AND INCORPORATED AREAS - Georgia DFIRM · AND INCORPORATED AREAS Community Community Name Number...

COWETA COUNTY

COWETA COUNTY, GEORGIA

AND INCORPORATED AREAS Community Community Name Number COWETA COUNTY (UNINCORPORATED AREAS) 130298 GRANTVILLE, CITY OF 130443 HARALSON, TOWN OF 130299 MORELAND, TOWN OF 130300 NEWNAN, CITY OF 130062 SENOIA, CITY OF 130301

∗SHARPSBURG, TOWN OF 130581 TURIN, TOWN OF 130475

∗ Non-Floodprone

Revised: February 6, 2013

FLOOD INSURANCE STUDY NUMBER 13077CV001B

VOLUME 1 OF 2

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: May 16, 2006

Revised Countywide FIS Effective Date: February 6, 2013

i

TABLE OF CONTENTS

Volume 1

1.0 INTRODUCTION..................................................................................................1

1.1 Purpose of Study ..............................................................................................1

1.2 Authority and Acknowledgements ..................................................................1

1.3 Coordination ....................................................................................................2

2.0 AREA STUDIED ...................................................................................................3

2.1 Scope of Study .................................................................................................3

2.2 Community Description ...................................................................................6

2.3 Principal Flood Problems .................................................................................7

2.4 Flood Protection Measures ..............................................................................7

3.0 ENGINEERING METHODS ...............................................................................8

3.1 Hydrologic Analyses ........................................................................................8

3.2 Hydraulic Analyses ........................................................................................23

3.3 Vertical Datum ...............................................................................................25

4.0 FLOODPLAIN MANANGEMENT APPLICATIONS....................................26

4.1 Floodplain Boundaries ...................................................................................26

4.2 Floodways ......................................................................................................27

5.0 INSURANCE APPLICATIONS.........................................................................67

6.0 FLOOD INSURANCE RATE MAP ..................................................................67

7.0 OTHER STUDIES ...............................................................................................68

8.0 LOCATION OF DATA .......................................................................................68

9.0 BIBLIOGRAPHY AND REFERENCES ..........................................................68

ii

TABLE OF CONTENTS

Volume 1 (continued)

FIGURES

Figure 1 – Floodway Schematic........................................................................................... 28

TABLES

Table 1 – Streams Studied by Detailed Methods .................................................................... 3

Table 2 – Stream Name Changes ........................................................................................... 5

Table 3 – Summary of Discharges ....................................................................................... 10

Table 4 – Manning’s “n” Values .......................................................................................... 24

Table 5 – Vertical Datum Conversion .................................................................................. 25

Table 6 – Floodway Data Table ........................................................................................... 29

Table 7 – Community Map History ..................................................................................... 69

EXHIBITS

Exhibit 1 - Flood Profiles

Chandlers Creek Panels 01P-04P

Chattahoochee River Panels 05P-07P

Keg Creek Panels 08P-09P

Lake Amlajack Creek Panels 10P-11P

Lake Summergrove Branch Panel 12P

Line Creek Panels 13P-22P

Little Creek Panels 23P-24P

Little Wahoo Creek Panels 25P-28P

Mineral Spring Branch Panels 29P-33P

Paradise Lakes Branch Panels 34P-35P

Peeks Creek Panel 36P

Persimmon Creek Panels 37P-39P

Sandy Creek Panels 40P-45P

Shoal Creek Panels 46P-50P

Snake Creek Panels 51P-54P

Tributary 1 to Line Creek Panels 55P-56P

Tributary 1 to Mineral Spring Branch Panels 57P-60P

iii

TABLE OF CONTENTS

Volume 2

EXHIBITS (continued)


Tributary 1 to Persimmon Creek Panels 61P-62P

Tributary 1 to Sandy Creek Panels 63P-64P

Tributary 1 to Shoal Creek Panel 65P

Tributary 1 to Snake Creek Panel 66P

Tributary 1 to Turkey Creek Panel 67P

Tributary 1 to Wahoo Creek Panel 68P

Tributary 1 to White Oak Creek Panels 69P-70P



Tributary 2 to Shoal Creek Panels 77P-78P


Tributary 2 to Wahoo Creek Panels 80P-81P


Tributary 3 to Shoal Creek Panels 84P- 85P











Turkey Creek Panels 96P-101P

Wahoo Creek Panels 102P-114P

White Oak Creek Panels 115P-120P

Exhibit 2 - Flood Insurance Rate Map Index

Flood Insurance Rate Map

1

FLOOD INSURANCE STUDY

COWETA 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 Coweta County,

including the Cities of Grantville, Newnan, and Senoia; the Towns of Haralson,

Moreland, Sharpsburg, and Turin; and the unincorporated areas of Coweta County

(referred to collectively herein as Coweta 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 Corinth was previously shown as geographically

located in Heard and Coweta Counties. The Town of Corinth has been absorbed

into the unincorporated areas of Heard and Coweta Counties. The portion

previously located in Coweta County, absorbed by this county, is included in this

FIS report. See the Heard County FIS report and Flood Insurance Rate Map

(FIRM) for flood-hazard information for the portion of Corinth absorbed by Heard

County.

The City of Palmetto is located geographically in Coweta County and Fulton

County. Also, the City of Palmetto is included, in its entirety, in the Fulton

County, GA FIS report. The Town of Corinth is located geographically in

Coweta County and Heard County. The FIS reports and Flood Insurance Rate

Maps (FIRMs) are printed separately. The Town of Haralson is geographically

located in Coweta County and Meriwether County. The Town of Haralson is

included in its entirety in this FIS report. Please note that the Town of Sharpsburg

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 are the National Flood Insurance Act of 1968

and the Flood Disaster Protection Act of 1973.

2

The hydrologic and hydraulic analyses for the May 15, 1978 FIS report for the

City of Newnan (FIA, 1978) were performed by Roy F. Weston, Inc., for the U.S.

Department of Housing and Urban Development, Federal Insurance

Administration (FIA), under Contract No. H-4048. The work was completed in

October 1977.

The hydrologic and hydraulic analyses for the FIS report for the unincorporated

areas of Coweta County, dated February 2, 1982 (FEMA, 1982), were performed

by Roy F. Weston, Inc., for the Federal Emergency Management Agency

(FEMA), under Contract No. H-4048. The work was completed in July 1980.

For the September 8, 1999 revision (FEMA, 1999), the hydrologic and hydraulic

analyses for White Oak Creek were prepared by Braswell Engineering, Inc., for

FEMA, under Contract No. EMW-93-C-4147. The work was completed in

October 1997.

The digital FIRM conversion for the initial countywide FIS report, dated May 16,

2006 (FEMA, 2006), was performed by the Georgia Department of Natural

Resources, under contract number EMA-2003-GR-5369. The work was

completed in April 2005.

For this revised countywide FIS, the hydrologic and hydraulic analyses were

performed by Dewberry and Davis LLC for FEMA, under Contract No.

EMA-2009-CA-5930. Detailed hydrologic and hydraulic analyses were

performed for the Chattahoochee River and approximately 37 miles of stream

within the Wahoo Creek sub-basin. All non-revised detailed study streams were

redelineated. Limited detailed/approximate hydrologic and hydraulic analyses

were performed for all Zone A and shaded Zone X floodplains. This work was

completed in July 2011.

Base map information shown on this FIRM was derived from Coweta County

aerial photography produced at a scale of 1:600 from photography dated 2009.

The coordinate system used for the production of the digital FIRM is State Plane

Coordinate System Georgia West Zone (FIPS zone 1002) based on Transverse

Mercator projection. The horizontal datum is North American Datum of 1983.

The use of the base map is restricted by the data agreement between Coweta

County and the Study Contractor.

1.3 Coordination

For the 1978 FIS report for the City of Newnan, the final Consultation

Coordination Officer (CCO) meeting was held on November 1, 1977, and was

attended by representatives of the FIA, Roy F. Weston, Inc., city officials, and

local residents (FIA, 1978).

For the 1982 FIS report for the unincorporated areas of Coweta County, an initial

Coordination meeting was held on July 7, 1978, and a final CCO meeting was

held on September 10, 1981. Both meetings were attended by representatives of

FEMA, Coweta County, and Roy F. Weston, Inc. (FEMA, 1982).

3

For the 1999 revision, the county was notified by a letter dated December 1, 1997,

that its FIS would be revised using the analysis prepared by Braswell

Engineering, Inc. (FEMA, 1999).

For the May 16, 2006, countywide FIS report, the initial scoping meeting was

held on September 23, 2004, and the final CCO meeting was held on May 5,

2005. Both meetings were attended by representatives of FEMA, the Georgia

Department of Natural Resources, and local communities.

For this revised countywide FIS report, a scoping meeting was held on April 16,

2010, and was attended by representatives of FEMA, the Georgia Department of

Natural Resources, local communities, and Dewberry and Davis LLC. The

purpose of this meeting was to discuss the scope of the FIS.

The results of this study were reviewed at the final CCO meeting held on October

27, 2011 and attended by representatives of FEMA, local communities, and

Dewberry and Davis LLC. All problems raised at that meeting have been

addressed.

2.0 AREA STUDIED

2.1 Scope of Study

This FIS covers the geographic area of Coweta 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 hazard areas and

areas of projected development or proposed construction.

The following table lists the flooding sources that have been studied by detailed

methods and are included in this FIS report:

Table 1 – Streams Studied by Detailed Methods

Chandlers Creek Tributary 1 to Wahoo Creek

Chattahoochee River Tributary 1 to White Oak Creek

Keg Creek Tributary 2 to Mineral Spring Branch

Lake Amlajack Creek Tributary 2 to Sandy Creek

Lake Summergrove Branch Tributary 2 to Shoal Creek

Line Creek Tributary 2 to Snake Creek

Little Creek Tributary 2 to Wahoo Creek

Little Wahoo Creek Tributary 3 to Sandy Creek

Mineral Spring Branch Tributary 3 to Shoal Creek

Paradise Lakes Branch Tributary 3 to Wahoo Creek

Peeks Creek Tributary 4 to Wahoo Creek

Persimmon Creek Tributary 5 to Wahoo Creek

4

Table 1 – Streams Studied by Detailed Methods

Sandy Creek Tributary 6 to Wahoo Creek

Shoal Creek Tributary 7 to Wahoo Creek

Snake Creek Tributary 8 to Wahoo Creek

Tributary 1 to Line Creek Tributary 9 to Wahoo Creek

Tributary 1 to Mineral Spring Branch Tributary 10 to Wahoo Creek

Tributary 1 to Persimmon Creek Tributary 11 to Wahoo Creek

Tributary 1 to Sandy Creek Tributary 12 to Wahoo Creek

Tributary 1 to Shoal Creek Turkey Creek

Tributary 1 to Snake Creek Wahoo Creek

Tributary 1 to Turkey Creek White Oak Creek

The limits of detailed study are indicated on the Flood Profiles (Exhibit 1) and on

the FIRM (Exhibit 2).

For this countywide revision, the Chattahoochee River received a new detailed

study and the following streams were restudied by detailed methods:

Little Wahoo Creek Tributary 6 to Wahoo Creek

Snake Creek Tributary 7 to Wahoo Creek

Tributary 1 to Snake Creek Tributary 8 to Wahoo Creek

Tributary 1 to Wahoo Creek Tributary 9 to Wahoo Creek

Tributary 2 to Snake Creek Tributary 10 to Wahoo Creek



Tributary 4 to Wahoo Creek Wahoo Creek

Tributary 5 to Wahoo Creek

This countywide revision incorporates the following Letter of Map Revision:

Case Number Determination Date Flooding Source

11-04-0184P April 22, 2011 Keg Creek

For this countywide revision, non-restudied reaches of streams that have been

studied by detailed methods were selected for redelineation based on more recent

topography. The topographic data source utilized for this study is contours

provided by the Coweta County Geographic Information System (GIS)

Department. The contours were created based on countywide topographic Light

Detection and Ranging (LiDAR) data acquired by Photo Science, Inc. in 2007

(Photo Science, 2007). The LiDAR data met the vertical and horizontal accuracy

requirements in FEMA’s Guidelines for Aerial Mapping and Surveying (FEMA,

2003).

5

The following streams were redelineated:

Chandlers Creek Tributary 1 to Persimmon Creek

Lake Amlajack Creek Tributary 1 to Sandy Creek

Lake Summergrove Branch Tributary 1 to Shoal Creek

Line Creek Tributary 1 to Turkey Creek

Little Creek Tributary 1 to White Oak Creek

Mineral Spring Branch Tributary 2 to Mineral Spring Branch

Paradise Lakes Branch Tributary 2 to Sandy Creek

Peeks Creek Tributary 2 to Shoal Creek

Persimmon Creek Tributary 3 to Sandy Creek

Sandy Creek Tributary 3 to Shoal Creek

Shoal Creek Turkey Creek

Tributary 1 to Line Creek White Oak Creek

Tributary 1 to Mineral Spring Branch

Limited detailed analyses/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 Coweta County. The

limited detail studies were incorporated into the FIRMs as Zone A for reaches

where Zone A exists on the initial countywide FIRM; and as shaded Zone X for

reaches where Zone A does not exist on the initial countywide FIRM.

Approximate studies were incorporated into the FIRMs as Zone A.

No stream name change was made for this FIS report. For the May 16, 2006,

countywide FIS report, in the process of combining the FIS reports for the City of

Newnan and Coweta County, the designated names for the numbered tributaries

were revised to avoid duplicate names and for general clarity. Table 2, “Stream

Name Changes” lists the numbered tributaries with their current and revised

names, along with the community FIS report where it was located originally.

