U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2011–5175

Prepared in cooperation with the City of Wichita Falls, Texas

Assessment of Channel Changes, Models of Historical Floods 

and Effects of Backwater on Flood Stage, and Flood Mitigation 

Alternatives for the Wichita River at Wichita Falls, Texas
Front cover: Looking downstream from Loop 11 and U.S. Geological Survey streamflow-gaging station 07312500 

Wichita River at Wichita Falls, Texas, August 23, 2010.

Back cover: 

Top photograph, Looking upstream along Holliday Creek, August 23, 2010. The arrow indicates the location of 

U.S. Geological Survey streamflow-gaging station 07312610 Holliday Creek at Wichita Falls, Texas.

Bottom photograph, Former U.S. Geological Survey colleague David Holmes and author Karl Winters in flight over the 

Wichita River, August 23, 2010.
Assessment of Channel Changes, 

Models of Historical Floods and Effects 

of Backwater on Flood Stage, and Flood 

Mitigation Alternatives for the Wichita 

River at Wichita Falls, Texas

By Karl E. Winters and Stanley Baldys III

Prepared in cooperation with the City of Wichita Falls, Texas

Scientific Investigations Report 2011–5175

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: 2011

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Suggested citation:

Winters, K.E., Baldys, Stanley, III, 2011, Assessment of channel changes, models of historical floods and effects 

of backwater on flood stage, and flood mitigation alternatives for the Wichita River at Wichita Falls, Texas: 

U.S. Geological Survey Scientific Investigations Report 2011-5175, 28 p.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................2

Previous Studies and Background Information...............................................................................2

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

Methods...........................................................................................................................................................2

Historical Streamflow Data ................................................................................................................2

Aerial and Ground Photography.........................................................................................................4

Channel Cross Sections ......................................................................................................................4

Channel Roughness..............................................................................................................................5

Step-Backwater Modeling..................................................................................................................5

Assessment of Channel Changes ...............................................................................................................6

Models of Historical Floods and Effects of Backwater on Flood Stage ............................................14

2007 Flood.............................................................................................................................................14

2008 Flood.............................................................................................................................................15

1941 Flood.............................................................................................................................................16

Effects of Backwater on Wichita River and Holliday Creek .......................................................16

Flood Mitigation Alternatives.....................................................................................................................20

Increasing Capacity on the Bypass Channel.21

Removing Bridge Obstructions.........................................................................................................22

Widening Aggraded Channel Banks ...............................................................................................22

Reducing Channel Roughness..........................................................................................................23

Comparison of Flood Mitigation Alternatives.................................................................................23

Summary........................................................................................................................................................25

References Cited..........................................................................................................................................27

Figures

1. Map showing location of study area ..................................................................................................3

2. Photograph of staff gage operated by the City of Wichita Falls, Texas ........................................5

3. Graph showing changes in the stage-discharge relation indicated by measurements 

at U.S. Geological Survey streamflow-gaging station 07312500 Wichita River 

at Wichita Falls, Texas (Loop 11 gage) .....................................................................................7

4. Graph showing mean velocities from measurements at U.S. Geological Survey 

streamflow-gaging station 07312500 Wichita River at Wichita Falls, Texas 

(Loop 11 gage)...............................................................................................................................7

5. Graph showing annual peak discharges at U.S. Geological Survey streamflowgaging station 07312500 Wichita River at Wichita Falls, Texas (Loop 11 gage) .................8

6. Aerial photograph showing Scott Avenue and Martin Luther King Junior Boulevard 

bridges on the Wichita River, February 7, 1968........................................................................9

7. Photographs of Wichita River looking downstream from Loop 11 in 1950, 1961, 1975, and 

2009 at U.S. Geological Survey streamflow-gaging station 07312500 Wichita River 

at Wichita Falls, Texas ...............................................................................................................10
iv

8. Aerial photograph of Wichita River looking downstream from Loop 11, August 23, 2010, 

Wichita Falls, Texas....................................................................................................................11

9. Graph showing historical channel cross sections of the Wichita River at U.S. Geological 

Survey streamflow-gaging station 07312500 Wichita River at Wichita Falls, Texas, 

1938–2009 ...................................................................................................................................11

10. Graph showing channel cross sections of the Wichita River between 0.9 and 2.6 miles 

downstream from Martin Luther King Junior Boulevard, Wichita Falls, Texas, 

1986 and 2009...............................................................................................................................12

11. Photograph of Wichita River obstructions A, on the right (south) bank at the 

downstream side of Scott Avenue bridge looking downstream and B, on the left 

bank at Martin Luther King Junior Boulevard bridge, looking downstream, 

February 23, 2009 ........................................................................................................................13

12. Graph showing Wichita River cross sections from 1986 and 2009, and the obstruction 

on the right (south) bank at the downstream side of Scott Avenue bridge in 

Wichita Falls, Texas....................................................................................................................13

13. Graph showing Wichita River cross sections from 1986 and 2009 and the obstruction 

on the left (north) bank at the downstream side of the Martin Luther King Junior 

Boulevard bridge in Wichita Falls, Texas ...............................................................................13

14. Graph showing calibrated water-surface profile for the 2007 flood on the Wichita 

River at Wichita Falls, Texas.....................................................................................................14

15. Graph showing calibrated water-surface profile for the 2008 flood on the Wichita 

River at Wichita Falls, Texas.....................................................................................................15

16. Graph showing cross-section conveyance computed from 1991 Federal Emergency 

Management (FEMA) HEC-2 model (1991 FEMA) and 2009 U.S. Geological Survey 

HEC-RAS model (2009 USGS) at U.S. Geological Survey streamflow-gaging station 

07312500 Wichita River at Wichita Falls, Texas (Loop 11 gage) .........................................16

17. Graph showing calibrated water-surface profiles for the 2007 and 1941 floods on the 

Wichita River at Wichita Falls, Texas......................................................................................17

18. Graph showing stage hydrographs during A, January 2010, and B, July 2010 at U.S. 

Geological Survey streamflow-gaging stations 07312500 Wichita River at Wichita 

Falls, Texas (Loop 11 gage), 07312610 Holliday Creek at Wichita Falls, Tex. 

(Holliday Creek gage), and 07312700 Wichita River near Charlie, Tex. (Wichita 

River near Charlie, Tex., gage)..................................................................................................17

19. Graph showing water-surface profiles computed for various streamflow amounts in 

Holliday Creek, with no backwater from the Wichita River, Wichita Falls, Texas ...........19

20. Graph showing water-surface profiles computed for various streamflow amounts in 

Holliday Creek, with backwater caused by streamflow of 10,100 cubic feet per 

second in the Wichita River (the 2007 flood peak), Wichita Falls, Texas ..........................19

21. Graph showing computed water-surface profiles for streamflow of 10,100 cubic feet per 

second (the 2007 flood peak) in the Wichita River, with backwater caused by 

various streamflow amounts in Holliday Creek, Wichita Falls, Texas ...............................20

22. Graph showing computed water-surface profiles for streamflow of 10,100 cubic feet per 

second (the 2007 flood peak) in the Wichita River, with bypass channel cut 

deeper by 4 feet and 8 feet, Wichita Falls, Texas..................................................................21

23. Graph showing computed water-surface profiles for streamflow of 10,100 cubic feet per 

second (the 2007 flood peak) in the Wichita River, with parts of the channel 

widened and obstructions near Scott Avenue and Martin Luther King Junior 

Boulevard bridges removed, Wichita Falls, Texas................................................................22
v

24. Photograph looking downstream from Loop 11 at the U.S. Geological Survey 

streamflow-gaging station 07312500 Wichita River at Wichita Falls, Texas, 

February 25, 2009 ........................................................................................................................23

25. Graph showing reduction in Manning’s roughness coefficient (n) corresponding to a 

reduction in channel-bank and flood-plain vegetation, Wichita River at 

Wichita Falls, Texas....................................................................................................................23

26. Graph showing water-surface profiles computed for streamflow of 10,100 cubic feet 

per second (the 2007 flood) in the Wichita River, with vegetation reduced 20 and 

50 percent on the channel banks and flood plain, Wichita Falls, Texas ...........................24

Tables

1. Continuous streamflow records on Wichita River and Holliday Creek.........................................4

2. Calibrated roughness coefficients for the Wichita River at U.S. Geological Survey 

streamflow-gaging station 07312500 Wichita River at Wichita Falls, Texas 

(Loop 11 gage)...............................................................................................................................6

3. Selected floods recorded at U.S. Geological Survey streamflow-gaging station 

07312500 Wichita River at Wichita Falls, Texas (Loop 11 gage)............................................8

4. Peak stages at U.S. Geological Survey streamflow-gaging stations on Wichita 

River and Holliday Creek, north Texas, October 2009–September 2010............................18

5. Computed water-surface elevations for 10,100 cubic feet per second (the peak 

discharge of the 2007 flood) on the Wichita River at Wichita Falls, Texas, for 

existing (2010) channel conditions and various flood-mitigation alternatives .................25

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2) 

Volume

cubic foot (ft3

) 0.02832 cubic meter (m3) 

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3

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

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).

A water year is the 12-month period October 1 through September 30 designated by the 

calendar year in which it ends.

Assessment of Channel Changes, Models of Historical 

Floods and Effects of Backwater on Flood Stage, and 

Flood Mitigation Alternatives for the Wichita River at 

Wichita Falls, Texas

By Karl E. Winters and Stanley Baldys III

Abstract

In cooperation with the City of Wichita Falls, the U.S. 

Geological Survey assessed channel changes on the Wichita 

River at Wichita Falls, Texas, and modeled historical floods 

to investigate possible causes and potential mitigation 

alternatives to higher flood stages in recent (2007 and 2008) 

floods. Extreme flooding occurred on the Wichita River 

on June 30, 2007, inundating 167 homes in Wichita Falls. 

Although a record flood stage was reached in June 2007, the 

peak discharge was much less than some historical floods 

at Wichita Falls. Streamflow and stage data from two gages 

on the Wichita River and one on Holliday Creek were used 

to assess the interaction of the two streams. Changes in 

the Wichita River channel were evaluated using historical 

aerial and ground photography, comparison of recent and 

historical cross sections, and comparison of channel roughness 

coefficients with those from earlier studies. The floods of 

2007 and 2008 were modeled using a one-dimensional stepbackwater model. Calibrated channel roughness was larger for 

the 2007 flood compared to the 2008 flood, and the 2007 flood 

peaked about 4 feet higher than the 2008 flood. Calibration 

of the 1941 flood yielded a channel roughness coefficient 

(Manning’s n) of 0.030, which represents a fairly clean natural 

channel. The step-backwater model was also used to evaluate 

the following potential mitigation alternatives: (1) increasing 

the capacity of the bypass channel near River Road in Wichita 

Falls, Texas; (2) removal of obstructions near the Scott Avenue 

and Martin Luther King Junior Boulevard bridges in Wichita 

Falls, Texas; (3) widening of aggraded channel banks in the 

reach between Martin Luther King Junior Boulevard and River 

Road; and (4) reducing channel bank and overbank roughness. 

Reductions in water-surface elevations ranged from 0.1 foot 

to as much as 3.0 feet for the different mitigation alternatives. 

The effects of implementing a combination of different floodmitigation alternatives were not investigated. 

Introduction

Continuous records of stage and discharge have been 

made at U.S. Geological Survey (USGS) streamflowgaging station 07312500 Wichita River at Wichita Falls, 

Tex. (hereinafter the Loop 11 gage) since 1938. Stage is the 

elevation of the water surface referenced to an arbitrary datum 

(Langbein and Isseri, 1960, p.10; Rantz and others, 1982, p. 

