U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5066

Prepared in cooperation with the Alabama Department of Transportation

Flood-Depth Frequency Relations for Rural Streams

in Alabama, 2003
Cover photographs. Front cover: Left: Alabama River near Montgomery Alabama. Right: Selma, Alabama, flooding of 1990. Back cover:

Clockwise from upper left: Lake Tuscaloosa, Tuscaloosa, Alabama; Selma, Alabama, flooding of 1979; Choctawhatchee River near 

Newton, Alabama; Styx River near Elsanor, Alabama. Center: Styx River near Elsanor, Alabama.
Flood-Depth Frequency Relations for Rural 

Streams in Alabama, 2003

By K.G. Lee and T.S. Hedgecock

Prepared in cooperation with the Alabama Department of Transportation

Scientific Investigations Report 2010–5066

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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Suggested citation:

Lee, K.G., and Hedgecock, T.S., 2010, Flood-depth frequency relations for rural streams in Alabama, 2003: 

U.S. Geological Survey Scientific Investigations Report 2010–5066, 25 p.

(Also available online at http://pubs.usgs.gov/sir/2010/5066/)

ISBN 978-1-4113-2844-0 
iii

Contents

Abstract...........................................................................................................................................................1

Introduction ....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................1

Previous Studies ..................................................................................................................................2

Description of the Study Area ............................................................................................................2

Definition of Flood Depths ............................................................................................................................2

Flood Magnitude and Frequency at Streamgages...................................................................................2

Determination of Flood-Depth Frequency Relations ...............................................................................6

Data Selection.......................................................................................................................................6

Regression Analysis.............................................................................................................................6

Accuracy and Limitations....................................................................................................................7

Application of Flood-Depth Frequency Equations....................................................................................8

Summary..........................................................................................................................................................9

References......................................................................................................................................................9

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used

in Alabama rural depth regression analyses.............................................................................13

Figures

1. Locations of physiographic provinces in Alabama ..........................................................................3

2. Locations of the four rural flood regions in Alabama.......................................................................5

Plate

[In pocket]

1. Locations of flood regions and streamgages in Alabama

Tables

1. T-year recurrence intervals with corresponding annual exceedance probabilities

 and P-percent chance exceedances for flood-frequency depth estimates................................4

2. Regional flood-frequency relations for rural streams in Alabama ................................................4

3. Basin characteristics considered for use in regional regression analysis..................................6

4. Regional flood-depth frequency relations for rural streams in Alabama......................................8

5. Accuracy of regional flood-depth frequency relations for rural streams

 in Alabama ..............................................................................................................................................9
iv

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2) 

acre 0.00405 square kilometer (km2

)

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

Hydraulic gradient

foot per mile (ft/mi) 0.1894 meter per kilometer (m/km)

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.
Abstract

Equations have been defined for estimating the depth 

of water for floods having a 67-, 50-, 20-, 10-, 4-, 2-, and 

1-percent chance exceedance on rural streams in Alabama. 

Multiple regression analyses of streamgage data were used to 

define the equations. Eight basin and climatic characteristics 

that were computed by using a geographical information system were evaluated as independent variables to determine their 

statistical significance for the dependent variable, flood depth. 

Drainage area was the most statistically significant independent variable tested. Addition of other significant variables 

did not decrease the standard error of prediction by more than 

2 percent. Regression relations, for four different hydrologic 

regions, were developed to estimate flood depth for rural, 

ungaged streams as a function of the basin drainage area. 

These relations are based on computed depths that correspond 

to the flood magnitude and frequency for 164 streamgages 

in Alabama and 42 streamgages in adjacent States having at 

least 10 years of consecutive record. These relations utilize 

observed flood data collected through 2003. The geologic, 

physiographic, and climatic variability affecting flood depth 

is reflected in the constant (intercept) and exponent (slope) 

for each regional regression equation. Average standard 

errors of prediction for these regression equations range from 

18 to 38 percent.

Introduction 

The Alabama Department of Transportation designs 

bridges, culverts, and highway embankments on the basis 

of flow magnitude and the associated flood depth. Depending on the capacity and volume of traffic on a highway, the 

flood depth associated with a flow magnitude having a 10-, 

4-, 2-, or 1-percent chance exceedance is used in the design. 

Additionally, the flood depth and flow magnitude are used by 

governmental agencies responsible for land-use development, 

flood-plain zoning, and flood-insurance studies. The U.S. 

Geological Survey (USGS), in cooperation with the Alabama 

Department of Transportation defined equations for estimating 

the depth of water for floods having a 67-, 50-, 20-, 10-, 4-, 2-, 

and 1-percent chance exceedance on rural streams in Alabama.

The approach to determine flood depths for hydraulic 

design of drainage structures and for flood-plain mapping 

is to determine flood-frequency flows by the best available 

methods and use an open-channel hydraulic model to obtain 

flood elevations, flow distributions, and velocities. Although 

these data are essential for many bridge and culvert design 

applications, this approach can be expensive and time consuming, because of the demands of collecting geometric surveys 

of the channel, flood plain, and associated hydraulic structures. 

Also, the field survey of the necessary calibration data could 

add substantial time and expense. In cases where flood management and planning require only a flood elevation (as for 

reconnaissance flood-plain mapping), an alternative approach 

is to estimate flood depths directly without determining flow 

or applying a hydraulic model. An example of this approach is 

Federal Emergency Management Agency’s (FEMA) “lessthan-detailed methods,” which are used to derive flood-hazard 

maps. A set of regional flood-depth frequency equations will 

aid engineers in hydraulic design and flood-risk management.

Purpose and Scope

The information in this report updates previously 

published flood-depth frequency information for Alabama 

by providing methods of estimating the depth frequency of 

floods at rural, ungaged streams. The data in this report are 

based on flood-frequency analyses of annual peak-flow data 

collected at streamgaging stations through September 2003. 

The flood-depth values that correspond to the flood-flow 

frequency were estimated and used to determine a flood-depth 

frequency for each streamgaging station. The report presents 

flood-depth frequency statistics at the 67-, 50-, 20-, 10-, 4-, 

2-, and 1-percent chance exceedance levels determined for 

206 rural, gaged stations in Alabama and adjacent States with 

unregulated flow conditions. The report (1) includes regional 

equations for estimating the magnitude and frequency of flood 

depths on rural, ungaged streams in Alabama that are not 

affected by regulation, (2) presents estimates of the magnitude 

of flood depths at the 67-, 50-, 20-, 10-, 4-, 2-, and 1-percent 

chance exceedance levels for 164 streamgaging stations in 

Alabama, (3) describes techniques used to develop regression 

equations for use in estimating the depth of floods for rural, 

ungaged sites in Alabama, (4) describes the accuracy and limitations of the equations, and (5) presents example applications 

of the methods.

Flood-Depth Frequency Relations for Rural Streams 

in Alabama, 2003

By K.G. Lee and T.S. Hedgecock
2 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

Previous Studies 

Flood-depth frequency relations have been described 

by Hains (1977) and Olin (1985b). When the U.S. Geological Survey began preparing maps of flood-prone areas as 

directed by the 89th Congress in House Document 465 (1966), 

a need arose for a method of determining flood depths for 

use in delineating approximate flood-prone areas. Regional 

flood-depth-frequency equations for the 10- and 1-percent 

chance exceedance were developed in Alabama for this purpose (Hains, 1977). These equations are based on 129 rural 

streamgages with drainage areas ranging from 1.0 to 800 

square miles (mi2). The equations were updated (Olin, 1985b) 

to include small rural gages, urban gages, and flood records

collected through 1983. Olin (1985b) evaluated the relation 

between basin characteristics and flood depths for the 50-, 

20-, 10-, 4-, 2-, 1-, and 0.5-percent chance exceedance at 

180 streamgages in Alabama (158 rural and 22 urban). 

Description of the Study Area

The study area includes all of Alabama, which covers an 

area of about 51,600 mi2

 in five physiographic provinces—

Coastal Plain, Piedmont, Valley and Ridge, Appalachian Plateaus, and Interior Lowland Plateaus (fig. 1). The area north of 

the Fall Line, which delineates the contact of the Coastal Plain 

with the other provinces, has a diverse topography with landsurface elevations ranging from 200 to 2,400 feet (ft) above 

the North American Vertical Datum of 1988 (NAVD 88). In 

the Coastal Plain, elevations range from 0 to 1,000 ft above 

NAVD 88 in the northwestern part of the State. The land 

surface generally slopes to the south and west.

Average annual precipitation ranges from about 48 inches 

in central and east-central Alabama to about 68 inches near 

the Gulf of Mexico and averages about 57 inches statewide 

(National Oceanic and Atmospheric Administration, 2002). 