Table 2 – Stream Name Changes Community Old Name Current Name

(Revised by initial county wide FIS)

City of Newnan Tributary 1 Tributary 1 to Wahoo Creek

Tributary 2 Tributary 2 to Wahoo Creek








6

Table 2 – Stream Name Changes (continued)

Community Old Name Current Name

(Revised by initial county wide FIS)

City of Newnan Tributary 10 Tributary 10 to Wahoo Creek



Tributary 13 Tributary 1 to Snake Creek

Tributary 14 Tributary 2 to Snake Creek

Tributary 15 Tributary 1 to Mineral Spring Branch


Coweta County

(Unincorporated Areas) Tributary 1 Tributary 1 to Wahoo Creek



Tributary 4 Tributary 1 to Sandy Creek



Tributary 7 Tributary 1 to Line Creek

Tributary 8 Tributary 1 to Shoal Creek



Tributary 11 Tributary 1 to Persimmon Creek

Tributary 12 Tributary 1 to Turkey Creek

Tributary 13 Tributary 1 to White Oak Creek

2.2 Community Description

Coweta County is located in the northwestern portion of Georgia and

encompasses an area of approximately 443 square miles. It is bordered by Carroll

and Fulton Counties to the north, Fayette and Spaulding Counties to the east,

Meriwether and Troupe Counties to the south, and Heard County to the west. The

population of Coweta County in 2010 was reported to be 127,317 (2010 U.S.

Census).

The climate of Coweta County is characterized by warm summers, mild winters,

and moderate to heavy rainfall. Summer and winter temperatures range from an

average high of 90 degrees Fahrenheit ( ̊F) in July to an average low of 34 ̊F in

January. The average annual precipitation is approximately 51 inches.

7

The topography of the area is typical of the Piedmont Region of Georgia in that

the land consists of gently rolling hills with steep slopes near the many streams

flowing throughout the area. The soils belong to three major groupings: The

Davidson-Cecil-Madison Association, the Mecklenburg-Iredell-Wilkes

Association, and the Chewacla-Augusta Association. The soils range from well

drained to poorly drained. The nearly level soils of the Chewacla-Augusta

Association are located in frequently flooded bottom lands and low stream

terraces. Because of the flooding hazard, development in these areas is limited

(FEMA, 1999).

2.3 Principal Flood Problems

Coweta County has a history of moderate flooding. Flooding in Coweta County

is due to a relatively high rate of runoff, flat floodplains, and intermittently

clogged and crooked stream channels. Most floods occur during the annual

planting, growing, and harvesting seasons. Floodwater is a major problem to the

county and state in maintaining roads and bridges. Traffic is occasionally

interrupted and is detoured around flooded crossings.

Coweta County has two U.S. Geological Survey (USGS) stream gages: 02344620

Shoal Creek near Sharpsburg (discharge records since 2007); and 02344700 Line

Creek near Senoia (discharge records since 1964).

Most recently, extensive flooding occurred in Coweta County following the

historical flooding event of September 2009, when the Chattahoochee River

reached a record high flood stage of 29.74 feet at Whitesburg. During the

September 2009 storm, much of the flood losses can be attributed to the

backwater effects of the Chattahoochee River.

2.4 Flood Protection Measures

No major flood protection measures exist in Coweta County.

A floodplain damage prevention ordinance has been enacted by Coweta County to

protect, maintain, and enhance the public health, safety, environment, and general

welfare and to minimize public and private losses due to flood conditions in flood

hazard areas. The ordinance also protects the beneficial uses of floodplain areas

for water quality protection, streambank and stream corridor protection, wetlands

preservation, and ecological and environmental protection (The Zoning and

Development Ordinance of Coweta County, Georgia, effective February 1995).

The City of Newnan has a zoning ordinance that designates Flood Hazard Districts

and limits the use of such floodplain lands (The Zoning Ordinance of the City of

Newnan, Georgia, effective November 2000).

8

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

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.

May 16, 2006, Countywide Analyses

Flood-flow frequency data for the 10-, 2-, and 1-percent-annual-chance floods for

all streams studied by detailed methods, except for Line Creek and White Oak

Creek, were estimated using the method for small natural streams in Georgia

(USGS, 1976) and the method for small urban watersheds in the Metropolitan

Atlanta Area (USGS, unpublished). The latter method was selected because it

allows the applicable rural regional-frequency relations to be adjusted for

urbanized conditions, such as those found in Newnan. The

0.2-percent-annual-chance flood flow was extrapolated from the 10-, 2-, and

1-percent-annual-chance flows on log-log paper.

Discharge-frequency values for Line Creek were estimated using U.S. Soil

Conservation Service (SCS) methodology, as described in Technical Release 55

(USDA, 1975) and the computer program TR-20 (USDA, 1965).

Peak discharges for White Oak Creek were estimated using USGS urban

regression equations (USGS, 1995). Basin drainage areas were delineated and

planimetered on USGS 7.5-Minute Series topographic maps. Impervious area for

each basin was estimated based on aerial tax maps, USGS quadrangle maps, and

field observation.

9

February 6, 2013 Countywide Analyses

This countywide revision incorporates a new detailed study for the Chattahoochee

River from Buford Dam downstream to the headwater of West Point Lake just

above the Heard County and Troup County boundaries. For the reach from the

Roswell gage downstream to the headwater of West Point Lake, discharges were

determined based on a logarithmic discharge – area relationship derived based on

flood-frequency analysis at selected gaging stations. Since Lake Lanier reached

its normal elevation in 1959, flood frequency analysis was performed for six

selected gages that have a minimum of 10 years of flood records from 1960 to

2009. Since the logarithms of the peak discharges were reasonably consistent with

Pearson Type III distribution, flood frequency analysis was performed based on

Bulletin 17B guidelines (IACWD, 1982).

For this revision, peak discharge-frequency relationships for the streams restudied

by detailed methods were determined using the U.S. Army Corps of Engineers

(USACE) HEC-HMS Version 3.4 computer program.

The 24-hour rainfall depths for 50-, 20-, 10-, 4-, 2-, 1-percent-annual-chance

events were determined based on National Weather Service Technical Paper 40

(U.S. Weather Bureau, 1961) and were extrapolated to the 0.2-percent-annual-

chance event. The SCS Type II storm distribution for 24-hour duration was

applied to each storm event (USDA, 1986).

Runoff volumes were calculated using the Natural Resources Conservation

Service (NRCS) Runoff Curve Number method documented in NRCS Technical

Reference 55 (TR-55) (USDA, 1986). Average antecedent moisture conditions

(AMC II) was assumed. Curve number was determined based on soil data

obtained from the NRCS Soil Survey Geographic database and existing land use

data created based on aerial imagery.

The hydrographs for sub-basins were developed based on the NRCS unit

hydrograph method (USDA, 2007). The lag time of each sub-basin was

determined based on the methods presented in TR-55.

Hydrograph routing to account for the attenuation of flows in open channel

segments was performed using the Muskingum-Cunge routing method. The

model parameters include reach length, roughness coefficients, energy grade, and

representative channel cross section for each reach. Energy grade was estimated

as the channel bed slope based on the LiDAR topographic data. A representative

cross section was assigned to each reach and the station/elevation data was

extracted from the topographic data and simplified to eight points.

For this revision, peak discharge-frequency relationships for the streams studied

by limited detailed methods were determined using the USACE HEC-HMS

Version 3.3 computer program.

10

For this revision, peak discharge-frequency relationships for the streams studied

by approximate methods were determined using regional regression equations for

rural areas in Georgia (USGS, 2009) and for urban areas in Georgia (USGS,

1999).

Peak discharge-drainage area relationships for all detailed studied streams are

shown in Table 3, “Summary of Discharges.”

Table 3 - Summary of Discharges

Peak Discharges (cubic feet per second)

Flooding Source and

Location

Drainage

Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

CHANDLERS CREEK

At confluence with

White Oak Creek

5.20 1,330 2,080 2,400 2,880

CHATTAHOOCHEE

RIVER

At Coweta/ Heard

County boundary

2,528.00 44,820 59,866 66,378 82,143

At State Highway 16 2,430.00 43,387 57,897 64,170 79,342

KEG CREEK

Just upstream of

Rockaway Road

14.50 * * 4,806 *

LAKE AMLAJACK

CREEK

At confluence with

White Oak Creek

2.79 970 1,500 1,740 2,100

LAKE

SUMMERGROVE

BRANCH

At confluence with

White Oak Creek

2.76 910 1,430 1,670 1,980

LINE CREEK

Approximately 2,350

feet downstream of

Rockaway Road

101.00 11,680 18,900 20,560 27,900

11

Table 3 - Summary of Discharges (continued)


Flooding Source and

Location

Drainage

Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

LINE CREEK (cont’d)

Approximately 5,000

feet upstream of the

confluence of Flat

Creek

74.50 9,760 15,800 17,200 23,380

Approximately 4,500

feet downstream of

the confluence of

Tributary 1 to Line

Creek

70.20 9,350 15,100 16,400 22,330

Approximately 6,500


confluence of Shoal

Creek

40.80 5,920 9,680 10,180 14,420

Just downstream of the

confluence of Little

Creek

30.51 4,600 7,860 8,640 14,080

Approximately 2,900



Creek

29.59 4,480 7,660 8,430 11,780

Approximately 8,500



Creek

27.94 4,275 7,320 8,040 11,250

Approximately 3,000

feet downstream of

Palmetto Tyrone

Road

26.29 4,070 6,970 7,660 10,720

At Palmetto Tyrone

Road

25.79 4,010 6,860 7,550 10,560

Approximately 3,300

feet upstream of

Palmetto Tyrone

Road

23.84 3,760 6,460 7,100 9,940


confluence of

Persimmon Creek

22.44 3,590 6,160 6,770 9,480

Approximately 2,300

feet downstream of

Collingsworth Road

11.17 2,180 3,780 4,150 5,830

12



Flooding Source and

Location

Drainage Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

LINE CREEK (cont’d)

At Collingsworth Road 9.40 1,900 3,400 3,800 5,000

Approximately 2,100

feet upstream of

Weldon Road

4.21 1,300 2,250 2,500 3,420

LITTLE CREEK

At confluence with Line

Creek

4.60 1,350 2,265 2,420 3,430

Approximately 2,900

feet upstream of

Minix Road

3.88 1,220 2,250 2,350 3,220

Approximately 4,600

feet downstream of

Major Road

2.90 990 1,720 1,900 2,600

At Major Road 1.84 690 1,220 1,350 1,850

Approximately 1,400

feet upstream of

Major Road

1.12 480 850 940 1,300

Approximately 1,500

feet downstream of

Shaw Road

0.77 370 630 710 980

LITTLE WAHOO

CREEK

At confluence with

Wahoo Creek

5.33 1,290 2,027 2,258 2,953

At Roscoe Road 4.09 1,241 1,946 2,166 2,830

Approximately 6,300

feet upstream of

Roscoe Road

3.28 1,229 1,930 2,148 2,841

Approximately 3,000

feet downstream of

Golf Club Drive

2.08 1,146 1,797 1,996 2,565

MINERAL SPRING

BRANCH

At confluence with

Mountain Creek

4.30 1,640 2,400 2,730 3,600

13



Flooding Source and

Location

Drainage Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

MINERAL SPRING

BRANCH (cont’d)

Approximately 2,700


confluence of

Tributary 1 to Mineral

Spring Branch

3.00 1,320 1,940 2,210 2,910

Approximately 3,800

feet downstream of

Belk Road

2.30 1,170 1,170 1,950 2,580

At Belk Road 1.15 810 1,180 1,340 1,770

At Colonial Drive 0.76 680 980 1,110 1,480

At Fourth Street 0.34 430 620 710 950

PARADISE LAKES

BRANCH

At confluence with

White Oak Creek

5.52 1,380 2,150 2,480 2,900

PEEKS CREEK


Creek

7.12 1,960 3,370 3,710 5,200

Approximately 2,800 feet

upstream of

Collingsworth Road

6.51 1,800 3,150 3,420 4,700

PERSIMMON CREEK


Creek

4.15 1,290 2,210 2,430 3,390

Approximately 900 feet

upstream of the

confluence of

Tributary 1 to

Persimmon Creek

3.68 1,190 2,040 2,240 3,100

Approximately 3,200

feet downstream of

Cannongate Road

3.14 1,050 1,820 2,000 2,760

At Cannongate Road 1.97 740 1,300 1,420 1,980

14



Flooding Source and

Location

Drainage

Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-Chance

SANDY CREEK


downstream of

Holbrook Road

16.32 2,610 4,040 4,620 6,540


upstream of

Holbrook Road

14.94 2,480 3,830 4,390 6,200


downstream of the

confluence of

Tributary 3 to Sandy

Creek

7.40 1,730 2,650 3,050 4,325

Approximately 7,800

feet downstream of

Old Corinth Road

5.90 1,510 2,330 2,680 3,780

Approximately 2,300

feet downstream of

Old Corinth Road

5.10 1,380 2,140 2,460 3,460

At Old Corinth Road 3.99 1,260 1,930 2,220 3,150

Approximately 5,300

feet upstream of Old

Corinth Road

3.42 1,150 1,760 2,030 2,875

Approximately 4,100

feet downstream of

Waterworks Road

2.84 1,030 1,580 1,820 2,580

Approximately 2,300

feet downstream of

Waterworks Road

2.14 870 1,340 1,550 2,180

Approximately 1,100

feet downstream of

Waterworks Road

0.71 520 780 900 1,300

At Alpine Drive 0.10 140 220 270 350

SHOAL CREEK


Creek

27.06 3,910 6,610 7,250 10,100


upstream of the

confluence with Line

Creek

26.49 3,860 6,530 7,170 9,995

15



Flooding Source and

Location

Drainage Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

SHOAL CREEK

(cont’d)