23). Discharge measurements at the Loop 11 gage location 

have been made sporadically beginning in 1900 and routinely 

since 1938. A record stage (since at least 1938) of 24.40 feet 

(ft) with a peak discharge of 10,100 cubic feet per second 

(ft3

/s) was recorded on June 30, 2007. On August 19, 2008, 

a flood stage of 20.51 ft with a peak discharge of 6,940 ft3

/s 

was recorded at the Loop 11 gage. The extreme flooding on 

the Wichita River on June 30, 2007, inundated 167 homes in 

Wichita Falls, Tex. (Federal Emergency Management Agency, 

2011). Understanding the causes for increased flood stages on 

the Wichita River in 2007 and 2008 floods compared to flood 

stages during floods of similar or smaller magnitude prior 

to 1972 is important to water resource managers in Texas. 

Accordingly, the USGS, in cooperation with the City of 

Wichita Falls, assessed channel changes on the Wichita River 

in Wichita Falls, and modeled historical floods to investigate 

possible causes and potential mitigation alternatives to reduce 

flood elevations such as those experienced in recent (2007 and 

2008) floods.

Changes in channel conveyance, a measure of the 

carrying capacity of a channel (Chow, 1959), can affect the 

reliability of streamflow gaging records used to determine 

annual exceedance probabilities for floods such as the 1- 

percent annual exceedance probability flood, commonly 

referred to as the 100-year flood (Holmes and Dinicola, 2010). 

The reliability of annual peak-streamflow data for the Loop 

11 gage requires an understanding of the factors affecting 

stream stage on the Wichita River. Factors affecting stream 

stage include riparian vegetation, obstructions in the channel, 
2 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

and backwater. The term “backwater” commonly refers to 

the increase in water-surface elevation upstream from an 

obstruction. In addition to being caused by obstructions, 

backwater can also be caused by interactions between streams. 

For example, a relatively higher water-surface elevation in 

one stream can impede flow entering from the mouth of the 

other stream, resulting in backwater in the impeded stream 

(Missouri Department of Transportation, 2011). Flooding 

without backwater is described as headwater flooding, where 

an area becomes inundated directly by surface runoff from 

upland areas (U.S. Army Corps of Engineers, 1987).

Purpose and Scope

This report documents changes in the channel of the 

Wichita River in Wichita Falls, Tex., and describes the results 

of a step-backwater model developed for modeling historical 

floods on the Wichita River and flood-mitigation alternatives. 

The effects of backwater on flood stage were also modeled. 

Wichita River channel changes and flow conditions affecting 

the 2007 flood are emphasized. This report does not include 

hydrologic or hydraulic assessment of design floods, such as 

the 1-percent annual exceedance probability flood (100-year 

flood).

Previous Studies and Background Information

Streamflow records during 1938–2007 at the Loop 11 

gage indicate seven or eight floods roughly similar (or greater) 

in magnitude than the 10,100 ft3

/s peak discharge of the 2007 

flood. Although the peak discharges of floods prior to 2007 

were of similar or greater magnitude compared to the 2007 

flood, none of the floods since 1938 reached the stage of the 

2007 flood. 

In 1993, the Federal Emergency Management Agency 

(FEMA) published a Flood Insurance Rate Map for Wichita 

Falls. Cross sections for the hydraulic analyses were based 

on a 1986 photogrammetric survey (Koogle and Pouls 

Engineering, 1986). In 2000, FEMA revised the Flood 

Insurance Rate Map for the City of Wichita Falls using 

new computed flood profiles for the Wichita River (Federal 

Emergency Management Agency, 2000). In 2010, FEMA 

published a Flood Insurance Rate Map for Wichita County, 

Tex., using the same photogrammetric surveys and hydraulic 

analyses that were used to develop the 2000 Flood Insurance 

Rate Map for Wichita Falls (Federal Emergency Management 

Agency, 2010). Winters and others (2010) described reduced 

channel conveyance on the Wichita River at Wichita Falls, 

Texas, during 1900–2009.

Dams impounding Lake Kemp and Lake Diversion were 

completed on the Wichita River about 40 miles (mi) west and 

upstream from Wichita Falls in 1923 and 1922, respectively 

(Red River Authority of Texas, 2011) (fig. 1). Collier and 

others (1996, p. 85) note that “floods are a key element in the 

future management of dams. Without periodic high flows, 

some channels downstream from dams will aggrade with 

sediment or narrow with overgrown vegetation. Two or three 

flood-free decades may have been traded for more devastating 

floods in the future.”

Description of the Study Area

The study area includes segments of the Wichita River 

and Holliday Creek in and near Wichita Falls. Wichita River 

drains from west to east, emptying into the Red River about 

25 mi northeast of Wichita Falls in north-central Tex. (fig. 1). 

The Tanglewood subdivision of Wichita Falls, where many of 

the 167 homes flooded in June 2007 are located, is near the 

upstream end of the study area. The Loop 11 gage is about 2 

mi downstream from the Tanglewood subdivision (fig. 1). The 

upstream end of the study reach is defined as where the FortWorth Denver Railroad crosses the Wichita River, upstream 

from the Tanglewood subdivision. The downstream end of 

the study reach is 1.9 mi downstream from the confluence 

of the Wichita River and Holliday Creek (this segment of 

the Wichita River downstream from Holliday Creek was 

included to ensure a sound solution of the hydraulic model 

at the confluence of the Wichita River with Holliday Creek). 

Because flow from Holliday Creek can affect flood stages 

in the Wichita River upstream from Holliday Creek (fig. 1), 

Holliday Creek was modeled from Bridwell Street in Wichita 

Falls to the confluence of Holliday Creek with the Wichita 

River, about 3.7 mi downstream from Bridwell Street. The 

Wichita River channel has wooded banks through much of 

the study reach. Holliday Creek has been highly altered and 

is a uniform, grass-lined, and trapezoidal channel. A manmade bypass channel near River Road in Wichita Falls (fig. 1) 

carries part of the flow in Wichita River during large floods. 

Flows in the bypass channel are governed primarily by the 

conveyance of its cross section at its entrance on the south 

bank of the Wichita River. The grass-lined bed of the bypass 

channel drops about 10 ft over a short (about 350 feet) stream 

segment, about 1,600 ft downstream from where it diverts 

flow from the Wichita River.

Methods

Historical Streamflow Data 

Data from three USGS streamflow-gaging stations were 

used to assess channel changes and evaluate flood-mitigation 

alternatives (table 1). In addition to data from the Loop 11 

gage (the primary gage on the Wichita River for this report), 

data from two other USGS streamflow-gaging stations 

(fig. 1) were used in this study: USGS streamflowgaging station 07312610 Holliday Creek at Wichita Falls, 

Tex. (hereinafter the Holliday Creek gage), and USGS 
Methods 3

#

#

4 4

§ ̈¦

Creek

Bypass Channel

Holl di

ay

Wichita

River

River

Wichita

TEERTS L BRIDWEL

MARTIN LUTHER

OL PO 11

BURNETT STREET

KING JUNIOR

ROAD

OHIO AVENUE

SCOTT AVENUE

R VI ER

BOULEVARD

FORT WORTH-DENVER RAILROAD

FORT WORTH-DENVER RAILROAD Tanglewood subdivision Wichita Falls

07312500

07312610

LucyPark

98°26' 98°28' 98°30' 98°32' 98°34'

33°56'33°54'

Wichita 

River

Red River

Beaver Creek

Little Wichita River

Holliday

Creek

Paradise 

Creek

Little Wichita River

CLAY

COUNTY

WICHITA

COUNTY

WILBARGER

 COUNTY

ARCHER

COUNTY BAYLOR COUNTY FOARD

COUNTY

KNOX

COUNTY

HARDEMAN

COUNTY

#

LAKEKEMP

LAKEDIVERSION

Charlie

07312700 Wichita

Falls

Study area

TEXAS

GULF OFMEXICO

Study Area

LOCATION MAP

0 1 MILE 0.50 1 KILOMETER 0.5

Study reachU.S. Geological Survey streamflow-gaging  station and numberStaff gage operated by the 

City of Wichita Falls

07312500

EXPLANATION

Base modified from U.S. Geological Survey digital data,Texas Department of Transportation roads and railroads,Texas Centric Mapping System, Albers Equal Area projection,North American Datum of 1983

Figure 1. Location of study area.
4 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

streamflow-gaging station 07312700 Wichita River near 

Charlie, Tex. (hereinafter the Wichita River near Charlie, 

Tex. gage). The Holliday Creek gage is located at Bridwell 

Street about 3.7 mi upstream from the mouth of Holliday 

Creek. About 16 mi northeast and downstream from the study 

area, streamflow is gaged at the Wichita River near Charlie, 

Tex., gage. Miscellaneous flood measurements made by the 

USGS between 1900 and 1936 at the location of the Loop 

11 gage are included in the analyses. Analyses of streamflow 

data and hydrographs from the Loop 11 and Holliday Creek 

gages provide insight as to how stages on Holliday Creek 

and Wichita River affect one another. The Wichita River near 

Charlie, Tex., gage was used to assess the timing of flood 

hydrographs and to help evaluate the interaction of the Wichita 

River and Holliday Creek in Wichita Falls.

Measurements of stage and discharge were evaluated 

to help determine hydraulic changes that have occurred over 

time in the Wichita River channel. All discharge measurement 

data used for these analyses are stored in the USGS National 

Water Information System (NWIS) database (U.S. Geological 

Survey, 2010). Channel width and area for flood-discharge 

measurements were obtained from NWIS. 

Aerial and Ground Photography

Aerial and ground photographs were analyzed to 

determine if an increase in vegetation in the channel or 

overbank in the reach of the river near the gage contributed 

to the elevated flood stages in 2007 and 2008 compared to 

historical flood stages for similar flood discharges. Aerial 

photographs taken during 1953–2008 (Tom Roehrig, Texas 

Table 1. Continuous streamflow records on Wichita River and 

Holliday Creek.

Station 

number

Station name (and 

station identifier)

Drainage 

area,

(square 

miles)

Period of 

record used 

07312500

Wichita River at 

Wichita Falls, Tex. 

(Loop 11 gage)

3,1401

 March 1938 

through 

September 2010

07312610

Holliday Creek at 

Wichita Falls, 

Tex. (Holliday 

Creek gage)

144

 May 2009 

through 

September 2010

07312700

Wichita River near 

Charlie, Tex. 

(Wichita River 

near Charlie, 

Tex. gage)

3,4391

October 1967 

through 

September 2010

1

A total area of 2,205 square miles is upstream from Lake Diversion.

Natural Resources Information System, written commun., 

2009) were analyzed to determine if channel changes were 

visible in the reach downstream from Loop 11. Aerial 

photographs were examined for evidence of development 

in the flood plain and for general changes in the density 

of riparian vegetation. The scale of these photographs 

ranged from 1:12,800 to 1:32,000. In addition to aerial 

photographs, photographs taken from the ground were used 

for documenting channel changes. Since 1950, oblique (side 

looking) photographs of the Wichita River channel at Loop 

11 have been taken periodically by personnel of the USGS. 

Oblique photographs of the channel at the Loop 11 gage 

provide valuable information about changes in the channel 

shape and vegetative cover. 

Channel Cross Sections 

During 1938–2010, more than 1,000 discharge 

measurements (U.S. Geological Survey, 2010) were made at 

the Loop 11 gage. These measurements provide a detailed 

history of channel cross sections in the Wichita River at Loop 

11. These measurements typically include between 25 and 

35 depth observations from which a detailed cross section 

is defined. Comparison of these cross sections over time 

provides insight to possible aggradation or degradation of the 

channel bed or banks.