Rainfall in Alabama generally is associated with the movement of warm and cold fronts across the State from November 

through April and isolated summer thunderstorms from May 

through October. Occasionally, tropical storms or hurricanes 

that enter the State along the gulf coast produce unusually heavy amounts of rainfall. Average annual runoff varies from approximately 12 to 40 inches. Runoff typically is 

greatest during February through April and least when rainfall 

decreases during September through November.

Definition of Flood Depths

Flood-depth values were computed for the 67-, 50-, 20-, 

10-, 4-, 2-, and 1-percent chance exceedance flows for each 

streamgage used in the analysis. Flood depths were computed 

as the difference in the elevation of the flood and the elevation 

of the gage height of zero flow. The weighted “best estimate” 

flow was used from “Magnitude and Frequency of Floods in 

Alabama, 2003” by Hedgecock and Feaster (2007) to develop 

the relation between flow and depth for each gage. This flow 

was used with the rating curve (gage height to flow relation) to 

determine a flood elevation for each exceedance probability. 

The stage values were converted to depth values by using 

the gage height of zero flow as a reference point. The gage 

height of zero flow is the gage height of the lowest point of 

the control. It represents the thalweg of the measuring section. 

The gage height of zero flow can change with time because 

of scouring, filling, and permanent changes. Because the 

gage height of zero flow is not static for all stations, several 

methods were used to compute an average value for the entire 

period of record for each gage. The majority of the stations 

used in the analysis have direct measurements of the gage 

height of zero flow. These measurements were inspected for 

variance throughout the period of record. An average value 

was computed and used as the reference point. In the instance 

that the gage has a culvert rating, the culvert invert was used 

as the point of reference. For stations lacking sufficient documentation of the gage height of zero flow, low-water discharge 

measurements were used to compute an average reference 

surface. These values were checked by examining the scale 

offset of the rating curve when available. 

The computed depth values represent a value that corresponds to a flow frequency for each gage rather than a computed frequency of depths for each gage. These depths provide 

estimates that correspond with percent chance of exceedance 

flood-flow magnitudes that can be used for design purposes.

Flood Magnitude and Frequency at 

Streamgages

A flood-frequency estimate is the relation of a flood 

characteristic to a probability of exceedance. Probability of 

exceedance refers to the chance that a given flood characteristic will be exceeded in any one year. For example, a 1-percent 

chance exceedance flood (formerly known as the “100-year 

flood”) corresponds to the flow magnitude that has a probability of 0.01 of being equaled or exceeded in any given year. A 

frequency analysis of annual peak-flow data at a streamgage 

provides an estimate of the flood magnitude and frequency 

at the specific stream site. Flood-frequency flows in previous 

USGS reports were expressed as T-year floods on the basis of 

the recurrence interval for that flood quantile (for example, the 

“100-year flood”). The use of recurrence-interval terminology 

is now discouraged because it sometimes causes confusion 

to the general public (Gotvald and others, 2009). The term is 

sometimes interpreted to imply that there are set time intervals between floods of a particular magnitude, when in fact 

floods are random processes that are best understood using 

probabilistic terms.

The terminology associated with flood-frequency estimates is undergoing a shift away from the T-year recurrence 
Flood Magnitude and Frequency at Streamgages 3

0 25 50 MILES

0 25 50 KILOMETERS

Base from U.S. Geological Survey digital data,

1:100,000, Universal Transverse Mercator Projection, 

Zone 16.

35

34

33

32

31

88 87 86 85

LAUDERDALE

LAWRENCE

MARION WINSTON

LAMAR

FAYETTE

WALKER

CULLMAN

BLOUNT

ETOWAH

CHEROKEE

ST. CLAIR CALHOUN

JEFFERSON

TUSCALOOSA

PICKENS SHELBY CLAY

COOSA

CHILTON

BIBB

HALE

PERRY

DALLAS

AUTAUGA

LOWNDES MONTGOMERY

BUTLER

ELMORE

LEE

RUSSELL

BARBOUR

HENRY

DALE

COFFEE

GENEVA

COVINGTON

ESCAMBIA

CONECUH

MONROE

WILCOX

CLARKE

CHOCTAW

WASHINGTON

MOBILE

BALDWIN

HOUSTON

PIKE

CRENSHAW

MACON

BULLOCK

MARENGO

GREENE

SUMTER

TALLAPOOSA

RANDOLPH

CHAMBERS

TALLADEGA

CLEBURNE

COLBERT

FRANKLIN

LIMESTONE

MADISON JACKSON

MORGAN

MARSHALL DEKALB

MISSISSIPPI

GEORGIA

FLORIDA

TENNESSEE

ALABAMA

GULF OF MEXICO

Fall Line

Interior Lowland

Plateaus

Appalachian

 Plateaus

Valley 

 and 

Ridge

Piedmont

Coastal Plain

Figure 1. Locations of physiographic provinces in Alabama.
4 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

interval flood to the P-percent chance exceedance flood 

(Gotvald and others, 2009). The use of percent chance exceedance flood conveys the probability, or odds, of a flood of a 

given magnitude being equaled or exceeded in any given 

year. T-year recurrence intervals with corresponding annual 

exceedance probabilities and P-percent chance exceedances 

are given in table 1.

The flood-frequency relations for the streamgages used 

in the previous flood-depth report (Olin, 1985b) are based 

on flow values computed using “Magnitude and Frequency 

of Floods in Alabama” by Olin (1985a). Since the completion of Olin’s (1985b) flood-depth report, three subsequent 

flood-frequency reports (Atkins, 1996; Hedgecock, 2004; 

Hedgecock and Feaster, 2007) have been published with the 

inclusion of more data. An additional 20 years of flood-depth 

data over a wider range of streams are now available. 

Methods of estimating flood flow magnitudes for the 67-, 

50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent chance exceedance have been developed for rural streams in Alabama that 

are not affected by regulation or urbanization (Hedgecock and 

Feaster, 2007). Regression relations were developed using 

generalized least-squares (GLS) regression techniques to 

estimate flood magnitude and frequency on ungaged streams 

as a function of the basin drainage area. These methods are 

based on flood-frequency characteristics for 169 streamgages 

in Alabama and 47 streamgages in adjacent States having 10 

or more years of record through September 2003.

Initial GLS regression analyses were performed for all 

the streamgages included in the study. The residuals for each 

streamgage were plotted on a State map and inspected for 

geographic bias. The residuals plot indicated the presence of 

geographic biases or clusters, and the four flood regions shown 

in figure 2 were delineated for Alabama on the basis of the 

residuals plot, previous flood-frequency studies, drainage area 

maps, geologic maps, and physiographic maps. 

Separate GLS multiple regression analyses were performed for each of the four flood regions, and the standard 

errors were reduced in comparison to a single statewide GLS 

regression relation. In each flood region, the contributing 

drainage area was the most statistically significant variable. 

Addition of other significant variables did not decrease the 

standard error of prediction by more than 2 percent. Generalized least-squares regression analysis, using contributing 

drainage area as the only explanatory variable, was applied to 

the four flood regions. The flood-frequency relations for the 

four flood regions are summarized in table 2.

Table 1. T-year recurrence intervals with corresponding 

annual exceedance probabilities and P-percent chance 

exceedances for flood-frequency depth estimates.

T-year recurrence 

interval

Annual exceedance 

probability

P-percent chance 

exceedance

 1.5 0.67 67

 2 0.50 50

  5 0.20 20

 10 0.10 10

 25 0.04 4

 50 0.02 2

 100 0.01 1

 200 0.005 0.5

 500 0.002 0.2

Table 2. Regional flood-frequency relations for rural streams in Alabama.

[Q, flood discharge, in cubic feet per second; A, contributing drainage area, in square miles]

Percent chance 

exceedance Rural regression equations for the indicated flood regions (fig. 2)

Region 1 Region 2 Region 3 Region 4

 67 Q = 

 184 A 0.666 Q =  126 A 0.663 Q =  254 A 0.565 Q = 157 A 0.586

 50 Q =  250 A 0.656 Q =  166 A 0.660 Q =  322 A 0.578 Q = 204 A 0.590

 20 Q =  466 A 0.636 Q =  291 A 0.652 Q = 562 A 0.593 Q =  367 A 0.590

 10 Q =  650 A 0.623 Q =  393 A 0.648 Q = 802 A 0.592 Q = 499 A 0.588

 4 Q =  918 A 0.610 Q =  532 A 0.645 Q = 1,206 A 0.586 Q = 692 A 0.584

 2 Q = 1,137 A 0.601 Q =  642 A 0.643 Q = 1,559 A 0.583 Q = 857 A 0.580

 1 Q = 1,368 A 0.593 Q =  763 A 0.641 Q = 1,930 A 0.584 Q = 1,036 A 0.578

 0.5 Q = 1,609 A 0.587 Q = 899 A 0.638 Q = 2,306 A 0.588 Q = 1,229 A 0.577

 0.2 Q = 1,943 A 0.579 Q = 1,109A 0.634 Q = 2,798 A 0.598 Q = 1,502 A 0.576
Flood Magnitude and Frequency at Streamgages 5

0 25 50 MILES

0 25 50 KILOMETERS

Base from U.S. Geological Survey digital data,

1:100,000, Universal Transverse Mercator Projection, 

Zone 16.

