U.S. Department of the Interior 

U.S. Geological Survey 

In cooperation with the 

Carroll County Water-Supply Board 

Hydrogeology and Simulation of 

Ground-Water Flow in the 

Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 

Water-Resources Investigations Report 98-4215 

U.S. Department of the Interior 

U.S. Geological Survey 

Hydrogeology and Simulation of 

Ground-Water Flow in the 

Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 

By Michael D. Unthank 

Water-Resources Investigations Report 98-4215 

In cooperation with the 

Carroll County Water-Supply Board 

Louisville, Kentucky 

1999 
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, 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 Branch of Information Services 

Water Resources Division Box 25286 

9818 Bluegrass Parkway Denver, CO 80225–0286 

Louisville, KY 40299–1906 
CONTENTS 

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

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

Purpose and scope ...................................................................................................................................................... 1
 

Approach .................................................................................................................................................................... 2
 

Previous studies .......................................................................................................................................................... 2
 

Description of the study area ...................................................................................................................................... 2
 

Hydrogeology of the alluvial aquifer..................................................................................................................................... 5
 

Geology ...................................................................................................................................................................... 5
 

Hydrologic data .......................................................................................................................................................... 9
 

Ground-water-level observation network ......................................................................................................... 9
 

Precipitation ...................................................................................................................................................... 9
 

Ground-water pumpage .................................................................................................................................... 9
 

Ground-water flow in the alluvial aquifer .................................................................................................................. 9
 

Bedrock beneath the alluvial aquifer .......................................................................................................................... 19
 

Stream-aquifer interaction .......................................................................................................................................... 19
 

Small streams .................................................................................................................................................... 19
 

Ohio River ........................................................................................................................................................ 25
 

Conceptual model of the ground-water-flow system............................................................................................................. 25
 

Simulation of ground-water flow in the alluvial aquifer ....................................................................................................... 25
 

Equation development ................................................................................................................................................ 26
 

Model assumptions ..................................................................................................................................................... 26
 

Model grid .................................................................................................................................................................. 26
 

Model boundaries ....................................................................................................................................................... 29
 

Input parameters ......................................................................................................................................................... 29
 

Model calibration and water budget ........................................................................................................................... 30
 

Sensitivity analysis ..................................................................................................................................................... 33
 

Limitations of the model ............................................................................................................................................. 35
 

Application of the ground-water-flow model ........................................................................................................................ 35
 

Summary and conclusions ..................................................................................................................................................... 47
 

References cited .................................................................................................................................................................... 47
 

FIGURES 

Maps showing: 

1.	 Location of study area and extent of the Ohio River alluvial aquifer................................................................ 3
 

2.	 Surficial geology of the Carrollton area, Kentucky ........................................................................................... 7
 

3.	 Observation well network ................................................................................................................................. 11
 

4.	 Typical water-level hydrographs for wells completed in the alluvial aquifer............................................................. 13
 

5.	 Map showing location and amounts of ground-water pumpage................................................................................. 15
 

6.	 Map showing altitude of potentiometric surface of the alluvial aquifer, near Carrollton, Kentucky, 

November 1995........................................................................................................................................................... 17 

7.	 Hydrographs showing response of water levels in the alluvial aquifer to an Ohio River flood pulse in a 
 

non-stressed area......................................................................................................................................................... 20
 

8.	 Hydrographs showing response of water levels in the alluvial aquifer to an Ohio River flood pulse in a 
 

heavily pumped area ................................................................................................................................................... 21
 

Contents III 
Contents 

9-11. Maps showing: 

9.	 Altitude of bedrock surface near Carrollton, Kentucky..................................................................................... 23
 

10.	 Extent of finite-difference model grid and location of model-calibration cells ................................................ 27
 

11.	 Model calibration by use of root-mean-square-error (RMSE) results............................................................... 31
 

12.	 Graphs showing sensitivity of simulated heads to changes in precipitation infiltration, riverbed conductance, 

hydraulic conductivity, boundary conductance, and river stage, Carrollton area, Kentucky ..................................... 34 

13-16. Maps showing: 

13.	 Simulated contributing areas to discharge boundaries of the alluvial aquifer................................................... 37
 

14.	 Simulated recharge areas and boundaries of the alluvial aquifer ...................................................................... 39
 

15.	 Simulated contributing area and time of travel to a withdrawal well near Ghent, Kentucky............................ 43
 

16.	 Simulated flowpaths and time of travel for a simulated contaminant release from a hypothetical 

hazardous-materials storage facility .................................................................................................................. 45 

TABLES 

1.	 Stratigraphic column of the geologic units in the Carrollton area, Kentucky...................................................... 6
 

2.	 Ground-water pumpage for public water-supply and industrial-supply wells, Carrollton, Kentucky, 

November 1995..................................................................................................................... ................................... 14 

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS 

Multiply By To obtain

cubic foot (ft )

3 0.02832 cubic meter 

cubic foot per day (ft3

/d) 0.02832 cubic meter per day 

cubic foot per second (ft3

/s) 0.02832 cubic meter per second 

foot (ft) 0.3048 meter 

foot per day (ft/d) 0.3048 meter per day 

gallon (gal) 0.003785 cubic meter 

gallon per day (gal/d) 0.003785 cubic meter per day 

gallon per minute (gal/min) 0.06309 liter per second 

inch (in.) 2.54 centimeter 

inch per year (in/yr) 25.4 millimeter per year 

mile (mi) 1.609 kilometer 

million gallons per day (Mgal/d) 0.04381 cubic meter per second 

square mile (mi2

) 2.590 square kilometer 

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. 

