
FLINT RIVER
(CONTINUED)
BH
BI
BJ
BK
BL
BM
BN
BO
BP
BQ
BR
BS
BT
BU
BV
BW
113,410
114,020
115,650
117,010
118,510
119,220
121,650
123,520
124,450
125,530
126,040
127,510
130,520
132,800
133,700
134,350
624
575
855
891
922
505
274
152
506
747
264
309
187
211
139
115
1
SECTION
AREA
(SQUARE
FEET)
4,411
4,811
5,897
6,969
6,163
3,754
2,255
1,995
5,648
7,139
1,253
2,432
1,935
1,520
1,143
1,031
MEAN
VELOCITY
(FEET PER
SECOND)
3.1
2.8
2.0
1.7
1.9
3.2
5.3
6.0
2.1
1.1
6.5
3.4
4.2
5.4
7.2
8.0
REGULATORY
(FEET NAVD)
832.6
834.2
836.4
838.0
839.0
840.5
847.6
853.1
855.2
855.9
855.9
859.9
875.8
884.1
886.9
889.8
WITHOUT
FLOODWAY
(FEET NAVD)
WITH
FLOODWAY
832.6
834.2
836.4
838.0
839.0
840.5
847.6
853.1
855.2
855.9
855.9
859.9
875.8
884.1
886.9
889.8
(FEET NAVD)
833.4
835.0
837.2
838.8
839.7
841.3
848.4
853.9
856.1
856.7
856.7
860.1
876.0
884.4
887.0
890.4
1
Feet above county boundary
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
FLINT RIVER
INCREASE
(FEET)
0.8
0.8
0.8
0.8
0.7
0.8
0.8
0.8
0.9
0.8
0.8
0.2
0.2
0.3
0.1
0.6
FLOODING SOURCE
CROSS SECTION
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
1
DISTANCE
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
REGULATORY
(FEET NAVD)
WITHOUT
FLOODWAY
WITH
FLOODWAY
849.0
852.3
860.6
865.4
867.0
871.5
871.1
874.5
0.9
0.6
0.8
0.9
0.7
0.6
0.0
0.0
783.0
802.3
815.3
815.7
816.7
830.8
830.8
835.4
841.2
854.1
865.5
881.4
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.6
1.0
1.0
1.0
(FEET NAVD)
FLINT RIVER
TRIBUTARY
A
B
C
D
E
F
G
H
2,975
3,820
5,420
6,900
7,100
7,275
8,525
9,000
118
80
70
50
91
193
51
81
571
262
390
265
398
2,439
131
275
2.8
6.1
3.1
4.5
3.0
0.5
9.2
2.9
848.1
851.7
859.8
864.5
866.3
870.9
871.1
874.5
848.1
851.7
859.8
864.5
866.3
870.9
871.1
874.5
HURRICANE CREEK
A
B
C
D
E
F
G
H
I
J
K
L
3,400
8,648
12,771
13,371
13,971
15,446
15,946
17,446
19,396
20,405
21,722
22,945
170
40
230
190
200
250
43
35
35
35
30
25
597
264
1,025
635
254
1,293
170
93
93
157
110
70
3.2
6.2
1.3
1.7
2.1
0.6
3.7
4.1
4.1
1.7
1.9
1.9
783.4
801.3
814.3
814.7
815.7
829.8
829.8
834.4
840.6
853.1
864.5
880.4
782.0
801.3
814.3
814.7
815.7
829.8
829.8
834.4
840.6
853.1
864.5
880.4
2
(FEET NAVD)
INCREASE
(FEET)
1
Feet above confluence with Flint River
Elevation computed without consideration of backwater effects from Flint River
2
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
FLINT RIVER TRIBUTARY - HURRICANE CREEK
FLOODING SOURCE
CROSS SECTION
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
1
DISTANCE
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
JESTER CREEK
A
860
562
3,332
1.6
B
2,205
443
2,567
2.0
C
3,120
588
2,848
1.8
D
3,455
110
634
8.2
E
3,680
193
1,292
4.0
F
3,900
101
809
6.4
G
5,330
383
4,031
1.3
H
6,320
363
2,245
2.3
I
7,530
259
2,317
1.9
J
8,390
91
673
6.7
K
9,925
411
1,781
2.5
L
11,150
249
1,396
3.2
M
12,170
289
1,509
3.0
N
13,590
529
2,882
1.6
O
14,920
574
2,539