35

34

33

32

31

88 87 86 85

LAUDERDALE

LAWRENCE

MARION WINSTON

LAMAR FAYETTE

WALKER

CULLMAN

BLOUNT

ETOWAH

CHEROKEE

CALHOUN ST. CLAIR

JEFFERSON

TUSCALOOSA

PICKENS SHELBY CLAY

COOSA CHILTON

BIBB

HALE

PERRY

DALLAS

AUTAUGA

LOWNDES MONTGOMERY

BUTLER

ELMORE

LEE

RUSSELL

BARBOUR

HENRY

DALE

COFFEE

GENEVA

COVINGTON

ESCAMBIA

CONECUH

MONROE

WILCOX

CLARKE

CHOCTAW

WASHINGTON

MOBILE

BALDWIN

HOUSTON

PIKE

CRENSHAW

MACON

BULLOCK

MARENGO

GREENE

SUMTER

TALLAPOOSA

RANDOLPH

CHAMBERS

TALLADEGA

CLEBURNE

COLBERT

FRANKLIN

LIMESTONE

MADISON JACKSON

MORGAN

MARSHALL DEKALB

MISSISSIPPI

GEORGIA

FLORIDA

ALABAMA

TENNESSEE

GULF OF MEXICO

REGION 1

REGION 2

REGION 3

REGION 4

Figure 2. Locations of the four rural flood regions in Alabama.
6 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

Determination of Flood-Depth 

Frequency Relations 

Flood-depth relations can be estimated at ungaged locations by developing regression equations. This was accomplished through the selection of data at streamgages and using 

regional analysis to extend the records spatially. 

Data Selection

Streamflow records for 216 streamgages were used 

in the development of the statewide rural flood-frequency 

analysis (Hedgecock and Feaster, 2007). Of these 216 stations, 

11 streamgages were not used for flood-depth analysis for one 

of two reasons: (1) stage-discharge relations were not defined 

at the upper end of the flow regime or (2) too much variation 

was determined in the gage height of zero flow. One additional 

site was included in region 3 (plate 1), Hamilton Branch near 

DeKalb, Mississippi (USGS gaging station 02467100). This 

site provided data for the lower range of drainage areas for 

region 3. 

A total of 206 streamgages were used to develop the 

flood-depth database. Records were analyzed to provide an 

approximate depth of flow having 67-, 50-, 20-, 10-, 4-, 2- and 

1-percent chance exceedance for 164 streamgages on rural 

streams in Alabama and 42 additional gaging stations in parts 

of the adjacent States of Florida, Georgia, Mississippi, and 

Tennessee. Natural forces create stream channels that are in 

balance with the magnitude and frequency of the flows of 

the stream. For mature streams that are in a state of quasiequilibrium, a correlation may exist between some measurable 

feature or combination of features of the stream channel and 

basin and the depth and frequency of overflows (Wiitala and 

others, 1961). Many different correlations were investigated in 

an attempt to find a significant and hydrologically meaningful 

relation between flood depth and various basin characteristics. 

Basin characteristics were computed for each gage by using 

Geographic Information System (GIS) coverages and included 

in the rural flood-depth dataset. The names, units of measure, 

and methods of measurement for the basin characteristics that 

were considered for use in the study are listed in table 3.

Regression Analysis

Since flood-depth information is collected only at 

streamgages, mathematical methods are required to transfer 

the measured information to ungaged sites within the State 

where flood-depth information is needed. A regional analysis 

provides a tool for doing this. Regional analysis is concerned 

with extending records spatially as differentiated from 

extending records in time. The specific purposes of a regional 

analysis are to provide estimates of the characteristics of 

the frequency distributions at ungaged sites and to improve 

Table 3. Basin characteristics considered for use in regional regression analysis.

Contributing Drainage Area Square miles Area that contributes flow to a point on a stream

Main channel length Miles Length along the main channel from the measuring location 

extended to the basin divide

Main channel slope Feet per mile Difference in the elevation at points corresponding to 10% and 

85% of the main channel divided by the main channel length 

between those two points

Lagtime Main channel length divided by the square root of the main 

channel slope 

Percent Forest Percent Percentage of area covered by forest

Percent Storage Percent Percentage of area of storage (lakes, ponds, reservoirs, and 

wetlands)

Slenderness Ratio Dimensionless Main channel length squared divided by the contributing 

 drainage area

Weighted 67 percent chance 

exceedance peak flow

Cubic feet per second Weighted maximum instantaneous flow that has a 67 percent 

chance of exceedance
Determination of Flood-Depth Frequency Relations 7

estimates of the frequency distributions of flow characteristics 

at gaged sites (Riggs, 1973).The regression model (Riggs, 

1973) used in regional flood-frequency analyses is:

QP= aAbBcCd (1)

where 

 QP is the flood magnitude having a P-percent 

chance of exceedance (dependent 

variable); 

 A, B, C are the basin and climatic characteristics 

of the drainage basin (independent 

variables); and 

 a, b, c, d are the constant and coefficients for a given 

percent chance of exceedance (P).

This regression model was used to develop the flooddepth equations. Multiple regression is directly useful as 

a regionalization tool because the flood depth for a given 

frequency level can be related to basin characteristics, leaving 

residuals that may be considered as due to chance. The regression line averages these residuals. Thus, in one operation, the 

effects of differing basin characteristics are preserved, and the 

chance variation is averaged (Riggs, 1973). Multiple regressions were performed using the stepwise procedure maximum 

R2 improvement (MAXR) used by the Statistical Analysis System (SAS) (SAS Institute Inc, 1982). R2

 is the coefficient of 

determination (square of the multiple correlation coefficient); 

it measures how much variation in the dependent variable 

can be accounted for by the model (independent variables). 

The MAXR method begins by finding the one-variable model 

producing the largest R2 and adds another variable that will 

produce the largest increase in R2. Each variable in the twovariable model is compared to each variable not in the model. 

The MAXR method determines if removing one variable and 

replacing it with another would improve R2. Comparison or 

replacement of variables continues until the “best” two-variable model, three-variable model, and so forth is derived. 

The initial results of the multiple regression analyses for 

206 rural, gaged stations showed that contributing drainage 

area, 67-percent chance exceedance flow, main channel slope, 

and storage were the four explanatory variables having the 

greatest statistical significance in relation to estimated flood 

depths at the gaging stations. Selection of suitable independent 

variables is often made on a statistical basis; that is, many 

variables are used in preliminary regressions and those that 

lack statistical significance are discarded. This practice occasionally results in the retention of a variable in the regression 

the effect of which does not conform to known hydrologic 

principles. Usually the effect of such a variable on the result is 

trivial (a few percentages of reduction in standard error). The 

multiple regression analysis indicated that the most significant 

basin characteristic tested was drainage area. The addition of 

other explanatory variables decreased the standard error of 

prediction by a maximum amount of 1 percent. 

Initially, analyses were preformed for the entire State 

and included data for 206 rural stations. The residuals from 

the regression analysis were plotted on a map to check for 

possible geographical bias. The map of residuals indicated the 

presence of geographic biases or clusters, and development of 

separate regression equations for smaller regions representing the clustered values was considered necessary to improve 

the flood-depth estimates. Regions previously developed in 

“Magnitude and Frequency of Floods in Alabama, 2003” by 

Hedgecock and Feaster (2007) were used because the flooddepth dataset is based on depths that correspond to flow magnitude and frequency for each gage as opposed to computing 

a flood-depth frequency for each gage (see previous section 

Definition of Flood Depths). 

Separate multiple regression analyses were performed for 

each of the four flood regions (fig. 2), and the standard error 

of prediction was reduced in comparison to a single statewide 

regression relation. In each flood region, the contributing 

drainage area was the most statistically significant variable. 

Addition of other significant variables did not decrease the 

standard error of prediction by more than 2 percent. Therefore, contributing drainage area was the only variable retained 

in the regression analyses. The locations of the rural gaging 

stations and regional divides can be viewed in plate 1. The 

resulting regression equations (table 4) for rural streams are in 

the form: 

DP = a (A)b (2)

where 

 DP is the flood depth having a P-percent chance 

of exceedance (dependent variable); 

 A is the basin and climatic characteristics of 

drainage basin (independent variable); and 

 a, b are the constant and coefficients for a given 

percent chance of exceedance (P). 

The regression results and the depth computed from the

stage-discharge relation for each gaging station are listed

in appendix 1.