Approximately 3,600

feet downstream of

State Highway 54

24.65 3,720 6,300 6,920 9,640

Approximately 1,000

feet downstream of

Lower Fayetteville

Road

17.25 3,130 5,360 5,880 8,210

Approximately 2,600

feet upstream of State

Highway 34

15.01 2,880 4,940 5,420 7,570


confluence of

Tributary 2 to Shoal

Creek

11.76 2,470 4,230 4,650 6,500

Approximately 2,500


confluence of


Creek

7.76 1,950 3,360 3,700 5,180


confluence of


Creek

6.57 1,800 3,110 3,420 4,800

Approximately 1,700

feet downstream of

Raymond Hill Road

5.44 1,575 2,750 3,000 4,200

Just downstream of

Raymond Hill Road

4.32 1,320 2,320 2,550 3,520

At Raymond Hill Road 3.56 1,150 2,000 2,150 3,000

Approximately 6,500

feet upstream of

Raymond Hill Road

3.15 1,050 1,825 2,000 2,760

SNAKE CREEK

At confluence with

Wahoo Creek

3.21 1,332 2,059 2,272 3,064

16



Flooding Source and

Location

Drainage Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

SNAKE CREEK

(cont’d)

Approximately 7100


confluence with

Wahoo Creek

2.32 1,420 2,110 2,321 2,933

At Hospital Road 1.09 1,699 2,551 2,817 3,548

Just upstream of the

confluence of

Tributary 1 to Snake

Creek

0.63 1,048 1,548 1,703 2,127


confluence of

Tributary 2 to Snake

Creek

0.37 608 896 982 1,226

TRIBUTARY 1 TO

LINE CREEK

At the confluence with

Line Creek

2.56 940 1,630 1,790 2,510

Approximately 9,000

feet downstream of

Christopher Road

2.40 850 1,500 1,650 2,280

Approximately 3,500

feet downstream of

Christopher Road

2.02 740 1,300 1,420 1,980

Just downstream of

Christopher Road

1.65 640 1,125 1,250 1,725

TRIBUTARY 1 TO

MINERAL SPRING

BRANCH

At confluence with

Mineral Spring Branch

1.02 670 1,000 1,150 1,470


upstream of Wallace

Gray Road

0.52 500 740 840 1,100

17



Flooding Source and

Location Drainage Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

TRIBUTARY 1 TO

PERSIMMON CREEK

At confluence with

Persimmon Creek

0.41 330 560 620 870

TRIBUTARY 1 TO

SANDY CREEK

At confluence with

Sandy Creek

1.38 570

920 1,080 1,440


downstream of Old

Corinth Road

1.15 520 830 970 1,310

TRIBUTARY 1 TO

SHOAL CREEK

At confluence with Shoal

Creek

5.53 1,600 2,750 3,075 4,200


upstream of the

confluence of Shoal

Creek

5.46 1,575 2,725 3,050 4,150

TRIBUTARY 1 TO

SNAKE CREEK

At confluence with Snake

Creek

0.08 103 169 189 248

TRIBUTARY 1 TO

TURKEY CREEK

At confluence with

Turkey Creek

1.37 520 900 1,010 1,590

TRIBUTARY 1 TO

WAHOO CREEK

At confluence with

Wahoo Creek

0.43 323 484 534 692

At Millard Farmer

Industrial Boulevard

0.17 208 268 279 303

TRIBUTARY 1 TO

WHITE OAK CREEK

At confluence with White

Oak Creek

2.70 1,100 1,650 1,900 2,340

18



Flooding Source and


(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

TRIBUTARY 2 TO

MINERAL SPRING

BRANCH

At confluence with

Mineral Spring

Branch

0.71 580 860 990 1,280

TRIBUTARY 2 TO

SANDY CREEK

At confluence with

Tributary 3 to

Sandy Creek

1.34 560 900 1,060 1,410

Approximately 2,500

feet upstream of

the confluence

with Tributary 3 to

Sandy Creek

0.20 180 300 360 450

TRIBUTARY 2 TO

SHOAL CREEK

At confluence with

Shoal Creek

4.27 1,330 2,300 2,525 3,475

Approximately

2,900 feet

upstream of the

confluence with

Shoal Creek

3.74 1,200 2,150 2,275 3,150

Approximately

1,900 feet

upstream of

Private Road to

McCollum-

Sharpsburg Road

2.98 1,000 1,750 1,900 2,650

TRIBUTARY 2 TO

SNAKE CREEK

At confluence with

Snake Creek

0.20 373 547 599 747

TRIBUTARY 2 TO

WAHOO CREEK

At confluence with

Wahoo Creek

0.80 724 1,019 1,102 1,333

19



Flooding Source and


(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

TRIBUTARY 3 TO

SANDY CREEK

Approximately 100

feet downstream

of Old Corinth

Road

4.58 1,170 1,840 2,140 2,920

At Old Corinth

Road

3.24 950 1,510 1,760 2,380

Approximately

1,500 feet

downstream of

Potts Road

2.24 760 1,220 1,420 1,910

At Potts Road 1.27 550 880 1,030 1,370

TRIBUTARY 3 TO

SHOAL CREEK

At confluence with

Shoal Creek

1.13 485 850 940 1,300

Approximately

1,700 feet

downstream of

Raymond Hill

Road

0.60 230 410 450 600

TRIBUTARY 3 TO

WAHOO CREEK

At confluence with

Tributary 2 to

Wahoo Creek

0.28 134 192 205 240

TRIBUTARY 4 TO

WAHOO CREEK

At confluence with

Tributary 3 to

Wahoo Creek

0.12 108 192 219 298

TRIBUTARY 5 TO

WAHOO CREEK

At confluence with

Tributary 2 to

Wahoo Creek

0.03 31 55 62 85

20



Flooding Source and

Location

Drainage

Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

TRIBUTARY 6 TO

WAHOO CREEK

At confluence with

Tributary 2 to

Wahoo Creek

0.04 32 58 67 92

TRIBUTARY 7 TO

WAHOO CREEK

At confluence with

Wahoo Creek

0.54 682 995 1,089 1,352

At Sprayberry Road 0.45 624 909 994 1,233

TRIBUTARY 8 TO

WAHOO CREEK

At confluence with

Wahoo Creek

0.16 319 457 498 613

TRIBUTARY 9 TO

WAHOO CREEK

At confluence with

Wahoo Creek

0.19 210 342 383 501

TRIBUTARY 10 TO

WAHOO CREEK

At confluence with

Wahoo Creek

0.14 147 239 267 349

TRIBUTARY 11 TO

WAHOO CREEK

At confluence with

Wahoo Creek

0.49 728 1,071 1,173 1,463

TRIBUTARY 12 TO

WAHOO CREEK

At confluence with

Wahoo Creek

0.34 516 763 837 1,046

21



Flooding Source and

Location

Drainage

Area

(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

TURKEY CREEK

At confluence with

White Oak Creek

6.43 1,840 2,740 3,130 3,980

WAHOO CREEK

At confluence with the

Chattahoochee River

34.86 5,141 8,034 9,022 12,080


downstream of Welcome

Sergeant Road

26.71 4,963 7,792 8,770 11,736


confluence of Snake

Creek

16.33 4,096 5,980 6,652 8,706



Wahoo Creek

10.93 2,931 4,169 4,604 5,944

At Roscoe Road 9.89 2,821 3,904 4,274 5,447


upstream of Roscoe Road

8.17 2,563 3,359 3,603 4,325


confluence of Tributary 1

to Wahoo Creek

6.90 2,317 2,791 2,926 3,302

At Millard Farmer Industrial

Boulevard

4.16 1,487 1,752 1,830 2,050

At Jefferson Street 3.56 2,706 3,650 3,948 4,673


confluence of Tributary 7

to Wahoo Creek

2.20 1,360 1,668 1,760 1,991

At Greison Trail 1.56 1,333 2,260 2,492 3,145

WHITE OAK

CREEK

At State Highway 54 64.88 7,830 11,900 13,870 18,630

At Gordon Road 54.74 7,070 10,720 12,480 16,720

At Cannon Road 43.42 6,060 9,180 10,680 14,300

At State Highway 16 36.80 5,480 8,280 9,630 12,860

At Norfolk Southern 31.58 5,060 7,620 8,840 11,770

At Goodynn Road 26.14 4,510 6,780 7,860 10,430

22



Flooding Source and


(square miles)

10-Percent-

Annual-

Chance

2-Percent-

Annual-

Chance

1-Percent-

Annual-

Chance

0.2-Percent-

Annual-

Chance

WHITE OAK

CREEK (cont’d)

At Lower

Fayetteville Road

10.34 2,470 3,690 4,270 5,620

At State Highway 34 7.09 1,940 2,880 3,340 4,380

At Walt Sanders

Road

3.39 990 1,510 1,760 2,360

Approximately

2,600 feet

upstream of Walt

Sanders Road

1.78 650 990 1,150 1,540

At Interstate

Highway 85/State

Highway 403

1.12 440 680 790 1,070

*Data not available

23

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 the

initial countywide FIS report in conjunction with the data shown on the FIRM.

May 16, 2006, Countywide Analyses

Cross sections for the flooding sources studied by detailed methods were

obtained from field surveys and aerial photographs at a scale of 1:12,000 in the

county (Jack W. Berry & Associates, Inc., 1977a) and 1:1,000 in the City of

Newnan. All bridges, dams, and culverts were field surveyed to obtain elevation

data and structural geometry.

Water surface elevations for floods of the selected recurrence intervals were

computed using the USACE HEC-2 step-backwater computer program

(USACE, 1984). Starting water surface elevations were calculated using the

slope-area method.

Roughness factors (Manning’s “n”) used in the hydraulic computations were

based on field inspection and aerial photographs (Jack W. Berry & Associates,

Inc., 1977a). For the 1999 White Oak Creek revision, the values ranged from

0.035 to 0.050 for the channel and 0.030 to 0.100 for the overbanks. The values

for all other streams in the initial countywide FIS report ranged from 0.033 to

0.045 for the channels and 0.025 to 0.080 for the overbanks.

For streams studied by approximate methods, the Flood Hazard Boundary Maps

were field checked and the boundaries were revised where necessary (FIA,

1976).

February 6, 2013 Countywide Analyses

For this revision, cross sections for the flooding sources studied by detailed

methods were cut from the digital terrain model of the topographic LiDAR data

(Photo Science, 2009) at desired locations. Field survey information was

incorporated in the model where cross sections were surveyed. Field survey

information was used to supplement the channel information at cut cross sections

outside the areas where field surveys were obtained. All bridges, culverts, and

dams were field surveyed to obtain elevation data and structural geometry.

24

Water surface elevations for floods of the selected recurrence intervals were

computed using the USACE HEC-RAS Version 4.0 computer program.

Starting water surface elevations were determined using normal depth unless a

coincident peak situation is assumed. The energy slope was approximated by

using the average slope of the channel at the lower limits of the model. Under a

coincident peak situation, a known water surface elevation was implemented as

the starting water surface elevation.

Roughness factors (Manning’s “n”) used in the hydraulic computations were

chosen by engineering judgment and were based on field inspection and aerial

photographs. The Manning’s “n” values for all the detailed studied streams are

listed in Table 4, “Manning’s “n” Values.”

Table 4 – Manning’s “n” Values

Stream Channel “n” Overbank “n”

Chattahoochee River 0.033-0.053 0.078-0.112

Little Wahoo Creek 0.045-0.05 0.03-0.1

Snake Creek 0.05 0.03-0.1

Tributary 1 to Snake Creek 0.05 0.06-0.08

Tributary 1 to Wahoo Creek 0.035-0.05 0.035-0.12

Tributary 2 to Snake Creek 0.05 0.06-0.1



Tributary 4 to Wahoo Creek 0.045 0.05-0.08









Wahoo Creek 0.03-0.05 0.03-0.12

For streams studied by limited detailed and approximate methods, cross sections

were obtained using digital terrain model of the topographic LiDAR data (Photo

Science, 2009). For limited detail analyses, field measurements were made to

approximate the geometry for bridges and culverts in the hydraulic models.

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).

25

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 National Geodetic Vertical Datum 1929 (NGVD29). With the

finalization of the National American Vertical Datum of 1988 (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 the initial

countywide FIS report to NAVD88 was calculated using the National Geodetic

Survey’s VERTCON online utility (NGS, 2004). The data points used to

determine the conversion factor are listed in Table 5, “Vertical Datum

Conversion.”

Table 5-Vertical Datum Conversion

Quad Name Corner Latitude Longitude Conversion from

NGVD29 to

NAVD88

Whitesburg NE 33.50 84.88 0.105 feet

Newnan North NE 33.50 84.75 0.102 feet

Madras NE 33.50 84.62 0.105 feet

Whitesburg SW 33.38 85.00 0.131 feet

Whitesburg SE 33.38 84.88 0.085 feet

Newnan North SE 33.38 84.75 0.066 feet

Madras SE 33.38 84.62 0.059 feet

Newnan

Southwest

SE 33.25 84.88 0.043 feet

Newnan South SE 33.25 84.75 0.007 feet

Sharpsburg SE 33.25 84.62 0.013 feet

Senoia SE 33.25 84.50 0.016 feet

AVERAGE 0.067 feet

26

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 flood

elevations and delineations of the 1- and 0.2-percent-annual-chance 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.