1.0
P
16,100
507
3,674
0.7
Q
16,750
480
2,974
0.9
R
17,620
211
458
5.7
S
18,495
420
1,666
1.2
T
19,147
553
3,338
0.6
U
19,950
57
455
4.4
V
20,750
370
5,038
0.4
1
Feet above confluence with Flint River
2
Elevation computed without consideration of backwater effects from Flint River
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
REGULATORY
(FEET NAVD)
815.8
815.8
815.8
815.8
817.5
818.6
823.3
823.6
824.9
825.4
828.7
832.7
835.4
837.7
839.6
848.0
848.2
849.2
853.8
860.1
860.1
870.9
WITHOUT
FLOODWAY
(FEET NAVD)
WITH
FLOODWAY
(FEET NAVD)
2
812.6
2
814.2
2
815.0
2
815.6
817.5
818.6
823.3
823.6
824.9
825.4
828.7
832.7
835.4
837.7
839.6
848.0
848.2
849.2
853.8
860.1
860.1
870.9
813.6
814.9
815.7
816.2
817.6
819.3
824.0
824.4
825.8
826.4
829.5
833.6
836.2
838.5
840.3
848.8
849.0
849.7
854.5
860.9
860.9
871.7
FLOODWAY DATA
JESTER CREEK
INCREASE
(FEET)
1.0
0.7
0.7
0.6
0.1
0.7
0.7
0.8
0.9
1.0
0.8
0.9
0.8
0.8
0.7
0.8
0.8
0.5
0.7
0.8
0.8
0.8
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
CROSS SECTION
DISTANCE
WIDTH
(FEET)
JESTER CREEK
(CONTINUED)
W
X
Y
Z
AA
AB
AC
AD
21,400
21,970
22,575
23,380
24,370
25,450
26,500
27,040
498
216
344
129
65
41
246
154
1
SECTION
AREA
(SQUARE
FEET)
5,022
1,648
2,125
794
425
258
1,286
972
MEAN
VELOCITY
(FEET PER
SECOND)
0.4
1.2
0.9
2.5
4.7
7.7
1.3
1.7
REGULATORY
(FEET NAVD)
870.9
870.9
871.2
874.4
875.9
879.1
884.0
884.8
WITHOUT
FLOODWAY
WITH
FLOODWAY
870.9
870.9
871.2
874.4
875.9
879.1
884.0
884.8
871.7
871.7
871.9
875.4
876.7
879.6
884.7
885.6
(FEET NAVD)
(FEET NAVD)
INCREASE
(FEET)
0.8
0.8
0.7
1.0
0.8
0.5
0.7
0.8
MUD CREEK
2
A
1,100
891
6,969
1.7
838.0
N/A
N/A
N/A
2
B
2,050
922
6,163
1.9
839.0
N/A
N/A
N/A
3
C
2,700
410
1,460
2.5
839.6
836.0
837.0
1.0
D
4,750
120
578
6.2
844.1
844.1
844.6
0.5
E
6,150
220
646
4.3
851.0
851.0
852.0
1.0
F
6,900
140
810
3.2
854.4
854.4
854.7
0.3
G
9,950
100
476
5.5
862.8
862.8
863.8
1.0
H
12,400
40
462
5.1
876.0
876.0
876.6
0.6
I
14,300
180
1,410
1.6
877.0
877.0
878.0
1.0
J
15,700
40
287
7.9
878.6
878.6
879.6
1.0
K
16,800
130
337
6.5
884.2
884.2
885.2
1.0
1
3
Feet above confluence with Flint River
Elevation computed without consideration of backwater effects from Flint River
2
Elevation computed with consideration of flooding controlled by Flint River
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
JESTER CREEK - MUD CREEK
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
1
CROSS SECTION
DISTANCE
NORTH FORK JESTER
CREEK
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
3,115
3,920
4,660
5,295
6,000
6,650
7,000
8,020
8,900
9,080
10,720
11,885
12,600
13,060
13,170
14,510
WIDTH
(FEET)
63
42
54
53
51
168
101
33
424
135
375
105
22
132
129
75
SECTION
AREA
(SQUARE
FEET)
559
352
483
527
473
1,373
1,218
356
2,805
829
894
653
169
372
445
343
MEAN
VELOCITY
(FEET PER
SECOND)
5.0
8.0
5.8
5.3
4.3
1.5
1.7
5.7
0.7
1.9
1.8
2.4
9.3
4.2
3.5
4.6
REGULATORY
(FEET NAVD)