In addition to historical cross sections measured at the 

Loop 11 gage during streamflow measurements, cross sections 

of the Wichita River in a reach of about 5 mi from Loop 11 

downstream to River Road (fig. 1) were surveyed by the 

USGS in 2009 using a total station and Real-Time Kinematic 

Global Positioning System (RTK-GPS) (Trimble, 2009). Cross 

sections for this reach of the Wichita River were compared 

to historical cross sections obtained from as-built plans for 

several bridges spanning the Wichita River from Loop 11 

downstream to River Road (Loop 11, Interstate Highway 44, 

Burnett Street, Scott Avenue, Ohio Avenue, Martin Luther 

King Junior Boulevard, and River Road). 

Changes in cross-section shape and vegetation 

density along a reach of the Wichita River channel in the 

study area were assessed by using historical streamflow 

measurements, aerial and ground photography, comparison 

of recent (2009) and historical cross sections and channel 

roughness coefficients (Manning’s n; described in the Channel 

Roughness section) from 2009 with those used in a 1991 

step-backwater model developed for the Federal Emergency 

Management Agency (FEMA). The 1991 step-backwater 

model was based on 1986 cross sections; the cross sections 

and Manning’s n values were documented in a HEC-2 model 

(HEC-2 is a step-backwater hydraulic model developed by 

the U.S. Army Corps of Engineers Hydrologic Engineering 

Center) prepared for FEMA (Cindy Mosier, Halff Associates, 

written commun., 2009), hereinafter referred to as the 1991 

FEMA HEC-2 model. Cross sections for the 1991 FEMA 

HEC-2 model were obtained by photogrammetry in 1986 
Methods 5

(Koogle and Pouls Engineering, 1986; Federal Emergency 

Management Agency, 2000). The flood-plain cross-section and 

channel roughness data were obtained from the 1991 FEMA 

HEC-2 model input file. 

Channel Roughness

All of the hydraulic models referenced in this report 

used Manning’s coefficient, n, to represent the roughness of 

the channel bed, banks, and overbank. Manning’s equation 

(Linsley and others, 1982) relates discharge to cross-section 

geometry, channel roughness, and channel slope and is defined 

as

Q = A x 1.486/n x R2/3 x S1/2 (1)

where 

Q = discharge, in cubic feet per second 

A = cross-sectional area of flow, in square feet 

n = manning’s n (coefficient of roughness), 

unitless

R = hydraulic radius, in feet 

S = slope of the channel, in foot per foot 

Manning’s n represents resistance to flow and is inversely 

proportional to flow velocity for a given depth. Manning’s 

n can be computed when the discharge, channel slope, and 

cross-section properties (area and depth) are known. Typically, 

however, in practice Manning’s n is selected based on 

knowledge of field conditions (channel-bed material, density 

of riparian vegetation, channel uniformity), guidance from 

field handbooks (Arcement and Schneider, 1989; Barnes, 

1967), and engineering judgment (Chow, 1959, p. 101). 

For this study, Manning’s n was determined by using stepbackwater modeling as described in the Step-Backwater 

Modeling section. 

Step-Backwater Modeling

A one-dimensional, steady-state, step-backwater model 

(Davidian, 1984) was developed by the USGS to assess 

channel changes on the Wichita River within the study reach 

(fig. 1) to evaluate different flood-mitigation alternatives. 

Winters and others (2010) used a step-backwater model to 

determine channel roughness and conveyance properties of 

the Wichita River from the Loop 11 gage downstream to River 

Road. Step-backwater computations are used to compute 

water-surface profiles on the basis of energy losses caused 

by friction from the moving water being in contact with the 

streambed, and from the expansion or contraction of the 

channel cross section. Energy losses caused by friction are 

related to the roughness of the streambed material, but are 

greatly affected by the density of vegetation in the channel 

or on the flood plain (Linsley and others, 1982). Required 

data for the model include cross-section geometry, channel 

and flood-plain roughness (Manning’s n), and boundary 

conditions, which included recorded peak stages at selected 

locations along the river and known or assumed initial stream 

stage or water-surface slope at the downstream end of the 

model. For this study, the water-surface elevation at the 

downstream end of the model was determined by using a 

normal depth (Chow, 1959) solution of Manning’s equation 

(equation 1). Brunner (2010, p. 3-2) states that this approach 

is “common practice” and that “any error at the boundary will 

diminish as the computations proceed upstream.” When the 

cross-section geometry, discharge, and boundary conditions 

are known, the model can also be used to solve for Manning’s 

n.

The U.S. Army Corps of Engineers Hydrologic 

Engineering Center River Analysis System (HEC-RAS) model 

(Brunner, 2008; U.S. Army Corps of Engineers, 2010) was 

used by the USGS for the computation of historical flood 

profiles (Winters and others, 2010). The calibrated HEC-RAS 

model was then used to assess the effect of various potential 

flood-mitigation alternatives. Additionally, the step-backwater 

model was used to assess the potential extent of backwater 

during flooding at the confluence of Wichita River and 

Holliday Creek. Calibration of the step-backwater model was 

done by using peak-stage data at the Loop 11 gage and from 

three staff gages in the study reach. The City of Wichita Falls 

maintains a network of staff gages, including three in the 

Wichita River study reach (figs. 1 and 2). Readings of these 

staff gages by City of Wichita Falls employees were typically 

every 15 to 30 minutes during the 2007 and 2008 floods to 

ensure reasonable definition of the flood hydrograph (Davis 

Powell, City of Wichita Falls, written commun., 2010). Initial 

values of Manning’s n for the channel and overbank at each 

cross section were selected during the 2009 survey. 

Figure 2. Staff gage operated by the City of Wichita Falls, Texas 

(photograph courtesy of Davis Powell, City of Wichita Falls).
6 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

One-dimensional step-backwater models require separate 

values of Manning’s n for the channel and the flood plain at 

each cross section (Davidian, 1984). Calibration of the channel 

and flood-plain (overbank) roughness is typically handled in 

this manner: (1) the channel roughness is first calibrated by 

using known stage and discharge for a flood contained within 

the channel; (2) flood-plain (overbank) roughness is calibrated 

to known stage and discharge for a higher (overbank) flood by 

using the channel roughness from the first step. Normally, this 

approach works well; however, if the channel roughness varies 

with depth, the distribution of roughness across the flood 

plain (channel compared to overbank) might not be optimal. 

This problem arises because the real distribution of flow 

across the cross section is generally not known. An approach 

to solving this problem is to set limits for the channel and 

overbank values of Manning’s n (that is, the smallest and 

largest roughness coefficients expected for observed channel 

and overbank flow conditions). Field references with example 

photographs of stream channels and flood plains with 

calibrated roughness coefficients (Arcement and Schneider, 

1989; Barnes, 1967) were also used for guidance in setting 

limits for Manning’s n and evaluating calibrated values for 

Manning’s n. The calibrated roughness coefficients for the 

2007 and 2008 peak flood stages at the Loop 11 gage are 

shown in table 2, along with calibrated roughness coefficients 

from a flood in 1941 with a peak flood stage similar to that 

of the 2007 flood; the 1941 flood is used for comparison with 

the 2007–8 floods because the channel in 1941 was different 

compared to the channel during 2007 and 2008.

In addition to the Wichita River cross sections surveyed 

in 2009 by the USGS in the 5-mi reach between Loop 11 and 

River Road (which were used for the historical comparisons), 

cross sections were used for flood-mitigation modeling 

purposes upstream from the Loop 11 gage to the Fort WorthDenver Railroad crossing (fig. 1), and downstream from River 

Road to a point 1.9 mi downstream from the confluence of 

Wichita River with Holliday Creek. Cross sections for these 

segments of Wichita River, as well as those for the 3.7-mi 

reach of Holliday Creek, were extracted from 2-ft contours 

provided by the City of Wichita Falls and based on a Light 

Detection and Ranging (LiDAR) survey (Davis Powell, City 

of Wichita Falls, written commun., 2010). Brunner (2010, 

p. 3-6) states that cross-section spacing is a function of the 

stream size, slope, and the uniformity of the cross-section 

shape. The maximum cross-section spacing used in the stepbackwater model developed by the USGS was 2,420 ft. The 

average spacing was 1,170 ft.

Assessment of Channel Changes

The more than 1,000 discharge measurements 

(U.S. Geological Survey, 2010) made at the Loop 11 gage 

during 1938–2010 indicate no substantial aggradation has 

occurred on the channel bed or banks near the Loop 11 gage. 

Aggradation, had it occurred, might have explained some 

of the increase in stage for the same volume of discharge 

(Heitmuller and Greene, 2009). Figure 3 depicts the relation 

between stage and discharge for discharge measurements 

made at the Loop 11 gage since 1938. Floods recorded in 

2007 and 2008 at this gaging station, including the record 

flood of June 30, 2007, have reached higher flood stages 

compared to floods before 1972 (fig. 3). Comparing flood 

measurements made during 1938–71 with flood measurements 

made during 1972–2007, stages have been about 1 to 3 ft 

higher since 1972 for floods that reached a stage of more than 

18 ft compared to stages measured for earlier floods of similar 

magnitude. Discharge measurements for stages of more than 

18 ft from 1938 to 2008 indicate a decrease in the measured 

mean velocity from about 3.5 ft/s in 1941 to about 2.0 ft/s 

in 2008 (fig. 4). This reduction in velocity was accompanied 

by an increase in stage to convey similar discharges through 

the system. 

Table 2. Calibrated roughness coefficients for the Wichita River at U.S. Geological Survey streamflow-gaging station 07312500 

Wichita River at Wichita Falls, Texas (Loop 11 gage).

[n, Manning’s roughness coefficient]

Date

Peak flood 

stage

(feet)1

Peak discharge

(cubic feet per second) Channel n

Average 

overbank n Maximum overbank n

10/03/1941 24.00 17,800 0.030 0.064 0.077

6/30/2007 24.40 10,100 0.048 0.18 0.22

8/19/2008 20.51 6,940 0.041 0.18 0.22

1

 Datum of gage is 924.53 feet above North American Vertical Datum of 1988.
Assessment of Channel Changes 7

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 18,000 20,000

Discharge, in cubic feet per second

0

5

10

15

20

25

30

Stage, in feet

1938-1971

1972-2007

EXPLANATION

1935 1945 1955 1965 1975 1985 1995 2005 2015

Year

0

1

2

3

4

Mean velocity, in feet per second

Figure 3. Changes in the stage-discharge relation indicated by measurements at U.S. Geological 

Survey streamflow-gaging station 07312500 Wichita River at Wichita Falls, Texas (Loop 11 gage). 

Figure 4. Mean velocities from measurements at U.S. Geological Survey streamflow-gaging station 

07312500 Wichita River at Wichita Falls, Texas (Loop 11 gage).
8 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

A record peak stage (since 1938 when stage records 

were first collected on a continuous basis) of 24.40 ft at the 

Loop 11 gage with an associated peak discharge of 10,100 

ft3/s was recorded on June 30, 2007 (table 3). On August 

19, 2008, flood stages again peaked at more than 20 ft at the 

Loop 11 gage, cresting at 20.51 ft with an associated peak 

discharge of 6,940 ft3/s. Peak flood stages measured for the 

peak streamflows in 2007 and 2008 were higher compared to 

the peak flood stages measured for floods of similar magnitude 

in previous years. In 1955, 1957, and 1961, annual peak 

discharges ranging from 7,200 to 7,640 ft3/s were recorded 

with peak stages ranging from 17.93 to 18.27 ft. Although 

the annual peak discharges of 1955, 1957, and 1961 were all 

slightly larger compared to the August 2008 flood of 6,940 

ft3/s, the peak stages associated with the floods in 1955, 1957, 

and 1961 were 2.24 to 2.58 ft lower compared to the peak 

stage of 20.51 ft associated with the August 2008 flood.