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 community. For

streams studied by detailed methods, streams restudied by detailed methods, and

redelineated streams, the 1- and 0.2-percent-annual-chance floodplain

boundaries have been delineated using the flood elevations determined at each

cross section. Between cross sections, the boundaries were interpolated using

digital elevation models of the topographic LiDAR data (Photo Science, 2009).

For streams studied by limited detailed or approximate method, the

1-percent-annual-chance floodplain boundaries have been delineated using the

flood elevations determined at each cross section. Between cross sections, the

boundaries were interpolated using digital elevation models of the topographic

LiDAR data (Photo Science, 2009).

27

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 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, only the 1-percent-annual-

chance floodplain boundary is shown on the FIRM (Exhibit 2).

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 6). In cases where the floodway and 1-percent-annual-chance floodplain

boundaries are either close together or collinear, only the floodway boundary has

been 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 of the 1-percent-annual-chance flood more than 1

28

foot at any point. Typical relationships between the floodway and the floodway

fringe and their significance to floodplain development are shown in Figure 1.

Figure1 - Floodway Schematic

29

FLOODING SOURCE FLOODWAY 1-PERCENT-ANNUAL-CHANCE-FLOOD

WATER SURFACE ELEVATION

CROSS SECTION DISTANCE1

WIDTH (FEET)

SECTION AREA

(SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NAVD)

WITHOUT FLOODWAY (FEET NAVD)

WITH FLOODWAY (FEET NAVD)

INCREASE (FEET)

CHANDLERS CREEK

A 3,570 200 892 2.7 791.6 791.6 792.6 1.0

B 6,070 57 344 7.0 798.6 798.6 799.6 1.0

C 9,570 224 813 3.0 804.9 804.9 805.6 0.7

D 12,450 284 945 2.5 814.7 814.7 815.4 0.7

E 14,170 577 510 3.5 822.8 822.8 822.8 0.0

F 16,220 348 953 1.9 827.9 827.9 828.8 0.9

G 17,200 205 487 3.7 832.2 832.2 833.0 0.8

H 18,090 170 608 2.9 837.2 837.2 838.1 0.9

I 19,490 202 828 2.2 840.8 840.8 841.8 1.0

J 21,100 74 205 7.2 846.6 846.6 847.0 0.4

1 Feet above confluence with White Oak Creek

TA

BL

E 6

FEDERAL EMERGENCY MANAGEMENT AGENCY

COWETA COUNTY, GA

AND INCORPORATED AREAS

FLOODWAY DATA

CHANDLERS CREEK

30

FLOODING SOURCE FLOODWAY

BASE FLOOD


(FEET NAVD)


WIDTH2

(FEET)

SECTION

AREA

(SQUARE

FEET)

MEAN

VELOCITY

(FEET PER

SECOND)

REGULATORY WITHOUT

FLOODWAY

WITH

FLOODWAY INCREASE

CHATTAHOOCHEE RIVER

AF 47.70 585\0 10,895 6.1 686.7 686.7 687.3 0.6 AG 48.32 778\600 12,954 5.1 688.1 688.1 688.7 0.6 AH 50.00 663\140 11,392 5.8 690.9 690.9 691.5 0.6 AI 52.15 2202\931 25,737 2.6 694.8 694.8 695.4 0.6 AJ 52.94 1,465\583 18,740 3.5 695.8 695.8 696.3 0.5 AK 53.67 1,065\910 13,148 5.1 697.1 697.1 697.6 0.5 AL 54.52 687\201 13,057 4.9 699.2 699.2 699.6 0.4 AM 54.91 501\321 7,908 8.1 699.3 699.3 699.7 0.4 AN 55.55 985\159 12,817 5.0 702.3 702.3 702.7 0.4 AO 56.77 492\314 10,521 6.1 706.3 706.3 706.8 0.5 AP 57.30 646\116 11,688 5.5 707.6 707.6 708.1 0.5 AQ 57.90 665\300 11,372 5.6 709.0 709.0 709.4 0.4 AR 58.08 853\260 15,162 4.2 711.1 711.1 711.7 0.6 AS 58.36 760\345 17,339 3.7 711.7 711.7 712.2 0.5 AT 58.62 901\406 16,606 3.9 712.5 712.5 712.9 0.4 AU 59.45 1,160\746 20,761 3.1 713.9 713.9 714.4 0.5 AV 61.77 1,248\993 20,548 3.0 716.0 716.0 716.6 0.6

1 Miles from West Point Dam

2 Total Width\Width Inside the County

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COWETA COUNTY, GA


FLOODWAY DATA

CHATTAHOOCHEE RIVER

31



CROSS SECTION DISTANCE1 WIDTH

(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

LAKE AMLAJACK

CREEK

A 1,620 57 257 6.8 835.8 835.8 836.8 1.0

B 4,120 105 351 5.0 844.1 844.1 845.1 1.0

C 5,070 864 7,863 0.2 855.6 855.6 856.6 1.0

D 5,700 1,551 9,573 0.1 855.6 855.6 856.6 1.0

E 6,580 388 461 2.5 856.5 856.5 856.7 0.2

F 8,700 96 150 6.4 870.6 870.6 870.6 0.0

LAKE SUMMERGROVE

BRANCH

A 690 57 252 7.5 797.7 797.7 798.7 1.0

B 8,090 41 247 7.0 827.6 827.6 828.0 0.4

C 9,190 92 377 4.6 831.1 831.1 831.6 0.5

D 10,490 164 449 2.6 835.4 835.4 836.3 0.9

E 11,600 118 260 4.2 839.1 839.1 839.3 0.2


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COWETA COUNTY, GA


FLOODWAY DATA

LAKE AMLAJACK CREEK - LAKE SUMMERGROVE BRANCH

32



CROSS SECTION DISTANCE1 WIDTH2

(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

LINE CREEK

A 66,450 1,320/150 9,640 2.1 749.8 749.8 750.8 1.0

B 68,130 1,560/1,420 14,640 1.4 751.3 751.3 752.3 1.0

C 68,670 1,650/1,350 15,740 1.3 751.6 751.6 752.6 1.0

D 72,250 1,230/800 11,080 1.9 754.4 754.4 755.4 1.0

E 74,050 1,220/1,020 12,120 1.4 755.7 755.7 756.7 1.0

F 77,650 1,780/570 19,010 0.9 757.8 757.8 758.8 1.0

G 79,250 500/260 5,010 3.3 759.1 759.1 759.6 0.5

H 80,770 910/120 7,590 2.2 760.4 760.4 761.3 0.9

I 83,050 370/240 4,680 3.5 763.8 763.8 764.2 0.4

J 84,400 1,410/470 19,530 0.8 764.7 764.7 765.2 0.5

K 87,010 730/240 8,660 1.9 765.1 765.1 765.8 0.7

L 90,940 1,310/1,130 11,790 1.4 766.8 766.8 767.5 0.7

M 91,530 1,340/1,000 12,850 1.3 767.0 767.0 767.6 0.6

N 91,860 590/500 3,970 4.3 767.3 767.3 767.3 0.0

O 93,820 680/200 7,510 2.3 771.8 771.8 772.7 0.9

P 95,100 470/190 7,360 2.3 773.1 773.1 774.1 1.0

Q 104,870 640/310 7,730 1.3 774.2 774.2 775.2 1.0

R 106,220 460/270 6,020 1.7 785.0 785.0 785.0 0.0

S 108,700 620/450 7,190 1.4 785.9 785.9 785.9 0.0

T 110,700 230/130 1,700 6.0 788.5 788.5 788.5 0.0

U 112,260 190/110 1,230 8.3 798.1 798.1 798.1 0.0

1 Feet above mouth 2 Total width/Width within Coweta County

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COWETA COUNTY, GA


FLOODWAY DATA

LINE CREEK

33




WIDTH2

(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

LINE CREEK

(CONTINUED)

V 115,250 210/150 2,620 3.9 816.0 816.0 816.8 0.8

W 116,770 200/60 2,820 3.6 817.8 817.8 818.8 1.0

X 117,250 450/45 2,220 4.6 818.4 818.4 818.4 0.0

Y 117,720 190/65 1,700 6.0 820.5 820.5 820.5 0.0

Z 118,120 210/135 3,110 3.3 826.9 826.9 827.2 0.3

AA 122,270 1,200/1,000 8,420 1.2 827.2 827.2 827.5 0.3

AB 123,790 1,270/900 9,990 1.0 827.5 827.5 827.9 0.4

AC 125,630 1,060/1,030 9,500 1.1 828.0 828.0 828.8 0.8

AD 128,030 790/500 6,720 1.3 828.9 828.9 829.7 0.8

AE 129,530 560/400 3,910 2.2 830.1 830.1 830.9 0.8

AF 130,930 370/200 3,780 2.2 832.0 832.0 832.8 0.8

AG 132,280 930/150 6,310 1.3 833.3 833.3 834.1 0.8

AH 134,580 280/180 1,990 4.2 836.4 836.4 837.2 0.8

AI 136,580 1,420/910 9,240 0.9 838.7 838.7 839.6 0.9

AJ 139,190 440/180 1,680 4.8 843.0 843.0 843.0 0.0

AK 141,370 200/100 2,240 3.6 850.1 850.1 850.9 0.8

AL 143,970 630/0 6,410 1.3 851.9 851.9 852.7 0.8

AM 145,870 160/100 1,900 4.0 852.7 852.7 853.5 0.8

AN 147,470 320/300 2,550 3.0 855.1 855.1 855.7 0.6

1 Feet above mouth

2 Total width/Width within Coweta County

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COWETA COUNTY, GA


FLOODWAY DATA

LINE CREEK

34




WIDTH2

(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

LINE CREEK

(CONTINUED)

AO 148,800 390/250 4,170 1.8 856.3 856.3 857.0 0.7

AP 150,730 500/370 2,710 2.8 857.9 857.9 858.6 0.7

AQ 152,160 740/150 5,520 1.3 859.8 859.8 860.6 0.8

AR 154,010 660/230 3,800 1.9 861.2 861.2 862.0 0.8

AS 156,410 380/180 3,080 2.2 864.2 864.2 865.1 0.9

AT 157,870 330/0 2,760 2.5 866.1 866.1 867.0 0.9

AU 159,250 600/410 5,170 1.3 867.4 867.4 868.3 0.9

AV 160,730 280/140 2,610 1.6 868.2 868.2 869.0 0.8

AW 162,830 200/160 1,580 2.4 869.7 869.7 870.5 0.8

AX 165,130 500/410 3,980 1.0 871.1 871.1 871.9 0.8

1 Feet above mouth

2 Total width/Width within Coweta County

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COWETA COUNTY, GA


FLOODWAY DATA

LINE CREEK

35




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

LITTLE CREEK

A 2,310 80 560 4.4 830.0 829.82

830.8 1.0

B 3,913 110 510 4.7 834.2 834.2 835.1 0.9

C 5,283 360 1,500 1.6 838.7 838.7 839.7 1.0

D 7,423 150 550 4.2 845.4 845.4 845.9 0.5

E 9,203 310 1,260 1.9 853.2 853.2 853.5 0.3

F 10,743 300 850 2.2 858.2 858.2 858.5 0.3

G 13,050 400 1,030 1.8 868.6 868.6 868.9 0.3

H 15,243 280 320 5.0 879.9 879.9 880.0 0.1

I 16,735 110 240 6.7 888.3 888.3 888.3 0.0

J 19,110 270 350 3.8 904.5 904.5 904.5 0.0

K 20,555 150 280 3.4 912.0 912.0 912.0 0.0

L 22,613 160 210 4.5 928.3 928.3 928.3 0.0

1 Feet above confluence with Line Creek

2 Elevation computed without consideration of backwater effects from Line Creek

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COWETA COUNTY, GA


FLOODWAY DATA

LITTLE CREEK

36




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

LITTLE WAHOO CREEK

A 1,220 153 709 3.2 799.9

799.9 800.6 0.7

B 3,143 358 1,096 2.1 804.4 804.4 805.0 0.6

C 4,594 283 1,050 2.2 808.8 808.8 809.6 0.8

D 6,320 86 364 6.0 814.2 814.2 814.9 0.7

E 8,558 190 692 3.1 821.2 821.2 821.6 0.4

F 10,712 133 526 4.1 828.0 828.0 828.9 0.9

G 11,780 60 291 7.4 832.0 832.0 832.5 0.5

H 12,531 70 408 5.3 835.5 835.5 835.5 0.0

I 13,445 200 881 2.4 838.7 838.7 839.7 1.0

J 14,454 274 800 2.7 841.4 841.4 842.2 0.8

K 16,751 148 467 4.6 851.0 851.0 851.5 0.5

L 17,695 123 586 3.4 855.5 855.5 856.0 0.5

M 18,423 108 537 3.7 859.3 859.3 859.9 0.6

N 19,066 165 546 3.7 863.0 863.0 863.1 0.1

O 20,511 40 265 7.5 869.1 869.1 869.5 0.4

1 Feet above confluence with Wahoo Creek

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COWETA COUNTY, GA


FLOODWAY DATA

LITTLE WAHOO CREEK

37

FLOODING SOURCE FLOODWAY 1-PERCENT-ANNUAL-CHANCE-FLOOD WATER SURFACE ELEVATION


WIDTH (FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

MINERAL SPRING

BRANCH

A 60 250 1,010 2.7 753.2 753.2 754.2 1.0

B 950 90 280 9.6 759.5 759.5 759.5 0.0

C 2,100 80 340 8.1 777.3 777.3 777.3 0.0

D 3,480 270 1,580 1.7 783.8 783.8 784.8 1.0

E 4,980 310 540 4.1 788.7 788.7 788.7 0.0

F 6,230 120 610 3.6 795.7 795.7 796.3 0.6

G 6,840 210 900 2.5 797.4 797.4 798.1 0.7

H 7,750 100 400 4.9 800.3 800.3 801.0 0.7

I 8,380 110 500 3.9 804.6 804.6 805.5 0.9

J 9,690 160 720 2.7 810.7 810.7 811.6 0.9

K 10,390 170 430 4.5 813.6 813.6 814.2 0.6

L 11,559 110 350 5.5 824.6 824.6 824.9 0.3

M 13,830 150 290 4.6 837.0 837.0 837.0 0.0

N 15,244 240 420 3.2 852.1 852.1 852.1 0.0

O 16,648 110 180 6.1 865.4 865.4 865.4 0.0

P 17,708 150 210 5.2 879.7 879.7 879.7 0.0

Q 18,381 70 200 5.6 885.2 885.2 885.2 0.0

R 18,861 70 100 11.2 889.3 889.3 889.3 0.0

S 19,629 70 80 6.5 894.2 894.2 894.2 0.0

T 21,014 70 45 7.7 909.9 909.9 909.9 0.0

1 Feet above confluence with Mountain Creek

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COWETA COUNTY, GA


FLOODWAY DATA

MINERAL SPRING BRANCH

38



CROSS SECTION DISTANCE WIDTH (FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

