U.S. Department of the Interior

U.S. Geological Survey

Water-Resources Investigations Report 01-4091

Calibration and Validation of a TwoDimensional Hydrodynamic Model of the

Ohio River, Jefferson County, Kentucky

In cooperation with the Ohio River Valley Water Sanitation Commission
U.S. Department of the Interior

U.S. Geological Survey

Calibration and Validation of a TwoDimensional Hydrodynamic Model of the

Ohio River, Jefferson County, Kentucky

By Chad R. Wagner and David S. Mueller

Water-Resources Investigations Report 01-4091

In cooperation with the Ohio River Valley Water Sanitation

Commission

Louisville, Kentucky

2001
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

For additional information write to: Copies of this report can be purchased from:

District Chief, Kentucky District U.S. Geological Survey

U.S. Geological Survey Information Services

9818 Bluegrass Parkway Box 25286

Louisville, KY 40299–1906 Denver, CO 80225–0286

http://ky.water.usgs.gov
Contents iii

CONTENTS

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

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

Background............................................................................................................................................. 1

Purpose and scope .................................................................................................................................. 2

Study area ............................................................................................................................................... 2

Model calibration and validation ..................................................................................................................... 4

Model description ................................................................................................................................... 4

Field data collection and interpretation .................................................................................................. 4

Water-surface elevations................................................................................................................ 8

Velocity and discharge................................................................................................................... 8

Bathymetry .................................................................................................................................... 8

Upstream river reach............................................................................................................................... 9

Computational-mesh configuration ............................................................................................... 9

Boundary conditions...................................................................................................................... 14

Calibration and validation results .................................................................................................. 14

Downstream river reach.......................................................................................................................... 15

Computational-mesh configuration ............................................................................................... 15

Boundary conditions...................................................................................................................... 21

Calibration and validation results .................................................................................................. 21

Summary and conclusions ............................................................................................................................... 32

References cited............................................................................................................................................... 33

FIGURES

1-4. Maps showing:

1. Location of study area near Louisville, Kentucky .................................................................... 3

2. McAlpine Locks and Dam configuration and U.S. Geological Survey (USGS)

gaging station locations near Louisville, Kentucky.................................................................. 5

3. Location of hydrographic-survey cross sections, surveyed water-surface elevation

stations, and USGS gaging stations in the upstream study reach near

Louisville, Kentucky................................................................................................................. 6

4. Location of hydrographic-survey cross sections, surveyed water-surface elevation

stations, and USGS gaging stations in the downstream study reach near

Louisville, Kentucky................................................................................................................. 7

5-21. Graphs showing:

5. Surface Water Modeling System (SMS) software triangulation of raw and straight-line

bathymetry data for a section of the upstream study reach in the Ohio River model

simulation near Louisville, Kentucky ....................................................................................... 10

6. Mesh configuration around the earthen dike adjacent to Louisville, Kentucky, and

upstream of McAlpine Locks and Dam in the Ohio River model simulation .......................... 11

7. Mesh configurations around Six- and Twelve-Mile Islands in the upstream Ohio River

study reach ................................................................................................................................ 12
iv Contents

8. Upstream reach mesh configuration around McAlpine Locks and Dam near

Louisville, Kentucky ................................................................................................................ 13

9. Field-measured and model-simulated velocity profiles for cross-section 5,

13 miles upstream from McAlpine Locks and Dam ................................................................ 16

10. Field-measured and model-simulated low-flow, distance-weighted average

cross-sectional velocities in the upstream study reach from the Ohio River model

simulation ................................................................................................................................. 17

11. Field-measured and model-simulated high-flow, distance-weighted average

cross-sectional velocities in the upstream study reach from the Ohio River model

simulation ................................................................................................................................. 18

12. Mesh configuration in the downstream study reach around the tailwater area of

McAlpine Locks and Dam ....................................................................................................... 20

13. Stage-discharge curve for McAlpine tailwater gaging station near Louisville,

Kentucky, 1990-2000 ............................................................................................................... 22

14. Stage-discharge curve at Kosmosdale gaging station near Louisville, Kentucky,

1995-2000................................................................................................................................. 23

15. Discharge-slope curve between McAlpine tailwater and Kosmosdale gaging stations

 near Louisville, Kentucky, 1995-2000 .................................................................................... 24

16. Field-measured and model-simulated low-flow velocity profiles for cross-sections 19

and 25 in the Ohio River model simulation.............................................................................. 26

17. Scatter plot of the cross-sectional area and average velocity differences between field

measurements and model-simulated results for the 18 downstream Ohio River

cross sections near Louisville, Kentucky ................................................................................. 28

18. Comparison of cross-section 24 bathymetry in the downstream Ohio River study reach ....... 29

19. Comparison of cross-section 20 bathymetry in the downstream Ohio River study reach ....... 29

20. Low-flow distance-weighted average cross-sectional velocity profile for the downstream

study reach in the Ohio River model simulation ...................................................................... 30

21. High-flow distance-weighted average cross-sectional velocity profile for the downstream

study reach in the Ohio River model simulation ...................................................................... 31

TABLES

1. Summary of water-surface elevation calibration and validation for the upstream study

reach in the Ohio River model simulation near Louisville, Kentucky............................................... 14

2. Summary of flow-split calibration and validation for islands in the upstream study reach

in the Ohio River model simulation ................................................................................................... 19

3. Summary of continuity checks in the upstream Ohio River model simulation ................................. 19

4. Evaluation of the Research Management Associates-2 (RMA-2) simulation representation

of the Ohio River rating developed for the downstream study reach near Louisville, Kentucky ...... 25

5. Summary of water-surface elevation calibration and validation for the downstream study

reach in the Ohio River model simulation ......................................................................................... 25

6. Summary of continuity checks in the downstream Ohio River model simulation............................. 32
Contents v

CONVERSION FACTORS AND VERTICAL DATUM

CONVERSION FACTORS

Multiply By To obtain

foot (ft) 0.3048 meter

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

cubic foot per second (ft3/s) 0.02832 cubic meter per second

mile (mi) 1.609 kilometer

VERTICAL DATUM

Sea level: In this report “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)—a geodetic datum derived

from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.