854.1
856.2
859.7
861.5
863.1
863.8
867.3
867.3
867.4
868.1
869.3
871.4
871.8
877.9
879.6
884.7
WITHOUT
FLOODWAY
(FEET NAVD)
854.1
856.2
859.7
861.5
863.1
863.8
867.3
867.3
867.4
868.1
869.3
871.4
871.8
877.9
879.6
884.7
WITH
FLOODWAY
(FEET NAVD)
854.2
856.7
860.5
862.5
864.0
864.7
867.4
867.5
868.3
868.5
870.3
872.0
872.7
878.2
879.6
885.4
1
Feet above confluence with Jester Creek
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
NORTH FORK JESTER CREEK
INCREASE
(FEET)
0.1
0.5
0.8
1.0
0.9
0.9
0.1
0.2
0.9
0.4
1.0
0.6
0.9
0.3
0.0
0.7
FLOODING SOURCE
CROSS SECTION
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
DISTANCE
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
REGULATORY
(FEET NAVD)
WITHOUT
FLOODWAY
(FEET NAVD)
WITH
FLOODWAY
(FEET NAVD)
INCREASE
(FEET)
PANTHER CREEK
A
B
C
D
E
F
G
H
I
J
K
6,540
1
9,090
1
11,690
1
13,740
1
16,440
1
19,340
1
20,740
1
22,415
1
25,315
1
26,740
1
29,040
1
545
240
295
70
200
280
85
130
345
85
85
4,377
1,397
2,022
532
1,735
1,710
667
822
2,190
409
526
1.0
3.0
2.0
7.1
2.1
1.2
3.0
2.3
0.8
2.6
2.0
751.8
756.8
761.9
767.6
775.7
782.0
786.5
792.3
799.2
806.0
817.2
751.8
756.8
761.9
767.6
775.7
782.0
786.5
792.3
799.2
806.0
817.2
752.3
756.8
762.9
768.6
776.7
782.9
787.5
793.3
799.6
806.9
818.2
0.5
0.0
1.0
1.0
1.0
0.9
1.0
1.0
0.4
0.9
1.0
PATES CREEK
A
B
40,230
2
44,257
2
42
26
319
210
6.7
7.5
785.2
800.2
785.2
800.2
786.2
801.2
1.0
1.0
1
Feet above confluence with Big Cotton Indian Creek
Feet above mouth
2
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
PANTHER CREEK - PATES CREEK
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
WITHOUT
FLOODWAY
WITH
FLOODWAY
795.3
806.8
824.7
825.7
832.8
840.3
795.3
806.8
824.7
825.7
832.8
840.3
796.2
807.8
825.7
826.7
833.8
841.1
0.9
1.0
1.0
1.0
1.0
0.8
1.1
0.4
11.5
9.6
804.2
804.2
808.6
822.7
804.2
804.2
808.6
822.7
805.2
805.2
809.2
823.3
1.0
1.0
0.6
0.6
6.4
775.9
771.1
772.1
1.0
CROSS SECTION
DISTANCE
REEVES CREEK
A
B
C
D
E
F
29,599
1
32,645
1
36,158
1
36,261
1
38,361
1
40,211
1
63
142
42
118
65
74
320
674
240
517
294
189
6.5
2.4
5.6
2.6
3.4
3.7
ROBERTS ROAD
TRIBUTARY
A
B
C
D
800
2
860
2
1,310
2
2,780
2
184
217
8
6
385
1,065
33
23
SHOAL CREEK
A
310
2
85
466
REGULATORY
(FEET NAVD)
(FEET NAVD)
3
(FEET NAVD)
INCREASE
(FEET)
1
Feet above confluence with Little Cotton Indian Creek
Feet above confluence with Flint River
3
Elevation computed without consideration of backwater effects from Flint River
2
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
REEVES CREEK - ROBERTS ROAD TRIBUTARY SHOAL CREEK
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
CROSS SECTION
DISTANCE
STRATFORD
TRIBUTARY
A
B
C
D
E
F
G
H
I
J
K
L
0
1
115
1
280
1
630
1
1,020
1
1,560
1
1,965
1
2,130
1
2,230
1
2,880
1
3,250
1
3,400
1
33
24
27
33
34
20
19
27
60
11
31
123
81
109
120
135
150
42
80
55
209
41
89
166
7.0
5.3
4.7
4.2
3.8
8.4
4.4
6.5
1.7
8.5
4.0
2.1