PARADISE LAKES

BRANCH

A 1,7901 123 483 5.1 788.1 785.0

2 786.0 1.0

B 3,4501 111 543 4.6 791.2 791.2 792.2 1.0

C 5,5701 76 245 8.9 795.9 795.9 795.9 0.0

D 7,3901 191 490 4.5 803.5 803.5 803.5 0.0

E 9,4901 41 251 8.6 808.9 808.9 809.6 0.7

PEEKS CREEK

A 1,7503 120 750 5.0 868.9 868.9 869.8 0.9

B 4,4303 200 1,480 2.5 877.5 877.5 878.5 1.0

C 5,7803 550 3,850 1.0 879.3 879.3 880.3 1.0

D 7,3403 480 1,980 1.6 880.2 880.2 881.1 0.9

E 9,8703 240 1,320 2.3 885.6 885.6 886.5 0.9

F 11,8603 260 980 3.1 892.2 892.2 893.1 0.9


2 Elevation computed without consideration of backwater effects from White Oak Creek


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COWETA COUNTY, GA


FLOODWAY DATA

PARADISE LAKES BRANCH-PEEKS CREEK

39




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

PERSIMMON CREEK

A 1,100 180 930 2.4 865.8 865.8 866.8 1.0

B 2,550 4302 1,960 1.1 867.3 867.3 868.3 1.0

C 4,150 170 480 4.6 869.4 869.4 869.9 0.5

D 5,650 220 900 2.2 876.9 876.9 877.5 0.6

E 7,150 160 430 4.6 885.6 885.6 885.6 0.0

F 8,650 210 1,430 1.0 893.8 893.8 894.4 0.6

G 9,260 290 2,020 0.7 896.8 896.8 897.5 0.7


2 Includes combined floodway width with Tributary 1 to Persimmon Creek

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COWETA COUNTY, GA


FLOODWAY DATA

PERSIMMON CREEK

40




WIDTH (FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

SANDY CREEK

A 18,370 210 1,260 3.7 712.4 712.4 713.2 0.8

B 18,870 200 1,210 3.8 713.7 713.7 714.6 0.9

C 19,450 400 1,630 2.8 715.9 715.9 716.8 0.9

D 19,930 460 2,130 2.2 717.7 717.7 718.5 0.8

E 21,290 130 770 5.7 721.2 721.2 722.0 0.8

F 21,850 280 1,660 2.6 723.3 723.3 724.3 1.0

G 22,540 280 1,680 2.6 724.7 724.7 725.7 1.0

H 23,230 640 3,630 0.8 725.4 725.4 726.4 1.0

I 24,100 240 1,020 3.0 725.9 725.9 726.8 0.9

J 32,930 320 640 4.2 752.5 752.5 752.5 0.0

K 34,070 210 750 3.3 760.4 760.4 760.4 0.0

L 34,780 210 1,020 2.4 762.9 762.9 763.3 0.4

M 35,540 240 640 3.9 765.0 765.0 766.0 1.0

N 35,990 120 580 4.3 767.8 767.8 768.5 0.7

O 36,300 290 1,490 1.7 769.6 769.6 770.1 0.5

P 37,800 200 1,260 1.9 771.9 771.9 772.9 1.0

Q 37,920 144 510 4.4 772.6 772.6 773.4 0.8

R 39,540 170 690 3.2 781.2 781.2 781.2 0.0

S 40,900 160 1,160 1.9 783.7 783.7 784.1 0.4

T 43,130 80 50 8.2 791.5 791.5 791.5 0.0


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COWETA COUNTY, GA


FLOODWAY DATA

SANDY CREEK

41




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

SANDY CREEK

(CONTINUED)

U 45,560 160 660 2.7 807.1 807.1 807.1 0.0

V 47,390 160 370 4.2 814.6 814.6 814.6 0.0

W 48,590 20 70 10.8 821.0 821.0 821.0 0.0

X 49,590 60 150 4.9 834.2 834.2 834.2 0.0

Y 50,250 40 120 6.4 841.7 841.7 841.7 0.0

Z 51,050 70 120 6.5 858.6 858.6 858.6 0.0

AA 52,070 20 70 7.6 867.4 867.4 867.4 0.0

AB 53,030 100 140 3.7 885.9 885.9 885.9 0.0

AC 53,580 110 140 1.9 896.8 896.8 896.8 0.0

AD 54,040 20 50 5.7 901.1 901.1 901.1 0.0


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COWETA COUNTY, GA


FLOODWAY DATA

SANDY CREEK

42




WIDTH (FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

SHOAL CREEK

A 3,650 310 1,980 3.7 774.5 774.5 775.3 0.8

B 4,790 320 2,320 3.1 778.5 778.5 779.4 0.9

C 6,130 660 4,070 1.8 781.3 781.3 782.2 0.9

D 8,830 260 2,100 3.4 785.5 785.5 786.3 0.8

E 10,230 230 1,750 4.0 788.8 788.8 789.6 0.8

F 11,900 170 1,900 3.6 792.2 792.2 793.1 0.9

G 13,460 250 2,170 3.2 794.5 794.5 795.3 0.8

H 15,400 220 2,000 3.5 797.4 797.4 798.2 0.8

I 17,300 1,110 8,020 0.7 798.1 798.1 798.9 0.8

J 18,260 380 2,370 2.5 798.1 798.1 798.9 0.8

K 19,900 210 750 7.7 800.0 800.0 800.0 0.0

L 22,330 940 4,970 1.2 806.2 806.2 806.5 0.3

M 23,600 150 530 10.9 807.8 807.8 807.8 0.0

N 26,300 440 2,730 2.0 817.9 817.9 818.4 0.5

O 28,970 360 2,140 2.5 822.2 822.2 823.1 0.9

P 31,130 380 1,830 2.7 828.3 828.3 829.2 0.9

Q 33,630 410 2,230 2.2 835.1 835.1 836.0 0.9

R 35,900 380 3,050 1.5 837.9 837.9 838.7 0.8

S 38,400 340 1,100 3.4 841.5 841.5 842.2 0.7

T 39,830 410 2,070 1.8 847.3 847.3 848.2 0.9

U 41,200 100 410 8.3 852.7 852.7 852.7 0.0


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COWETA COUNTY, GA


FLOODWAY DATA

SHOAL CREEK

43




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

SHOAL CREEK

(CONTINUED)

V 43,790 210 1,410 2.1 862.9 862.9 863.5 0.6

W 45,440 250 1,020 2.5 865.4 865.4 866.2 0.8

X 47,080 290 1,230 1.8 867.7 867.7 868.6 0.9

Y 49,000 250 500 4.3 875.1 875.1 875.1 0.0

Z 51,000 330 1,490 1.3 881.0 881.0 881.6 0.6


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COWETA COUNTY, GA


FLOODWAY DATA

SHOAL CREEK

44




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

SNAKE CREEK

A 2,014 257 719 3.2 799.2

798.32

799.1 0.8

B 3,645 360 1,047 2.2 804.4 804.4 805.3 0.9

C 5,764 252 809 2.8 814.6 814.6 814.6 0.0

D 9,469 184 531 4.4 829.4 829.4 830.0 0.6

E 12,276 49 298 7.8 843.1 843.1 843.6 0.5

F 12,477 85 818 2.8 848.1 848.1 848.6 0.5

G 13,855 58 277 7.0 851.9 851.9 851.9 0.0

H 14,132 135 1,240 2.2 863.7 863.7 863.7 0.0

I 15,022 205 1,214 2.3 864.1 864.1 864.1 0.0

J 15,595 169 1,445 2.0 869.1 869.1 869.1 0.0

K 16,430 129 994 2.8 875.2 875.2 875.5 0.3

L 17,383 117 617 2.8 880.5 880.5 881.0 0.5

M 18,110 176 971 1.8 891.5 891.5 891.6 0.1

N 18,462 107 369 2.7 891.5 891.5 891.6 0.1

O 18,979 68 172 5.7 898.1 898.1 898.2 0.1

P 19,314 71 263 3.7 902.8

902.8

902.8 0.0

Q 19,462 105 401 2.5 907.4 907.4 908.0 0.6

R 20,089 27 104 9.4 909.2 909.2 909.3 0.1

S 20,522 104 177 5.5 917.3 917.3 917.3 0.0

T 21,157 20 87 11.2 927.1 927.1 927.1 0.0


2 Elevation computed without consideration of backwater effects from Wahoo Creek

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COWETA COUNTY, GA


FLOODWAY DATA

SNAKE CREEK

45



CROSS SECTION DISTANCE WIDTH

(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 1 TO LINE

CREEK

A 7001 1,300

2 450 4.0 773.4 764.2

3 765.2 1.0

B 2,4701 150 600 3.0 773.4 771.0

4 772.0 1.0

C 3,8501 220 920 1.8 775.5 775.5 776.5 1.0

D 5,9801 110 340 4.2 784.4 784.4 785.1 0.7

E 7,3001 130 490 2.9 789.7 789.7 790.5 0.8

TRIBUTARY 1 TO

MINERAL SPRING

BRANCH

A 5005 370 290 4.0 785.1 785.1 785.1 0.0

B 2,0805 250 270 3.2 797.0 797.0 797.0 0.0

C 3,7505 100 90 9.4 810.5 810.5 810.5 0.0

D 4,4505 90 120 6.8 821.9 821.9 821.9 0.0

E 6,8705 70 80 5.6 857.5 857.5 857.5 0.0

F 8,9305 60 60 7.6 893.3 893.3 893.3 0.0


5 Feet above confluence with Mineral Spring Branch

2 Includes combined floodway width with Line Creek

3 Elevation computed without consideration of flooding controlled by Line Creek

4 Elevation computed without consideration of backwater effects from Line Creek

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COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 1 TO LINE CREEK-

TRIBUTARY 1 TO MINERAL SPRING BRANCH

46




SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 1 TO

PERSIMMON CREEK

A 8651 430

2 180 3.4 867.3 864.0

3 865.0

1.0

B 3,0601 130 170 3.7 890.4 890.4 890.4 0.0

C 5,3901 110 180 3.4 912.7 912.7 912.7 0.0

TRIBUTARY 1 TO

SANDY CREEK

A 504 240 510 2.1 718.3 715.6

5 716.6 1.0

B 1,5804 150 530 2.0 724.4 724.4 725.4 1.0

C 2,8004 110 240 4.0 733.4 733.4 733.7 0.3

1 Feet above confluence with Persimmon Creek

2 Includes combined floodway width with Persimmon Creek

3 Elevation computed without consideration of flooding controlled by Persimmon Creek

4 Feet above confluence with Sandy Creek

5 Elevation computed without consideration of backwater effects from Sandy Creek

TA

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E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 1 TO PERSIMMON CREEK-