Altitude, as used in this report, refers to distance above or below sea level. 

Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times foot 

of aquifer thickness [(ft3

/d)/ft2]ft. In this report, the mathematically reduced form, foot squared per 

day (ft2/d), is used for convenience. 

IV 
 

Hydrogeology and Simulation of Ground-Water 

Flow in the Ohio River Alluvial Aquifer Near 

Carrollton, Kentucky 

By Michael D. Unthank 

Abstract 

The alluvial aquifer near Carrollton, 

Kentucky, lies in a valley eroded by glacial 

meltwater that was later part filled with outwash 

sand and gravel deposits. The aquifer is 

unconfined, and ground water flows from the 

adjacent bedrock-valley wall toward the Ohio 

River and ground-water withdrawal wells. 

Ground-water-level and Ohio River stage data 

indicate the alluvial aquifer was at or near steadystate condition in November 1995. 

A two-dimensional, steady-state groundwater-flow model was developed to estimate the 

hydraulic properties, the rate of recharge, and the 

contributing areas to discharge boundaries for the 

Ohio River alluvial aquifer at Carrollton and the 

surrounding area. Results from previous 

investigations, available hydrogeologic data, and 

observations of water levels from area groundwater wells were compiled to conceptualize the 

ground-water-flow system and construct the 

numerical model. Ground water enters the 

modeled area by induced infiltration from the 

Ohio River and smaller streams, flow from the 

bedrock-valley wall, and infiltration of 

precipitation. Ground water exits the modeled 

area primarily through withdrawal wells and flow 

to the Ohio River. A sensitivity analysis of the 

model indicates that it is most sensitive to 

changes in the stage of the Ohio River and 

conductance values for the riverbed material. A 

particle-tracking simulation was used to 

delineate recharge and discharge boundaries of 

the flow system and contributing areas for 

withdrawal wells, and to estimate time of travel 

through the flow system. 

INTRODUCTION 

The Ohio River alluvial aquifer beneath 

Carrollton, Ky., is an important water resource for the 

cities of Carrollton and Ghent, as well as for several 

industries in the area. Regional water managers and 

environmental coordinators seek the data and tools 

needed to understand and plan for current and future 

effects on this resource to ensure proper water use and 

environmental planning by all ground-water users in 

the Carrollton area. This is especially important in the 

Carrollton area because the aquifer is of limited areal 

extent (the width is less than 1.0 mi in some areas), 

and several ground-water users are located near one 

another along this narrow band. The interaction 

between the users on a regional scale becomes a 

limiting factor in the development of ground-water 

supplies in the area (Whitesides and Ryder, 1969). 

In 1994, the U.S. Geological Survey (USGS), 

in cooperation with the Carroll County Water-Supply 

Board, began an investigation to characterize the 

hydrogeology of the Ohio River alluvial aquifer 

beneath Carrollton and the surrounding area. This 

investigation will provide water managers and other 

decisionmakers the types of information and tools 

necessary for the rational management of the area’s 

ground-water resources. 

Purpose and Scope 

This report describes the results of an 

investigation conducted from 1994 to 1997 to refine 

the understanding of the hydrogeology of the alluvial 

aquifer in the Carroll and Gallatin County areas of 

northern Kentucky and to characterize the groundwater-flow system. The hydrologic significance of 

geologic units in the study area are briefly discussed 

on the basis of results of previous investigations, 

INTRODUCTION 1 
 

 

existing and newly gathered hydrologic and lithologic 

data, and observations of water levels. A 

conceptualization of the ground-water-flow system is 

represented in a two-dimensional, steady-state, finitedifference ground-water-flow model. Numerical 

simulation of the ground-water-flow system is a quick 

and thorough way to develop a regionally consistent 

tool that can be used as the basis for water-use and 

environmental-planning decisions. The study area 

was limited to the alluvial aquifer adjacent to the Ohio 

River in Carroll and Gallatin Counties, Ky. 