Elevation, as used in this report, refers to the distance above or below sea level.
INTRODUCTION 1

Calibration and Validation of a Two-Dimensional

Hydrodynamic Model of the Ohio River, Jefferson

County, Kentucky

By Chad R. Wagner and David S. Mueller

Abstract

The quantification of current patterns is

an essential component of a Water Quality

Analysis Simulation Program (WASP)

application in a riverine environment. The

U.S. Geological Survey (USGS) provided a

field validated two-dimensional Resource

Management Associates-2 (RMA-2)

hydrodynamic model capable of quantifying the

steady-flow patterns in the Ohio River extending

from river mile 590 to 630 for the Ohio River

Valley Water Sanitation Commission

(ORSANCO) water-quality modeling efforts on

that reach. Because of the hydrodynamic

complexities induced by McAlpine Locks and

Dam (Ohio River mile 607), the model was split

into two segments: an upstream reach, which

extended from the dam upstream to the upper

terminus of the study reach at Ohio River

mile 590; and a downstream reach, which

extended from the dam downstream to a lower

terminus at Ohio River mile 636.

The model was calibrated to a low-flow

hydraulic survey (approximately 35,000 cubic

feet per second (ft3/s)) and verified with data

collected during a high-flow survey

(approximately 390,000 ft3

/s). The model

calibration and validation process included

matching water-surface elevations at

10 locations and velocity profiles at 30 cross

sections throughout the study reach. Based on

the calibration and validation results, the model

is a representative simulation of the Ohio River

steady-flow patterns below discharges of

approximately 400,000 ft3

/s.

INTRODUCTION

Combined sewer overflows (CSO’s), sanitary

sewer overflows (SSO’s), nonpoint sources, and

storm-water runoff are all sources of wet-weather

pollution that contribute to the degradation of our

Nation’s vital water resources. In situations where

more than one of these sources contributes to the

impairment of water quality, a holistic approach

defining the relative importance of each source’s

contribution to the problem is the most efficient way

to arrive at an economical control plan. In order to

determine the relative significance of the various

sources of wet-weather pollution on major

waterways, an understanding of the local

hydrodynamics, pollutant land loading, and

pollutant-transport characteristics is essential.

Background

The Ohio River Valley Water Sanitation

Commission (ORSANCO) is nearing completion of

a national demonstration study to develop a waterquality model that is capable of simulating pollutant

concentrations in the river during wet-weather

periods and is able to quantify improvements to the

water quality resulting from pollution control bestmanagement practices. The initial project was

completed on a reach of the Ohio River, which

included the Cincinnati/northern Kentucky

metropolitan area. The Water Quality Analysis

Simulation Program (WASP) was utilized to

simulate the water-quality constituent transport and

transformation during low-flow periods spanning

the recreational-contact period May-September. The

flow field required by WASP was simulated by use

of a two-dimensional Resource Management

Associates-2 (RMA-2) hydrodynamic model.
2 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

In order to demonstrate the transferability of

this project to other riverfront metropolitan areas, a

similar study was initiated in the Louisville,

Kentucky, metropolitan area; this study involved

both hydrodynamic and water-quality modeling and

field data collection. The U.S. Geological Survey

(USGS), in cooperation with ORSANCO,

developed a field-validated hydrodynamic model to

support the water-quality model being developed by

a consultant contracted by ORSANCO.

Purpose and Scope

This report describes the calibration and

validation of the two-dimensional RMA-2 model to

simulate the complex hydrodynamics of a 40-mi

study reach of the Ohio River near Louisville, Ky.

(Ohio River mile 590 to 630; fig. 1). The field data

used to calibrate and validate the model also are

described. Because of the hydrodynamic

complexities induced by McAlpine Locks and Dam

(Ohio River mile 607), the model was split into two

segments: an upstream reach, which extended from

the dam upstream to the upper terminus of the study

reach at Ohio River mile 590; and a downstream

reach, which extended from the dam downstream to

a lower terminus at Ohio River mile 636.

Floodplains were not included in the model

domain because of the project emphasis on low-flow

periods spanning the recreational-contact period

May-September. The final model was used to

simulate the steady-flow patterns of the Ohio River

for flows ranging from 6,500 to 197,700 ft3/s. The

lower limit of the simulated flows (6,500 ft3/s) is

consistent with the discharge during a dye-tracing

survey done by ORSANCO in September 1999. The

upper limit of the range of simulated flows

(197,700 ft3

/s) corresponds to the 90-percentile

flow during the recreational-contact period based on

historical discharge data during 1987–98. Although

more historical discharge data are available,

ORSANCO and the private consultant chose to use

only recent data (1987–98) to determine the

90-percentile flow. The process and methodology

used to calibrate and validate the model with field

data as well as the results of the model simulations

are discussed in this report.

Study Area

The Ohio River study area begins at the

northeast corner of Jefferson County, Ky., and

extends southwestward through the county and ends

6 river miles downstream from the mouth of the Salt

River (fig. 1). The upstream reach is in the

McAlpine Locks and Dam pool and the water level

is kept at an elevation of approximately 420 ft above

sea level during low-flow periods. The downstream

reach of the study area is in the tailwater of

McAlpine Locks and Dam. The water level at the

dam is held at a normal pool level of 383 ft above

sea level by the Cannelton Locks and Dam, which is

located 150 river miles downstream. The channel

has a generally trapezoidal geometry with steep

banks rising at slopes greater than 22 percent

(0.22 ft/ft). The banks along the upstream reach

extend to an approximate elevation of 440 ft,

whereas the banks of the downstream reach rise to

approximately 420 ft.

The following river characteristics were

determined from the data collected during the

hydrographic surveys. At a discharge of

36,000 ft3/s, the average depth of the river thalweg

was approximately 30 ft in the upstream reach and

20 ft in the downstream reach. The average width of

the river at a discharge of 36,000 ft3

/s was

approximately 3,000 ft in the upstream reach and

1,600 ft in the downstream reach. A discharge of

390,000 ft3

/s produced an average depth in the

thalweg of approximately 45 ft in both the upstream

and downstream reaches. The width of the river at a

discharge of 390,000 ft3/s was approximately

4,000 ft in the upstream reach and 2,500 ft in the

downstream reach. The bank and bed material of the

study reach varies between cohesive and

noncohesive sediment. The bank vegetation

predominately consists of small shrubbery and

vegetation, void of large trees.
INTRODUCTION 3

Study Area

Kentucky

0 1 2 4 6 8 10

0 2 4 6 8 10 KILOMETERS

38o

86o

MILES

Downstream

model terminus

McAlpine

Locks and Dam Twelve-Mile Island

Upstream

model terminus

Six-Mile Island

1

Salt River

590

605

595

600

610

615

620

625

630

635

EXPLANATION

River mile marker 615 Ohio River Mile

38030’ 

380

15’ 

85 0

45’ 85030’ 

Figure 1. Location of study area near Louisville, Kentucky.
4 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