Accuracy and Limitations

The accuracy of a flood-frequency relation has been 

expressed in two ways—as mean standard error of estimate 

(SEE) or as mean standard error of prediction (SEP). The SEE

is a measure of how well the regression equation fits the data 

used to derive the relation and often is referred to as the model 

error. The SEE is the standard deviation of the differences 

between station data and the corresponding values computed 

from the regression equation. The SEE for this investigation ranged from a minimum of 17 percent (region 3) to a 

maximum of 36 percent (region 2). The SEP is a measure 

of how well the regression relation estimates flood depths 

when applied to ungaged basins. The SEP is the square root 
8 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

of the mean square error of prediction, MSEP. The MSEP is 

the sum of two components—the mean square error resulting 

from the model and the sampling mean square error, which 

results from estimating the model parameters from samples 

of the population. The SEP for this investigation ranged from 

a minimum of 18 percent (region 3) to a maximum of 38 

percent (region 2). Table 5 gives the standard error of estimate 

and standard error of prediction by hydrologic region for the 

selected recurrence intervals. 

The regression relations are valid for ungaged basins 

where the drainage area is within the minimum and maximum 

drainage areas used in the regression analysis. Drainage area 

for the streamgages used in the regression analyses ranged 

from 0.24 to 1,370 mi2. However, the distribution of drainage 

areas varies by hydrologic regions. The user is cautioned that 

if the equations are used outside the limits shown, errors may 

be greater than those defined by the data. Reliability of the 

regression relations for drainage areas outside of the flood 

region limits is unknown. The range of applicable drainage 

areas for each flood region is as follows: 

Flood region 1 0.50 to 1,027 mi2

Flood region 2 0.24 to 1,370 mi2

Flood region 3 0.97 to 607 mi2

Flood region 4 0.76 to 1,344 mi2

When computing flood depths for a minor tributary near

the confluence of a major tributary, the drainage area below 

the confluence should be used in the areas of backwater 

because the major tributary could cause backwater for some 

distance upstream in the minor tributary. The regression 

relations should not be used where dams, flood-detention 

structures, tides, and channelization have a significant effect 

on peak discharges nor should they be used for streams in 

urban areas unless the effects of urbanization are insignificant. 

Application of Flood-Depth Frequency 

Equations

Flood depths can be estimated for the 67-, 50-, 20-, 10-, 

4-, 2-, and 1-percent chance exceedance for most ungaged 

rural streams within the drainage area limits by solving the 

equations in table 4. The hydrologic areas used for selecting 

the applicable equations are shown on plate 1. Flood depth 

estimated from these equations is the depth in feet from the 

gage height of zero flow to the water-surface elevation. The 

boundaries of the hydrologic regions shown on plate 1 were 

drawn to avoid crossing most streams except for large streams 

(streams with drainage areas greater than those used to define 

the equations). Flood-depth relations should not be used to 

obtain flood discharges; the methods for flood-discharge 

estimation are presented in reports by Hedgecock and Feaster 

(2007). Average flood depths may be estimated by the following procedure: (1) locate the drainage basin on plate 1 to determine in which hydrologic region it is located, (2) determine 

the drainage area upstream from the site of interest by using 

a topographic map or aerial photograph, and (3) use the 

equations (table 4) for the appropriate hydrologic region to 

compute average flood-depth values for the probability of 

exceedance of interest.

An example of the application of the procedure described 

above is the following computation of the 50-percent chance 

exceedance depth for the streamgage on Wehadkee Creek 

below Rock Mills, Alabama (USGS gaging station 02339225).

Locate the drainage basin on plate 1 to find which hydrologic region it is in. For example, Wehadkee Creek below 

Rock Mills, Alabama, is in hydrologic region 1. 

Determine the contributing drainage area upstream from 

the site at the road crossing. The published drainage area 

as determined from a U.S. Geological Survey quadrangle 

map is 60.2 mi2

. 

Table 4. Regional flood-depth frequency relations for rural streams in Alabama.

[d, flood depth, in feet; A, contributing drainage area, in square miles]

Percent chance 

exceedance Rural regression equations for the indicated flood regions (fig. 2)

Region 1 Region 2 Region 3 Region 4

 67 d = 

2.7 A 0.283 d = 2.6 A 0.284 d = 4.8 A 0.215 d = 3.4 A 0.225

 50 d = 3.3 A 0.275 d = 3.0 A 0.275 d = 5.3 A 0.220 d = 3.9 A 0.226

 20 d = 4.4 A 0.257 d = 4.1 A 0.244 d = 6.2 A 0.219 d = 4.9 A 0.220

 10 d = 5.1 A 0.247 d = 4.8 A 0.230 d = 7.1 A 0.205 d = 5.6 A 0.214

 4 d = 6.0 A 0.237 d = 5.9 A 0.206 d = 8.6 A 0.180 d = 6.7 A 0.200

 2 d = 6.7 A 0.226 d = 6.5 A 0.196 d = 9.9 A 0.160 d = 7.0 A 0.203

 1 d = 7.3 A 0.221 d = 7.2 A 0.182 d = 11.2 A 0.142 d = 7.5 A 0.201
 References 9

Using the equations for hydrologic region 1 from table 4, 

the 50-percent chance exceedance depth is estimated as 10.2 ft 

above the gage height of zero flow. 

The estimates of flood depth produced by these 

regression equations correspond to flood-flow frequency at 

particular exceedance probability levels. The equations provide estimated values and are not technically equivalent to a 

calibrated hydraulic model.

Summary

Flood depths for selected exceedance probabilities were 

determined for 164 gaging stations on rural streams in Alabama and 42 additional stations in parts of the adjacent States 

of Florida, Georgia, Mississippi, and Tennessee. Data for these 

sites were used to develop regional flood-depth frequency relations that can be used to estimate flood depths for 67- , 50-, 

20-, 10-, 4-, 2-, and 1-percent chance exceedance flows for 

ungaged, unregulated rural streams in Alabama. 

The depth of floods at streamgages was computed by 

taking the difference between the elevation of flood with the 

exceedance probability of 67, 50, 20, 10, 4, 2, and 1 percent 

and the gage height of zero flow. Multiple regression analyses 

were made using the “MAXR” maximum R2 improvement 

procedures. Eight basin and climatic characteristics that were 

computed by using a GIS were evaluated as predictors of flood 

depth in the multiple regression analyses. 

Multiple regression analyses were performed on the rural 

flood-depth dataset for each of the four flood regions. In each 

flood region, the contributing drainage area was the most 

statistically significant variable. Addition of other significant 

variables did not decrease the standard error of prediction by 

more than 2 percent. Therefore, contributing drainage area was 

the only variable retained in the final regression equations. 

The regional flood-depth frequency equations can 

be applied to streams in Alabama that are not affected by 

backwater, regulation, urbanization, tides, or channelization. 

Methods are presented in the report for determining flood 

depths for selected exceedance probabilities on ungaged and 

gaged streams. The equations can be used for streams with 

drainage areas within the limits shown in this report (0.24 to 

1,370 mi2

). When computing flood depths for a minor tributary near the confluence of two streams, the drainage area 

below the confluence in the area of backwater should be used 

in the computation because the major tributary could cause 

backwater for some distance upstream in the minor tributary. 

The flood-depth relations should not be used to compute flood 

flows; methods for computing flood flows are given in reports 

by Hedgecock and Feaster (2007). 

References

Atkins, J.B., 1996, Magnitude and frequency of floods in 

Alabama: U.S. Geological Survey Water-Resources 

Investigations Report 95-4199, 234 p.

Gotvald, A.J., Feaster, T.D., and Weaver, J.C., 2009, Magnitude and frequency of rural floods in the southeastern 

United States, 2006—Volume 1, Georgia: U.S. Geological 

Survey Scientific Investigations Report 2009-5043, 120 p.

Hains, C.F., 1977, Regional flood-depth frequency relation for 

Alabama: Geological Survey of Alabama Circular 97, 13 p. 

Table 5. Accuracy of regional flood-depth frequency relations for rural streams in Alabama.

[n= number of streamgages (pl. 1) used in regional regressions]

Percent 

chance 

exceedance

Region 1

(n=96)

Region 2

(n=29)

Region 3

(n=19)

Region 4

(n=62)

Mean Standard error of 

prediction 

(percent)

Mean Standard error 

of estimate 

(percent)

Mean Standard error of 

prediction 

(percent)

Mean Standard error 

of estimate 

(percent)

Mean Standard error of 

prediction 

(percent)

Mean Standard error 

of estimate 

(percent)

Mean Standard error of 

prediction 

(percent)

Mean Standard error 

of estimate 

(percent)

67 32 32 38 36 26 22 30 29

50 31 31 37 35 25 20 30 29

20 30 29 33 32 24 19 30 30

10 30 29 33 32 23 19 32 32

4 30 30 36 35 22 19 33 33

2 30 30 35 34 18 17 32 31

1 32 32 36 35 20 19 33 32
10 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

Hedgecock, T.S., 2004, Magnitude and frequency of floods 

on small rural streams in Alabama: U.S. Geological Survey 

Scientific Investigations Report 2004-5135, 10 p.