Approach 

The evaluation of the hydrogeology and 

ground-water flow in the Ohio River alluvial aquifer 

at Carrollton, Ky., consisted of four parts: (1) 

collection of hydrogeologic parameters and data, both 

in the field and from published literature; (2) 

conceptualization of the ground-water-flow system; 

(3) development and calibration of a numerical model 

of flow in the sand and gravel deposits of the alluvial 

aquifer; and (4) application of the numerical model 

through a particle-tracking simulation. Literature and 

data-file searches yielded information concerning 

well locations, yields and pumping rates, groundwater levels, Ohio River stage data, and geologic and 

water-bearing characteristics of area deposits. These 

data were used to develop a conceptual model of the 

ground-water-flow system to identify areas of 

recharge and discharge, boundary conditions, and 

regional flow patterns. Four semi-annual synoptic 

water-level measurements, beginning in November 

1994, were used to determine seasonal highs and lows 

in water levels. Eight ground-water observation wells 

were equipped with continuous water-level recorders 

to determine trends in the water levels through the 

year and the aquifer’s response to floodwaves from 

the Ohio River. A series of boreholes were drilled to 

determine the depth to bedrock and lithology of the 

unconsolidated deposits in the study area where preexisting data were sparse. A steady-state, numerical 

model of flow in the alluvial aquifer was calibrated to 

ground-water levels in November 1995. Results from 

the calibrated ground-water-flow model were applied 

to an advective-flow particle-tracking program to 

delineate ground-water flowpaths, contributing areas 

to withdrawal wells, and time-of-travel estimates. 

Previous Studies 

The hydrology and geology of Carrollton and 

the surrounding area have been described in 

numerous reports and hydrologic investigations 

atlases. A general discussion of the Ohio River Valley 

and its alluvial deposits is presented by Walker 

(1957); the hydrology of the alluvial deposits in the 

Ohio River Valley, including the availability, quality, 

and development of ground-water supplies, is present 

by Gallaher and Price (1966). Details of the study area 

are included in two hydrologic investigations atlases. 

Hall and Palmquist (1960) describe the availability of 

ground water in a multi-county study, which includes 

Carroll County and the Carrollton area. The atlas 

presents a generalized geologic columnar section and 

a listing of the water-bearing characteristics of the 

area deposits. The geology and hydrology of the 

alluvial deposits along the Ohio River near 

Carrollton, including sections and fence diagrams, is 

the subject of an atlas by Price (1964). Whitesides and 

Ryder (1969) present the effects of pumping from the 

alluvial aquifer between Carrollton and Ghent, Ky. 

The report includes ground-water pumpage values, 

water levels, and transmissivity values are 

documented for several area well fields. The potential 

for induced infiltration from the Ohio River and total 

amount of ground water available for withdrawal also 

are discussed. Aquifer diffusivity (the ratio of 

transmissivity to the storage coefficient) was 

calculated by Grubb and Zehner (1973) using the 

floodwave-response method for a site midway 

between Carrollton and Ghent, Ky. 

Description of the Study Area 

The study area is in Carroll and Gallatin 

Counties in north central Kentucky (fig. 1) and 

consists of approximately 20 mi2 in the Ohio River 

Valley from the Kentucky River at Carrollton 

northeast to Markland Locks and Dam. It is about 

15 mi long and ranges in width from about 1.5 mi 

near Ghent to about 3 mi at Carrollton. The study area 

is bound on the northwest by the Ohio River and on 

the southeast by steep bedrock valley walls; soils in 

the area are mostly silt and clay. Land-surface 

altitudes in the study area range from 420 to 490 ft in 

the valley to slightly more than 800 ft atop the valley 

2 Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 
CARROLL COUNTY

GALLATIN COUNTY

Mar

L oc

kland

Damks and 

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

Ghent 

42
 

Carrollton 

42
 

227
 

71
 

Base from U.S. Geological Survey
 

Carrollton 1:24,000, 1994
 

Sanders 1:24,000, 1987
 

Florence 1:24,000, 1981
 

Vevay North 1:24,000, 1981
 

Vevay South 1:24000, 1980
 0 2 4 6 8 10 MILES
 

0 2 4 6 8 10 KILOMETERS
 

EXPLANATION 

Study Area 

Alluvial aquifer 

KENTUCKY 

INTRODUCTION 3
 

Figur e 1. Location of study area and extent of the Ohio River alluvial aquifer. 
Page 4 - BLANK - (back of figure 1 page) 
walls. Normal pool stage of the Ohio River and the 

Kentucky River in the study area is 421 ft above sea 

level. Most of the area has been cleared for industrial 

use, but areas of agriculture are interspersed with 

institutional, recreational, and residential areas. 

The population of Carrollton was 3,715 in 

1990; Carroll County had a population of 9,292 

(U.S. Department of Commerce, Bureau of the 

Census). The climate is temperate, and the average 

annual precipitation from 1947 to 1994 was 44.39 in. 

(Kentucky Cabinet for Economic Development, 

1996, p. 20). The average annual discharge of the 

Ohio River at Markland Dam from 1970 to 1996 was 

115,600 ft3/s (McClain and others, 1997). 