The structures that compose McAlpine Locks

and Dam are located on the northwestern side of

Louisville, Ky., and extend from Ohio River

mile 604.4 to 607.4. The current locks-and-dam

configuration (fig. 2) consists of a hydroelectric

powerhouse; two lock chambers (one 600 by 110 ft

and the other 1,200 by 110 ft in length and width,

respectively); nine tainter gates, four near the

powerhouse and five just upstream of the Conrail

Railroad Bridge; and a fixed weir with a crest at an

elevation of 422 ft at the downstream gates,

incrementally raised to an elevation of 423 ft at the

upper set of gates. An earthen dike was constructed

at the upstream end of Shippingport Island to reduce

the crosscurrents affecting vessels navigating the

lock canal. The shoal area that exists downstream

from the upper gates and fixed weir is referred to as

the Falls of the Ohio and is an area of archeological

importance. To facilitate public use of the fossil

beds at the Falls of the Ohio, the U.S. Army Corps

of Engineers (COE) has agreed to a 2-month

operational period (typically August-October) each

year when the fixed weir and upper gates are not

used to pass flow, except for extreme hydrological

events. Under low flow or when the upper gates of

McAlpine Locks and Dam are not in operation, the

Falls of the Ohio is an area of slack flow.

MODEL CALIBRATION AND

VALIDATION

At least two data sets are required to

adequately calibrate and validate a numerical

model. The general procedure used to calibrate and

validate the RMA-2 model was to first collect field

data in order to develop the computational mesh.

The model then was calibrated to the water-surface

elevations and velocities observed in the field for the

initial flow. A second flow condition then was

simulated without changing the computational mesh

or model parameters, and the simulated watersurface elevations and velocities were compared

with those observed in the field for this second flow

condition.

Model Description

RMA-2 is a two-dimensional depth-averaged

finite-element hydrodynamic numerical model

capable of computing water-surface elevations and

horizontal-velocity components for subcritical, freesurface flow in two-dimensional flow fields

(U.S. Army Corps of Engineers, 1997). The model

is designed for problems in which vertical

accelerations are negligible, and velocity vectors

generally point in the same direction over the entire

depth of the water column at any discrete period in

time.

Typical applications of the RMA-2 numerical

model include calculating water-surface elevations

and flow distribution around islands; flow patterns at

bridges having one or more relief openings, in

contracting and expanding reaches, into and out of

off-channel hydropower plants, and at river

junctions; circulation and transport in water bodies

with wetlands; and water levels and flow patterns in

rivers, reservoirs, and estuaries.

One of the predominating operating

assumptions in RMA-2 is that acceleration of flow

in the vertical direction is negligible. The model is

not intended for applications in which vortexes,

vibrations, or vertical accelerations are the primary

interests; therefore, the simulation of vertically

stratified flow fields is beyond the capabilities of

RMA-2 (U.S. Army Corps of Engineers, 1997).

Field Data Collection and

Interpretation

Water-surface elevations, channelbathymetry, and detailed water-velocity

measurements were collected at two different flow

conditions (36,000 and 390,000 ft3

/s) and used in

the model for calibration and validation,

respectively. Water-surface elevations were

measured at 10 locations (4 upstream and

6 downstream) along the study reach concurrent

with both hydraulic surveys. Detailed water-velocity

measurements and channel-bathymetry data were

collected at 30 cross sections (12 upstream and

18 downstream)—spaced approximately 1.5 mi

apart—during each of the hydraulic surveys (figs. 3

and 4). A separate data-collection trip from the two

hydrographic surveys was used to collect channelbathymetry data in sufficient detail for the

development of a computational mesh.
MODEL CALIBRATION AND VALIDATION 5

Fixed 

weir

Upper 

gates

Lower 

gates

Earthen dike

38017' 

85046' 

38016' 

85048' 

03294650

03293550

85047' 

CC4

CC5

CC2

CC3

CC1

1 MILE 0

1 KILOMETER 0

USGS gaging station location

03294600 USGS gaging station number

EXPLANATION

CC3 Continuity line name

.25 .50 .75 

.25 .50 .75 

Continuity check line

Figure 2. McAlpine Locks and Dam configuration and U.S. Geological Survey (USGS) gaging station locations near Louisville,Kentucky.
6 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

85045' 850

35' 

38025' 

38015' 

0 1 2 3 4

0 1 234 KILOMETERS

MILES

Survey cross section

10 Cross-section number

USGS gaging station location

03294600 USGS gaging station number

Surveyed water-surface 

elevation location

EXPLANATION

1

2

3L

4

5

12

11

10

9

8 7L

Six-Mile 6

Island

Twelve-Mile 

Island

03293548

03293550

Louisville

7R

3R

595

600

605

590

River mile marker

600 Ohio River Mile

Figure 3. Location of hydrographic-survey cross sections, surveyed water-surface elevation stations, and

U.S. Geological Survey (USGS) gaging stations in the upstream study reach near Louisville, Kentucky.
MODEL CALIBRATION AND VALIDATION 7

38016’

0 1 2 3 4 5 MILES

012345 KILOMETERS

Survey cross section

10 Cross-section number

15

16

17

18

19

20

21

22

23

24

25

26

27

28

3029

31 32

USGS gaging station location

03294600 USGS gaging station number

Surveyed water-surface 

elevation location

EXPLANATION

38008’

380

860

01’ 850

53’ 850

45’

032946500

03294600

Salt River

605

610

615

620

625

630

635

River mile marker

600 Ohio River Mile

Figure 4. Location of hydrographic-survey cross sections, surveyed water-surface elevation stations, and

U.S. Geological Survey (USGS) gaging stations in the downstream study reach near Louisville, Kentucky.
8 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

Water-Surface Elevations

Water-surface elevations at the seven

locations throughout the reach (figs. 3 and 4) were

surveyed with a total station. To document the

changes in river stage during a hydraulic survey, the

water-surface elevations were surveyed in the

morning and then again in the afternoon. The

average water-surface elevation was used to

determine a water-surface slope corresponding to

the average discharge measured during the survey.

The 40-mi study section of the Ohio River

includes a total of four USGS stream gages—two

each in both the upstream and downstream reaches.

Both upstream gages—one located on the Second

Street Bridge (number 03293548) and the other at

Indiana Pass (number 03293550)—are located near

river mile 604 and provided to assist the COE,

Louisville District in maintaining the McAlpine

Locks and Dam normal pool elevation. The Second

Street Bridge gage is located on a pier near the

center of the channel about 4,000 ft upstream from

McAlpine Locks and Dam; the Indiana Pass gage is

located on the Indiana shore about 500 ft

downstream from the Second Street Bridge gage

(fig. 3). The McAlpine tailwater and Kosmosdale

gaging stations (numbers 03294500 and 03294600,

respectively) are located within the downstream

reach (fig. 4). The McAlpine tailwater gage is

located near the Kentucky shore on the downstream

end of the lock guide wall (river mile 607). The

Kosmosdale gage is located on the Kentucky shore,

19.8 mi downstream from the tailwater gage (river

mile 628).