Hedgecock, T.S., and Feaster, T.D., 2007, Magnitude and 

frequency of floods in Alabama, 2003: U.S. Geological 

Survey Scientific Investigations Report 2007–5204, 

28 p., + app. (available online at http://pubs.water.usgs.gov/ 

sir/2007/5204/).

House Document 465, 1966, A unified national program for 

managing flood losses, 89th Congress, 2d session: U.S. 

Government Printing Office, 47 p.

National Oceanic and Atmospheric Administration, Monthly 

station normals of temperature, precipitation, and heating 

and cooling degree days 1971–2000, 2002: National Environmental Satellite, Data, and Information Service, National 

Climatic Data Center, Climatography of the United States 

No. 81, 26 p., (available online at http://nsstc.uah.edu/aosc/

files/ALnorm.pdf).

Olin, D.A., 1985a, Magnitude and frequency of floods in 

Alabama: U.S. Geological Survey Water-Resources 

Investigations Report 84-4191, 96 p., 1 pl. 

Olin, D.A., 1985b, Flood-depth frequency relations for 

streams in Alabama: U.S. Geological Survey WaterResources Investigations Report 85-4296, 50 p.

Riggs, H.C., 1973, Regional analysis of streamflow characteristics: U.S. Geological Survey Techniques of WaterResources Investigations, book 4, chap. B3, 15 p. 

SAS Institute, Inc., 1982, SAS Users Guide–statistics: Cary, 

NC, SAS Institute, Inc., 584 p. 

Wiitala, S.W., Jetter, K.R., and Sommerville, A.J., 1961, 

Hydraulic and hydrologic aspects of flood-plain planning: 

U.S. Geological Survey Water-Supply Paper 1526, 78 p.
Appendix 1

11

Appendix 1
12 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003
Appendix 1 13

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02339225 1 Wehadkee Creek 

below Rock Mills 60.2 9.5 10.4 12.3 13.4 14.8 15.7 16.5

8.6 10.2 12.6 14.0 15.8 16.9 18.1

02340750 1 Osanippa Creek 

near Fairfax 99.7 7.0 8.0 10.3 11.8 13.3 14.2 15.1

9.9 11.7 14.4 15.9 17.9 19.0 20.2

02342150 4 Uchee Creek near 

Seale 162 9.0 9.8 11.1 11.9 12.7 13.3 13.9

10.7 12.3 15.0 16.6 18.5 19.7 20.9

02342200 1 Phelps Creek near 

Opelika 6.67 7.4 7.8 8.5 8.8 9.2 9.4 9.6

4.6 5.6 7.2 8.1 9.4 10.3 11.1

02342500 4 Uchee Creek near 

Fort Mitchell 322 9.2 11.5 17.0 20.4 23.1 24.2 24.9

12.5 14.4 17.5 19.3 21.3 22.6 23.9

02342933 4

South Fork Cowikee 

Creek near Batesville112 14.4 16.8 21.9 25.3 29.9 33.3 36.7

9.8 11.3 13.8 15.4 17.2 18.2 19.4

02343275 4 Abbie Creek near 

Abbeville 48.7 5.9 6.3 7.4 8.1 8.9 9.6 10.0

8.2 9.4 11.5 12.9 14.6 15.4 16.4

02343300 4 Abbie Creek near 

Haleburg 146 9.7 11.9 19.2 25.0 29.0 31.2 33.0

10.4 12.0 14.7 16.3 18.2 19.3 20.4

02343700 4 Stevenson Creek 

near Headland 14 5.3 6.2 8.0 9.1 10.1 11.2 12.1

6.2 7.1 8.8 9.9 11.4 12.0 12.7

02358785 4 Cowarts Creek near 

Cottonwood 103 6.9 7.7 9.4 10.2 11.2 12.2 13.1

9.6 11.1 13.6 15.1 16.9 17.9 19.0

02360000 4

West Fork Choctawhatchee River 

at Blue Springs

86.8 5.5 6.2 7.9 6.0 10.7 11.9 13.1

9.3 10.7 13.1 14.6 16.4 17.3 18.4

02360275 4 Judy Creek near 

Ozark 102 11.3 13.1 15.9 17.0 18.4 19.5 20.4

9.6 11.1 13.6 15.1 16.9 17.9 19.0

02360500 4

East Fork 

Choctawhatchee 

River near 

Midland City

291 13.8 16.1 19.6 21.9 24.4 26.2 28.0

12.2 14.1 17.1 18.9 20.8 22.1 23.5
14 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02361000 4

Choctawhatchee 

River near 

Newton

686 16.1 20.3 27.8 31.2 34.5 36.3 38.1

14.8 17.1 20.6 22.7 24.7 26.4 27.9

02362610 4 Pea River near 

Midway 18.7 9.4 9.8 10.4 11.1 11.8 12.5 13.0

6.6 7.6 9.3 10.5 12.0 12.7 13.5

02363000 4 Pea River near 

Ariton 498 12.4 15.2 17.8 19.3 21.0 22.1 23.2

13.8 15.9 19.2 21.2 23.2 24.7 26.1

02363005 4

Pea River 

tributary near 

Roeton

0.76 2.4 3.1 4.7 5.8 7.2 8.3 9.5

3.2 3.7 4.6 5.3 6.3 6.6 7.1

02364000 4 Pea River at Elba 959 19.8 22.8 30.0 34.4 40.2 43.6 45.8

15.9 18.4 22.2 24.3 26.5 28.2 29.8

02364500 4 Pea River near 

Samson 1182 24.4 27.9 34.3 37.8 41.3 43.5 45.3

16.7 19.3 23.2 25.5 27.6 29.4 31.1

02365310 4

Grants Branch 

tributary near 

Fadette

1.44 4.7 5.5 7.5 8.9 9.5 9.6 9.7

3.7 4.2 5.3 6.1 7.2 7.5 8.1

02367500 4 Lightwood Knot 

Creek at Babbie 114 7.7 8.1 9.7 10.9 12.4 13.8 15.1

9.9 11.4 13.9 15.4 17.3 18.3 19.4

02367800 4 Yellow River near 

Wing 461 12.5 13.7 16.4 17.7 19.2 20.1 20.8

13.5 15.6 18.9 20.8 22.8 24.3 25.7

02369800 4 Blackwater River 

near Bradley 87.7 11.2 13.6 17.3 19.5 22.0 23.5 24.4

9.3 10.7 13.1 14.6 16.4 17.4 18.4

02371000 4 Conecuh River 

near Troy 257 11.1 12.3 14.4 15.5 16.7 17.6 18.7

11.8 13.7 16.6 18.4 20.3 21.6 22.9

02371200 4 Indian Creek near 

Troy 8.87 3.9 4.2 4.9 5.3 5.7 6.0 6.1

5.6 6.4 7.9 8.9 10.4 10.9 11.6

02371500 4 Conecuh River at 

Brantley 500 16.2 18.4 21.2 22.5 23.9 24.7 25.6

13.8 15.9 19.2 21.2 23.2 24.7 26.2
Appendix 1 15

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02372000 4 Patsaliga Creek at 

Luverne 254 12.3 13.2 14.7 15.6 16.5 17.3 17.9

11.8 13.6 16.6 18.3 20.3 21.5 22.8

02372250 4 Patsaliga Creek 

near Brantley 442 18.0 19.3 21.0 21.9 23.1 24.0 23.7

13.4 15.5 18.7 20.6 22.7 24.1 25.5

02372500 4 Conecuh River 

near Andalusia 1344 23.5 29.1 34.5 37.4 40.1 42.1 43.8

17.2 19.9 23.9 26.2 28.3 30.2 31.9

02372800 4 Stallings Creek 

near Greenville 37.8 8.4 9.0 10.0 10.4 11.1 11.7 12.2

7.7 8.9 10.9 12.2 13.9 14.6 15.6

02373000 4 Sepulga River 

near Mckenzie 470 9.7 13.0 19.1 21.9 24.0 25.3 27.0

13.6 15.7 19.0 20.9 22.9 24.4 25.8

02373500 4 Pigeon Creek near 

Thad 307 15.9 18.4 22.9 24.9 26.9 28.6 30.0

12.3 14.2 17.3 19.1 21.1 22.4 23.7

02374500 4 Murder Creek 

near Evergreen 176 10.7 11.6 13.4 14.6 15.9 16.9 17.9

10.9 12.5 15.3 16.9 18.8 20.0 21.2

02374970 4

Sizemore 

Creek near 

Robinsonville

79.4 7.6 8.2 9.4 10.0 11.0 11.6 12.3

9.1 10.5 12.8 14.3 16.1 17.0 18.1

02375000 4 Big Escambia 

Creek at Flomaton 330 11.2 12.1 16.1 17.6 18.7 19.2 19.7

12.5 14.5 17.5 19.4 21.4 22.7 24.1

02377500 4 Styx River near 

Loxley 92.2 8.8 12.2 16.9 18.3 19.5 20.5 21.3

9.4 10.8 13.3 14.7 16.6 17.5 18.6

02378500 4 Fish River near 

Silver Hill 55.3 9.6 11.0 14.1 15.8 17.8 19.3 20.8

8.4 9.7 11.8 13.2 14.9 15.8 16.8

02398300 1 Chattooga River 

above Gaylesville 366 13.7 15.6 18.2 19.8 21.5 22.7 23.9

14.3 16.7 20.1 21.9 24.3 25.4 26.9

02398500 1 Chattooga River 

at Gaylesville 379 15.9 16.8 18.5 19.5 20.7 21.7 22.5

14.5 16.9 20.2 22.1 24.5 25.6 27.1
16 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02399000 1 Little River near 