HYDROGEOLOGY OF THE ALLUVIAL 

AQUIFER 

The study area lies within the Ohio River 

alluvium physiographic region of Kentucky. The 

exposed consolidated rocks of the area are of 

sedimentary origin and the Ordovician age. The 

Ordovician rocks were eroded by glacial meltwater of 

the Pleistocene Epoch. Deep valleys were excavated 

prior to the deposition of a thick body of sand and 

gravel. Ground water in the study area typically flows 

from the valley wall toward the Ohio River. Groundwater discharges to the Ohio River, the Kentucky 

River, and to water-supply wells. 

Geology 

The rocks underlying the alluvial aquifer in the 

Carrollton area are primarily shales and limestones of 

Ordovician Age. The pertinent formation, the Kope 

Formation, is characterized by interbedded shale and 

limestone (table 1). The shale comprises about 

80 percent of the deposits; limestone is present as 

single beds separated by a few inches to several feet 

of shale (Swadley, 1976). 

During the Pleistocene or glacial epoch, ice 

sheets repeatedly advanced south from Canada. As 

the ice thawed, meltwaters eroded a deep valley 

through the Carrollton area. Down-cutting of the 

bedrock surface and deposition of alluvial materials 

occurred during the Wisconsin age. The depth to the 

valley floor or bedrock surface from the present land 

surface ranges from 100 ft at Carrollton and Ghent to 

as much as 150 ft in some places of the study area. 

The Pleistocene valley averages about 2.0 mi wide in 

the study area. The valley broadens at Carrollton near 

the confluence of the Kentucky River and the Ohio 

River. The down-cutting of the bedrock and the 

subsequent filling of the valley has left the upper part 

of the Kope Formation exposed along the valley 

walls. The Kope Formation is overlain by additional 

shales and limestones of the Upper Ordovician Series, 

namely the Calloway Creek Limestone and Fairview 

Formation, the Grant Lake Limestone, and the Bull 

Fork Formation. These Upper Ordovician formations 

do not figure prominently in the hydrogeology of the 

alluvial aquifer and are mentioned here only for 

thoroughness. Figure 2 shows the surficial geology of 

the study area. The geologic history of the area is 

described in detail by Walker (1957). 

As the ice sheets of the Wisconsin Age 

advanced and melted, heavier, coarse-grained 

alluvium was deposited as the sediment-transport 

capacity of the floodwaters decreased. This portion of 

the alluvium is characterized by medium- to coarsegrained sand with lenses of gravel in the lower part; 

gravels as much as 3 in. in diameter are present in the 

study area. The coarse-grained alluvium was topped 

by a thick sheet of fine-grained alluvium during the 

final glacial melting of the Wisconsin Age, and this 

upper part of the alluvium consists of fine-grained 

sand and silt. 

The alluvium is capped throughout the study 

area with a layer of silt and clay. These are non-glacial 

sediments brought to the area by the Ohio River and 

its tributaries. 

Continued down-cutting by the Ohio River and 

the removal of Wisconsin Age alluvial fill are the 

principal features of post-glacial history. The Ohio 

River continues to meander from side to side, eroding 

the alluvium in its bed and along its banks. 

Floodwaters deposit a thin layer of sand, silt, and clay 

on the land surface, but a net gain is not necessarily 

realized as there is a considerable amount of scour 

accompanying the early stages of flooding (Walker, 

1957). 

HYDROGEOLOGY OF THE ALLUVIAL AQUIFER 5 
Table 1. Stratigraphic column of the geologic units in the Carrollton area, Kentucky 

[gal/min, gallons per minute; gal/d, gallons per day] 

System Series Formation Thickness (in 

feet) Lithology and remarks 

Quaternary Pleistocene and 

Holocene 

Alluvium 0-80+ Clay, silt, sand, and gravel. 

Yields as much as 

500 gal/min to wells in 

the Ohio River Valley. 

Pleistocene Terrace deposits 

Glacial outwash 

Glacial drift 

0-79+ 

0-80+ 

0-90+ 

Mixtures of clay, silt, sand, 

and gravel. 

Outwash represents the 

primary aquifer in the 

Carrollton area. 

Ordovician Upper Ordovician Bull Fork Formation 195-210 Interbedded limestone and 

shale. 

Grant Lake 

Limestone 

60-85 Thin-bedded limestone, 

very irregular and 

discontinuous. 

Fairview Formation 

and Calloway 

Creek Limestone 

85-105 Alternating rubbly 

limestone and lumpy 

calcareous shale. 

Wells yield 100 to 500 gal/d 

from thick limestone 

beds. 

Kope Formation 145+ Interbedded shale 

(80 percent) and 

limestone. 

Yields 100 to 500 gal/d from 

wells in broad valley 

bottoms. 

Information compiled from Hall and Palmquist (1960), Price (1964), and Swadley (1976). 