Velocity and Discharge

Water-velocity and discharge data were

collected from a moving boat. The horizontal

position of the boat was measured using a

differentially corrected global positioning system

(DGPS) receiver. The DGPS system used receives

its differential corrections from a commercial

service’s communications satellite. The unit is

specified by the manufacturer to be accurate to 3.3 ft

at two standard deviations; tests and prior use of this

unit indicate that typically about 80 percent of the

data are within 3.3 ft of the true location.

Recent advances in velocity-measurement

technology allow three-dimensional velocities to be

collected from a moving boat using an acoustic

Doppler current profiler (ADCP) (Oberg and

Mueller, 1994; Mueller, 1996). All velocities were

measured with an ADCP. The ADCP allows threedimensional velocities to be measured from

approximately 4 ft beneath the water surface to

within 6 percent of the depth to the bottom.

Established methods were used to estimate the

discharge in the unmeasured top and bottom

portions of the profile (Simpson and Oltmann,

1991). Cross-sectional average velocities were

computed by dividing the measured discharge by

the measured cross-sectional area. In addition,

depth-averaged velocities were computed for

subsections of the flow in each cross section;

however, these discrete depth-averaged velocities

were computed as an average of the measured

velocity and did not account for the velocity in the

unmeasured portions of the water column.

In order to compensate for the slight changes

in discharge of the river during the survey, all the

discharge measurements collected were averaged to

produce a flow rate that was representative of the

entire survey period. The time necessary to

complete a hydraulic survey on each of the

simulated sections did not permit both the upstream

and downstream reaches to be surveyed on the same

day; therefore, minor differences are present in the

discharge measurements used to calibrate and

validate the upper and lower models.

Bathymetry

Bathymetry data also were collected from a

moving boat. The horizontal position of the boat

was measured using the DGPS receiver. During the

initial low-water survey, a 200-kHz echo sounder

was used to measure the channel bathymetry at the

30 predefined cross sections.
MODEL CALIBRATION AND VALIDATION 9

The channel bathymetry obtained from the

initial bathymetric survey at the 30 velocitymeasurement cross sections was compared to the

1963 COE hydrographic survey of the area. The

surveyed data points of the 1963 hydrographic

survey were digitized along straight cross sections

spaced at 1/4-mi intervals and oriented

perpendicular to flow. All data points were digitized

from paper maps. A triangulated irregular network

(TIN) of the 1963 data was generated to extract

cross sections from the 1963 data for the

30 locations surveyed for this project. The shapes of

the cross sections measured in the downstream

reach were similar to cross sections extracted from

the 1963 hydrographic-survey data. Differences in

elevation were within the errors expected from the

survey technologies of 1963 and those used in this

survey; therefore, data from the 1963 hydrographic

survey were used for the channel bathymetry in the

downstream hydrodynamic model. The shape of the

cross sections measured in the upstream reach

displayed differences from the cross sections

extracted from the 1963 hydrographic-survey data;

therefore, a second bathymetric survey of the

upstream reach was completed with cross sections

spaced approximately 1,000 ft apart. The data from

the second bathymetry survey was used for the

channel bathymetry in the upstream hydrodynamic

model.

Bathymetric data surveyed with the echo

sounder in the upstream reach did not fall on

perfectly straight cross sections because of

inconsistencies in the boat course across the river.

The internal triangulation routine done by the

RMA-2 interface software package—Surface-water

Modeling Systems (SMS), version 7.0 (Brigham

Young University, 1999)—did not properly interpret

the collected bathymetry data, resulting in

triangulation within the same cross section and a

large portion of the area between two cross sections

estimated with only three data points. An example

of the raw-data triangulation is presented in

figure 5a. The raw data collected along each cross

section was mathematically forced onto a straight

line and re-triangulated; figure 5b shows the

re-triangulation of the section shown in figure 5a.

Although forcing the data points onto a straight line

does introduce some error, the straight-line cross

sections produced a better representation of the

upstream channel bathymetry than the unadjusted

data.

Upstream River Reach

The simulated upstream reach begins 3 mi

upstream of the Jefferson/Oldham County line

(Ohio River mile 590) in Kentucky, and extends

downstream to McAlpine Locks and Dam (Ohio

River mile 607). Two islands are present that add

hydraulic complexities to this reach: Twelve-Mile

Island located at Ohio River mile 593, and Six-Mile

Island located at Ohio River mile 598. The

configuration of McAlpine Locks and Dam includes

upper and lower sets of tainter gates and a

hydropower plant that served as downstream

boundary conditions for the model.

Computational-Mesh Configuration

The finite-element network for the upstream

river reach consisted of 6,920 elements. The islands

and dike were simulated by installing gaps in the

mesh because the simulated flows did not overtop

these features (figs. 6 and 7). The boundary nodes at

the upstream and downstream points of the islands

were specified as “stagnation points” (locations of

zero velocity). These specifications generally are

located in corners of grids or along boundaries with

relatively negligible flow velocities and are applied

to reduce artificial loss of discharge out of the

channel boundaries. The resolution of the grid was

increased in the area around McAlpine Locks and

Dam in order to reproduce the hydraulic

complexities induced by these structures (fig. 8). In

order to maintain numerical stability, the sloping

banks were truncated at an elevation of 418 ft.

Above this elevation, the banks were assumed to be

vertical walls.
10 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

A. Triangulation of raw data

B. Triangulation of straight-line data 

Bathymetricsurvey lines 

Bathymetricsurvey lines 

Flow

Flow 

Figure 5. Surface Water Modeling System (SMS) software triangulation of raw and straight-line

bathymetry data for a section of the upstream study reach in the Ohio River model simulation near

Louisville, Kentucky.
MODEL CALIBRATION AND VALIDATION 11

Earthen dike 

Shippingport Island 

00

500 1,000 FEET 

150 300 METERS 

Figure 6. Mesh configuration around the earthen dike adjacent to Louisville, Kentucky, and upstream of McAlpine Locks and Dam in the Ohio River modelsimulation near Louisville, Kentucky.
12 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

A. Mesh configuration around Six-Mile Island 

B. Mesh configuration around Twelve-Mile Island

0

0

1 MILE

1 KILOMETER

.25 .50 .75 

.25 .50 .75

Flow 

Flow 

Six-Mile Island 

Twelve-Mile 

Island

Figure 7. Mesh configurations around Six- and Twelve-Mile Islands in the upstream Ohio

River study reach near Louisville, Kentucky.
MODEL CALIBRATION AND VALIDATION 13 Earthen dike 

Upper gates 

Lower gates 

Hydropower

plant

Shippingport Island 

McAlpine Locks 

Fixed Weir 

0

0 1 KILOMETER

1 MILE .25 .50 .75

.25 .50 .75

Flow 

Figure 8. Upstream reach mesh configuration around McAlpine Locks and Dam near Louisville, Kentucky.
14 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

Boundary Conditions

Steady-state discharges of 34,000 and

383,000 ft3

/s were used to calibrate and validate the

model. These discharges were used as the upstreamboundary condition for the model and the lateralflow distribution was assumed to be uniform across

the inflow boundary for both discharges.