STREAM A
A
B
C
D
E
450
2
1,380
2
2,760
2
3,160
2
3,763
2
18
27
41
94
97
40
88
65
264
236
8.6
3.9
2.8
0.7
0.6
WITHOUT
FLOODWAY
WITH
FLOODWAY
843.3
845.0
849.4
851.2
853.1
857.0
862.2
863.6
867.2
872.3
880.3
882.3
843.3
845.0
849.4
851.2
853.1
857.0
862.2
863.6
867.2
872.3
880.3
882.3
843.6
846.0
849.5
851.8
853.8
857.0
862.7
864.3
867.2
872.3
881.3
882.6
0.3
1.0
0.1
0.6
0.7
0.0
0.5
0.7
0.0
0.0
1.0
0.3
854.0
868.4
894.0
909.2
912.9
854.0
868.4
894.0
909.2
912.9
854.0
868.4
894.0
909.2
912.9
0.0
0.0
0.0
0.0
0.0
REGULATORY
(FEET NAVD)
(FEET NAVD)
(FEET NAVD)
INCREASE
(FEET)
1
Feet above limit of detailed study (limit of detailed study is approximately 200 feet downstream of Harbin Wood Drive)
Feet above confluence with Camp Creek
2
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
STRATFORD TRIBUTARY - STREAM A
FLOODING SOURCE
CROSS SECTION
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
DISTANCE
STREAM B
A
B
C
D
E
F
G
H
I
J
K
L
5,272
1
5,475
1
5,682
1
5,964
1
6,464
1
6,719
1
7,019
1
7,404
1
7,904
1
8,325
1
8,586
1
9,011
STREAM BT
A
B
C
D
180
2
680
2
1,200
2
1,800
1
2
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
19
20
60
60
32
38
28
50
11
13
50
50
76
92
205
307
84
51
37
45
23
24
79
64
6.9
5.7
2.6
1.7
6.3
3.7
5.1
4.2
6.5
5.9
1.8
2.2
851.3
852.2
854.4
855.0
855.6
862.0
866.9
876.5
880.0
886.9
891.2
897.4
851.3
852.2
854.4
855.0
855.6
862.0
866.9
876.5
880.0
886.9
891.2
897.4
186
188
45
88
1.8
1.8
7.5
3.2
862.1
870.2
871.5
875.8
861.2
870.2
871.5
875.8
60
60
19
25
REGULATORY
(FEET NAVD)
WITHOUT
FLOODWAY
(FEET NAVD)
3
WITH
FLOODWAY
(FEET NAVD)
851.3
852.2
854.5
856.0
856.3
862.0
866.9
876.5
880.0
886.9
891.2
897.4
0.0
0.0
0.1
1.0
0.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
862.1
870.6
871.7
875.8
0.9
0.4
0.2
0.0
1
Feet above confluence with Stream C
Feet above confluence with Stream B
3
Elevation computed without consideration of backwater effects from Stream B
2
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
INCREASE
(FEET)
FLOODWAY DATA
STREAM B - STREAM BT
FLOODING SOURCE
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
WITHOUT
FLOODWAY
WITH
FLOODWAY
865.0
870.8
870.8
875.6
880.5
887.1
889.3
900.4
865.0
870.8
870.8
875.6
880.5
887.1
889.3
900.4
865.0
871.0
871.0
876.4
880.7
887.5
889.3
900.4
0.0
0.2
0.2
0.8
0.2
0.4
0.0
0.0
2.0
0.8
2.0
9.3
4.4
3.1
857.7
863.8
875.5
899.6
901.6
914.2
857.7
863.8
875.5
899.6
901.6
914.2
857.7
863.8
875.5
899.6
901.6
914.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
904.9
904.9
906.0
904.9
904.9
906.0
904.9
904.9
906.0
0.0
0.0
0.0
CROSS SECTION
DISTANCE
STREAM C
A
B
C
D
E
F
G
H
7,350
1
7,529
1
7,762
1
8,585
1
9,241
1
9,910
1
10,251
1
10,975
1
75
85
185
17
182
93
55
35
105
492
322
41
395
68
37
37
3.9
0.7
1.1
7.4
0.6
2.9
4.4
4.4
STREAM CT
A
B
C
D
E
F
711
2
985
2
2,565
2
3,920
2
4,125
2
4,780
2
247
458
61
11
30
84
309
771
309
128
58
84
500
440
310