Jamestown 125 7.2 8.2 10.1 11.3 12.6 13.5 14.3

10.6 12.4 15.2 16.8 18.8 20.0 21.2

02399200 1 Little River near 

Blue Pond 199 7.6 8.2 9.8 10.7 11.9 12.7 13.6

12.1 14.1 17.1 18.9 21.0 22.2 23.5

02400000 1 Terrapin Creek 

near Piedmont 116 9.1 9.9 11.2 11.9 12.6 13.2 13.6

10.4 12.2 14.9 16.5 18.5 19.6 20.9

02400033 1 Nances Creek 

near White Plains 4.62 3.1 3.6 5.1 6.1 7.3 8.3 9.2

4.2 5.0 6.5 7.4 8.6 9.5 10.2

02400100 1 Terrapin Creek at 

Ellisville 252 9.8 10.9 13.1 14.2 15.4 16.3 17.1

12.9 15.1 18.2 20.0 22.2 23.4 24.8

02401000 1 Big Wills Creek 

near Reece City 182 9.8 10.6 12.1 13.1 14.2 15.0 15.6

11.8 13.8 16.8 18.4 20.6 21.7 23.1

02401370 1 Big Canoe Creek 

near Springville 45 9.2 9.8 11.0 11.9 12.9 13.7 14.3

7.9 9.4 11.7 13.1 14.8 15.8 16.9

02401390 1 Big Canoe Creek 

at Ashville 141 14.5 15.1 16.2 16.8 17.6 18.1 18.6

11.0 12.9 15.7 17.3 19.4 20.5 21.8

02401470 1 Little Canoe 

Creek near Steele 22.3 5.7 6.1 6.8 7.2 7.6 8.0 8.2

6.5 7.7 9.8 11.0 12.5 13.5 14.5

02401500 1 Big Canoe Creek 

near Gadsden 253 13.9 15.4 18.3 22.1 24.0 26.1 28.2

12.9 15.1 18.2 20.0 22.3 23.4 24.8

02404000 1 Choccolocco 

Creek near Jenifer 277 8.4 10.2 14.2 16.4 19.0 20.7 22.5

13.3 15.5 18.7 20.5 22.8 23.9 25.3

02404400 1

Choccolocco 

Creek at Jackson 

Shoals near 

Lincoln

481 10.2 12.2 17.0 20.2 23.8 26.3 28.9

15.5 18.0 21.5 23.4 25.9 27.1 28.6
Appendix 1 17

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02404500 1

Choccolocco 

Creek near 

Lincoln

496 13.4 16.9 21.6 23.1 25.1 26.0 27.1

15.6 18.2 21.7 23.6 26.1 27.2 28.8

02405500 1 Kelly Creek near 

Vincent 193 15.2 17.7 21.9 24.0 25.3 26.0 26.7

12.0 14.0 17.0 18.7 20.9 22.0 23.4

02406500 1 Talladega Creek 

at Alpine 150 10.2 11.0 12.1 12.8 13.4 13.9 14.1

11.1 13.1 15.9 17.6 19.7 20.8 22.1

02407500 1 Yellowleaf Creek 

near Wilsonville 96.5 13.2 15.5 17.9 19.1 20.4 21.5 22.6

9.8 11.6 14.2 15.8 17.7 18.8 20.0

02407680 1

Waxahatchee 

Creek near 

Columbiana

32.9 9.4 10.8 13.4 14.9 16.9 18.4 19.8

7.3 8.6 10.8 12.1 13.7 14.8 15.8

02408500 1 Hatchet Creek 

near Rockford 233 14.5 17.1 20.4 22.5 24.9 26.4 27.9

12.6 14.8 17.9 19.6 21.8 23.0 24.4

02408540 1 Hatchet Creek 

below Rockford 263 12.3 15.1 21.0 24.8 29.4 32.9 36.0

13.1 15.3 18.4 20.2 22.5 23.6 25.0

02409000 1 Weogufka Creek 

near Weogufka 73.4 8.1 9.1 10.9 11.9 12.9 13.8 14.5

9.1 10.8 13.3 14.7 16.6 17.7 18.9

02409540 1 Proctor Creek 

near Rockford 1.01 3.3 4.0 5.8 6.8 8.1 9.3 10.3

2.7 3.3 4.4 5.1 6.0 6.7 7.3

02410000 1 Paterson Creek 

near Central 4.91 3.9 5.3 8.0 8.8 9.4 9.6 9.8

4.2 5.1 6.6 7.6 8.7 9.6 10.4

02412000 1 Tallapoosa River 

near Heflin 448 15.7 18.5 22.4 24.3 26.7 28.6 30.4

15.2 17.7 21.1 23.0 25.5 26.6 28.1

02412065 1

Cane Creek at 

U.S. Hwy. 78 near 

Heflin

52.8 10.4 10.9 11.6 12.1 12.7 13.0 13.6

8.3 9.8 12.2 13.6 15.4 16.4 17.5
18 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02412500 1 Tallapoosa River 

near Ofelia 792 9.5 11.6 15.4 17.8 20.3 22.1 23.6

17.9 20.7 24.5 26.5 29.2 30.3 31.9

02413300 1 Little Tallapoosa 

River near Newell 406 11.5 13.4 16.5 17.7 18.6 19.3 19.8

14.8 17.2 20.6 22.5 24.9 26.0 27.5

02413400 1 Wedowee Creek 

above Wedowee 6.87 5.0 5.6 6.8 7.7 8.8 9.6 10.3

4.7 5.6 7.2 8.2 9.5 10.4 11.2

02413475 1 Wedowee Creek 

near Wedowee 46.6 8.6 10.0 12.3 13.8 15.4 16.7 17.5

8.0 9.5 11.8 13.2 14.9 16.0 17.1

02413500 1

Little Tallapoosa 

River near 

Wedowee

591 13.3 15.4 18.7 20.5 22.5 23.8 24.6

16.4 19.1 22.7 24.7 27.2 28.3 29.9

02414800 1 Harbuck Creek 

near Hackneyville 7.97 3.8 4.8 6.9 8.1 9.4 10.3 11.4

4.9 5.8 7.5 8.5 9.8 10.7 11.5

02415000 1 Hillabee Creek 

near Hackneyville 190 12.2 14.7 19.1 21.3 23.7 25.4 26.7

11.9 14.0 16.9 18.6 20.8 21.9 23.3

02416481 1 Norrell Branch 

near Dadeville 0.5 1.3 2.0 3.3 4.6 6.4 7.7 9.1

2.2 2.7 3.7 4.3 5.1 5.7 6.3

02419000 4 Uphapee Creek 

near Tuskegee 333 11.6 14.6 20.0 22.4 25.3 27.4 29.3

12.6 14.5 17.6 19.4 21.4 22.8 24.1

02421000 3 Catoma Creek 

near Montgomery 290 19.5 21.5 23.9 25.7 27.6 28.6 29.4

16.2 18.5 21.5 22.7 23.9 24.5 25.1

02421300 2 Ivy Creek at 

Mulberry 10.7 2.9 3.7 6.5 9.5 14.3 17.6 20.9

5.1 5.8 7.3 8.3 9.6 10.3 11.1

02422000 3 Big Swamp Creek 

near Lowndesboro 244 16.0 16.7 17.7 18.5 19.4 20.0 20.7

15.7 17.8 20.7 21.9 23.1 23.9 24.4

02422500 2 Mulberry Creek at 

Jones 203 8.6 10.7 15.7 19.0 22.4 25.2 28.1

11.8 12.9 15.0 16.3 17.6 18.4 18.9
Appendix 1 19

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02423500 1 Cahaba River near 