The downstream-boundary condition

consisted of outflows through the lower gates and

hydropower plant (low-flow only) and a head

condition assigned to the upper gates. The lower set

of tainter gates carried 14,000 ft3/s, whereas the

hydropower plant passed the remaining 20,000 ft3

/s

under the low-flow condition. At 383,000 ft3/s, the

flow is divided between the upper and lower gates,

with 126,350 ft3

/s passing through the lower gates

and the remaining 256,650 ft3

/s passing through the

upper gates. The McAlpine Locks and Dam pool

elevations for both discharges were determined

from the USGS gaging station records at Indian

Pass (number 03293550) and Second Street Bridge

(number 03293548). Normal pool elevation

(419.6 ft) was used for 34,000 ft3

/s flow, and a pool

elevation of 423.9 ft was used for 383,000 ft3

/s

flow.

Calibration and Validation Results

Data from the low-flow (34,000 ft3/s)

hydraulic survey were used to calibrate the model,

and data from the high-flow (383,000 ft3

/s) survey

were used to validate the model. The calibration and

validation process consisted of comparing the

simulated water-surface elevations at the

4 upstream water-surface-elevation stations and

12 cross-sectional velocity profiles with those

surveyed in the field. A Manning’s roughness

coefficient (n) was assigned to each element and

iteratively adjusted until the model adequately

simulated the surveyed water-surface elevations and

velocity profiles.

Inspection of the velocity profiles collected in

the field revealed no-slip conditions along the

riverbanks, indicating that the shear stress along the

banks is great enough to cause the tangential

velocity to approach zero. To simulate this

characteristic with RMA-2, the Manning’s n value

was increased to 0.035 for one row of elements

along the outer boundary of the mesh. The

calibrated Manning’s n in the remainder of the

channel was 0.024. This combination produced the

best simulation of water-surface elevation (table 1),

velocity magnitudes, and lateral-velocity

distribution for both low- and high-flow conditions.

Matching the high-flow water-surface elevations

verified that the area lost by truncating the banks

was negligible in the model simulation.

Table 1. Summary of water-surface elevation calibration and validation for the upstream study reach in the Ohio River

model simulation near Louisville, Kentucky

Station

(8/13/98) Low-flow condition (2/16/00) High-flow condition

Field

water-surface

elevation

(feet above

sea level)

Model

water-surface

elevation

(feet above

sea level) Difference1

Field

water-surface

elevation

(feet above

sea level)

Model

water-surface

elevation

(feet above

sea level) Difference1

Harmony Landing 419.99 419.66 -0.33 427.59 427.68 0.09

Louisville Water Company 419.91 419.64 -.27 426.51 426.46 -.05

Cox’s Park Well 419.86 419.62 -.24 425.19 425.04 -.15

Indiana Pass 419.60 419.60 0 423.88 423.90 .02

1

Differences are determined by subtracting field from model-simulated water-surface elevation.
MODEL CALIBRATION AND VALIDATION 15

The simulated velocity magnitudes and

distributions compared well with the field

measurements. A comparison of the model and

field-velocity profiles for cross-section number 5

(13 mi upstream from McAlpine Locks and Dam)

is shown in figure 9. The shape of the field- and

model-velocity distributions were similar, whereas

on average, the velocity magnitudes were within

0.1 ft/s. The average cross-sectional velocities for

the 12 cross sections also were compared. The

model adequately reproduced the average field

velocities (figs. 10 and 11). The model also

accurately reproduced the measured-flow

distributions around Twelve- and Six-Mile Islands

(table 2).

Continuity was checked throughout the

downstream model to assure that mass was being

conserved. The model conserved mass throughout

the reach under high flow, but a 3 percent loss

resulted under low flow in the approach to the lower

tainter gates and hydropower plant (table 3). A

tolerance of +/- 3 percent in mass-conservation

discrepancy is typically acceptable for most models

(U.S. Army Corps of Engineers, 1997). Algorithms

used to import RMA-2 output into the WASP waterquality model can correct for mass-conservation

discrepancies.

Downstream River Reach

The simulated reach begins at the McAlpine

Locks and Dam (Ohio River mile 607) and extends

downstream to Ohio River mile 636, 6 mi

downstream from the mouth of the Salt River. This

section of the model includes part of the Cannelton

Locks and Dam pool, which is held at a normal pool

elevation of 383 ft. The two sets of tainter gates, the

hydropower plant, a lock wall supported on piles

that allows flow beneath the wall, and Sand Island

all contribute to the hydraulic complexities of the

area located immediately downstream of the

McAlpine Locks and Dam.

Computational-Mesh Configuration

The finite-element network for the

downstream river reach consisted of

10,803 elements. In order to maintain numerical

stability, the sloping banks were truncated at an

elevation of 380 ft. Above this elevation, the banks

were assumed to be vertical walls.

Sand Island and an unnamed island in the

Falls of the Ohio region were simulated by

installing gaps in the mesh at the location of these

features. The resolution of the grid is increased in

the area around Sand Island, the hydropower plant,

the lock wall, and both sets of tainter gates to

improve simulation of the hydraulic complexities

induced by these structures (fig. 12). In order to

simulate the passage of flow under the lock wall, an

increased Manning’s roughness value (n = .50) was

assigned to the elements representing the lock wall;

this value allowed flow through the elements under

a much greater resistance. Stagnation points were

created at sharp break points along Sand Island and

the mesh boundary in the area of the lower tainter

gates to reduce artificial loss of discharge through

the boundaries.
16 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

A. Low-flow velocity profile comparison 

B. High-flow velocity profile comparison 

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800

DISTANCE FROM LEFT BANK, IN FEET

0.0

0.2

0.4

0.6

0.8

VELOCITY, IN FEET PER SECOND

Field

Model

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800

DISTANCE FROM LEFT BANK, IN FEET

0

1

2

3

4

5

6

VELOCITY, IN FEET PER SECOND

Field

Model

Figure 9. Field-measured and model-simulated velocity profiles for cross-section 5, 13 miles upstream from