6 Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

42 

42 

227 

71 

Base from U.S. Geological Survey Geology from Swadley 1973, 1976 Carrollton 1:24,000, 1994 

Sanders 1:24,000, 1987 

Florence 1:24,000, 1981 

Vevay North 1:24,000, 1981 

Vevay South 1:24000, 1980 0 2 4 6 8 10 MILES 

0 2 4 6 8 10 KILOMETERS 

EXPLANATION 

Alluvium 

Terrace Deposits 

Glacial Outwash 

Bull Fork Formation 

Grant Lake Limestone 

Fairview Formation 

Study Area 

KENTUCKY 

Glacial Drift 

High-level Fluvial Deposits 

Calloway Creek Limestone 

Kope Formation 

Figure 2. Surficial geology of the Carrollton area, Kentucky. 

HYDROGEOLOGY OF THE ALLUVIAL AQUIFER 7 
Page 8 - BLANK - (back of figure 2 page) 
 

 

 

Hydrologic Data 

The alluvial aquifer beneath Carrollton 

typically has been studied as part of larger 

investigations that focused on the geology, hydrology, 

and alluvial deposits of the Ohio River Valley. The 

geology of the Carrollton area has been described by 

Swadley (1973, 1976). Price (1964) compiled 

available lithologic data, including fence diagrams, 

that described the geology and hydrology of the 

alluvial deposits for Carrollton and adjacent areas 

along the Ohio River. More general descriptions of 

the hydrology and physical characteristics of the 

alluvial deposits were presented by Gallaher and Price 

(1966) and Walker (1957). A variety of new 

hydrologic and geologic data were collected as part of 

this investigation. A ground-water-level observation 

network of 94 wells was monitored during the period 

November 1994–May 1996. Included in this network 

were eight wells equipped with continuous-recording 

devices that measured changes in the ground-water 

level and temperature. Geologic and lithologic data 

were collected during a drilling program. 

Twenty-seven boreholes were drilled to determine the 

thickness and lithology of the unconsolidated deposits 

at selected sites throughout the study area. 

Ground-Water-Level Observation Network 

A total of 94 ground-water-level observation 

wells were inventoried as part of this investigation. 

The network included abandoned domestic, 

commercial, and industrial wells, active domesticsupply wells, observation and test wells near public 

water-supply wells, monitoring wells from active and 

dormant remediation activities, and piezometers. 

Continuous recorders were installed on eight of the 

wells to document trends in water levels and the 

aquifer’s response to stresses such as pumpage, 

precipitation, and flooding. Of the 94 wells, waterlevel measurements from 49 wells are used for 

presentation of the data and model calibration; the 

only criterion for choosing these 49 wells was 

location. Many of the original 94 wells are in clusters 

at industrial sites in the study area, and presentation of 

data at the scale used for this investigation makes the 

data cumbersome and hard to read. Therefore, a 

subset of 49 wells, evenly distributed throughout the 

study area, is used for presentation and calibration. 

Figure 3 shows the location of all the inventoried 

wells (94 wells). 

Synoptic ground-water-level measurements 

were made four times during the course of this 

investigation: November 1994, May 1995, 

November 1995, and May 1996. The May and 

November time periods represent typical high and 

low points in ground-water levels, respectively. 

Hydrographs of water levels from wells 2 and 3 show 

seasonal trends in the ground-water levels and are 

indicative of trends in all of the recorder wells (fig. 4). 

Water-level measurements for the subset of 49 wells 

were available for each of the four synoptics. 

Precipitation 

A record of daily precipitation is kept at the 

U.S. Army Corps of Engineers office at the Markland 

Locks and Dam, on the Ohio River at the upstream 

end of the study area (fig. 1). The total precipitation 

recorded at this site for the period July 1994– 

June 1995 was 42.05 in. The normal annual 

precipitation for the study area is 44.39 in. 

Ground-Water Pumpage 

Ground water is used for public and domestic 

drinking-water supplies in the study area and for 

processing at many of the area industries. Table 2 

summarizes the ground-water users inventoried for 

use in the model simulation. Pumpage volume and 

number of operational wells presented here are for 

November 1995 as reported by each ground-water 

user. Figure 5 shows the location of the inventoried 

ground-water withdrawals. 

Ground-Water Flow in the Alluvial 

Aquifer 

Under natural conditions, regional groundwater flow in the alluvial aquifer is predominantly 

horizontal, from the alluvium/bedrock boundary at 

the valley wall toward the Ohio River. This flow 

pattern is interrupted in areas of large ground-water 

withdrawals, where cones of depression in the 

potentiometric surface have formed (fig. 6). 

Water-level measurements and lithologic data 

indicate the alluvial aquifer to be unconfined. 