TRIBUTARY 1 TO SANDY CREEK

47




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 1 TO

SHOAL CREEK

A 1001 400 1,210 2.6 797.8 791.8

2 792.8

1.0

B 2,3301 120 740 4.1 799.9 799.9 800.9 1.0

1 Feet above confluence with Shoal Creek

2 Elevation computed without consideration of backwater effects from Shoal Creek

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 1 TO SHOAL CREEK

48




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 1 TO

SNAKE CREEK

A 2651

31 36 5.3 875.3

873.22

873.2 0.0

B 5311

25 91 2.1 880.5 880.5 880.5 0.0

C 9341

21 37 5.2 888.5 888.5 889.0 0.5

D 1,2971

24 63 3.0 893.1 893.1 893.8 0.7

TRIBUTARY 1 TO

TURKEY CREEK

A 1,5403 37 277 4.6 876.3 876.3 877.3 1.0

B 1,6403 663 5,403 0.2 896.5 896.5 896.5 0.0

C 4,3203 330 2,033 0.6 896.5 896.5 896.5 0.0

1 Feet above confluence with Snake Creek

2 Elevation computed without consideration of backwater effects from Snake Creek

3 Feet above confluence with Turkey Creek

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 1 TO SNAKE CREEK-

TRIBUTARY 1 TO TURKEY CREEK

49




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 1 TO

WAHOO CREEK

A 386 36 79 6.7 842.1 838.52

838.7 0.2

B 708 87 387 1.4 843.1 843.1 843.5 0.4

C 1,090 248 940 0.9 857.9 857.9 857.9 0.0

D 2,064 204 238 3.4 858.2 858.2 858.2 0.0

E 3,434 30 129 6.2 872.0 872.0 872.4 0.4

F 3,902 241 1,780 0.5 889.3 889.3 889.3 0.0

G 4,239 90 222 2.6 889.4 889.4 889.4 0.0

H 5,065 15 68 8.4 907.2 907.2 907.3 0.1

I 5,427 28 171 3.3 917.4 917.4 918.4 1.0

J 5,943 19 58 10.1 941.0 941.0 941.5 0.5

1

Feet above confluence with Wahoo Creek


TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 1 TO WAHOO CREEK

50




WIDTH (FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 1 TO

WHITE OAK CREEK

A 1,300 94 366 5.2 804.1 804.1 805.1 1.0

B 2,410 79 285 6.7 808.4 808.4 809.3 0.9

C 3,210 131 366 5.2 811.2 811.2 812.2 1.0

D 4,030 77 231 8.2 814.8 814.8 815.5 0.7

E 5,110 95 362 5.2 820.5 820.5 821.4 0.9

F 6,110 196 795 2.4 823.8 823.8 824.5 0.7

G 7,030 72 236 8.1 831.5 831.5 831.5 0.0

H 8,920 27 159 6.6 842.8 842.8 843.1 0.3


TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 1 TO WHITE OAK CREEK

51




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 2 TO

MINERAL SPRING

BRANCH

A 210 280 370 2.7 830.2 825.32

825.3

0.0

B 2,180 100 180 5.6 836.4 836.4 836.4 0.0

C 3,630 60 100 7.7 847.9 847.9 847.9 0.0

D 4,430 50 120 6.3 856.0 856.0 856.0 0.0

E 5,100 80 80 9.8 866.8 866.8 866.8 0.0

F 5,920 70 35 7.6 879.0 879.0 879.0 0.0

G 6,320 70 45 5.8 887.7 887.7 887.7 0.0

H 6,690 70 30 8.2 895.9 895.9 895.9 0.0

I 7,300 70 30 8.0 916.3 916.3 916.3 0.0

1 Feet above confluence with Mineral Spring Branch

2 Elevation computed without consideration of backwater effects from Mineral Spring Branch

TA

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E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 2 TO MINERAL SPRING BRANCH

52




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 2 TO

SANDY CREEK

A 2501 120 200 5.2 795.3 795.3 795.3 0.0

B 2,4501 60 100 3.6 813.2 813.2 813.2 0.0

C 4,3101 20 50 7.9 855.9 855.9 855.9 0.0

TRIBUTARY 2 TO

SHOAL CREEK

A 7002 370 1,260 2.0 838.7 834.6

3 835.5

0.9

B 2,9202 170 660 3.5 843.2 843.2 844.1 0.9

C 4,7002 140 660 3.5 848.6 848.6 849.6 1.0

D 6,2002 170 420 4.5 853.4 853.4 854.1 0.7

E 8,2202 270 400 4.7 860.3 860.3 860.4 0.1

1 Feet above confluence with Tributary 3 to Sandy Creek 2 Feet above confluence with Shoal Creek


TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 2 TO SANDY CREEK-

TRIBUTARY 2 TO SHOAL CREEK

53




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 2 TO

SNAKE CREEK

A 315

16 55 11.0 891.5 890.42

890.4 0.0

B 574

20 93 6.4 897.6 897.6 898.3 0.7

C 864

27 270 2.2 908.6 908.6 909.0 0.4

D 1,224

71 370 1.6 918.1 918.1 918.1 0.0

E 1,395

37 274 2.2 918.2 918.2 918.2 0.0

F 1,877

12 53 11.4 927.5 927.5 927.6 0.1

1 Feet above confluence with Snake Creek

2 Elevation computed without consideration of backwater effects from Snake Creek

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 2 TO SNAKE CREEK

54




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 2 TO

WAHOO CREEK

A 982 144 274 4.0 861.3 861.3 861.3 0.0

B 1,553 39 231 4.8 864.2 864.2 864.5 0.3

C 2,142 60 330 3.3 867.9 867.9 868.1 0.2

D 2,847 60 229 2.4 868.4 868.4 869.3 0.9

E 3,151 267 682 1.7 871.3 871.3 871.4 0.1

F 3,850 34 118 5.6 872.4 872.4 872.4 0.0

G 4,059 31 120 5.5 876.5 876.5 876.5 0.0

H 4,756 32 156 3.5 880.8 880.8 881.4 0.6

I 4,996 38 337 1.6 891.8 891.8 891.8 0.0

J 5,472 41 428 1.3 899.9 899.9 899.9 0.0

K 6,168 61 219 2.5 903.7 903.7 903.8 0.1

L 6,334 59 456 1.2 908.7 908.7 909.5 0.8

M 6,690 40 151 3.7 909.5 909.5 910.4 0.9

N 7,377 31 103 5.4 920.4 920.4 921.0 0.6


TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA


55




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 3 TO

SANDY CREEK

A 6,600 260 880 3.1 740.0 740.0 740.7 0.7

B 8,300 160 940 2.9 744.7 744.7 745.5 0.8

C 9,700 460 770 3.5 748.8 748.8 749.1 0.3

D 12,000 260 630 4.3 758.1 758.1 758.1 0.0

E 14,400 460 870 2.8 766.0 766.0 766.1 0.1

F 16,100 290 580 4.1 777.9 777.9 777.9 0.0

G 17,640 310 1,350 1.8 784.3 784.3 784.7 0.4

H 19,900 100 470 4.5 790.6 790.6 790.9 0.3

I 22,500 210 310 5.7 804.6 804.6 804.6 0.0

J 27,680 160 490 2.1 832.4 832.4 832.4 0.0

K 29,180 70 170 6.2 836.1 836.1 836.1 0.0

L 30,630 180 360 2.8 848.0 848.0 848.0 0.0

1 Feet above confluence with Sandy Creek

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 3 TO SANDY CREEK

56




SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 3 TO

SHOAL CREEK

A 4751 220 420 2.2 854.0 853.4

2 853.4 0.0

B 2,2951 170 484 1.9 859.9 859.9 859.9 0.0

C 3,3151 200 240 3.9 871.0 871.0 871.0 0.0

D 5,0151 220 350 1.3 883.8 883.8 883.8 0.0

E 6,7451 25 50 8.5 896.4 896.4 896.4 0.0

TRIBUTARY 3 TO

WAHOO CREEK

A 2273

71 430 0.5 868.2 868.2 868.4 0.2

B 5303

176 833 0.8 870.6 870.6 870.9 0.3

C 1,2923

61 118 1.6 870.9 870.9 871.0 0.1

D 1,5463

70 50 3.7 876.2 876.2 876.2 0.0

E 2,0723

48 191 1.0 885.4 885.4 885.4 0.0

1 Feet above confluence with Shoal Creek


3 Feet above confluence with Tributary 2 to Wahoo Creek

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 3 TO SHOAL CREEK-


57




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 4 TO

WAHOO CREEK

A 3001

96 147 1.5 871.0 871.0 871.0 0.0

B 6841

41 51 4.3 873.2 873.2 873.2 0.0

C 7711

25 38 5.7 876.7 876.7 876.9 0.2

D 9671

203 829 0.3 884.7 884.7 884.7 0.0

TRIBUTARY 5 TO

WAHOO CREEK

A 2802

22 37 1.7 879.1 879.1 879.4 0.3

B 5792

16 12 5.0 887.9 887.9 888.0 0.1

TRIBUTARY 6 TO

WAHOO CREEK

A 2442

7 13 5.1 881.4 881.4 882.0 0.6

B 5922

132 862 0.1 896.7 896.7 896.7 0.0



TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 4 TO WAHOO CREEK –

TRIBUTARY 5 TO WAHOO CREEK –


58




WIDTH (FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 7 TO

WAHOO CREEK

A 464 27 112 9.7 859.7 855.62

856.0 0.4

B 647 123 1,159 0.9 864.5 864.5 865.3 0.8

C 1,540 63 330 3.3 865.1 865.1 865.7 0.6

D 1,718 245 1,180 0.9 881.2 881.2 881.2 0.0

E 2,392 58 143 7.6 881.7 881.7 881.7 0.0

F 2,453 75 161 6.2 887.0 887.0 887.0 0.0

G 2,973 27 97 10.3 890.7 890.7 890.7 0.0

H 3,426 30 106 9.3 898.3 898.3 898.5 0.2

TRIBUTARY 8 TO

WAHOO CREEK

A 668 50 117 4.3 865.6 865.6 865.8 0.2

B 1,132 23 121 4.1 870.1 870.1 870.2 0.1

C 1,785 30 70 7.1 891.4 891.4 892.1 0.7

D 2,160 22 127 3.9 898.6 898.6 899.3 0.7

TRIBUTARY 9 TO

WAHOO CREEK

A 672 29 60 6.3 875.7 875.7 875.7 0.0

B 1,334 50 71 5.4 883.0 883.0 883.2 0.2

C 1,815 42 59 6.5 904.7 904.7 905.1 0.4



TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 7 TO WAHOO CREEK-



59




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 10 TO

WAHOO CREEK

A 302 29 49 5.5 883.1 883.1 883.2 0.1

B 1,106 119 90 3.0 896.5 896.5 896.5 0.0

C 2,326 21 50 5.3 914.9 914.9 915.2 0.3

D 3,321 19 42 6.3 934.3 934.3 934.6 0.3

TRIBUTARY 11 TO

WAHOO CREEK

A 343 229 559 2.1 881.1 881.1 881.1 0.0

B 719 69 163 7.2 882.6 882.6 882.8 0.2

C 986 75 247 4.8 888.3 888.3 888.3 0.0

D 1,240 70 410 2.9 894.0 894.0 894.6 0.6

E 1,676 58 252 4.7 894.6 894.6 895.3 0.7

F 2,601 59 257 4.6 905.9 905.9 906.1 0.2


TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TRIBUTARY 10 TO WAHOO CREEK-


60




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TRIBUTARY 12 TO

WAHOO CREEK

A 507 58 128 6.5 898.0 898.0 898.2 0.2

B 1,017 30 89 9.4 903.9 903.9 903.9 0.0

C 1,712 21 77 10.9 911.9 911.9 911.9 0.0

D 1,934 91 196 4.3 918.3 918.3 918.8 0.5

E 2,502 33 126 6.6 924.6 924.6 925.0 0.4

F 3,000 48 167 5.0 935.4 935.4 935.4 0.0

G 3,215 19 187 4.5 940.3 940.3 941.2 0.9

H 3,634 33 122 6.8 944.1 944.1 944.9 0.8


TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA


61




WIDTH (FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

TURKEY CREEK

A 2,700 67 339 9.2 791.1 790.32 791.1 0.8

B 4,510 107 371 8.4 797.0 797.0 797.1 0.1

C 7,930 145 499 6.3 805.9 805.9 806.2 0.3

D 8,005 103 314 10.0 813.2 813.2 813.2 0.0

E 8,030 965 3,310 0.9 814.9 814.9 814.9 0.0

F 10,400 112 319 6.8 816.2 816.2 816.3 0.1

G 11,720 216 739 3.0 820.9 820.9 821.5 0.6

H 14,400 70 330 6.1 831.1 831.1 831.1 0.0

I 16,730 34 191 10.5 847.0 847.0 847.1 0.1

J 18,640 71 225 8.9 863.8 863.8 863.8 0.0

K 20,550 383 1,567 0.9 870.1 870.1 871.1 1.0

L 21,230 153 493 2.8 870.3 870.3 871.3 1.0

M 22,210 129 300 4.7 872.9 872.9 873.2 0.3

N 22,290 89 206 6.8 874.3 874.3 874.3 0.0

O 23,370 28 128 11.0 882.5 882.5 882.5 0.0

P 24,490 63 203 6.9 889.5 889.5 889.5 0.0


2 Elevation computed without consideration of backwater effects from White Oak Creek

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

TURKEY CREEK

62




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

WAHOO CREEK

A 2,698 766 7,178 1.3 700.6 698.32

698.3 0.0

B 3,641 343 2,697 3.4 700.6 698.32

698.3 0.0

C 6,823 165 1,468 6.2 702.1 702.1 702.9 0.8

D 8,904 122 1,128 8.0 715.0 715.0 715.3 0.3

E 10,680 133 1,568 5.8 719.5 719.5 720.0 0.5

F 13,544 156 1,850 4.8 722.6 722.6 723.0 0.4

G 15,103 277 3,916 2.3 725.9 725.9 726.5 0.6

H 17,548 1,012 11,747 0.8 726.9 726.9 727.6 0.7

I 19,148 510 4,513 2.0 727.0 727.0 727.7 0.7

J 19,558 573 4,887 1.8 727.2 727.2 727.9 0.7

K 21,753 988 6,376 1.4 729.0 729.0 729.8 0.8

L 22,893 697 4,837 1.8 731.6 731.6 732.2 0.6

M 24,791 551 3,153 2.8 733.0 733.0 733.5 0.5

N 27,109 187 1,050 8.4 736.1 736.1 736.5 0.4

O 27,918 130 935 9.4 739.9 739.9 740.1 0.2

P 28,169 166 1,111 7.9 749.9 749.9 749.9 0.0

Q 29,294 114 641 12.6 753.5 753.5 753.5 0.0

R 29,358 122 1,246 6.5 760.1 760.1 760.6 0.5

S 30,321 268 2,081 3.9 777.5 777.5 777.6 0.1

T 31,693 290 1,980 4.1 779.5 779.5 779.5 0.0

U 33,263 1,104 6,753 1.4 783.6 783.6 784.2 0.6

1 Feet above confluence with Chattahoochee River

2 Elevation computed without consideration of backwater effects from Chattahoochee River

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

WAHOO CREEK

63




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

WAHOO CREEK

(CONTINUED)