McAlpine Locks and Dam near Louisville, Kentucky.
MODEL CALIBRATION AND VALIDATION 17 1 2 3R 3L 4 5 6 7R 7L 8 9 10 11 12 CROSS SECTION, IN DOWNSTREAM ORDER

0

0.70.60.50.40.30.20.1

AVERAGE CROSS-SECTIONAL VELOCITY,

 IN FEET PER SECOND

FieldModel

.49 .49

.41

.48

.55

.53

.46

.36

.32

.55

.48 .49

.46

.43 .43

.67

.54

.56

.54

.53

.58

.48

.52

.56

Figure 10. Field-measured and model-simulated low-flow, distance-weighted average cross-sectional velocities in the upstreamstudy reach from the Ohio River model simulation near Louisville, Kentucky.
18 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky 1 2 3R 3L 4 5 6 7R 7L 8 9 10 11 12 CROSS SECTION, IN DOWNSTREAM ORDER 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0

AVERAGE CROSS-SECTIONAL VELOCITY, 

 IN FEET PER SECOND

FieldModel

4.76

4.29 4.38

4.75

4.87

3.84

4.28 4.37

4.48

4.67 4.69

4.37

3.84

3.33

4.37

4.53

4.37 4.44

3.88

4.15

4.05

4.35

5.08

5.32

4.17

4.83

0

4.71 

Figure 11. Field-measured and model-simulated high-flow, distance-weighted average cross-sectional velocities in the upstream studyreach from the Ohio River model simulation near Louisville, Kentucky.
MODEL CALIBRATION AND VALIDATION 19

Table 2. Summary of flow-split calibration and validation for islands in the upstream study reach in the Ohio River

model simulation near Louisville, Kentucky

Location

Low flow High flow

Field

flow split

(percent)

Model

flow split

(percent)

Field

flow split

(percent)

Model

flow split

(percent)

Twelve-Mile Island – Right 53.6 51.7 51.6 49.9

Twelve-Mile Island – Left 46.4 48.3 48.4 49.5

Six-Mile Island – Right 8.9 7.8 11.2 10.0

Six-Mile Island – Left 91.1 92.0 88.8 90.0

Table 3. Summary of continuity checks in the upstream

Ohio River model simulation near Louisville, Kentucky

Continuity check

line description

(fig. 3)

Percent of total discharge

Low flow High flow

Inflow 100 100

Cross section 2 99.5 99.8

Cross section 3R 51.8 50.1

Cross section 3L 48.2 49.5

Cross section 5 100 100

Cross section 7R 8.0 10.2

Cross section 7L 92.0 89.6

Cross section 11 100 99.7

Upper gates 0 66.5

Lower gates 45.2 32.8

Hydropower plant 52.0 0

Total outflow 97.2 99.3
20 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky Lower gates Upper gates Sand Island Lock wall Hydropower plant Unnamed Island Fixed weir 0 0 2000 4,000 FEET 600 1,200 METERS Flow Figure 12. Mesh configuration in the downstream study reach around the tailwater area of McAlpine Locks and Dam near Louisville, Kentucky.
MODEL CALIBRATION AND VALIDATION 21

Boundary Conditions

Steady-state discharges of 36,000 and

397,000 ft3

/s were used to calibrate and validate the

model, respectively. At 36,000 ft3/s, the

hydropower plant passed 22,000 ft3

/s, whereas the

lower gates passed 14,000 ft3/s. At 397,000 ft3

/s,

the inflow is divided between the upper and lower

gates, with 266,030 ft3/s from the upper gates and

130,970 ft3

/s from the lower gates.

The downstream head-boundary conditions

for both discharges were determined from

stage-discharge relations developed from USGS

gaging-station records at the McAlpine tailwater

(number 032946500) and Kosmosdale

(number 03294600) gages. The relation between

stage and discharge was determined by plotting the

discharge computed for the McAlpine gage with the

stage measured at the McAlpine tailwater and

Kosmosdale gaging stations (figs. 13 and 14). A

relation between discharge and water-surface slope

between the McAlpine tailwater and Kosmosdale

gages also was developed (fig. 15). The downstream

head-boundary conditions were determined by

translating the observed water-surface elevations

from the Kosmosdale gage 5 mi downstream to the

model boundary by use of the discharge watersurface slope relation. For simulated flows other

than those measured for calibration and validation,

the stage at Kosmosdale can be determined from a

known discharge and the stage-discharge relation

and then translated to the downstream end of the

model based on the discharge water-surface slope

relation (fig. 15). The difference between the

McAlpine tailwater rating and the water-surface

elevation (simulated by RMA-2 based on the

downstream boundary condition estimated from the

technique described above) ranges from 0.16 to

0.4 ft (table 4).

Calibration and Validation Results

Similar to the upstream reach, the low-flow

(36,000 ft3

/s) hydraulic survey was used to calibrate

the model, and the high-flow (397,000 ft3

/s) survey

was used to validate the simulation. The calibration

and validation process consisted of comparing the

simulated water-surface elevations at the

6 downstream water-surface elevation stations and

18 cross-sectional velocity profiles (fig. 4) with

those surveyed in the field. A Manning’s roughness

coefficient (n) was assigned to each element and

iteratively adjusted until the model adequately

simulated the surveyed water-surface elevations and

velocity profiles.

Inspection of the velocity profiles collected in

the field revealed no-slip conditions along the

riverbanks, which were similar to the upstream

reach. To simulate this characteristic with RMA-2,

the Manning’s n value was increased to 0.035 for

one row of elements along the outer boundary of the

mesh. The calibrated Manning’s n in the remainder

of the channel was 0.024. This combination

produced the best simulation of water-surface

elevation (table 5), velocity magnitude, and lateralvelocity distribution for both low- and high-flow

conditions. Matching the high-flow water-surface

elevations verified that the area lost by truncating

the banks was negligible.