Annual peak discharges measured between 1938 and 

2008 and miscellaneous flood measurements between 1900 

and 1936 at the location of the Loop 11 gage (fig. 5) indicate 

the magnitude of annual peak discharges has decreased since 

the Lake Kemp and Lake Diversion dams were completed 

on the Wichita River. The two largest annual peak discharges 

since these two reservoirs were built in the 1920s measured 

15,500 and 17,800 ft3/s in June and October of 1941, 

representing water years 1941 and 1942, respectively (a 

water year is the 12-month period from October 1 through 

September 30 and is designated by the calendar year in which 

it ends). Before 1941, miscellaneous flood measurements of 

16,700, 37,400, and 50,000 ft3/s were obtained at Loop 11 in 

1900, 1901, and 1915, respectively. Prior to the June 2007 

flood, which peaked at 10,100 ft3/s, none of the annual peak 

Table 3. Selected floods recorded at U.S. Geological Survey 

streamflow-gaging station 07312500 Wichita River at Wichita Falls, 

Texas (Loop 11 gage).

Date Stage (feet)1 Peak discharge

(cubic feet per second)

10/03/1941 24.00 17,800

9/27/1955 18.12 7,200

5/3/1957 18.27 7,200

3/19/1961 17.93 7,640

6/30/2007 24.40 10,100

8/19/2008 20.51 6,940

1

 Datum of gage is 924.53 feet above North American Vertical Datum 

of 1988.

discharges since 1943 had exceeded 10,000 ft3/s, although five 

annual peak discharges exceeded 7,500 ft3/s (fig. 5).

The computed peak discharge (10,100 ft3/s) at the Loop 

11 gage associated with the 2007 flood peak (24.40 ft) was 

based on a June 30, 2007, measured discharge of 9,900 ft3/s at 

a stage of 24.22 ft.

Streamflow at the Wichita River near Charlie, Tex., gage 

peaked on July 4, 2007, with a peak discharge of 11,100 ft3/s. 

Although no gage was being operated on Holliday Creek in 

2007, a USGS employee noted that while the Wichita River 

0

10,000

20,000

30,000

40,000

50,000

60,000

Peak discharge, in cubic feet per second

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

2010

Water year

Lake Kemp and Lake Diversion dams

(fig. 1) upstream from the gaging station

were completed on the Wichita River in

1923 and 1922, respectively

Figure 5. Annual peak discharges at U.S. Geological Survey streamflow-gaging station 07312500 Wichita River 

at Wichita Falls, Texas (Loop 11 gage).
Assessment of Channel Changes 9

was cresting at Loop 11, Holliday Creek was about two-thirds 

bank full and flowing. 

Aerial photographs were examined for evidence of 

development in the flood plain and for general changes in the 

density of riparian vegetation. Notable changes within the 

study reach between 1953 and 2008 include a general increase 

in vegetation density in the riparian area along the Wichita 

River channel. The aerial photographs indicate an increase in 

vegetation between 1953 and 1991 along the banks and in the 

flood plain at Lucy Park, 1 to 2 mi downstream from Loop 11. 

Photographs from 1968 and subsequent years (including 1971 

and 1979, not shown here) indicate fill was placed on the south 

bank immediately downstream from Scott Avenue between 

1971 and 1979. A long-term resident of the area indicated 

that a substantial amount of fill also was deposited on the 

north bank of the channel downstream from the Scott Avenue 

bridge in the early 1960s (Peter Pullin, oral commun., June 23, 

2009). Aerial photographs as recent as 1968 show houses on 

the north bank of the Wichita River immediately downstream 

from Martin Luther King Junior Boulevard built on earth fill 

in the channel (fig. 6). The earth fill placed at the downstream 

side of Martin Luther King Junior bridge is currently (2011) a 

vacant field.

Houses were present on earth fill downstream from Martin Luther 

King Junior Boulevard when this photograph was taken.

Earth fill was not present downstream from Scott 

Avenue when this photograph was taken.

Figure 6. Scott Avenue and Martin Luther King Junior Boulevard 

bridges on the Wichita River, February 7, 1968 (photograph courtesy 

Tom Roehrig, Texas Natural Resources Information System). 

Ground photographs taken near the Loop 11 gage 

were compiled for 1950, 1961, 1975, and 2009 (fig. 7). 

The photographs indicate a substantial amount of riparian 

vegetation growth occurred between 1950 and 2009. When 

reservoirs are constructed, riparian growth in downstream 

reaches often increases (Collier and others, 1996; Shafroth 

and others, 2002; Heitmuller and Greene, 2009). An August 

23, 2010, aerial photograph indicated a dense corridor of 

riparian growth along the segment of the river immediately 

downstream from Loop 11 (fig. 8). 

Cross sections were used to assess the stability of the 

Wichita River channel in the study area. A plot of Loop 11 

cross sections over time (fig. 9) indicates that, while minor 

changes in cross-section shape are observed, the thalweg 

(elevation of the flowline joining the lowest points along 

the streambed, thus defining the deepest channel of the 

stream) and the width of the channel are fairly stable. Most 

of the Wichita River cross sections surveyed in 2009 by 

the USGS compared favorably with those from the 1986 

photogrammetric survey, indicating that much of the Wichita 

River channel in the study area appears to be fairly stable. 

However, four consecutive cross sections between 0.9 and 2.6 

mi downstream from Martin Luther King Junior Boulevard 

indicated substantial narrowing (fig. 10). For those four cross 

sections, the loss in channel width was typically 30 to 50 ft.

For most bridges, comparison of the 2009 surveys of 

the channels and bridge openings to the as-built bridge plans 

indicates no change in cross section. Obstructions caused by 

earth fill are evident in cross sections on the right bank at the 

downstream side of the Scott Avenue bridge (south span) and 

on the left bank at the Martin Luther King Junior bridge (north 

span). Obstructions in the cross section near the Scott Avenue 

bridge (fig. 11A; fig. 12) reduce the effective conveyance of 

the bridge section during floods. The obstruction at the Martin 

Luther King Junior bridge only partially blocks flow, reducing 

channel conveyance during floods (fig. 11B; fig. 13).

Values of Manning’s n selected by USGS personnel 

during the 2009 survey of Wichita River cross sections in the 

5-mi reach of the Wichita River downstream from the Loop 

11 gage were compared to values used in the 1991 FEMA 

HEC-2 model. Roughness values selected for the channel 

were nearly identical to values from the 1991 FEMA HEC-2 

model. However, roughness values selected for the overbank 

were about 2.5 times larger than those used in the 1991 FEMA 

HEC-2 model.
10 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

1950 1961

1975 2009

Figure 7. Wichita River looking downstream from Loop 11 in 1950, 1961, 1975, and 2009 at U.S. Geological Survey streamflow-gaging 

station 07312500 Wichita River at Wichita Falls, Texas.

“Floods are a key 

element in the future 

management of dams. 

Without periodic high 

flows, some channels 

downstream from 

dams will aggrade 

with sediment or 

narrow with overgrown 

vegetation. Two or three 

flood-free decades may 

have been traded for 

more devastating floods 

in the future.”

- from Dams and Rivers: 

A Primer on the 

Downstream Effects of 

Dams (Collier and others, 

1996)

U.S. Geological Survey 

Circular 1126

1961

2009

1950 1961

1975 2009

1961

2009
Assessment of Channel Changes 11

0 50 100 150 200 250 300 350 400 450

Distance, in feet

920

925

930

935

940

945

950

955

960

Elevation, in feet above

North American Vertical Datum of 1988

1938

1971

1986

2009

EXPLANATION

Figure 8. Wichita River looking downstream from Loop 11, August 23, 2010, Wichita Falls, Texas.

Figure 9. Historical channel cross sections of the Wichita River at U.S. Geological Survey streamflow-gaging station 07312500 

Wichita River at Wichita Falls, Texas, 1938–2009. 
12 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

0 100 200 300 400 500

Distance, in feet

950945940935930925920915910950945940935930925920915910

Elevation in feet above

North American Vertical Datum of 1988

0 100 200 300 400 500

1986 cross sections by photogrammetry (Koogle and Pouls Engineering)2009 cross sections surveyed by U.S. Geological Survey

EXPLANATION

0.9 miles downstream from Martin Luther King Junior Boulevard 1.7 miles downstream from Martin Luther King Junior Boulevard

2.0 miles downstream from Martin Luther King Junior Boulevard 2.6 miles downstream from Martin Luther King Junior Boulevard

Figure 10. Channel cross sections of the Wichita River between 0.9 and 2.6 miles downstream from Martin Luther King Junior Boulevard, Wichita Falls, Texas, 1986 and 2009.
Assessment of Channel Changes 13

A 

B Elevation, in feet above

North American Vertical Datum of 1988

915

920

925

930

935

940

945

950

955

0 100 200 300 400

Distance, in feet

bridge deck

1986 (at upstream face of bridge)

2009 (underneath bridge)

2009 (immediately downstream from bridge)

Blocked opening

EXPLANATION

Elevation, in feet above

North American Vertical Datum of 1988

950

945

940

930

935

925

920

915

Distance, in feet

0 100 200 300 400 500 600

1986 (at upstream face of bridge)

EXPLANATION

B

Elevation, in feet above

North American Vertical Datum of 1988

915

920

925

930

935

940

945

950

955

0 100 200 300 400

Distance, in feet

bridge deck

1986 (at upstream face of bridge)

2009 (underneath bridge)

2009 (immediately downstream from bridge)

Blocked opening

EXPLANATION

Elevation, in feet above

North American Vertical Datum of 1988

950

945

940

930

935

925

920

915

Distance, in feet

0 100 200 300 400 500 60

1986 (at upstream face of bridge)

2009 (immediately downstream from bridge)

Blocked opening

EXPLANATION

Figure 11. Wichita River obstructions A, on the right (south) bank at the downstream side of Scott Avenue bridge looking downstream 

and B, on the left bank at Martin Luther King Junior Boulevard bridge, looking downstream, February 23, 2009.

Figure 12. Wichita River cross sections 

from 1986 and 2009, and the obstruction on 

the right (south) bank at the downstream side 

of Scott Avenue bridge in Wichita Falls, Texas.

Figure 13. Wichita River cross sections from 

1986 and 2009 and the obstruction on the left 

(north) bank at the downstream side of the 

Martin Luther King Junior Boulevard bridge in 

Wichita Falls, Texas.

A B
14 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

Models of Historical Floods and Effects 

of Backwater on Flood Stage 

The floods of 2007, 2008, and 1941 on the Wichita 

River were modeled by using the one-dimensional, steadystate, step-backwater model described in the Step-Backwater 

Modeling section to prepare the calibrated model for 

evaluating different flood-mitigation alternatives. The 2007 

flood is of greatest interest because it crested at a higher stage 

than any other flood since at least 1938. The 2008 flood was 

also used to calibrate the step-backwater model. Because 

channel conditions during 1941 were different compared to 

channel conditions during 2007 and 2008, modeling of the 

1941 flood is useful in the analysis of potential mitigation 

alternatives. Calibration of the 2007 and 2008 floods was done 

by adjusting Manning’s n so that differences in computed and 

observed water-surface elevations at the Loop 11 gage and the 

staff gages were minimized. Interaction of Wichita River and 

Holliday Creek flows and water-surface elevations was also 

modeled to assess the effects of backwater on flood stage.