2,790
1,980
900
STREAM CT-A
3
A
195
3
B
313
3
C
603
1
Feet above confluence with Flint River
2
Feet above confluence with Stream C
3
Feet above confluence with Stream CT
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
REGULATORY
(FEET NAVD)
(FEET NAVD)
(FEET NAVD)
INCREASE
(FEET)
FLOODWAY DATA
STREAM C - STREAM CT - STREAM CT-A
FLOODING SOURCE
CROSS SECTION
DISTANCE
STREAM D
A
B
C
131
1
334
1
600
SULLIVAN CREEK
A
B
C
D
E
F
G
H
I
J
K
L
M
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
WIDTH
(FEET)
1
98
9
96
2
295
44
53
40
154
46
62
30
133
73
51
80
4
34
1,100
2
2,810
2
3,900
2
5,000
2
6,400
2
7,290
2
8,230
2
8,980
2
9,315
2
10,840
2
11,850
2
12,300
2
13,960
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
REGULATORY
(FEET NAVD)
WITHOUT
FLOODWAY
WITH
FLOODWAY
892.7
894.1
902.5
0.0
0.0
0.0
858.4
862.8
866.8
872.6
879.1
880.4
889.8
893.9
897.3
900.8
905.6
908.9
918.9
1.0
0.6
0.4
1.0
0.4
0.3
0.9
0.8
0.1
0.4
0.2
0.4
0.4
(FEET NAVD)
84
18
58
1.8
8.4
1.5
892.7
894.1
902.5
892.7
894.1
902.5
1,472
330
446
298
1,151
335
345
294
883
509
485
660
518
2.5
11.2
8.3
12.4
3.2
11.0
10.7
12.6
4.2
7.3
7.0
5.2
6.6
860.1
862.2
866.4
871.6
878.7
880.1
888.9
893.1
897.2
900.4
905.4
908.5
918.5
857.4
862.2
866.4
871.6
878.7
880.1
888.9
893.1
897.2
900.4
905.4
908.5
918.5
3
(FEET NAVD)
1
Feet above Taylor Road
Feet above confluence with Flint River
3
Elevation computed without consideration of backwater effects from Flint River
4
Floodway width located in Area Not Included
2
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
STREAM D - SULLIVAN CREEK
INCREASE
(FEET)
FLOODING SOURCE
CROSS SECTION
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
DISTANCE
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
REGULATORY
(FEET NAVD)
WITHOUT
FLOODWAY
(FEET NAVD)
WITH
FLOODWAY
(FEET NAVD)
INCREASE
(FEET)
SWAMP CREEK
A
B
C
D
E
F
G
H
I
J
650
1
4,210
1
4,279
1
4,527
1
7,070
1
8,707
1
10,857
1
10,958
1
12,907
1
14,857
1
549
32
148
285
87
279
135
42
162
74
4,560
236
437
516
317
1,068
488
277
705
283
0.4
7.0
3.8
3.2
5.2
1.6
3.4
6.0
2.4
5.9
790.0
793.1
794.3
805.3
806.7
812.2
821.5
824.1
831.4
844.2
N/A
793.1
794.3
805.3
806.7
812.2
821.5
824.1
831.4
844.2
N/A
794.1
794.9
806.3
807.4
813.2
822.4
824.9
832.4
845.0
N/A
1.0
0.6
1.0
0.7
1.0
0.9
0.8
1.0
0.8
TAR CREEK
A
B
4,050
2
6,140
2
125
40
708
207
8.0
9.1
779.2
791.3
779.2
791.3
780.2
792.3
1.0
1.0
UPTON CREEK
A
B
2,500
3
5,350
3
200
27
424
143
2.2
6.0
806.0
817.4
806.0
817.4
807.0
818.4
1.0
1.0
1
Feet above confluence with Flint River
Feet above confluence with Big Cotton Indian Creek
3
Feet above Double Bridge Road
2
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
SWAMP CREEK - TAR CREEK - UPTON CREEK
FLOODING SOURCE
CROSS SECTION
1-PERCENT-ANNUAL-CHANCE-FLOOD
WATER SURFACE ELEVATION
FLOODWAY
WIDTH
(FEET)
SECTION
AREA
(SQUARE
FEET)
MEAN
VELOCITY
(FEET PER
SECOND)
REGULATORY
1