Comparison of the simulated velocity

magnitudes and distributions with field

measurements showed good agreement for the lowflow simulation but less favorable agreement for the

high-flow simulation. Examples of the general

agreement between the low-flow simulated

velocities and the field measured velocities are

shown in figure 16. The maximum difference at low

flow was about 0.25 ft/s. For the high-flow

condition, the simulated velocities consistently were

greater than the measured velocities, despite

excellent agreement in the water-surface elevations.
22 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky 0 50,000 100,000 150,000 200,000 DISCHARGE, IN CUBIC FEET PER SECOND 403 402 401 400 399 398 397 396 395 394 393 392 391 390 389 388 387 386 385 384 383

ELEVATION AT MCALPINE TAILWATER 

GAGING STATION, IN FEET ABOVE SEA LEVEL Best-fit line 

Figure 13. Stage-discharge curve for McAlpine tailwater gaging station near Louisville, Kentucky, 1990-2000.
MODEL CALIBRATION AND VALIDATION 23 0 50,000 100,000 150,000 200,000 DISCHARGE, IN CUBIC FEET PER SECOND

400399398397396395394393392391390389388387386385384383382

ELEVATION AT KOSMOSDALE GAGING STATION, 

IN FEET ABOVE SEA LAEVEL

Best-fit line 

Figure 14. Stage-discharge curve at Kosmosdale gaging station near Louisville, Kentucky, 1995-2000.
24 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky 0 50,000 100,000 150,000 200,000 DISCHARGE, IN CUBIC FEET PER SECOND 0.0e0 6.0e-5 5.0e-5 4.0e-5 3.0e-5 2.0e-5 1.0e-5

SLOPE BETWEEN MCALPINE TAILWATER AND KOSMOSDALE 

GAGING STATIONS, IN FOOT PER FOOT Best-fit line 

Figure 15. Discharge-slope curve between McAlpine tailwater and Kosmosdale gaging stations near Louisville, Kentucky,1995-2000.
MODEL CALIBRATION AND VALIDATION 25

Table 4. Evaluation of the Resource Management Associates-2 (RMA-2) simulation

representation of the Ohio River rating developed for the downstream study reach near

Louisville, Kentucky

Downstream discharge

(cubic feet per second)

Boundary condition

(elevation

above sea level)

Rating

water-surface elevation,

McAlpine tailwater

(elevation

above sea level)

Model

water-surface elevation,

McAlpine tailwater

(elevation

above sea level)

16,000 382.74 383.60 383.22

23,000 382.98 384.20 383.80

43,000 383.86 386.10 385.94

97,000 387.25 391.80 392.23

200,000 395.54 402.60 402.27

Table 5. Summary of water-surface elevation calibration and validation for the downstream study reach in the

Ohio River model simulation near Louisville, Kentucky

Station

(5/19/00) Low-flow condition (2/17/00) High-flow condition

Field

water-surface

elevation

(feet above

sea level)

Model

water-surface

elevation

(feet above

sea level) Difference1

Field

water-surface

elevation

(feet above

sea level)

Model

water-surface

elevation

(feet above

sea level) Difference1

McAlpine tailwater 385.20 384.90 -0.30 416.18 416.13 -0.05

Shawnee well 384.75 384.50 -.25 415.10 415.21 .11

RR-22 well 384.68 384.20 -.48 413.65 413.83 .18

Kosmosdale 383.85 383.50 -.35 410.10 410.12 .02

West Point 383.54 383.40 -.14 409.70 409.50 -.20

1

Differences are determined by subtracting field from model-simulated water-surface elevation.
26 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

A. Low-flow velocity profile for cross-section 19 

B. Low-flow velocity profile for cross-section 25 

0 200 400 600 800 1,000 1,200 1,400 1,600

DISTANCE FROM LEFT BANK, IN FEET

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

VELOCITY, IN FEET PER SECOND

Field

Model

0 200 400 600 800 1,000 1,200 1,400 1,600

DISTANCE FROM LEFT BANK, IN FEET

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

VELOCITY, IN FEET PER SECOND

Field

Model

Figure 16. Field-measured and model-simulated low-flow velocity profiles for cross-sections 19

and 25 in the Ohio River model simulation near Louisville, Kentucky.
MODEL CALIBRATION AND VALIDATION 27

To identify the cause of the disagreement

between the simulated and measured velocities for

the high-flow condition, the cross-sectional areas of

the model and the field were evaluated. The

difference between the magnitudes of the model and

field average cross-sectional velocities is correlated

closely with differences in cross-sectional area

(fig. 17). This difference in areas for the high-flow

condition indicates that truncating the channel

bathymetry at an elevation of 380 ft may not be

acceptable for high flows. Extending the bathymetry

to an elevation of 390 ft improved the agreement

between field and model velocities but failed to

explain all of the error. For low-flow conditions, the

errors between the field data and the model are

somewhat randomly distributed around zero. The

errors for the high-flow condition with banks

truncated at an elevation of 380 ft show a linear

pattern, while the errors for the high-flow condition

with banks truncated at an elevation of 390 ft show a

less distinct pattern but still well below zero. The

patterns indicated by the high-flow data indicate that

something outside the scope of the model may be

responsible for the apparent errors. Scouring of the

channel bottom occurred during high flow and is

partially responsible for the large difference

between the model and field cross-sectional areas

and average velocities because the model is not able

to simulate the scouring of the channel bed (figs. 18

and 19). A comparison of the average crosssectional velocities for the field and two model

meshes are shown in figures 20 and 21.

Although extending the banks to an elevation

of 390 ft improved the overall accuracy of the highflow simulation (3.4 percent in average crosssectional velocity), the primary reason for the

difference between the model and field crosssectional areas and velocities is that the model has a

fixed bed and the river adjusted its cross section in

the downstream reach during high flow. To

minimize errors of future simulations, the

bathymetry was truncated at an elevation of 380 ft

for flows less than 200,000 ft3

/s, and bathymetry

was truncated at an elevation of 390 ft for flows

ranging from 200,000 to 400,000 ft3/s.

Continuity was checked throughout the model

to ensure that mass was being conserved. The

location of the continuity-check lines near Sand

Island and the Falls of the Ohio is shown in figure 2;

mass is conserved around Sand Island and the Falls

of the Ohio (table 6). Based on the calibration and

validation results, the model is a representative

simulation of the Ohio River steady-flow patterns

below discharges of approximately 400,000 ft3

/s.
28 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky -15 -10 -5 0 5 10 15 20 25 30 DIFFERENCE IN CROSS-SECTIONAL AREA, IN PERCENT -10 -15 -20 -25-5

50

1510

Low FlowHigh Flow 380 feetHigh Flow 390 feet

DIFFERENCE IN AVERAGE VELOCITY, IN PERCENT

EXPLANATION

High Flow 380 feet - All bathymetry truncated at elevation 380 feet above sea levelHigh Flow 390 feet - All bathymetry truncated at elevation 390 feet above sea level

Figure 17. Scatter plot of the cross-sectional area and average velocity differences between field measurements andmodel-simulated results for the 18 downstream Ohio River cross sections near Louisville, Kentucky.
MODEL CALIBRATION AND VALIDATION 29

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800

DISTANCE FROM LEFT BANK, IN FEET

360

370

380

390

400

410

420

ELEVATION, IN FEET ABOVE SEA LEVEL

Model

Field (high flow)

1963 survey

Figure 18. Comparison of cross-section 24 bathymetry in the downstream Ohio River study

reach near Louisville, Kentucky.