2007 Flood

Calibration of the model to the June 2007 flood indicated 

Manning’s n was as large as 0.22 in the roughest areas of 

the flood plain (the densely vegetated banks and overbanks 

composing the flood plain) and 0.048 in the Wichita River 

channel (for comparison, in the 1991 FEMA HEC-2 model, 

average Manning’s n for the flood plain and channel were 

0.07 and 0.04, respectively.) The relatively large calibrated 

roughness values for the June 2007 flood are indicative 

of a densely vegetated flood plain and a rougher-thanaverage natural channel (Chow, 1959). These relatively 

large roughness values also correspond with relatively low 

streamflow velocities (fig. 4). The calibrated water-surface 

profile elevations (fig. 14) for the 2007 flood are within 

0.02 ft of the recorded peak stage at the Loop 11 gage and 

within 0.06 ft of the observed peak stage at the Tanglewood 

subdivision. The calibrated water-surface profile elevations 

were 0.45 and 0.42 ft lower, respectively, than the observed 

peak stages at the city staff gages near Interstate 44 and 

downstream from Martin Luther King Junior Boulevard 

(fig. 14). The greater differences in water-surface profile 

elevations at these two locations might be because of the 

magnitude or timing of the flood peak on Holliday Creek.

 2008 Flood

The August 2008 flood peaked about 4 ft lower than the 

2007 flood. Calibration of the August 2008 flood indicated 

flood-plain roughness as large as 0.22 in the roughest areas 

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Channel station, in feet

930

935

940

945

950

955

960

Elevation, in feet above

North American Vertical Datum of 1988

Mouth of Holliday Creek

Martin Luther King

 Junior Boulevard

Scott Avenue

Interstate 44

Station 07312500

at Loop 11

Tanglewood subdivision

Modeled 2007 flood (10,100 cubic feet per second)

Recorded peak stage

Observed peak stage

EXPLANATION

Figure 14. Calibrated water-surface profile for the 2007 flood on the Wichita River at Wichita Falls, Texas.
Models of Historical Floods and Effects of Backwater on Flood Stage 15

of the flood plain, but the Wichita River channel roughness 

was 0.041; this is a fairly typical value for a natural channel 

(Chow, 1959). The difference between the 2007 and 2008 

calibrated Manning’s n for the Wichita River channel could be 

because of the 4-ft stage difference between the two floods and 

the increased effect of overhanging branches at higher stages 

(as shown in the 2009 photograph in fig. 7). The calibrated 

water-surface profile elevations (fig. 15) for the 2008 flood are 

within 0.02 ft of the recorded peak stage at the Loop 11 gage 

and the observed peak stage at the city staff gage downstream 

from Martin Luther King Junior Boulevard. The calibrated 

water-surface profile elevation was 0.30 ft higher than the 

observed peak stage near Interstate 44 and 1.06 ft lower 

than the observed peak stage at the Tanglewood subdivision 

(fig. 15). Channel roughness might vary longitudinally 

upstream from the Loop 11 gage. During the calibration, 

no attempt was made to assess the longitudinal variability of 

the channel roughness.

Cross-section conveyance at Loop 11 from the 1991 

FEMA model (with 1991 roughness coefficients) and crosssection conveyance from 2009 (with roughness coefficients 

selected in 2009 by the USGS) were compared (fig. 16). 

The stage (elevation) associated with a given conveyance is 

consistently lower in the 1991 FEMA model compared to 

the 2009 flood, and the divergence between the two curves 

increases markedly at higher stages. While this might be 

in part because of the manner in which the 1991 roughness 

coefficients were selected, it likely indicates that additional 

cross-section conveyance has been lost between 1991 and 

2009 because of the growth of riparian vegetation.

1941 Flood

The October 3, 1941, flood peaked at 24.00 ft at the 

Loop 11 gage with a discharge of 17,800 ft3

/s. The much 

larger 1941 flood discharge flowed at a slightly lower stage 

compared to the 2007 flood of 10,100 ft3

/s. A “clean” channel 

free of vegetation conveys water more efficiently and has 

a smaller Manning’s n value compared to a channel with 

vegetation growing on the banks and overbanks. The 1941 

flood is useful for answering the question of how “clean” 

930

935

940

945

950

955

960

Elevation, in feet above

North American Vertical Datum of 1988

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Channel station, in feet

925

Modeled 2008 flood (6,940 cubic feet per second)

Recorded peak stage

Observed peak stage

EXPLANATION

Mouth of Holliday Creek

Martin Luther King Junior Boulevard

Scott Avenue

Interstate 44

Station 07312500

at Loop 11

Tanglewoodsubdivision

Figure 15. Calibrated water-surface profile for the 2008 flood on the Wichita River at Wichita Falls, Texas.
16 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

was the channel historically. The first steps in modeling 

the 1941 flood include the simulated removal of all bridge 

obstructions near Scott Avenue and Martin Luther King Junior 

Boulevard (figs. 11-13), and of the aggraded channel banks 

downstream from Martin Luther King Junior Boulevard 

(fig. 10). The extent of the earth-fill areas in cross sections 

near the Scott Avenue and Martin Luther King Junior bridges 

was determined from patterns in the 2-ft elevation contours, 

and these fill areas—as evidenced from aerial photographs, 

historical cross sections, and discussions with the owner of a 

business on Scott Avenue adjacent to the Wichita River (Peter 

Pullin, oral commun., June 23, 2009)—were most likely 

placed after the 1941 flood. These fill areas near the Scott 

Avenue and Martin Luther King Junior bridges were removed 

from the cross sections used to model the 1941 flood. The 

1941 flood was calibrated solely on the basis of its recorded 

peak stage at the Loop 11 gage. The calibrated Manning’s

n for the Wichita River channel for the 1941 flood is 0.030, 

which is a relatively small value for a natural channel, 

indicating that the channel was cleaner in 1941 compared 

to 2007 when the Manning’s n for the Wichita River was 

0.048. The calibrated water-surface profile for the 1941 flood 

is shown in figure 17, along with the calibrated 2007 flood 

profile for comparison.

Effects of Backwater on Wichita River and 

Holliday Creek 

Stages on Wichita River at the Loop 11 gage and 

Holliday Creek gage are at times affected by backwater—a 

large inflow from Holliday Creek can cause backwater at 

the Loop 11 gage, and large flows in the Wichita River can 

cause backwater at the Holliday Creek gage. During low-flow 

conditions, the streams often act independently of each 

other and there is no relation between their stages. However, 

moderate rises on either stream can cause backwater, affecting 

the stage on the other stream. Because of the difference in 

drainage area of the two streams, flood peaks on Holliday 

Creek typically occur several hours earlier than peaks on 

the Wichita River. However, depending on the timing of the 

rainfall in the two basins, the Wichita River and Holliday 

Creek can rise concurrently. Eight storm hydrographs on 

Wichita River and Holliday Creek during the 2010 water year 

were analyzed to determine the timing of peaks on the two 

streams and to assess the degree to which each was affected 

by backwater. Understanding backwater effects during 

runoff events in 2010 provides insight into how flow-induced 

backwater might have contributed to higher stages during the 

2007 flood. 

 Stage hydrographs for the Loop 11, Holliday Creek, 

and Wichita River near Charlie, Tex., gages were plotted for 

each storm hydrograph inspected for indications of backwater 

effects. The stage hydrographs for two of the eight storms, 

one during January 27–February 3, 2010, and another during 

July 8–13, 2010, are depicted (fig. 18). For the eight storms, 

four of the Holliday Creek runoff peaks produced minor 

backwater in the Wichita River at the Loop 11 gage. Three of 

the eight storms resulted in a backwater rise at the Holliday 

Creek gage followed by a peak unaffected by backwater. 

Despite the difference in drainage-area sizes of the Wichita 

River and Holliday Creek basins, runoff from the Holliday 

Creek basin during concurrent runoff events often contributes 

to peak stages at the Wichita River near Charlie gage (table 4). 

The timing of peak flow on each stream affects 

backwater, and the lag time between flow at the Holliday 

Creek gage and the Loop 11 gage is variable. On the basis of 

the storm hydrographs from the 2010 water year, the Wichita 

Cross section conveyance, in cubic feet per second

Elevation, in feet above

North American Vertical Datum of 1988

955

950

945

940

935

930

925

0 400,000 800,000 1,200,000

Figure 16. Cross-section conveyance computed from 1991 Federal Emergency Management (FEMA) HEC-2 model (1991 FEMA) and 

2009 U.S. Geological Survey HEC-RAS model (2009 USGS) at U.S. Geological Survey streamflow-gaging station 07312500 Wichita River 

at Wichita Falls, Texas (Loop 11 gage). 
Models of Historical Floods and Effects of Backwater on Flood Stage 17

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Channel station, in feet

930

935

940

945

950

955

960

Elevation, in feet above

North American Vertical Datum of 1988

EXPLANATION

Modeled 2007 flood (10,100 cubic feet per second)

Modeled 1941 Flood (17,800 cubic feet per second)

Mouth of Holliday Creek

Martin Luther King Junior Boulevard 

Scott Avenue

Interstate 44

Station 07312500

at Loop 11

Tanglewood

subdivision

Jl

2010 January February

27 28 29 30 31 1 2 3

8 9 10 11 12 13

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Stage, in feet

11

10

9

8

7

6

5

4

3

2

1

0

Stage, in feet

A

B

2010

July

2010 January February

27 28 29 30 31 1 2 3

8 9 10 11 12 13

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Stage, in feet

11

10

9

8

7

6

5

4

3

2

1

0

Stage, in feet

A

B

EXPLANATION

07312500 Wichita River at Wichita Falls, Tex. 

 (Datum of gage is 924.53 feet above North American 

 Vertical Datum of 1988 [NAVD 88])

07312610 Holliday Creek at Wichita Falls, Tex. 

 (Datum of gage is 919.61 feet above NAVD 88)

07312700 Wichita River near Charlie, Tex. 

 (Datum of gage is 872.99 feet above NAVD 88)

2010

July

2010 January February

27 28 29 30 31 1 2 3

8 9 10 11 12 13

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Stage, in feet

11

10

9

8

7

6

5

4

3

2

1

0

Stage, in feet

A

B

EXPLANATION

07312500 Wichita River at Wichita Falls, Tex. 

 (Datum of gage is 924.53 feet above North American 

 Vertical Datum of 1988 [NAVD 88])

07312610 Holliday Creek at Wichita Falls, Tex. 

 (Datum of gage is 919.61 feet above NAVD 88)

07312700 Wichita River near Charlie, Tex. 

 (Datum of gage is 872.99 feet above NAVD 88)

Figure 17. Calibrated water-surface profiles for the 2007 and 1941 floods on the Wichita River at Wichita Falls, Texas.

Figure 18. Stage hydrographs during A, January 2010, and B, July 2010 at U.S. Geological Survey streamflow-gaging stations 07312500 

Wichita River at Wichita Falls, Texas (Loop 11 gage), 07312610 Holliday Creek at Wichita Falls, Tex. (Holliday Creek gage), and 07312700 

Wichita River near Charlie, Tex. (Wichita River near Charlie, Tex., gage).
18 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

River at Loop 11 typically peaks about 34 hours after Holliday 

Creek. However, the lag varied from as little as about 7 hours 

to as much as 44 hours (table 4). Although the January 2010 

storm peaked at the Loop 11 gage 44 hours after the Holliday 

Creek gage, the Wichita River was nearing its peak within 

about 24 hours of the peak at the Holliday Creek gage (fig. 

18A). During the July 2010 storm, the Wichita River at Loop 

11 peaked only about 7 hours after Holliday Creek (fig. 18B). 

Holliday Creek was observed by USGS personnel to be 

flowing at the peak of the 2007 flood recorded at the Loop 11 

gage, and the peaks from Wichita River and Holliday might 

have occurred at approximately the same time during the 2007 

flood. When the rivers rise concurrently, the stage of the peak 

on Wichita River can increase because of backwater effects. 

The January 2010 hydrographs (fig. 18A) might represent the 

typical stream responses at all three gages: a sharp rise and 

recession on Holliday Creek, a broad rise on the Wichita River 

at the Loop 11 gage, and a lagged and dampened pattern at 

the Wichita River near Charlie, Tex., gage compared to the 

hydrographs of the upstream gages. 