V 35,956 474 1,921 4.9 784.4 784.4 784.8 0.4

W 38,983 170 1,037 9.1 790.8 790.8 790.8 0.0

X 40,335 358 3,707 2.5 797.2 797.2 797.7 0.5

Y 41,917 5122

5,121 1.8 798.9 798.9 799.9 1.0

Z 44,685 432 2,022 2.3 799.7 799.7 800.6 0.9

AA 47,848 211 1,641 2.8 810.2 810.2 811.0 0.8

AB 49,980 419 2,418 1.9 812.4 812.4 813.1 0.7

AC 51,440 453 3,425 1.3 816.7 816.7 816.9 0.2

AD 54,418 422 1,061 4.0 820.6 820.6 820.9 0.3

AE 55,565 226 1,356 2.7 825.6 825.6 826.3 0.7

AF 56,195 530 4,461 0.8 831.7 831.7 831.9 0.2

AG 58,077 246 809 4.5 832.2 832.2 832.6 0.4

AH 59,614 301 1,944 1.9 839.3 839.3 839.8 0.5

AI 60,104 358 1,980 1.8 839.4 839.4 840.0 0.6

AJ 61,306 314 2,096 1.4 842.2 842.2 842.6 0.4

AK 63,427 128 806 2.3 848.6 848.6 849.0 0.4

AL 64,567 210 856 2.1 849.1 849.1 849.8 0.7

AM 65,415 698 6,892 0.7 859.3 859.3 860.0 0.7

AN 67,855 85 508 3.5 859.8 859.8 860.3 0.5

AO 68,970 312 2,135 1.4 867.1 867.1 867.1 0.0


2 Includes combined floodway width with Snake Creek

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

WAHOO CREEK

64




(FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

WAHOO CREEK

(CONTINUED)

AP 71,697 240 738 4.0 871.9 871.9 872.4 0.5

AQ 72,975 257 1,113 2.8 880.4 880.4 880.4 0.0

AR 73,865 243 448 2.6 881.6 881.6 881.6 0.0

AS 74,825 29 135 8.5 887.3 887.3 887.8 0.5

AT 75,603 235 650 0.9 896.6 896.6 896.7 0.1

AU 76,612 19 67 8.6 905.5 905.5 906.1 0.6

AV 77,421 19 92 6.3 919.4 919.4 919.6 0.2

AW 77,898 47 574 1.0 935.4 935.4 936.3 0.9

AX 78,241 19 116 5.0 935.4 935.4 936.1 0.7

AY 78,808 14 53 11.0 944.7 944.7 944.7 0.0


TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

WAHOO CREEK

65




WIDTH (FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

WHITE OAK CREEK

A 36,400 391 4,059 3.4 772.5 772.5 773.5 1.0

B 38,740 220 2,899 4.3 775.2 775.2 776.0 0.8

C 41,650 1,136 15,143 0.8 776.6 776.6 777.4 0.8

D 42,500 419 5,418 2.3 776.6 776.6 777.4 0.8

E 44,900 574 6,699 1.6 777.6 777.6 778.4 0.8

F 46,780 389 4,325 2.5 779.4 779.4 780.0 0.6

G 49,090 898 9,445 1.1 780.5 780.5 781.1 0.6

H 51,600 681 5,170 2.1 780.9 780.9 781.9 1.0

I 54,380 393 3,959 2.7 783.8 783.8 784.3 0.5

J 57,650 286 2,988 3.2 787.6 787.6 788.3 0.7

K 60,380 1,150 7,799 1.0 788.8 788.8 789.7 0.9

L 63,160 920 5,139 1.5 790.6 790.6 791.1 0.5

M 66,010 610 3,042 2.1 792.2 792.2 793.0 0.8

N 68,240 700 2,287 2.7 797.4 797.4 797.4 0.0

O 68,760 405 1,912 2.9 797.5 797.5 797.6 0.1

P 70,560 320 870 6.3 799.5 799.5 799.7 0.2

Q 71,660 467 1,922 2.8 801.6 801.6 802.5 0.9

R 74,260 468 1,210 4.5 807.2 807.2 807.7 0.5

S 76,360 400 1,381 3.1 813.4 813.4 813.9 0.5

T 77,840 539 2,897 1.3 816.7 816.7 816.8 0.1

U 78,840 217 703 5.5 817.1 817.1 817.2 0.1

1 Feet above county boundary

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

WHITE OAK CREEK

66




WIDTH (FEET)

SECTION AREA

(SQUARE FEET)





INCREASE (FEET)

WHITE OAK CREEK

(CONTINUED)

V 80,930 369 1,628 2.4 823.3 823.3 824.3 1.0

W 82,950 103 608 5.5 826.5 826.5 827.1 0.6

X 85,190 150 538 6.2 831.5 831.5 832.1 0.6

Y 86,000 300 1,341 2.5 833.2 833.2 833.7 0.5

Z 87,240 400 3,054 0.6 837.8 837.8 837.8 0.0

AA 88,140 500 1,329 1.3 837.8 837.8 837.8 0.0

AB 89,730 197 432 4.1 841.0 841.0 841.0 0.0

AC 91,200 309 850 2.1 846.7 846.7 847.0 0.3

AD 93,100 155 501 2.3 853.2 853.2 853.5 0.3

AE 94,400 222 303 3.8 861.0 861.0 861.1 0.1

AF 97,000 336 436 1.8 872.0 872.0 872.1 0.1

AG 98,550 72 151 5.2 881.9 881.9 882.6 0.7

1 Feet above county boundary

TA

BL

E 6


COWETA COUNTY, GA


FLOODWAY DATA

WHITE OAK CREEK

67

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, 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 risk 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, 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.

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.

This countywide FIRM presents flooding information for the entire geographic area of

Coweta County. Previously, FIRMs were prepared for each incorporated community and

68

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 7, “Community Map History.”

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, Federal

Regional Center, 3003 Chamblee-Tucker Road, Atlanta, Georgia 30341.

9.0 BIBLIOGRAPHY AND REFERENCES

1. 2010 U.S. Census: Coweta County, Georgia. Retrieved on April 19, 2011,

from http://factfinder2.census.gov

2. Dewberry and Davis LLC, Georgia Department of Natural Resources

Cooperating Technical Partner Mapping Activity Statement No. FY09.09,

FEMA Contract Number: EMA-2009-CA-5930, Chattahoochee River

Hydrologic Study: Buford Dam to West Point Lake, April 2011.



FEMA Contract Number: EMA-2009-CA-5930, Chattahoochee River

Hydraulic Study, May 2011.



FEMA Contract Number: EMA-2009-CA-5930, Coweta County, GA:

Hydrology Report, October 2010.



FEMA Contract Number: EMA-2009-CA-5930, Coweta County, GA:

Hydraulic Report, October 2010.

69

COMMUNITY NAME

INITIAL IDENTIFICATION

FLOOD HAZARD BOUNDARY MAP REVISION DATE

FIRM EFFECTIVE DATE

FIRM REVISION DATE

Coweta County (Unincorporated Areas)

April 30, 1976 None August 2, 1982 September 8, 1999

Grantville, City of May 16, 2006 None May 16, 2006 None

Haralson, Town of May 16, 2006 None May 16, 2006 None

Moreland, Town of April 18, 1975 None September 27, 1985 None

Newnan, City of May 31, 1974 February 6, 1976 November 15, 1978 None

Senoia, City of April 4, 1975 None July 1, 1987 None

Sharpsburg, Town of N/A N/A N/A N/A

Turin, Town of May 16, 2006 None May 16, 2006 None

TA

BL

E 7


COWETA COUNTY, GA AND INCORPORATED AREAS

COMMUNITY MAP HISTORY

Table 1 - Community

70

6. Federal Emergency Management Agency, Flood Insurance Study, Coweta

County, Georgia (Unincorporated Areas), Flood Insurance Study, February 2,

1982; Flood Insurance Rate Map, August 2, 1982.


County, Georgia (Unincorporated Areas), September 8, 1999.

8. Federal Emergency Management Agency, Guidelines and Specifications for

Flood Hazard Mapping Partners, 2003.


County, Georgia and Incorporated Areas, May 16, 2006.

10. Interagency Advisory Committee on Water Data, Guidelines for determining

flood flow frequency: Bulletin 17B of the Hydrology Subcommittee, Office of

Water Data Coordination, U.S. Geological Survey, Reston, VA, 1982.

11. Jack W. Berry & Associates, Inc., Aerial Photographs, Coweta County,

Georgia, Scale 1:12,000, 1977a.

12. Jack W. Berry & Associates, Inc., Topographic Maps, Scale 1:4,800, Contour

Interval 5 feet: Coweta County, Georgia, 1977b.

13. NGS: VERTCON-North American Vertical Datum Conversion Utility.

Retrieved on November 18, 2004, from http://www.ngs.noaa.gov/

14. Photo Science, Inc., Coweta County countywide topographic LiDAR dataset,

2007.

15. U.S. Army Corps of Engineers, Hydrologic Engineering Center, HEC-2 Water

Surface Profiles, Davis, California, November 1976, revised April 1984.

16. U.S. Department of Agriculture, Soil Conservation Service, Technical Release

No. 20, Computer Program, Project Formulation, Hydrology, Washington,

D.C., May 1965.

17. U.S. Department of Agriculture, Soil Conservation Service, Technical Release

No. 55, Urban Hydrology for Small Watersheds, 1975.

18. U.S. Department of Agriculture, Natural Resources Conservation Service,

Technical Release No. 55, Urban Hydrology for Small Watersheds, 1986.

19. U.S. Department of Agriculture, Natural Resources Conservation Service,

Hydrographs, National Engineering Handbook, Part 630 Hydrology: Chapter

16, 2007.

71

20. U.S. Department of Housing and Urban Development, Federal Insurance

Administration, Flood Hazard Boundary Map, Coweta County, Georgia

(Unincorporated Areas), Scale 1:24,000, April 1976.

21. U.S. Department of Urban and Housing Development, Federal Insurance

Administration, Flood Insurance Study, City of Newnan, Coweta County,

Georgia, May 15, 1978.

22. U.S. Geological Survey, 7.5-Minute Series Topographic Maps, Scale 1:24,000,

Contour Interval 20 Feet: Brooks, Georgia, 1965; Fairburn, Georgia, 1954,

photorevised 1968 and 1973; Grantville, Georgia, 1964, photorevised 1973;

Haralson, Georgia, 1971; Hogansville, Georgia, 1964, photorevised 1973;

Hollonville, Georgia 1971; Lowell, Georgia, 1964; Lutherville, Georgia, 1971;

Madras, Georgia, 1965, photorevised 1973; Newnan North, Georgia, 1965,

photorevised 1973; Newnan South, Georgia, 1965, photorevised 1973; Newnan

SW, Georgia 1965; Palmetto, Georgia, 1954, photorevised 1968; Rico,

Georgia, 1958, photorevised, 1968; Senoia, Georgia, 1965; Sharpsburg,

Georgia, 1965; Tyrone, Georgia, 1965; Whitesburg, Georgia, 1965.

23. U.S. Geologic Survey, Flood-Frequency Analysis for Small Natural Streams in

Georgia by H.G. Golden and McG. Price, July 1976

24. U.S. Geological Survey, Preliminary Flood-Frequency Relations, Urban

Streams, Metropolitan Atlanta, Georgia by V.B. Sauer, Atlanta, Georgia,

unpublished.

25. U.S. Geological Survey, Flood-Frequency Relations for Urban Streams in

Georgia, 1994 Update, Atlanta, Georgia, 1995.

26. U.S. Geological Survey, The National Flood-Frequency Program – Methods for

Estimating Flood Magnitude and Frequency in Rural and Urban Areas in

Georgia, 1999.

27. U.S. Geological Survey, Magnitude and frequency of rural floods in the

southeastern United States, 2006: Volume 1, Georgia by A.J. Gotvald, T.D.

Feaster, and J.C. Weaver, 2009.

28. U.S. Weather Bureau, Technical Paper No. 40, Rainfall Frequency Atlas of the

United States, 1961.