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800

DISTANCE FROM LEFT BANK, IN FEET 

360

370

380

390

400

410

420

ELEVATION, IN FEET ABOVE SEA LEVEL

Model

Field (high flow)

1963 survey

Figure 19. Comparison of cross-section 20 bathymetry in the downstream Ohio River study

reach near Louisville, Kentucky.
30 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky 0 5 10 15 20 25 DISTANCE FROM MCALPINE LOCKS AND DAM, IN MILES 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 0.00

AVERAGE CROSS-SECTIONAL VELOCITY, 

IN FEET PER SECOND

FieldModel

Figure 20. Low-flow distance-weighted average cross-sectional velocity profile for the downstream study reach in theOhio River model simulation near Louisville, Kentucky.
MODEL CALIBRATION AND VALIDATION 31 0 5 10 15 20 25 DISTANCE FROM MCALPINE LOCKS AND DAM, IN MILES

6.56.05.55.04.54.03.53.0

AVERAGE CROSS-SECTIONAL VELOCITY, 

IN FEET PER SECOND Field Model 380 feet Model 390 feet

EXPLANATION

Model 380 feet - All bathymetry truncated at elevation 380 feet above sea levelModel 390 feet - All bathymetry truncated at elevation 390 feet above sea level

Figure 21. High-flow distance-weighted average cross-sectional velocity profile for the downstream study reach in the Ohio Rivermodel simulation near Louisville, Kentucky.
32 Calibration and Validation of a Two-Dimensional Hydrodynamic Model of the Ohio River, Jefferson County, Kentucky

Table 6. Summary of continuity checks in the

downstream Ohio River model simulation near

Louisville, Kentucky

Continuity check

line description

(figs. 2, 4)

Percent of total discharge

Low flow High flow

Upper gates - inflow 0.0 67.0

Hydropower - inflow 60.4 0

Lower gates - inflow 39.4 33.0

Total inflow 99.8 100.0

CC1 .1 65.6

CC2 84.0 101

CC3 17.6 -.4

CC4 79.4 100.7

CC5 19.2 -.5

Cross section 15 102 98.4

Cross section 22 100 99.9

Outflow 100 100

SUMMARY AND CONCLUSIONS

The determination of current patterns is an

essential component of a Water Quality Analysis

Simulation Program (WASP) in a riverine

environment. The U.S. Geological Survey (USGS),

in cooperation with the Ohio River Valley Water

Sanitation Commission (ORSANCO), developed a

field-validated two-dimensional hydrodynamic

model capable of quantifying the steady flow

patterns in the reach of the Ohio River extending

from Ohio River mile 590 to 630 for the

ORSANCO water-quality modeling efforts on that

reach. The model was calibrated to a low-flow

hydraulic survey (approximately 35,000 cubic feet

per second (ft3/s)) and validated with data collected

during a high-flow survey (approximately

390,000 ft3

/s). The model calibration and

verification process included matching watersurface elevations at 10 locations and velocity

profiles at 30 cross sections in the study reach. The

study area was separated into an upper and lower

river reach separated at McAlpine Locks and Dam

(Ohio River mile 607). A bathymetric survey was

conducted on the upstream reach to determine the

channel geometry. Data from the Ohio River survey

(1963) done by the U.S. Army Corps of Engineers

was used to determine bathymetry on the

downstream reach. Data collected during the

upstream bathymetric survey was mathematically

forced onto straight cross-section lines providing a

more accurate triangulation of the data in the

modeling software package. Bathymetry of both

reaches was truncated along the banks to eliminate

Resource Management Associates-2 (RMA-2)

convergence problems associated with the steeply

sloping banks of the Ohio River. The upper reach

was truncated at an elevation of 418 ft for both flow

conditions, whereas the lower reach was truncated

at an elevation of 380 ft for low flows (less than

200,000 ft3/s) and an elevation of 390 ft for high

flows (from 200,000 to 400,000 ft3

/s).

Based on historical discharge data during

1987–98, the 90-percentile flow during this

recreational-contact period (May-September) is

197,700 ft3

/s; therefore, only the model with

bathymetry truncated at an elevation of 380 ft is

needed to simulate these flows.
REFERENCES CITED 33

The model was calibrated and validated by

use of water-surface elevations and average crosssectional velocities to achieve the minimum error

for both high- and low-flow conditions. The

simulated low-flow water-surface elevations

typically were biased between 0.2 and 0.3 ft low,

whereas the simulated high-flow water-surface

elevations were within 0.1 ft of the field conditions.

Simulated average cross-sectional velocities were

typically within 0.1 ft/s for low flow and 0.3 ft/s for

high flow when compared with field data.

REFERENCES CITED

Brigham Young University, 1999, Surface-Water

Modeling System (SMS) Reference Manual

(ver. 7.0): Provo, Utah, Environmental Modeling

Research Laboratory, [variously paged].

Mueller, D.S., 1996, Scour at bridges—Detailed data

collection during floods, in Federal Interagency

Sedimentation Conference, 6th, Las Vegas, Nev.,

1996, Proceedings: Subcommittee on

Sedimentation, Interagency Advisory Committee

on Water Data, p. 41–48.

Oberg, K.A., and Mueller, D.S., 1994, Recent

applications of Acoustic Doppler Current Profiles,

in Fundamentals and Advancements in Hydraulic

Measurements and Experimentation, Buffalo,

New York, 1994, Proceedings: Hydraulics

Division/American Society of Civil Engineers

(ASCE), p. 341–350.

Simpson, M.R., and Oltmann, R.N., 1991, Dischargemeasurement system using an Acoustic Doppler

Current Profiler with applications to large rivers and

estuaries: U.S. Geological Survey Water-Resources

Investigations Report 91-487, 49 p.

U.S. Army Corps of Engineers, 1997, Users Guide to

RMA2 WES (ver. 4.3): Vicksburg, Miss., Waterways

Experiment Station, 227 p.
Wagner and Mueller—CALIBRATION AND VALIDATION OF A TWO-DIMENSIONAL HYDRODYNAMIC MODEL OF THE OHIO RIVER,

JEFFERSON COUNTY, KENTUCKY—U.S. Geological Survey Water-Resources Investigations Report 01-4091U.S. GEOLOGICAL SURVEY9818 BLUEGRASS PARKWAYLOUISVILLE, KY 40299–1906

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