20
65
25
25
30
9
9
91
314
84
77
54
44
20
12.8
3.5
6.0
6.6
0.4
7.0
8.4
792.3
801.7
809.8
825.7
853.5
862.0
878.8
792.3
801.7
809.8
825.7
853.5
862.0
878.8
792.3
802.7
810.7
825.8
853.5
862.0
878.8
0.0
1.0
0.9
0.1
0.0
0.0
0.0
2
24
15
200
101
88
15
11
34
84
53
1,838
565
344
36
45
43
6.9
10.8
0.3
0.5
0.8
7.8
6.1
6.4
836.0
840.6
850.1
850.1
851.2
851.4
856.7
864.9
836.0
840.6
850.1
850.1
851.2
851.4
856.7
864.9
836.5
840.6
850.5
850.5
851.6
851.6
857.6
865.0
0.5
0.0
0.4
0.4
0.4
0.2
0.9
0.1
DISTANCE
WALLIS CREEK
A
B
C
D
E
F
G
3,210
1
5,880
1
8,575
1
10,560
1
13,075
1
13,770
1
15,274
YORK TRIBUTARY
A
B
C
D
E
F
G
H
0
2
145
2
260
2
455
2
601
2
1,095
2
1,330
2
1,700
(FEET NAVD)
WITHOUT
FLOODWAY
(FEET NAVD)
WITH
FLOODWAY
(FEET NAVD)
INCREASE
(FEET)
1
Feet above confluence with Flint River
Feet above limit of detailed study (limit of detailed study is approximately 190 feet downstream of Meadowbrook Lane)
2
TABLE 5
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
FLOODWAY DATA
WALLIS CREEK - YORK TRIBUTARY
floodplain boundaries are either close together or collinear, only the floodway
boundary has been shown.
On Pates Creek, no floodway is applicable through Orr’s Lake. Above Orr’s
Lake, the steep stream and overbank slopes convey hazardous velocity flows
for the base flood and, thus no floodway is shown.
In the City of Forest Park, floodways were not included due to the velocities
produced by the steep gradients of the streambeds in order to pass the base flood.
Under natural conditions, channel velocities range from 5 feet to 13 feet per
second. Floodplain encroachments would increase velocities even more.
Therefore, the floodways were considered to be the limits of the 1-percent-annualchance floodplain boundaries (Reference 6).
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 of the 1-percent-annual-chance 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 2.
Figure 2 - Floodway Schematic
47
5.0
INSURANCE APPLICATIONS
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 risk zone that corresponds to the 1-percent-annual-chance
floodplains that are determined in the FIS by approximate methods. Because detailed
hydraulic analyses are not performed for such areas, no BFEs or base flood depths are
shown within this zone.
Zone AE
Zone AE is the flood insurance risk zone that corresponds to the 1-percent-annual-chance
floodplains that are determined in the FIS by detailed methods. In most instances, wholefoot BFEs derived from the detailed hydraulic analyses are shown at selected intervals
within this zone.
Zone AO
Zone AO is the flood insurance risk zone that corresponds to the areas of 1-percentannual-chance shallow flooding (usually sheet flow on sloping terrain) where average
depths are between 1 and 3 feet. Average whole-foot base flood depths derived from the
detailed hydraulic analyses are shown within this zone.