Acton 230 19.3 23.5 31.8 35.8 39.1 41.2 43.2

12.6 14.7 17.8 19.5 21.8 22.9 24.3

02423555 1 Cahaba River near 

Helena 335 14.2 17.4 25.4 31.7 38.2 41.7 45.5

14.0 16.3 19.6 21.4 23.8 24.9 26.4

02423800 1

Little Cahaba 

River near 

Brierfield

147 11.0 13.3 18.2 20.9 23.9 26.0 27.7

11.1 13.0 15.9 17.5 19.6 20.7 22.0

02424000 1 Cahaba River at 

Centreville 1027 25.0 28.0 32.0 33.9 35.6 36.7 38.1

19.2 22.2 26.1 28.3 31.0 32.1 33.8

02424010 2 Sandy Creek near 

Centreville 0.59 3.0 3.6 4.9 5.7 6.7 7.5 8.5

2.2 2.6 3.6 4.3 5.3 5.9 6.5

02424500 2 Cahaba River at 

Sprott 1370 15.0 17.2 20.2 21.9 23.7 25.3 27.0

20.2 21.9 23.9 25.3 26.1 26.8 26.8

02424940 2 Oakmulgee Creek 

near Augustin 220 9.8 12.5 16.4 18.1 19.9 21.2 22.3

12.0 13.2 15.3 16.6 17.9 18.7 19.2

02425500 3 Cedar Creek at 

Minter 211 14.0 17.1 19.7 20.4 21.2 21.6 22.0

15.2 17.2 20.0 21.3 22.5 23.3 23.9

02425655 3 Mush Creek near 

Selma 44.4 7.2 8.4 10.6 11.8 13.3 14.4 15.5

10.8 12.2 14.2 15.5 17.0 18.2 19.2

02426000 3

Boguechitto 

Creek near 

Browns

95.4 14.6 14.9 16.2 17.3 18.8 19.9 21.1

12.8 14.4 16.8 18.1 19.5 20.5 21.4

02427250 3 Pine Barren Creek 

near Snow Hill 261 17.5 18.7 21.2 22.8 24.5 26.2 27.4

15.9 18.0 21.0 22.2 23.4 24.1 24.7

02427300 4 Prairie Creek near 

Oak Hill 10.3 8.3 9.6 12.3 14.5 16.9 18.7 20.3

5.7 6.6 8.2 9.2 10.7 11.2 12.0

02427700 3 Turkey Creek at 

Kimbrough 97.5 12.7 15.1 20.1 21.7 22.8 23.5 24.0

12.8 14.5 16.9 18.2 19.6 20.6 21.5
20 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02427875 4 Pursley Creek 

near Camden 64.3 10.8 12.3 15.6 17.6 20.6 24.1 25.3

8.7 10.0 12.2 13.7 15.4 16.3 17.3

02428500 4 Big Flat Creek 

near Fountain 247 12.4 14.6 18.2 19.6 21.1 21.9 23.6

11.7 13.5 16.5 18.2 20.2 21.4 22.7

02429000 4 Limestone Creek 

near Monroeville 121 8.6 9.4 10.8 11.8 12.9 13.7 14.5

10.0 11.5 14.1 15.6 17.5 18.5 19.7

02429595 4 Little River near 

Uriah 99.2 8.1 9.5 12.3 13.7 15.4 16.6 17.8

9.6 11.0 13.5 15.0 16.8 17.8 18.9

02429650 4 Majors Creek near 

Tensaw 44.4 10.9 12.2 14.7 16.3 18.1 19.4 20.5

8.0 9.2 11.3 12.6 14.3 15.1 16.1

02437800 1 Barn Creek near 

Hackleburg 13.1 5.7 7.5 10.7 12.0 13.8 14.9 16.0

5.6 6.7 8.5 9.6 11.0 12.0 12.9

02438000 1

Buttahatchee 

River below 

Hamilton

277 18.9 21.9 25.7 27.4 29.4 30.8 32.0

13.3 15.5 18.7 20.5 22.8 23.9 25.3

02442000 2 Luxapallila Creek 

near Fayette 130 11.2 11.6 12.3 12.7 13.1 13.5 13.7

10.4 11.4 13.4 14.7 16.1 16.9 17.5

02442500 2 Luxapallila Creek 

at Millport 247 11.3 11.7 12.3 12.6 13.0 13.3 13.5

12.4 13.6 15.7 17.0 18.4 19.1 19.6

02443230 2 Mud Creek near 

Fernbank 35.8 6.9 7.3 7.7 8.0 8.5 8.8 9.1

7.2 8.0 9.8 10.9 12.3 13.1 13.8

02443730 2

Kincaide Creek 

tributary near 

Ethelsville

0.24 1.2 1.4 2.3 2.5 3.3 3.8 4.3

1.7 2.0 2.9 3.5 4.4 4.9 5.6

02444000 2 Coal Fire Creek 

near Pickensville 126 8.2 8.8 9.9 10.5 11.1 11.7 12.3

10.3 11.3 13.3 14.6 16.0 16.8 17.4

02445000 2 Lubbub Creek 

near Carrollton 112 8.7 9.0 10.4 11.5 12.8 13.6 14.4

9.9 11.0 13.0 14.2 15.6 16.4 17.0
Appendix 1 21

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02445245 1 New River near 

Winfield 59.3 14.0 15.6 18.6 20.4 22.3 23.6 24.9

8.6 10.1 12.6 14.0 15.8 16.9 18.0

02445500 2 Sipsey River at 

Fayette 282 13.0 13.7 14.8 15.3 16.1 16.6 17.2

12.9 14.2 16.2 17.6 18.9 19.6 20.1

02446000 2 Sipsey River at 

Moores Bridge 413 14.0 14.5 15.6 16.3 17.3 17.8 18.3

14.4 15.7 17.8 19.2 20.4 21.2 21.5

02446500 2 Sipsey River near 

Elrod 528 13.2 13.8 14.8 15.6 16.9 17.1 17.5

15.4 16.8 18.9 20.3 21.5 22.2 22.5

02447000 2 Sipsey River near 

Pleasant Ridge 769 15.7 17.2 20.3 22.8 25.1 26.4 27.3

17.2 18.7 20.7 22.1 23.2 23.9 24.1

02448500 2 Noxubee River 

near Geiger 1097 31.3 34.5 38.5 39.8 41.4 42.5 43.5

19.0 20.6 22.6 24.0 25.0 25.6 25.7

02448900 3 Bodka Creek near 

Geiger 158 16.8 17.9 19.6 20.3 22.0 22.7 23.7

14.3 16.1 18.8 20.0 21.4 22.3 23.0

02449245 2 Brush Creek near 

Eutaw 43.2 13.4 15.1 16.9 18.0 19.3 20.1 21.0

7.6 8.5 10.3 11.4 12.8 13.6 14.3

02449400 3 Jones Creek near 

Epes 11.8 13.4 14.9 17.1 18.6 20.1 21.1 22.1

8.2 9.1 10.6 11.8 13.4 14.7 15.9

02450000 1 Mulberry Fork 

near Garden City 365 12.9 14.9 18.1 19.8 21.6 22.8 23.8

14.3 16.7 20.0 21.9 24.3 25.4 26.9

02450180 1 Mulberry Fork 

near Arkadelphia 487 25.7 28.6 33.7 36.4 39.7 41.9 43.9

15.6 18.1 21.6 23.5 26.0 27.1 28.7

02450200 1 Dorsey Creek 

near Arkadelphia 13 6.1 6.8 8.7 9.8 11.3 12.4 13.3

5.6 6.7 8.5 9.6 11.0 12.0 12.9

02450250 1 Sipsey Fork near 

Grayson 92.1 20.6 24.3 30.8 34.0 37.6 39.8 41.6

9.7 11.4 14.1 15.6 17.5 18.6 19.8
22 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02450825 1