HYDROGEOLOGY OF THE ALLUVIAL AQUIFER 9 
Page 10 - BLANK 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞4

38∞40′

38∞40′

3 R 

1 42 R 

5 

3 

2 

R 

R 

4 

8 4 

3 

4 

R 

5 

3 R 

6 

R 

3 

7 

42 

R 

8 

227 

71 

Base from U.S. Geological Survey 

Carrollton 1:24,000, 1994 

Sanders 1:24,000, 1987 

Florence 1:24,000, 1981 

Vevay North 1:24,000, 1981 

Vevay South 1:24000, 1980 0 2 4 6 8 10 MILES 

0 2 4 6 8 10 KILOMETERS 

EXPLANATION 

Alluvial aquifer R 

2 Observation well with continuous recorder 

Study Area 

KENTUCKY 

Observation well 

3 Multiple observation wells 

HYDROGEOLOGY OF THE ALLUVIAL AQUIFER 11 

5′

Figure 3. Observation well network. 
Page 12 - BLANK - (back of figure 3 page) 
O N D J F M A M J J A S O N D J F 

1994 1995 1996 

32

52 

32 

34 

36 

38 

40 

42 

44 

46 

48 

50 

DEPTH TO WATER, IN FEET BELOW LAND SURFACE 

CONTINUOUS RECORDER NUMBER 3 

O N D J F M A M J J A S O N D J F 

1994 1995 1996 

48

70 

48 

50 

52 

54 

56 

58 

60 

62 

64 

66 

68 

DEPTH TO WATER, IN FEET BELOW LAND SURFACE 

CONTINUOUS RECORDER NUMBER 2
 

Figure 4. Typical water-level hydrographs for wells completed in the alluvial aquifer. 
Table 2. Ground-water pumpage for public water-supply and industrial-supply wells, Carrollton, Kentucky, 

November 1995 

[Mgal/d, million gallons per day] 

Map 

number Ground-water user Number of wells Volume pumped 

(Mgal/d) 

1 Carrollton Utilities 3 0.7 

2 Elf Atochem 4 2.8 

3 Dow Corning 9 12.4 

4 Dayton-Walther 1 <.1 

5 Carroll County Water District 2 .5 

6 Kentucky Utilities 5 .4 

14 Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

5 6

42 1 

42 3 4

2 

227 

71 

Base from U.S. Geological Survey 

Carrollton 1:24,000, 1994 

Sanders 1:24,000, 1987 

Florence 1:24,000, 1981 

Vevay North 1:24,000, 1981 

Vevay South 1:24000, 1980 0 2 4 6 8 10 MILES 

0 2 4 6 8 10 KILOMETERS 

Alluvial aquifer 

EXPLANATION 

Pumpage, in million gallons/day 

> 3.0 0.5-1.0 

Study Area 

1.0-3.0 0.0-0.5 

KENTUCKY 

HYDROGEOLOGY OF THE ALLUVIAL AQUIFER 15 

Figure 5. Location and amounts of ground-water pumpage. 
Page 16 - BLANK - (back of figure 5 page) 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

422

422 

422 

416 

418 

406

400 

408

420

424 

424 

422 

426 

422
 42 

42
 

227
 

71
 

Base from U.S. Geological Survey
 

Carrollton 1:24,000, 1994
 

Sanders 1:24,000, 1987
 

Florence 1:24,000, 1981
 

Vevay North 1:24,000, 1981
 

Vevay South 1:24000, 1980
 0 2 4 6 8 10 MILES
 

0 2 4 6 8 10 KILOMETERS
 

EXPLANATION 

Study Area 

Alluvial aquifer 

KENTUCKY 422
 WATER-LEVEL CONTOURS ­

Showing altitude of water level. 

Contour interval 2 feet; datum 

is sea level 

HYDROGEOLOGY OF THE ALLUVIAL AQUIFER 17
 

Figure 6. Altitude of potentiometric surface of the alluvial aquifer near Carrollton, Kentucky, November 1995. 
Page 18 - BLANK - (back of figure 6 page) 
 

 

 

Recharge to the alluvial aquifer is from vertical 

infiltration of precipitation, flow from the valley wall, 

and infiltration from the Ohio River, both natural and 

induced. The bedrock beneath the alluvium is 

considered to be a no-flow boundary, thus not 

contributing water to or extracting water from the 

alluvium. Natural infiltration of water from the Ohio 

River to the alluvial aquifer may occur during highriver stages. Flood pulses originating from the Ohio 

River reverse the ground-water gradients and 

recharge water back into the aquifer. Ground-water 

levels near the river rise during periods of flooding as 

water from the Ohio River recharges the aquifer and 

causes a mounding of ground water (fig. 7). 

Additional recharge to the alluvial aquifer occurs 

when pumping at wells along the river lowers the 

water table below the stage of the river, thus inducing 

infiltration of river water (fig. 8). 

Discharge from the alluvial aquifer is by flow to 

the Ohio River and to pumped wells. 

Bedrock Beneath the Alluvial Aquifer 

Bedrock beneath the glacial outwash in the 

Carrollton area is composed primarily of shales and 

limestones of Ordovician Age. Altitudes at the top of 

the bedrock surface beneath the alluvial aquifer were 

compiled from data contained in previous studies, 

project files of the USGS, files from industries and 

utilities in the study area, and a drilling program 

conducted during this investigation. Altitudes of the 

bedrock surface are shown in figure 9. Knowledge of 

the type of rock, its water-bearing characteristics, and 

the altitudes of the surface are important because this 

surface forms the lower boundary for the alluvial 

aquifer. 