Zone X
Zone X is the flood insurance risk zone that corresponds to areas outside the 0.2-percentannual-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 1percent-annual-chance flooding where the contributing drainage area is less than 1 square
mile, and areas protected from the 1-percent-annual-chance flood by levees. No BFEs or
base flood depths are shown within this zone.
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 risk 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 the zones and BFEs in conjunction with information on structures
and their contents to assign premium rates for flood insurance policies.
48
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
Clayton 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, where applicable. Historical data relating to the maps prepared for
each community are presented in Table 6.
7.0
OTHER STUDIES
This report either supersedes or is compatible with all previous studies on streams studied
in this report and should be considered authoritative for 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, Federal Insurance and Mitigation Division, 3003
Chamblee-Tucker Road, Atlanta, Georgia 30341.
9.0
BIBLIOGRAPHY AND REFERENCES
1.
Federal Insurance Administration, Flood Insurance Study, Clayton County,
Georgia (Unincorporated Areas), U.S. Department of Housing and Urban
Development, June 15, 1978.
2.
Federal Emergency Management Agency, Flood Insurance Study, Clayton
County, Georgia (Unincorporated Areas), May 1, 1984.
3.
Federal Emergency Management Agency, Flood Insurance Study, Clayton
County, Georgia (Unincorporated Areas), November 6, 1991.
4.
Federal Emergency Management Agency, Flood Insurance Study, City of
Morrow, Clayton County, Georgia, Flood Insurance Study Report August 16,
1982; Flood Insurance Rate Map, February 16, 1983.
49
COMMUNITY
NAME
INITIAL
IDENTIFICATION
FLOOD HAZARD
BOUNDAY MAP
REVISION DATE
FIRM
EFFECTIVE DATE
FIRM
REVISION DATE
Clayton County
(Unincorporated Areas)
October 31, 1975
None
June 15, 1978
May 1, 1984
November 6, 1991
September 20, 1996
November 20, 2000
August 16, 2007
Forest Park, City of
May 31, 1974
None
May 16, 1977
August 16, 2007
Jonesboro, City of
August 16, 2007
None
August 16, 2007
Lake City, City of
May 31, 1974
May 14, 1976
September 4, 1986
Lovejoy, City of
August 16, 2007
None
August 16, 2007
Morrow, City of
May 24, 1974
July 30, 1976
February 16, 1983
August 16, 2007
Riverdale, City of
June 14, 1974
January 30, 1976
February 15, 1978
January 7, 1983
November 6, 1991
August 16, 2007
None
August 16, 2007
None
TABLE 6
FEDERAL EMERGENCY MANAGEMENT AGENCY
CLAYTON COUNTY, GA
AND INCORPORATED AREAS
Table 1 - Community Map History
COMMUNITY MAP HISTORY
5.
Federal Emergency Management Agency, Flood Insurance Study, Clayton
County, Georgia (Unincorporated Areas), November 20, 2000.
6.
Federal Insurance Administration, Flood Insurance Study, City of Forest Park,
Clayton and Fulton Counties, U.S. Department of Housing and Urban
Development, Flood Insurance Study Report, November 16, 1976; Flood
Insurance Rate Map, May 16, 1977.
7.
Federal Insurance Administration, Flood Insurance Study, City of Riverdale,
Clayton County, Georgia, U.S. Department of Housing and Urban Development,
November 6, 1991.
8.
U.S. Census Bureau, American FactFinder, Clayton County, Georgia, 2000.
Retrieved October 26, 2005, from http://factfinder.census.gov.
9.
The Weather Channel, Monthly Averages for Jonesboro, Georgia. Retrieved
November 29, 2005, from http://www.weather.com.
10.
U.S. Geological Survey, Water Resources Investigations 77-57, USGS
Preliminary Flood Frequency Relations for Urban Streams, Metropolitan Atlanta,
Georgia, U.S. Department of the Interior, August 1977.
11.
Hydrologic Engineering Center, HEC-1 Flood Hydrograph Package, Davis,
California, U.S. Army Corps of Engineers, September 1981, revised January
1985.
12.
U.S. Geological Survey, Water Resources Investigations 88-4085, Flood
Frequency Relations for Urban Streams in Georgia, U.S. Department of the
Interior, 1988.
13.