Water-surface profiles were computed for Holliday 

Creek without backwater from Wichita River using the 

HEC-RAS model and cross sections obtained from the 2-ft 

elevation contours provided by the City of Wichita Falls. 

Channel roughness was calibrated on the basis of the 

April 19, 2010, measured discharge of 1,220 ft3

/s at a stage 

of 8.90 ft (928.51 ft above NAVD 88) at the Holliday Creek 

gage. The calibrated Manning’s n for Holliday Creek is 

0.031, a reasonable value for a relatively straight, grass-lined 

channel (Chow, 1959). The water-surface profiles (fig. 19) 

were initiated at the mouth of Holliday Creek using slopeconveyance computations.

The 2010 step-backwater model was used to assess the 

potential extent of backwater during flooding at the confluence 

of Wichita River and Holliday Creek. Large floods on the 

Wichita River result in backwater conditions on Holliday 

Creek. Backwater conditions in Holliday Creek caused by a 

discharge of 10,100 ft3

/s (the 2007 flood) in the Wichita River 

channel were modeled. Flows in Holliday Creek ranging from 

200 to 6,000 ft3/s were modeled assuming a flow of 

10,100 ft3/s in Wichita River. Figure 20 depicts computed 

water-surface profiles for Holliday Creek with backwater 

caused by a streamflow of 10,100 ft3/s (the peak discharge of 

the 2007 flood) in the Wichita River.

Figure 21 depicts the effects of backwater from Holliday 

Creek on computed water-surface profiles on the Wichita 

River at Wichita Falls, Tex., for a flood in the Wichita River 

of 10,100 ft3

/s (the peak of the 2007 flood). Water-surface 

profiles were computed starting 1.9 mi downstream from the 

confluence of the Wichita River and Holliday Creek upstream 

to where the Fort Worth-Denver Railroad crosses the Wichita 

River, upstream from the Tanglewood subdivision. The effects 

of flows ranging from 0 to 6,000 ft3/s in Holliday Creek on 

water-surface elevation were modeled for the Wichita River. 

Water-surface elevations downstream from the confluence 

of the two streams represent the combined flows of Wichita 

Table 4. Peak stages at U.S. Geological Survey streamflow-gaging stations on Wichita River and Holliday Creek, north 

Texas, October 2009–September 2010.

07312500 Wichita River 

at Wichita Falls, Tex. 

(Loop 11 gage)

07312610 Holliday Creek 

at Wichita Falls, Tex. 

(Holliday Creek gage)

07312700 Wichita River

 near Charlie, Tex. 

(Wichita River near Charlie gage)

Date Time Peak stage, 

(feet)1 Date Time Peak stage, 

(feet)2 Date Time Peak stage, (feet)3

10/10/2009 1630 5.15 10/08/2009 2345 8.82 10/09/2009 2145 7.42

1/30/2010 1230 11.78 1/28/2010 1630 7.78 1/31/2010 1615 12.44

4/18/2010 2130 12.44 4/17/2010 2200 10.07 4/19/2010 0330 15.87

5/15/2010 0815 11.77 5/14/2010 0815 12.09 5/15/2010 1700 16.36

6/16/2010 1830 4.03 6/14/2010 2330 7.64 6/15/2010 1915 7.27

7/09/2010 1915 6.69 7/09/2010 1200 9.72 7/10/2010 1030 9.53

9/03/2010 0015 3.52 9/02/2010 0030 9.43 9/02/2010 1930 6.694

9/09/2010 1430 6.32 9/08/2010 0800 8.98 9/09/2010 0500 8.31

1

 Datum of gage is 924.53 feet above North American Vertical Datum of 1988.

2

 Datum of gage is 919.61 feet above North American Vertical Datum of 1988.

3

 Datum of gage is 872.98 feet above North American Vertical Datum of 1988.

4 No stage data for 9/04/2010 through 9/06/2010. 
Models of Historical Floods and Effects of Backwater on Flood Stage 19

Holliday Creek channel station, in feet

-3,000 0 3,000 6,000 9,000 12,000 15,000 18,000 21,000 Mouth of Holliday Creek Martin Luther King Junior Boulevard Scott Avenue Station 07312610 at Bridwell Street

Elevation, in feet above

North American Vertical Datum of 1988

915

920

925

930

935

940

945

EXPLANATION

200 cubic feet per second

1,000 cubic feet per second

2,000 cubic feet per second

3,000 cubic feet per second

4,000 cubic feet per second

5,000 cubic feet per second

6,000 cubic feet per second

0 5,000 10,000 15,000 20,000 25,000

Holliday Creek channel station, in feet

930

935

940

945

950

Elevation, in feet above

North American Vertical Datum of 1988

4,000 cubic feet per second

5,000 cubic feet per second

6,000 cubic feet per second 

EXPLANATION

200 cubic feet per second

1,000 cubic feet per second

2,000 cubic feet per second

3,000 cubic feet per second

Mouth of Holliday Creek

Martin Luther King Junior

Boulevard 

Scott Avenue

Station 07312610

at Bridwell Street

Holliday Creek channel s

-3,000 0 3,000 6,000 9,000 

915

EXPLANATION

200 cubic feet per second

1,000 cubic feet per second

2,000 cubic feet per second

3,000 cubic feet per second

4

5

6

Holliday Creek channel station, in feet

-3,000 0 3,000 6,000 9,000 12,000 15,000 18,0

Nort

915

920

EXPLANATION

200 cubic feet per second

1,000 cubic feet per second

2,000 cubic feet per second

3,000 cubic feet per second

4,000 cubic feet per second

5,000 cubic feet per second

6,000 cubic feet per second

Holliday Creek channel station, in feet

-3,000 0 3,000 6,000 9,000 12,000 

915

EXPLANATION

200 cubic feet per second

1,000 cubic feet per second

2,000 cubic feet per second

3,000 cubic feet per second

4,000 cubic feet per 

5,000 cubic feet per 

6,000 cubic feet per 

0 5,000 10,000 

Holliday Creek cha

930

935

940

945

950

Elevation, in feet above

North American Vertical Datum of 1988

EXPLANAT

200 cubic feet per second

1,000 cubic feet per second

2,000 cubic feet per second

3,000 cubic feet per second

Mouth of Holliday Creek

Martin Luther King Junior

Boulevard 

Scott Avenue

0 5,000 10,000 15,000 20,000 

Holliday Creek channel station, in feet

930

935

940

945

950

Elevation, in feet above

North American Vertical Datum of 1988

4,000 cubic feet per second

5,000 cubic feet per second

6,000 cubic feet per second 

EXPLANATION

200 cubic feet per second

1,000 cubic feet per second

2,000 cubic feet per second

3,000 cubic feet per second

Mouth of Holliday Creek

Martin Luther King Junior

Boulevard 

Scott Avenue

Station 07312610

at Bridwell Street

Holliday Creek channel station, in fee

-3,000 0 3,000 6,000 9,000 12,000 

Mouth of Holliday Creek Martin Luther King Junior Boulevard Scott Avenue 

Elevation, in feet above

North American Vertical Datum of 1988

915

920

925

930

935

940

945

EXPLANATION

200 cubic feet per second

1,000 cubic feet per second

2,000 cubic feet per second

3,000 cubic feet per second

4,000 cubic fee

5,000 cubic fee

6,000 cubic fee

Figure 19. Water-surface profiles computed for various streamflow amounts in Holliday Creek, with no backwater from the Wichita River, 

Wichita Falls, Texas.

Figure 20. Water-surface profiles computed for various streamflow amounts in Holliday Creek, with backwater caused by streamflow of 

10,100 cubic feet per second in the Wichita River (the 2007 flood peak), Wichita Falls, Texas.
20 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

River and Holliday Creek. The effects of backwater decrease 

with distance upstream from the confluence (fig. 21). With 

6,000 ft3

/s of flow in Holliday Creek, computed watersurface elevations for the 2007 flood on the Wichita River at 

Loop 11 were 0.27 ft higher than those with no flow (0 ft3

/s) in 

Holliday Creek.

Flood Mitigation Alternatives

Potential flood-mitigation alternatives were analyzed 

to determine what reduction in flood stages might be gained 

in response to each of several possible solutions. Four 

alternatives were considered:

1. Increasing capacity of the bypass channel—what if the 

entrance to the bypass channel (south of River Road) were 

deepened? Could enough flow be diverted from the main 

channel to substantially reduce flood stages upstream 

from the bypass channel?

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Channel station, in feet

930

935

940

945

950

955

960

Elevation, in feet above

North American Vertical Datum of 1988

Mouth of Holliday Creek

Martin Luther King Junior

Boulevard 

Scott Avenue

Interstate 44

Station 07312500

at Loop 11

Tanglewoodsubdivision

EXPLANATION

Holliday Creek flow = 3,000 cubic feet per second

Holliday Creek flow = 4,000 cubic feet per second

Holliday Creek flow = 5,000 cubic feet per second

Holliday Creek flow = 6,000 cubic feet per second

Holliday Creek flow = 0 cubic feet per second

Holliday Creek flow = 200 cubic feet per second

Holliday Creek flow = 1,000 cubic feet per second

Holliday Creek flow = 2,000 cubic feet per second

2. Removing bridge obstructions—what if the obstructions 

were removed from the downstream side of Scott Avenue 

and Martin Luther King Junior Boulevard? 

3. Widening aggraded channel banks—what if sections 

that have narrowed (as evidenced by the comparison of 

cross sections from the 1986 photogrammetric survey 

with those from the 2009 cross section survey by the 

U.S. Geological Survey) were widened to match those 

observed in 1986?

4. Reducing channel roughness—what if vegetation on the 

banks and overbanks was thinned by 20 or 50 percent?

To make side-by-side comparisons possible, each 

potential mitigation alternative was modeled using the 2007 

flood-peak discharge (10,100 ft3

/s). The results of each 

alternative scenario were compared with the calibrated 2007 

flood profile, which was used to represent channel conditions 

as they existed in 2007.

Figure 21. Computed water-surface profiles for streamflow of 10,100 cubic feet per second (the 2007 flood peak) in the Wichita River, 

with backwater caused by various streamflow amounts in Holliday Creek, Wichita Falls, Texas.
Flood Mitigation Alternatives 21

Increasing Capacity on the Bypass Channel

The bypass channel diverges from the Wichita River 

channel upstream from River Road (fig. 1). During large 

floods, the bypass carries flow away from the Wichita River 

on a steep and circuitous path and reenters the Wichita River 

immediately upstream from the mouth of Holliday Creek. In 

2009, the elevation of the flow line (thalweg) of the bypass 

channel near its entrance was 938 ft, so the bypass only 

conveys flow when stages on the Wichita River exceed that 

elevation at the entrance to the bypass. The bypass channel 

did not flow during the 2008 flood. Flow in the bypass 

channel during the 2007 flood was computed to be 1,450 ft3

/s 

(14 percent of the total flow). Bypass channel flows were 

computed by determining what distribution of flow between 

the bypass and the Wichita River channel (north of the 

bypass) results in similar water-surface elevations (computed 

separately for both the Wichita River and the bypass channel 

by using the step-backwater model) at the inlet to the 

bypass channel. 