Conceptually, the bedrock beneath the alluvial 

aquifer and along the valley walls serves as a 

“container” for the glacial-outwash deposits. Wells 

completed in the bedrock are expected to produce 

only 100 to 500 gal/d (Hall and Palmquist, 1960), 

whereas wells completed in the alluvial deposits 

produce up to 500 gal/min. 

Stream-Aquifer Interaction 

Surface water is an important factor in the 

hydrologic framework of the Carrollton area. The 

Ohio River is a dominant feature and an important 

source of recharge for the alluvial aquifer. The Ohio 

River is hydraulically connected to the alluvial 

aquifer throughout its course in the study area. The 

Kentucky River, to a lesser extent, is a source of 

recharge for the ground-water-flow system, during 

periods of high water and flooding. Several small 

streams contribute much of their flow to the groundwater-flow system; therefore, they are considered an 

important source of recharge. 

Small Streams 

Five small streams (Fourmile Creek, McCools 

Creek, Black Rock Creek, Agniels Creek, and 

Stephens Creek) provide most of the surface-water 

drainage in the study area. These streams do not have 

adequate flow for dependable supplies, however, and 

may cease to flow for a few days or weeks during 

extended drought periods. During this investigation, 

the only water observed in the reaches of Fourmile 

Creek and McCools Creek (within the study area) was 

backwater from the Ohio River. It was assumed for 

this investigation that the amounts of discharge 

calculated from the respective drainage areas of those 

streams and daily rainfall would be used for recharge 

to the ground-water-flow model. Additional studies, 

such as discharge measurements under various 

conditions would need to be conducted to ascertain a 

more accurate representation of these streams in the 

model. Altitudes for the water surface in Black Rock 

Creek and Agniels Creek were approximated, and the 

creeks were assumed to be discharge points for the 

ground-water-flow system. Stephens Creek flows 

near the upstream boundary of the study area and was 

not considered an integral part of the hydrologic 

system. Like Fourmile and McCools Creeks, 

additional studies are needed on all of the area small 

streams to account for their potential effect and 

possible contribution to the ground-water-flow 

system. 

HYDROGEOLOGY OF THE ALLUVIAL AQUIFER 19 
15.0 

14.5 

14.0 

13.5 

13.0 

12.5 

12.0 

11.5 

40
 

42
 

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
 

May 1996
 

OHIO RIVER STAGE AT MARKLAND DAM 

GAGE HEIGHT, IN FEET 

DEPTH TO WATER, IN FEET BELOW LAND SURFACE 44
 

46
 

48
 

50
 

52
 

54
 

56
 

58
 

60
 

62
 

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
 

May 1996
 

CONTINUOUS RECORDER NUMBER 6
 

Figure 7. Response of water levels in the alluvial aquifer to an Ohio River flood pulse in a non-stressed area. 

20	 Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 
DEPTH TO WATER, INFEET BELOW LAND SURFACE DEPTH TO WATER, IN FEET BELOW LAND SURFACE GAGE HEIGHT, IN FEET 

15 

14
 

13
 

12
 

11
 

24
 

26
 

28
 

30
 

32
 

46
 

48
 

50
 

52
 

54
 

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
 

May 1996
 

OHIO RIVER STAGE AT MARKLAND DAM 

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
 

May 1996
 

CONTINUOUS RECORDER NUMBER 3
 

5 6 7 8 9 10 11 12 13 14 15 16 17 18
 19
 

May 1996
 

CONTINUOUS RECORDER NUMBER 4
 

Figure 8. Response of water levels in the alluvial aquifer to an Ohio River flood pulse in a heavily pumped area. 

HYDROGEOLOGY OF THE ALLUVIAL AQUIFER 21
 
Page 22 - Blank 
CARROLL COUNTY

GALLATIN COUNTY

ALTITUDE ABOVE SEA LEVEL, IN FEET

ALTITUDE ABOVE SEA LEVEL, IN FEET

ALTITUDE ABOVE SEA LEVEL, IN FEET

ALTITUDE ABOVE SEA LEVEL, IN FEET

ALTITUDE ABOVE SEA LEVEL, IN FEET

ALTITUDE ABOVE SEA LEVEL, IN FEET

ALTITUDE ABOVE SEA LEVEL, IN FEET

ALTITUDE ABOVE SEA LEVEL, IN FEET

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

365 

A D E 354 F 371 393 G 

446 

365 

413 

429 

405 

365 

365 

360 

354 368 

42 

338 

357 

376 

416 

445 

B 

B’ 

384 

385 

352 

372 

402 

355 

352 

366 

405 

360 

380 

442 

C 

C’ 

353 

385 

347 

347 347 

353 

353363 

392 432 393 

355 

346 

351 

356 

369 

403 D’ 

365 

350 361 

361 

373 

425 

E’ 

376 370 

395 

431 

F’ 

389 390 336 

365 

386 

388 

412 

G’ 

42 390 

355 

379 

402 

484 

H 

H’ 

A’ 