National Weather Service, Rainfall Frequency Atlas of the United States, 30Minute to 24-Hour Durations, 1- to 100-Year Return Periods, Technical Paper
No. 40, U.S. Department of Commerce, 1961.
14.
National Oceanographic and Atmospheric Administration, National Weather
Service, Technical Memorandum NWS Hydro-35, Five- to 60-Minute
Precipitation Frequency for the Eastern and Central United Sates, Silver Spring,
MD, U.S. Department of Commerce, National Climatic Center, June 1977.
51
15.
Hydrologic Engineering Center, HEC-2 Water-Surface
California, U.S. Army Corps of Engineers, April 1984.
16.
Soil Conservation Service, Technical Release No. 55, Urban Hydrology for Small
Watersheds, U.S. Department of Agriculture, January 1975.
17.
Soil Conservation Service, Soil Survey of Fulton County, Georgia, U.S.
Department of Agriculture, 1958.
18.
Soil Conservation Service, Soil Survey of Clayton, Fayette, and Henry Counties,
Georgia, U.S. Department of Agriculture, 1979.
19.
U.S. Geological Survey, Water Resources Investigations 83-4203, Flood
Frequency Relations for Urban Streams in Metropolitan Atlanta, Georgia. U.S.
Department of the Interior, 1983
20.
U.S. Geological Survey, Water Resources Investigations Report 78-137, Floods in
Georgia, Magnitude and Frequency, U.S. Department of the Interior, October
1979.
21.
U.S. Army Corps of Engineers, Mobile District, Topographic Maps, Scale
1:4,800, Contour Interval 4 feet: Clayton County, Unincorporated Areas, Georgia,
January 1989.
22.
U.S. Department of the Army, Corps of Engineers, Savannah District, Flood Plain
Information, Metropolitan Atlanta, Conley Creek-South River, Georgia, July
1968.
23.
U.S. Department of the Army, Corps of Engineers, Savannah District, Flood Plain
Information, Little Cotton Indian Creek, Henry County, Georgia, June 1975.
24.
U.S. Department of the Army, Corps of Engineers, Mobile District, Flood Plain
Information, Metropolitan Atlanta, Georgia, Upper Flint River, Mud Creek and
Jester Creek, January 1969.
25.
National Geodetic Survey, VERTCON-North American Vertical Datum
Conversion
Utility.
Retrieved
September
21,
2005,
from
http://www.ngs.noaa.gov/.
52
Profiles,
Davis,
26.
U.S. Geological Survey, 7.5-Minute Series Topographic Maps, Scale 1:24,000,
Contour Interval 10 feet: Southwest Atlanta, Southeast Atlanta, Riverdale, and
Jonesboro, U.S. Department of the Interior, various dates.
27.
U.S. Geological Survey, 7.5 Minute Series Topographic Maps, Scale 1:24,000,
Contour Interval 10 feet: Riverdale, Georgia, U.S. Department of the Interior,
Photorevised 1973.
28.
Clayton County Planning Commission, Topographic Maps, Scale 1:12,000,
Contour Interval 10 feet: Clayton County, Georgia, revised January 1973.
29.
Soil Conservation Service, 7.5-Minute Series Flood-Prone Area Maps, Scale
1:24,000, Contour Interval 10 feet: Jonesboro, Georgia, U.S. Department of
Agriculture, April 1974.
30.
Soil Conservation Service, 7.5-Minute Series Flood-Prone Area Maps, Scale
1:24,000, Contour Interval 20 feet: Stockbridge, Georgia, U.S. Department of
Agriculture, April 1974.
31.
U.S. Geological Survey, 7.5-Minute Series Flood-Prone Area Maps, Scale
1:24,000, Contour Interval 10 feet: Riverdale, Georgia, U.S. Department of the
Interior, 1969.
32.
U.S. Geological Survey, 7.5-Minute Series Flood-Prone Area Maps, Scale
1:24,000, Contour Interval 20 feet: Brooks, Georgia 1969; Fayetteville, Georgia
1969; Griffin North, Georgia 1974; Hampton, Georgia, 1973, U.S. Department of
the Interior, various dates.
33.
Mayes, Sudderth & Etheredge, Inc., Flood Plain Study, City of Morrow, Georgia,
June 1980.
53