The 2007 flood was modeled using two scenarios 

to assess the benefits of enlarging the entrance to the 

bypass channel by simulated channel excavations (cuts) 

to depths that were deeper by 4 and 8 ft. For each of these 

scenarios, the bypass channel was modeled using a 900-ft 

long, trapezoidal (100-ft top width, 20-ft bottom 

width) channel traversing a topographic high point along 

the bank of the Wichita River that controls flow into the 

bypass channel. First the cut was made to an elevation of 

934 ft (4 ft below the existing flow line). The second cut 

was made to an elevation of 930 ft (8 ft below the existing 

flow line). Computed flood profiles for these two scenarios 

are shown in figure 22. With the bypass channel cut to an 

elevation of 934 ft, computed water-surface elevations were 

reduced as much as 0.7 ft. With the bypass channel cut to an 

elevation of 930 ft, computed water-surface elevations were 

reduced as much as 1.4 ft. The greatest reduction occurs near 

the entrance to the bypass channel. Computed flows conveyed 

by the bypass channel are 2,500 ft3

/s (25 percent of the total 

flow) for the 934-ft elevation and 3,500 ft3/s (35 percent of 

the total flow) for the 930-ft elevation. 

Removing Bridge Obstructions

The 2007 flood discharge was modeled with obstructions 

removed near the Scott Avenue and Martin Luther King 

930

935

940

945

950

955

960

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Channel station, in feet

Elevation, in feet above

North American Vertical Datum of 1988

Mouth of Holliday Creek

Martin Luther King Junior

Boulevard 

Scott Avenue

Interstate 44

Station 07312500

at Loop 11

Tanglewoodsubdivision

Entrance to bypass channel

Bypass channel rejoins Wichita River

EXPLANATION

Existing conditions

Bypass channel entrance cut to an elevation of 934 feet

Bypass channel entrance cut to an elevation of 930 feet

Figure 22. Computed water-surface profiles for streamflow of 10,100 cubic feet per second (the 2007 flood peak) in the Wichita River, 

with bypass channel cut deeper by 4 feet and 8 feet, Wichita Falls, Texas.
22 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

Junior Boulevard bridges. The obstructed cross sections at the 

downstream side of each bridge were replaced with the section 

representing the unblocked bridge opening. Modeling the 

removal of the earth fill near these bridges (on the basis of the 

surveyed bridge-opening cross sections and the shape of the 

2-ft elevation contours) includes the following modifications 

to the step-backwater model: (1) 100 ft downstream from 

Scott Avenue, remove (“cut”) 20 ft from the north banks 

and 30 ft from the south bank; (2) 300 ft downstream from 

Scott Avenue, “cut” 40 ft from the north bank; and (3) 660 ft 

upstream from Martin Luther King Junior Boulevard, “cut” 

30 ft from the north bank.

With the bridge obstructions removed from the cross 

sections, the modeled 2007 flood discharge yielded no 

reduction in water-surface elevation greater than 0.1 ft at 

any location along the water-surface profile. A possible 

explanation for this is that most of the flow was conveyed by 

the main channel during the 2007 flood near the Scott Avenue 

and Martin Luther King Junior Boulevard bridges, so minor 

changes on the edge of the overbank had scant effects on 

water-surface elevations.

Widening Aggraded Channel Banks

The 2007 flood discharge was modeled with the aggraded 

channel banks (as surveyed in 2009, fig. 10) removed in the 

channel reach between 0.9 and 2.6 mi downstream from 

Martin Luther King Junior Boulevard. On the basis of average 

channel characteristics in this part of the study reach for 

the 1986 and 2009 cross sections, the 2009 cross sections 

between 0.9 and 2.6 mi downstream from Martin Luther King 

Junior Boulevard were widened 40 ft at the top of the flood 

channel and 20 ft at the channel bed. The results of widening 

the channel downstream from Martin Luther King Junior 

Boulevard and removing obstructions near the Scott Avenue 

and Martin Luther King Junior Boulevard bridges are shown 

in figure 23. The greatest reduction in water-surface elevations 

was 1.1 ft, at the upstream end of the widened part of the 

reach near the Scott Avenue and Martin Luther King Junior 

Boulevard bridges.

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Channel station, in feet

930

935

940

945

950

955

960

Elevation, in feet above

North American Vertical Datum of 1988

EXPLANATION

Existing conditions

Parts of Wichita River channel widened and obstructions

 removed in vicinity of Scott Avenue and Martin Luther King

 Junior Boulevard bridges

Mouth of Holliday Creek

Martin Luther King Junior

Boulevard 

Scott Avenue

Interstate 44

Station 07312500

at Loop 11

Tanglewood

subdivision

Entrance to bypass channel

Bypass channel rejoins Wichita River

Channel obstructions removed in vicinity of Scott Avenue

and Martin Luther King Junior Boulevard bridges 

Channel widened to 1986 conditions

Figure 23. Computed water-surface profiles for streamflow of 10,100 cubic feet per second (the 2007 flood peak) in the Wichita River, 

with parts of the channel widened and obstructions near Scott Avenue and Martin Luther King Junior Boulevard bridges removed, 

Wichita Falls, Texas.
Flood Mitigation Alternatives 23

Reducing Channel Roughness

The 2007 flood discharge was modeled using two 

scenarios with different Manning’s n values representing 

different degrees of brush thinning on the channel banks and 

overbanks. In the first scenario, 20 percent of the vegetation 

was removed from the channel banks and overbank areas 

throughout the study reach. In the second scenario, 50 percent 

of the vegetation was removed. 

The vegetation-density method (Arcement and Schneider, 

1989; Petryk and Bosmajian, 1975) can be used for estimating 

Manning’s n for a given area on the flood plain on the basis 

of the number of trees of specified diameters growing in 

that part of the flood plain. Typically the method is used 

to estimate an unknown roughness, but the method can be 

“reverse engineered” to calculate a vegetation density for a 

given Manning’s n value. Figure 24 shows the vegetation for 

a segment of the overbank downstream from the Loop 11 

gage when the leaves are off the trees. Tree counts for five 

tree-diameter classes in increments of 0.1 ft between 0.1 ft 

and 0.5 ft were estimated for a selected area of the overbank 

in the photograph. To determine Manning’s roughness 

coefficient with less vegetation, the tree counts were reduced 

(proportionally for each class), and the corresponding 

roughness was computed. Figure 25 shows the resulting 

reduction in Manning’s roughness coefficient corresponding 

to a reduction in vegetation ranging from 0 to 100 percent 

of 2010 vegetation. Note that the curve in figure 25 is based 

on a uniform tree-count distribution across all classes, and a 

base Manning’s n of 0.032 for a channel with no vegetation 

(Arcement and Schneider, 1989, p. 4). The curve is not 

transferable to other applications; it is a tool to approximate 

the relation between vegetation density and Manning’s n

for the Wichita River at Wichita Falls, Tex. From figure 25, 

the Manning’s n corresponding to a 20-percent reduction of 

vegetation is 0.20 (a 9-percent reduction in the roughness 

coefficient); the Manning’s n corresponding to a 50-percent 

reduction in vegetation is 0.16 (a 27-percent reduction in 

roughness). Finally, the 2007 flood discharge is modeled for 

a 20-percent and a 50-percent reduction in vegetation. For 

a 20-percent reduction in vegetation, computed flood stages 

were reduced as much as 1.0 ft and, on average (for the 

entire modeled reach), 0.9 ft. For a 50-percent reduction in 

vegetation, computed flood stages were reduced as much as 

3.0 ft and, on average, 2.6 ft (fig. 26).

The density of vegetation on the overbank during the 

1941 flood was estimated by applying the calibrated overbank 

roughness coefficient (table 2) to the curve in figure 25. An 

overbank roughness of 0.064 indicates that vegetation might 

have been about 90 percent less in 1941 than in 2010 (fig. 25). 

Photographs of the channel indicate substantial vegetation 

growth occurred on the channel banks between 1950 and 

2009 (fig. 7).

Comparison of Flood Mitigation Alternatives

Comparisons of the computed flood profiles between 

various mitigation alternatives are difficult, primarily because 

of the arbitrary degree to which each alternative was applied 

in the modeling scenarios. For example, a 4-ft and an 8-ft cut 

were modeled for the bypass channel. Why not 12 ft? Similar 

questions can be raised for the other modeled flood-mitigation 

alternatives. Manning’s roughness coefficient (n)

0.25

0.20

0.15

0.10

0.05

0

Percent reduction of vegetation 

from current (2010) conditions

0 20 40 60 80 100

Figure 24. Looking downstream from Loop 11 at the U.S. 

Geological Survey streamflow-gaging station 07312500 Wichita 

River at Wichita Falls, Texas, February 25, 2009.

Figure 25. Reduction in Manning’s roughness coefficient (n) 

corresponding to a reduction in channel-bank and flood-plain 

vegetation, Wichita River at Wichita Falls, Texas.
24 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Channel station, in feet

930

935

940

945

950

955

960

Elevation, in feet above

North American Vertical Datum of 1988

EXPLANATION

Existing conditions

Vegetation reduced 20 percent on channel banks and flood plain

Vegetation reduced 50 percent on channel banks and flood plain

Mouth of Holliday Creek

Martin Luther King Junior

Boulevard 

Scott Avenue

Interstate 44

Station 07312500

at Loop 11

Tanglewood

subdivision

In general, deepening the upper reaches of the bypass 

channel yielded the greatest reduction in flood stage 

immediately upstream from the entrance to the bypass. The 

4-ft cut resulted in as much as a 0.8-ft reduction in flood 

stage at the upstream end of the bypass channel; the 8-ft cut 

resulted in as much as a 1.4-ft reduction in flood stage at the 

upstream end of the bypass channel. This reduction is less at 

locations further upstream or downstream from the entrance to 

the bypass channel (fig. 22). The 4-ft bypass cut results in less 

than a 0.1-ft reduction at the Tanglewood subdivision 

(fig. 22). Computed water-surface elevations for various 

flood-mitigation alternatives are presented along with those 

for existing (2010) conditions in table 5.

Widening the narrowed segment of the channel between 

Martin Luther King Junior Boulevard and River Road and 

removing fill near the Scott Avenue and Martin Luther 

King Junior Boulevard bridges yielded as much as a 1.1-ft 

reduction in flood elevation, with the maximum reduction at 

the upstream end of the widened part of the reach (fig. 23). 

Reductions in flood elevation computed for this scenario 

translate upstream somewhat, with a 0.7-ft reduction at 

Interstate Highway 44. However, the reduction in flood 

elevation is only about 0.3 ft at Loop 11. 

The final potential flood-mitigation alternative is the 

thinning of channel bank and flood-plain vegetation to reduce 

Manning’s n. Without thinning, Manning’s n was as large 

as 0.22 in the roughest areas of the flood plain, the densely 

vegetated banks and overbanks. A 20-percent reduction in 

riparian vegetation on the banks and overbanks resulted in a 

9-percent reduction in Manning’s n. A 50-percent reduction 

in riparian vegetation resulted in a 27-percent reduction in 

Manning’s n. The 2007 flood discharge was modeled using 

these reduced roughness coefficients. For a 20-percent 

reduction in riparian vegetation, mean reduction in flood 

elevation was about 0.9 ft. For a 50-percent reduction in 

riparian vegetation, mean reduction in flood elevation was 

about 2.6 ft. These values represent thinning of vegetation 

throughout the model; for areas left in their current (2011) 

state, flood elevations might deviate from these results. 

The effects of implementing a combination of different 

flood-mitigation alternatives were not investigated. Although 

the reduction in flood elevations achieved through a 

Figure 26. Water-surface profiles computed for streamflow of 10,100 cubic feet per second (the 2007 flood) in the Wichita River, with 

vegetation reduced 20 and 50 percent on the channel banks and flood plain, Wichita Falls, Texas. 
Summary 25

combination of mitigation alternatives might be greater than 

the reduction from any one remedy alone, the combined 

effects of individual mitigation alternatives might not be 

strictly cumulative.