Clear Creek 

at New Hope 

Church nr Poplar 

Springs

101 9.0 10.9 14.4 16.6 19.4 21.3 23.1

10.0 11.7 14.4 15.9 17.9 19.0 20.2

02451000 1 Clear Creek at 

Falls City 149 5.0 6.0 8.1 9.6 11.4 12.7 13.8

11.1 13.1 15.9 17.6 19.6 20.8 22.1

02453000 1 Blackwater Creek 

near Manchester 181 6.2 7.2 9.1 10.3 11.7 12.8 13.8

11.8 13.8 16.7 18.4 20.6 21.7 23.0

02453950 1 Lost Creek near 

Jasper 115 19.3 20.4 22.7 24.2 25.6 26.8 27.8

10.3 12.2 14.9 16.5 18.5 19.6 20.8

02454000 1 Lost Creek near 

Oakman 134 17.5 21.2 25.4 28.7 29.7 30.4 30.9

10.8 12.7 15.5 17.1 19.2 20.3 21.5

02454200 1 Wolf Creek near 

Oakman 85 14.6 16.7 20.1 22.5 25.3 27.8 29.0

9.5 11.2 13.8 15.3 17.2 18.3 19.5

02454500 1 Locust Fork 

below Snead 147 17.0 19.4 24.4 28.4 31.0 32.5 34.0

11.1 13.0 15.9 17.5 19.6 20.7 22.0

02455000 1 Locust Fork near 

Cleveland 303 10.1 11.0 13.1 14.5 16.2 17.5 18.7

13.6 15.9 19.1 20.9 23.2 24.4 25.8

02455500 1 Locust Fork at 

Trafford 624 27.8 32.1 40.1 45.6 52.4 57.1 62.3

16.7 19.4 23.0 25.0 27.6 28.7 30.3

02456000 1 Turkey Creek at 

Morris 80.9 13.0 15.1 19.2 21.6 24.3 25.6 27.4

9.4 11.0 13.6 15.1 17.0 18.1 19.3

02456500 1 Locust Fork at 

Sayre 885 23.8 27.7 34.6 38.8 43.8 47.2 50.2

18.4 21.3 25.2 27.3 30.0 31.1 32.7

02462000 1 Valley Creek near 

Oak Grove 148 13.4 16.8 21.7 23.9 26.4 28.0 29.7

11.1 13.0 15.9 17.5 19.6 20.7 22.0

02462600 1 Blue Creek near 

Oakman 5.32 4.4 5.0 6.1 6.7 7.4 7.9 8.3

4.3 5.2 6.8 7.7 8.9 9.8 10.6
Appendix 1 23

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02462800 1 Davis Creek 

below Abernant 45.3 8.6 9.6 13.0 15.2 18.3 21.0 23.2

7.9 9.4 11.7 13.1 14.8 15.9 17.0

02463500 1 Hurricane Creek 

near Holt 108 7.9 9.4 14.4 17.4 20.2 22.1 23.9

10.2 12.0 14.7 16.2 18.2 19.3 20.5

02464000 1 North River near 

Samantha 223 12.6 15.0 20.2 24.0 28.4 31.3 34.3

12.5 14.6 17.7 19.4 21.6 22.7 24.1

02465205 2 Jay Creek near 

Coker 3.65 3.9 4.5 5.2 5.5 5.8 6.0 6.2

3.8 4.3 5.6 6.5 7.7 8.4 9.1

02465493 2 Elliotts Creek at 

Moundville 32.3 5.2 5.5 6.3 6.7 7.3 7.6 7.8

7.0 7.8 9.6 10.7 12.1 12.8 13.6

02465500 2 Fivemile Creek 

near Greensboro 73.6 6.7 7.0 8.0 8.6 9.4 9.9 10.4

8.8 9.8 11.7 12.9 14.3 15.1 15.7

02466500 3 Big Prairie Creek 

near Gallion 171 16.6 17.3 18.1 18.6 19.3 20.1 20.7

14.5 16.4 19.1 20.4 21.7 22.5 23.2

02467500 3

Sucarnoochee 

River at 

Livingston

607 18.3 21.3 24.6 26.5 28.9 30.7 32.2

19.0 21.7 25.2 26.4 27.3 27.6 27.8

02468000 3 Alamuchee Creek 

near Cuba 62.3 11.1 13.9 15.7 16.8 17.9 18.7 19.3

11.7 13.2 15.3 16.6 18.1 19.2 20.1

02468500 3 Chickasaw Bogue 

near Linden 257 20.1 21.8 24.6 25.8 27.6 29.5 31.4

15.8 18.0 20.9 22.1 23.3 24.1 24.6

02469000 3 Kinterbish Creek 

near York 90.9 12.1 15.3 20.1 21.4 22.4 23.4 23.6

12.7 14.3 16.6 17.9 19.4 20.4 21.2

02469500 3 Tuckabum Creek 

near Butler 115 12.9 16.1 18.9 20.1 21.4 22.1 22.8

13.3 15.1 17.5 18.8 20.2 21.2 22.0

02469550 3 Horse Creek near 

Sweet Water 60.4 13.7 14.3 15.7 16.1 16.6 17.2 17.3

11.6 13.1 15.2 16.5 18.0 19.1 20.1
24 Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

02469700 4 Okatuppa Creek 

at Gilbertown 148 9.8 11.1 14.1 15.3 16.3 16.7 17.2

10.5 12.1 14.7 16.3 18.2 19.3 20.5

02469800 3 Satilpa Creek near 

Coffeeville 164 11.9 12.6 13.9 14.6 15.6 16.2 16.8

14.4 16.3 18.9 20.2 21.5 22.4 23.1

02470100 4 Bassett Creek at 

Walker Springs 195 8.2 8.8 10.1 10.7 11.6 12.3 12.6

11.1 12.8 15.6 17.3 19.2 20.4 21.6

02471001 4 Chickasaw Creek 

near Kushla 125 13.5 15.0 17.4 18.7 20.3 21.4 22.1

10.1 11.6 14.2 15.7 17.6 18.7 19.8

02479431 4 Pond Creek near 

Deer Park 20.4 10.5 12.2 15.6 17.9 20.8 23.0 25.0

6.7 7.7 9.5 10.7 12.2 12.9 13.7

02479560 4

Escatawpa River 

near Agricola, 

Miss.

562 15.6 16.5 18.6 20.0 21.9 23.1 23.9

14.1 16.3 19.7 21.7 23.8 25.3 26.8

02479980 4 Crooked Creek 

near Fairview 8.08 6.4 6.9 8.1 8.8 9.7 10.3 10.9

5.4 6.3 7.8 8.8 10.2 10.7 11.4

03572110 1 Crow Creek at 

Bass 131 14.5 15.1 16.1 16.6 17.2 17.6 17.9

10.7 12.6 15.4 17.0 19.1 20.2 21.4

03572900 1 Town Creek near 

Geraldine 141 11.8 13.7 17.7 20.0 23.1 25.2 27.4

11.0 12.9 15.7 17.3 19.4 20.5 21.8

03573000 1 Short Creek near 

Albertville 91.6 9.6 11.1 13.2 15.1 16.9 19.0 20.2

9.7 11.4 14.0 15.6 17.5 18.6 19.8

03574500 1 Paint Rock River 

near Woodville 320 17.6 18.5 19.9 20.7 21.6 22.2 22.7

13.8 16.1 19.4 21.2 23.5 24.7 26.1

03575000 1 Flint River near 

Chase 342 10.4 12.9 17.4 19.9 22.8 25.0 27.2

14.1 16.4 19.7 21.6 23.9 25.0 26.5

03575830 1 Indian Creek near 

Madison 49 6.5 7.2 8.5 9.2 10.2 10.8 11.4

8.1 9.6 12.0 13.3 15.1 16.1 17.3
Appendix 1 25

Appendix 1. Flood depths for selected exceedance probabilities at rural streamgages used in Alabama rural depth

regression analyses.—Continued

[mi2, square miles; top line is the average computed depth; bottom line is the result of the regional regression equations]

Station 

number

Flood 

region 

(fig.2)

Station name Drainage 

area (mi2

)

Flood depth, in feet, for indicated exceedance probability in percent

 67 50 20 10 4 2 1

03576250 1 Limestone Creek 

near Athens 119 9.6 10.6 12.4 13.4 14.6 15.3 15.9

10.4 12.3 15.0 16.6 18.6 19.7 21.0

03576400 1 Piney Creek near 

Athens 55.8 5.9 6.7 8.1 9.1 10.1 10.9 11.6

8.4 10.0 12.4 13.8 15.6 16.6 17.8

03576500 1 Flint Creek near 

Falkville 86.3 12.0 12.6 13.6 14.1 14.7 15.0 15.4

9.5 11.2 13.8 15.3 17.3 18.3 19.6

03585300 1 Sugar Creek near 

Good Springs 152 9.9 10.7 11.4 11.9 12.7 13.1 13.6

11.2 13.1 16.0 17.6 19.7 20.9 22.2

03586500 1 Big Nance Creek 

at Courtland 166 16.3 18.3 20.5 21.3 22.0 22.6 23.0

11.5 13.5 16.4 18.0 20.2 21.3 22.6

03590000 1 Cypress Creek 

near Florence 209 9.1 11.3 15.3 17.7 20.4 22.4 24.2

12.2 14.3 17.4 19.1 21.3 22.4 23.8

03591800 1 Bear Creek near 

Hackleburg 143 16.3 20.6 25.7 29.4 34.2 37.7 40.9

11.0 12.9 15.8 17.4 19.5 20.6 21.9

03592200 2 Cedar Creek near 

Pleasant Site 189 16.0 17.8 20.5 22.3 24.0 25.3 27.2

11.5 12.7 14.7 16.0 17.4 18.2 18.7

03592300 2 Little Bear Creek 

near Halltown 78.2 10.0 11.1 13.0 13.6 14.4 15.3 16.1

9.0 9.9 11.9 13.1 14.5 15.3 15.9

03592500 2 Bear Creek at 

Bishop 667 15.3 17.3 19.2 20.4 21.6 22.6 23.2

16.5 17.9 20.0 21.4 22.5 23.3 23.5


K.G. Lee and T.S Hedgecock—Flood-Depth Frequency Relations for Rural Streams in Alabama, 2003—Scientific Investigations Report 2010–5066

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