600

620

640 640

660 660

680 680

700 700

720 720

740 740

760 760

780 780

47.50 48.00 48.50 49.00 49.50 50.00 50.50 51.00 51.50 52.00 52.50 53.00 53.50 54.00

ELE

VA

TIO

N IN

FEET

(N

AV

D 8

8)

STREAM DISTANCE IN MILES FROM WEST POINT DAM

FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y,

GA

AN

D I

NC

OR

PO

RA

TED

AR

EA

S

FLO

OD

PR

OFIL

ES

CH

AT

TA

HO

OC

HEE R

IVER

05P

AF AG AH AI

AJ AK

CO

UN

TY

BO

UN

DA

RY

LEGEND

0.2% ANNUAL CHANCE FLOOD

1% ANNUAL CHANCE FLOOD



STREAM BED

CROSS SECTION LOCATION

LIM

IT O

F F

LOO

DIN

G A

FFEC

TIN

G C

OM

MU

NIT

Y

620

640

660 660

680 680

700 700

720 720

740 740

760 760

780 780

800 800

54.00 54.50 55.00 55.50 56.00 56.50 57.00 57.50 58.00 58.50 59.00 59.50 60.00 60.50

ELE

VA

TIO

N IN

FEET

(N

AV

D 8

8)


FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y,

GA

AN

D I

NC

OR

PO

RA

TED

AR

EA

S

FLO

OD

PR

OFIL

ES

CH

AT

TA

HO

OC

HEE R

IVER

06P

AL AM AN AO AP AQ AR AS AT

AU

ST

AT

E R

OU

TE 1

6

CO

NFL

UEN

CE O

F T

HO

MA

S C

REEK

CO

NFL

UEN

CE O

F M

OO

RE C

REEK

CO

NFL

UEN

CE O

F W

AH

OO

CR

EEK

CO

NFLU

EN

CE O

F C

ED

AR

CR

EEK

RA

ILR

OA

D

LEGEND





STREAM BED


620

640

660 660

680 680

700 700

720 720

740 740

760 760

780 780

800 800

60.50 61.00 61.50 62.00 62.50 63.00 63.50 64.00 64.50 65.00 65.50 66.00 66.50 67.00

ELE

VA

TIO

N IN

FEET

(N

AV

D 8

8)


FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y,

GA

AN

D I

NC

OR

PO

RA

TED

AR

EA

S

FLO

OD

PR

OFIL

ES

CH

AT

TA

HO

OC

HEE R

IVER

07P

AV AW

CO

UN

TY

BO

UN

DA

RY

LEGEND





STREAM BED


LIM

IT O

F F

LOO

DIN

G A

FFEC

TIN

G C

OM

MU

NIT

Y

740

745

750 750

755 755

760 760

765 765

770 770

775 775

780 780

785 785

0 500 1000 1500 2000 2500 3000 3500 4000

ELE

VA

TIO

N IN

FEET

(N

AV

D)

STREAM DISTANCE IN FEET ABOVE LIMIT OF DETAILED STUDY

FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y,

GA

AN

D I

NC

OR

PO

RA

TED

AR

EA

S

FLO

OD

PR

OFI

LES

KEG

CR

EEK

08P

*LI

MIT

OF D

ET

AIL

ED

ST

UD

Y

LEGEND

0.2% ANNUAL CHANCE FLOOD*


2% ANNUAL CHANCE FLOOD*


STREAM BED


HUTCHINS LAKE FREEMAN LAKE

* DATA NOT AVAILABLE* LIMIT OF DETAILED STUDY IS APPROXIMATELY

40 FEET UPSTREAM OF ROCKAWAY ROAD

750

755

760 760

765 765

770 770

775 775

780 780

785 785

790 790

795 795

4000 4500 5000 5500 6000 6500 7000

ELE

VA

TIO

N IN

FEET

(N

AV

D)

STREAM DISTANCE IN FEET ABOVE *LIMIT OF DETAILED STUDY

FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y,

GA

AN

D I

NC

OR

PO

RA

TED

AR

EA

S

FLO

OD

PR

OFI

LES

KEG

CR

EEK

09P

LIM

IT O

F D

ET

AIL

ED

ST

UD

Y

LEGEND

0.2% ANNUAL CHANCE FLOOD*




STREAM BED


* DATA NOT AVAILABLE 40 FEET UPSTREAM OF ROCKAWAY ROAD

* LIMIT OF DETAILED STUDY IS APPROXIMATELY

770

780

790 790

800 800

810 810

820 820

830 830

840 840

850 850

860 860

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

ELE

VA

TIO

N IN

FEET

(N

AV

D)

STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WAHOO CREEK

FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y, G

AA

ND

IN

CO

RP

OR

AT

ED

AR

EA

S

FLO

OD

PR

OFI

LES

LIT

TLE

WA

HO

O C

REEK

25P

A B C

D

CO

NFLU

EN

CE W

ITH

WA

HO

O C

REEK

RO

SC

OE R

OA

D

LEGEND





STREAM BED


1% ANNUAL CHANCE BACKWATER EFFECTS FROM WAHOO CREEK

780

790

800 800

810 810

820 820

830 830

840 840

850 850

860 860

870 870

6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

ELE

VA

TIO

N IN

FEET

(N

AV

D)


FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y, G

AA

ND

IN

CO

RP

OR

AT

ED

AR

EA

S

FLO

OD

PR

OFI

LES

LIT

TLE

WA

HO

O C

REEK

26P

E F

G H

FA

ST

GU

AR

D F

AR

MS

LEGEND





STREAM BED


800

810

820 820

830 830

840 840

850 850

860 860

870 870

880 880

890 890

13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500

ELE

VA

TIO

N IN

FEET

(N

AV

D)


FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y, G

AA

ND

IN

CO

RP

OR

AT

ED

AR

EA

S

FLO

OD

PR

OFI

LES

LIT

TLE

WA

HO

O C

REEK

27P

I J K L

M

BR

IDG

E

BR

IDG

E

BR

IDG

E

LEGEND





STREAM BED


830

840

850 850

860 860

870 870

880 880

890 890

900 900

910 910

920 920

19000 19500 20000 20500 21000 21500 22000 22500 23000 23500 24000 24500 25000 25500

ELE

VA

TIO

N IN

FEET

(N

AV

D)


FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y, G

AA

ND

IN

CO

RP

OR

AT

ED

AR

EA

S

FLO

OD

PR

OFI

LES

LIT

TLE

WA

HO

O C

REEK

28P

N O

LIM

IT O

F S

TU

DY

PO

ND

LEGEND





STREAM BED


855

860

865 865

870 870

875 875

880 880

885 885

890 890

895 895

900 900

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000

ELE

VA

TIO

N IN

FEET

(N

AV

D)

STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH LINE CREEK

FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y,

GA

AN

D I

NC

OR

PO

RA

TED

AR

EA

S

F LO

OD

PR

OFI

LES

PEEK

S C

REEK

36P

A B C D E

F

CO

NFL

UEN

CE W

ITH

LIN

E C

REEK

1% ANNUAL CHANCE BACKWATER EFFECTS FROM LINE CREEK

FLOODING CONTROLLED BY LINE CREEK

CO

LLIN

SW

OR

TH

RO

AD

LIM

IT O

F D

ET

AIL

ED

ST

UD

Y

LEGEND





STREAM BED


770

780

790 790

800 800

810 810

820 820

830 830

840 840

850 850

860 860

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

ELE

VA

TIO

N IN

FEET

(N

AV

D)


FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y, G

AA

ND

IN

CO

RP

OR

AT

ED

AR

EA

S

FLO

OD

PR

OFI

LES

SN

AK

E C

REEK

51P

A B

C

CO

NFLU

EN

CE W

ITH

WA

HO

O C

REEK

LEGEND





STREAM BED



790

800

810 810

820 820

830 830

840 840

850 850

860 860

870 870

880 880

6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

ELE

VA

TIO

N IN

FEET

(N

AV

D)


FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y, G

AA

ND

IN

CO

RP

OR

AT

ED

AR

EA

S

FLO

OD

PR

OFI

LES

SN

AK

E C

REEK

52P

D

E F

NEW

NA

N B

YP

AS

S

LEGEND





STREAM BED


CULVERT

820

830

840 840

850 850

860 860

870 870

880 880

890 890

900 900

910 910

13000 13500 14000 14500 15000 15500 16000 16500 17000 17500

ELE

VA

TIO

N IN

FEET

(N

AV

D)


FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y, G

AA

ND

IN

CO

RP

OR

AT

ED

AR

EA

S

FLO

OD

PR

OFI

LES

SN

AK

E C

REEK

53P

G H I J K L

HO

SP

ITA

L R

OA

D

CH

RIS

TIA

N D

RIV

E

PA

RK

VIE

W D

RIV

E

TA

LIA

FER

RO

DR

IVE

CO

NFL

UEN

CE O

F T

RIB

UT

AR

Y 1

TO

SN

AK

E C

REEK

LEGEND





STREAM BED


CULVERT

CULVERT

CULVERT

CULVERT

870

880

890 890

900 900

910 910

920 920

930 930

940 940

950 950

960 960

17500 18000 18500 19000 19500 20000 20500 21000 21500

ELE

VA

TIO

N IN

FEET

(N

AV

D)


FED

ER

AL

EM

ER

GEN

CY

MA

NA

GEM

EN

T A

GEN

CY

CO

WET

A C

OU

NT

Y, G

AA

ND

IN

CO

RP

OR

AT

ED

AR

EA

S

FLO

OD

PR

OFI

LES

SN

AK

E C

REEK

54P

M N O P

Q

R S T

LIM

IT O

F S

TU

DY

WIL

LOW

DR

IVE

DIX

ON

ST

REET

CU

LVER

T

CU

LVER

T

CU

LVER

T

CO

NFL

UEN

CE O

F T

RIB

UT

AR

Y 2

TO

SN

AK

E C

REEK

LEGEND





STREAM BED


CULVERT

CULVERT

COWETA COUNTY

COWETA COUNTY, GEORGIA

AND INCORPORATED AREAS Community Community Name Number COWETA COUNTY (UNINCORPORATED AREAS) 130298 GRANTVILLE, CITY OF 130443 HARALSON, TOWN OF 130299 MORELAND, TOWN OF 130300 NEWNAN, CITY OF 130062 SENOIA, CITY OF 130301

∗SHARPSBURG, TOWN OF 130581 TURIN, TOWN OF 130475

∗ Non-Floodprone

Revised: February 6, 2013

FLOOD INSURANCE STUDY NUMBER

13077CV002B

VOLUME 2 OF 2

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: May 16, 2006

Revised Countywide FIS Effective Date: February 6, 2013

i

TABLE OF CONTENTS

Volume 1

1.0 INTRODUCTION.............................................................................................. 1

1.1 Purpose of Study .......................................................................................... 1

1.2 Authority and Acknowledgements ................................................................ 1

1.3 Coordination ................................................................................................ 2

2.0 AREA STUDIED ............................................................................................... 3

2.1 Scope of Study ............................................................................................. 3

2.2 Community Description ............................................................................... 6

2.3 Principal Flood Problems ............................................................................. 7

2.4 Flood Protection Measures ........................................................................... 7

3.0 ENGINEERING METHODS ............................................................................ 8

3.1 Hydrologic Analyses .................................................................................... 8

3.2 Hydraulic Analyses .................................................................................... 23

3.3 Vertical Datum ........................................................................................... 25

4.0 FLOODPLAIN MANANGEMENT APPLICATIONS .................................. 26

4.1 Floodplain Boundaries ............................................................................... 26

4.2 Floodways .................................................................................................. 27

5.0 INSURANCE APPLICATIONS ..................................................................... 67

6.0 FLOOD INSURANCE RATE MAP ............................................................... 67

7.0 OTHER STUDIES ........................................................................................... 68

8.0 LOCATION OF DATA ................................................................................... 68

9.0 BIBLIOGRAPHY AND REFERENCES ........................................................ 68

ii

TABLE OF CONTENTS

Volume 1 (continued)

FIGURES

Figure 1 – Floodway Schematic .......................................................................................... 28

TABLES

Table 1 – Stream Studied by Detailed Methods ..................................................................... 3

Table 2 – Streams Name Changes ......................................................................................... 5

Table 3 – Summary of Discharges ....................................................................................... 10

Table 4 – Manning’s “n” Values.......................................................................................... 24

Table 5 – Vertical Datum Conversion .................................................................................. 25

Table 6 – Floodway Data Table ........................................................................................... 29

Table 7 – Community Map History ..................................................................................... 69

EXHIBITS


Chandlers Creek Panels 01P-04P

Chattahoochee River Panels 05P-07P

Keg Creek Panels 08P-09P

Lake Amlajack Creek Panels 10P-11P

Lake Summergrove Branch Panel 12P

Line Creek Panels 13P-22P

Little Creek Panels 23P-24P

Little Wahoo Creek Panels 25P-28P

Mineral Spring Branch Panels 29P-33P

Paradise Lakes Branch Panels 34P-35P

Peeks Creek Panel 36P

Persimmon Creek Panels 37P-39P

Sandy Creek Panels 40P-45P

Shoal Creek Panels 46P-50P

Snake Creek Panels 51P-54P

Tributary 1 to Line Creek Panels 55P-56P


iii

TABLE OF CONTENTS

Volume 2

EXHIBITS (continued)


Tributary 1 to Persimmon Creek Panels 61P-62P


Tributary 1 to Shoal Creek Panel 65P


Tributary 1 to Turkey Creek Panel 67P


Tributary 1 to White Oak Creek Panels 69P-70P



Tributary 2 to Shoal Creek Panels 77P-78P


Tributary 2 to Wahoo Creek Panels 80P-81P


Tributary 3 to Shoal Creek Panels 84P- 85P











Turkey Creek Panels 96P-101P

Wahoo Creek Panels 102P-114P

White Oak Creek Panels 115P-120P

Exhibit 2 - Flood Insurance Rate Map Index

Flood Insurance Rate Map

840

850

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AV

D)

STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SNAKE CREEK

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NT

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RP

OR

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ED

AR

EA

S

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OD

PR

OFI

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TR

IBU

TA

RY

1 T

O S

NA

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A B C D

CO

NFL

UEN

CE W

ITH

SN

AK

E C

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S D

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LUB

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ILL

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LAR

D F

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MER

IN

DU

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RIA

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OU

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STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SNAKE CREEK

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ELE

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ER

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AV

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AA

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Date post:	28-Jun-2020
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