Summary

Continuous records of stage and discharge have been 

made at U.S. Geological Survey (USGS) streamflow-gaging 

station 07312500 Wichita River at Wichita Falls, Texas, 

since 1938. A record stage (since at least 1938) of 24.40 feet 

(ft) with a peak discharge of 10,100 cubic feet per second 

(ft3

/s) was recorded on June 30, 2007. On August 19, 2008, 

a flood stage of 20.51 ft with a peak discharge of 6,940 ft3

/s 

was recorded at USGS streamflow-gaging station 07312500. 

Understanding the causes for increased flood stages on the 

Wichita River in 2007 and 2008 floods compared to flood 

stages during floods of similar or smaller magnitude prior 

to 1972 is important to water resource managers in Texas. 

The reliability of annual peak-streamflow data for USGS 

streamflow-gaging station 07312500 requires an understanding 

of the factors affecting stream stage on the Wichita River. The 

USGS, in cooperation with the City of Wichita Falls, assessed 

channel changes on the Wichita River in Wichita Falls, and 

modeled historical floods to investigate possible causes and 

potential mitigation alternatives to reduce flood elevations 

such as those experienced in recent (2007 and 2008) floods.

Streamflow records during 1938–2007 at streamflowgaging station 07312500 indicate seven or eight floods roughly 

similar (or greater) in magnitude than the 10,100 ft3

/s peak 

discharge of the 2007 flood. Although the peak discharges 

of floods prior to 2007 were of similar or greater magnitude 

compared to the 2007 flood, none of the floods since 1938 

reached the stage of the 2007 flood. Data from three USGS 

streamflow-gaging stations were used to assess channel 

changes and evaluate flood-mitigation alternatives. In addition 

to data from streamflow-gaging station 07312500, data from 

USGS streamflow-gaging stations 07312610 Holliday Creek at 

Wichita Falls, Tex., and 07312700 Wichita River near Charlie, 

Tex., were used in this study. Streamflow-gaging station 

07312610 Holliday Creek at Wichita Falls, Tex., is located at 

Bridwell Street about 3.7 (mi) upstream from the mouth of 

Holliday Creek. The more than 1,000 discharge measurements 

made at streamflow-gaging station 07312500 Wichita 

River at Wichita Falls, Tex., during 1938–2010 indicate no 

substantial aggradation has occurred on the channel bed or 

banks near Loop 11. Discharge measurements for stages of 

more than 18 ft from 1938 to 2008 indicate a decrease in the 

measured mean velocity from about 3.5 feet per second (ft/s) 

in 1941 to about 2.0 ft/s in 2008. This reduction in velocity 

was accompanied by an increase in stage to convey similar 

discharges through the system.

Aerial and ground photographs were analyzed to 

determine an increase in vegetation in the channel or overbank 

in the reach of the river near the gage contributed to the 

Table 5. Computed water-surface elevations for 10,100 cubic feet per second (the peak discharge of the 2007 flood) on the Wichita 

River at Wichita Falls, Texas, for existing (2010) channel conditions and various flood-mitigation alternatives

Computed water-surface elevation, in feet above North American Vertical Datum of 1988

Location

(fig. 1)

Existing 

channel 

conditions

4-foot 

bypass cut

8-foot 

bypass cut

Widening of 

narrowed sections

20 percent 

vegetation 

reduction

50 percent 

vegetation 

reduction

River Road 937.58 937.46 937.35 937.58 936.68 934.94

Martin Luther King 

Junior Boulevard 943.77 943.33 942.96 942.95 942.91 941.21

Scott Avenue 944.46 944.08 943.76 943.68 943.60 941.91

Interstate Highway 44 945.42 945.10 944.84 944.73 944.54 942.79

Loop 11 948.73 948.60 948.50 948.46 947.96 946.43

Tanglewood subdivision 952.29 952.24 952.20 952.18 951.55 950.00

Fort Worth-Denver Railroad 954.23 954.20 954.18 954.17 953.45 951.85
26 Assessment of Channel Changes, Models of Floods, and Flood Mitigation Alternatives for the Wichita River

elevated flood stages in 2007 and 2008 compared to historical 

flood stages for similar flood discharges. Since 1950, oblique 

photographs of the Wichita River channel at Loop 11 have 

been taken periodically by personnel of the USGS. The aerial 

photographs indicate an increase in vegetation between 1953 

and 1991 along the banks and in the flood plain at Lucy Park, 

1 to 2 mi downstream from Loop 11. Ground photographs 

taken near Loop 11 in 1950, 1961, 1975, and 2009 indicate 

a substantial amount of riparian vegetation growth occurred 

between 1950 and 2009.

Channel cross sections at Loop 11 at streamflow-gaging 

station 07312500 Wichita River at Wichita Falls, Tex., during 

1938–2009 indicate that, while minor changes in crosssection shape are observed, the thalweg and the width of the 

channel are fairly stable. Cross sections surveyed in 2009 

by the USGS between Loop 11 and River Road compared 

favorably with those from a 1986 photogrammetric survey. 

However, four consecutive cross sections located between 

0.9 and 2.6 mi downstream from Martin Luther King Junior 

Boulevard indicated substantial narrowing. For those four 

cross sections, the loss in channel width was typically 30 

to 50 ft. Comparison of the 2009 surveys of the channels to 

bridge openings shown on as-built bridge plans indicates 

no change in cross section. Obstructions were noted at the 

downstream side of the Scott Avenue bridge (south span) and 

at the Martin Luther King Junior bridge (north span), which 

only partially block flow but could reduce channel conveyance 

during floods.

The floods of 2007, 2008, and 1941 were modeled 

using a one-dimensional, steady-state, step-backwater model 

developed by the USGS for the Wichita River in Wichita Falls 

in order to prepare a calibrated model useful for modeling 

different flood-mitigation alternatives (the 1941 flood is used 

for comparison with the 2007–8 floods because the channel 

in1941 was different compared to the channel in 2007 and 

2008). Calibration of the 2007 and 2008 floods was done by 

adjusting Manning’s n so that differences in computed and 

observed water-surface elevations at the Loop 11 gage and the 

staff gages were minimized. Calibration of the model to the 

June 2007 flood indicated Manning’s n was as large as 0.22 in 

the roughest areas of the flood plain and 0.048 in the Wichita 

River channel. The relatively large calibrated roughness 

values for the June 2007 flood are indicative of a densely 

vegetated flood plain and a rougher-than-average natural 

channel. Calibration of the August 2008 flood indicated 

flood-plain roughness as large as 0.22 in the roughest areas of 

the flood plain, but the Wichita River channel roughness was 

0.041. The difference between the 2007 and 2008 calibrated 

Manning’s n for the Wichita River channel could be because 

of the 4-ft stage difference between the two floods and the 

increased effect of overhanging branches at higher stages. The 

October 3, 1941, flood peaked at 24.00 ft at streamflow-gaging 

station 07312500 Wichita River at Wichita Falls, Tex., with a 

discharge of 17,800 ft3

/s. The calibrated Manning’s n for the 

Wichita River for the 1941 flood is 0.030, which is a relatively 

small value for a natural channel, indicating that the channel 

conveyed flow more efficiently in 1941 than in 2007.

A large inflow from Holliday Creek can cause backwater 

on the Wichita River, and large flows in the Wichita River 

can cause backwater on Holliday Creek. During low-flow 

conditions, the streams often act independently of each other 

and there is no relation between the stage on one stream 

and the stage on the other stream. Eight concurrent rises on 

Wichita River and Holliday Creek were analyzed to determine 

the timing of peaks on the two streams and to assess the 

degree to which each was affected by backwater. Based on 

analysis of the storm hydrographs from the 2010 water year, 

the Wichita River at Loop 11 typically peaks about 34 hours 

after Holliday Creek. However, the lag varied from as little as 

7 hours to as much as 44 hours. Holliday Creek was observed 

by USGS personnel to be flowing at the peak of the 2007 flood 

recorded at the Loop 11 gage, corroborating the possibility 

that the peaks from Wichita River and Holliday might have 

peaked concurrently during the 2007 flood.

The 2010 step-backwater model was used to assess the 

potential extent of backwater during flooding at the confluence 

of Wichita River and Holliday Creek. Flood profiles were 

computed for Holliday Creek without backwater and in 

backwater conditions; the backwater conditions simulated the 

conditions likely to have occurred during the large 2007 flood. 

Channel roughness for Holliday Creek was calibrated on the 

basis of the April 19, 2010, measured discharge of 1,220 ft3

/s 

at a stage of 8.90 ft (928.51 ft above North American Vertical 

Datum of 1988) at the Holliday Creek gage. The calibrated 

Manning’s n for Holliday Creek is 0.031. The effects of flows 

ranging from 0 to 6,000 ft3

/s in Holliday Creek on watersurface elevation were modeled for the Wichita River. With 

6,000 ft3

/s of streamflow in Holliday Creek, computed watersurface elevations for the 2007 flood on the Wichita River at 

Loop 11 were 0.27 ft higher than with no streamflow (0 ft3

/s) 

in Holliday Creek.

Potential flood-mitigation alternatives were analyzed to 

determine what reduction in flood stages might be gained in 

response to each of several possible solutions. Four scenarios 

were considered: increasing capacity of the bypass channel, 

removing bridge obstructions, widening aggraded channel 

banks, and reducing channel roughness. To make side-by-side 

comparisons possible, each potential mitigation alternative 

was modeled using the 2007 flood-peak discharge. 

In the first flood-mitigation alternative, the bypass 

channel was modeled as being deeper by different amounts. 

In 2009, the elevation of the flow line (thalweg) of the bypass 

channel near its entrance was 938 ft, so the bypass only 

conveys flow when stages on the Wichita River exceed that 

elevation at the entrance to the bypass. With the bypass cut 

to an elevation of 934 ft, computed water-surface elevations 

were reduced as much as 0.7 ft. With the bypass channel cut 

to an elevation of 930 ft, computed water-surface elevations 

were reduced as much as 1.4 ft. The greatest reduction 

in water-surface elevation occurs near the entrance to the 

bypass channel. In the second flood-mitigation alternative, 
References Cited 27

bridge obstructions removed near Martin Luther King Junior 

Boulevard and Scott Avenue bridges were removed in the 

model. No reductions in water-surface elevation greater 

than 0.1 ft were computed at any location along the watersurface profile for 2007 flood. In the third flood-mitigation 

alternative, aggraded channel banks between 0.9 and 2.6 mi 

downstream from Martin Luther King Junior Boulevard were 

removed from the channel reach. The greatest reduction in 

water-surface elevations was 1.1 ft at the upstream end of the 

widened part of the reach near the Scott Avenue and Martin 

Luther King Junior Boulevard bridges. In the fourth floodmitigation alternative, two Manning’s n values representing 

different degrees of brush thinning on the channel banks 

and overbanks (20 and 50 percent thinning of the vegetation 

removed from the channel banks and overbank areas 

throughout the study reach) were modeled. A 20-percent 

reduction in vegetation results in a Manning’s n of 0.20 for 

the banks and overbanks, a 9-percent reduction from the 

Manning’s n of 0.22 (determined without any thinning). For 

a 20-percent reduction in vegetation, computed flood stages 

were reduced as much as 1.0 ft, and on average by 0.9 ft. A 

50-percent reduction in vegetation results in a Manning’s n of 

0.16 (a 27-percent reduction in roughness). For a 50-percent 

reduction in vegetation, computed flood stages were reduced 

by as much as 3.0 ft and on average were reduced by 2.6 ft. 

The calibrated overbank roughness during the 1941 flood 

was 0.064. This indicates that vegetation might have been 

about 90 percent less in 1941 compared to 2010. The effects 

of implementing a combination of different flood-mitigation 

alternatives were not investigated. Although the reduction in 

flood elevations achieved through a combination of mitigation 

alternatives might be greater than any one remedy alone, the 

combined effects of individual mitigation alternatives might 

not be strictly cumulative.

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