481 

458 

381 

227 

71 

Base from U.S. Geological Survey 

Carrollton 1:24,000, 1994 

Sanders 1:24,000, 1987 

Florence 1:24,000, 1981 0 2
 4 6
 8
 10 MILES
 

Vevay North 1:24,000, 1981 

Vevay South 1:24000, 1980 

0 2 4 6 8 10 KILOMETERS 

520 

SECTION A-A’ 

520 

SECTION C-C’ EXPLANATION 520 

SECTION E-E’ 

520 

SECTION G-G’ 

480 

500 

480 

500 FOR MAP 480 

500 

480 

500 

460 460 460 460 

400 

420 

440 

400 

420 

440 

Section lines 

Alluvial aquifer 

400 

420 

440 CLAY/ALLUVIUM 

INTERFACE UNDETERMINED 

400 

420 

440 

340 

360 

380 

340 

360 

380 

Well or borehole with bedrock 

altitude, in feet above sea level 340 

360 

380 

340 

360 

380 

320 

520 

0 500 1000 1500 

SECTION B-B’ 

2000 2500 3000 3500 4000 4500 

FEET 

5000 5500 6000 6500 

520 

320 0 500 1000 1500 2000 2500 3000 3500 

FEET 

SECTION D-D’ 

4000 4500 5000 5500 

EXPLANATION 

FOR SECTIONS 

320 

0 

520 

500 1000 1500 2000 2500 3000 3500 4000 FEET 

SECTION F-F’ 

4500 5000 5500 

520 

320 0 500 1000 

SECTION H-H’ 

1500 2000 2500 3000 3500 4000 

FEET 

4500 5000 5500 

500 500 500 500 

480 480 480 480 

420 

440 

460 

420 

440 

460 

CLAY/ALLUVIUM 

INTERFACE 

UNDETERMINED 

Clay 

420 

440 

460 

420 

440 

460 

380 

400 

380 

400 Alluvium 380 

400 

380 

400 

360 360 360 360 

320 

340 

0 500 1000 1500 2000 2500 3000 

FEET 

3500 4000 4500 5000 5500 320 

340 

0 500 1000 1500 2000 2500 3000 

FEET 

3500 4000 4500 5000 5500 Bedrock 320 

340 

0 500 1000 1500 2000 2500 3000 

FEET 

3500 4000 4500 5000 5500 320 

340 

0 500 1000 1500 2000 2500 3000 

FEET 

3500 4000 4500 5000 5500 

Figure 9. Altitude of bedrock surface near Carrollton, Kentucky. 

HYDROGEOLOGY OF THE ALLUVIAL AQUIFER 23 
Page 24 - BLANK - (back of figure 9 page) 
 

 

Ohio River 

A system of locks and dams controls the 

navigational channel and stage for the Ohio River 

through a series of pools. The McAlpine Dam at 

Louisville creates a pool that extends upstream for 

approximately 75 mi to Markland Dam. Markland 

Dam is at the upstream boundary of the study area 

(fig. 1). The water level in the pool at Carrollton is 

normally maintained at about 421 ft above sea level. 

Under natural conditions, the Ohio River is a 

discharge point or sink for the ground-water-flow 

system. Hydrographs for several observation wells in 

the study area show ground-water flow to be toward 

the river during periods of normal pool elevation 

(figs. 7 and 8). During periods of high water on the 

Ohio River, gradients may “flatten out” or reverse as 

water from the river becomes a source of recharge to 

the alluvial aquifer (fig. 6). Induced infiltration from 

the Ohio River is evident from hydrographs from 

observation wells in areas of high ground-water 

pumpage near the river (fig. 8). Cones of depression 

extend toward the river, thereby gaining an additional 

source of recharge. 

CONCEPTUAL MODEL OF THE GROUNDWATER-FLOW SYSTEM 

A preliminary step in designing a groundwater-flow model is to devise a conceptual model of 

the flow system. The conceptual model is a simplified 

representation of the important hydrogeologic 

conditions of the natural flow system. Field-based 

data such as aquifer characteristics, ground-water 

levels, and infiltration rates are measured or estimated 

to provide a clear and easily understood physical 

picture of the flow system. Errors in the development 

of the conceptual model can result in the failure of the 

mathematical model to make accurate predictions. 

Gallaher and Price (1966) visualized the Ohio 

River Valley as a huge water container where water is 

stored on or flows across the valley surface in the 

Ohio River and its tributaries with additional amounts 

of water present beneath the land surface. The 

container was formed as a trench cut out of the 

surrounding bedrock formations by meltwaters from 

glaciers, then part filled with water-deposited 

sediments of gravel, sand, silt, and clay. Gradual 

down cutting by the Ohio River since the retreat of the 

last glacier has shaped the surface of the valley to its 

present level. 

From the concept of a trench-shaped container, 

the model design treats the alluvial aquifer as a single 

layer. The layer is bounded on the bottom and along 

the length of the container by the bedrock. The open 

ends of the trench allow the flow of the Ohio and 

Kentucky Rivers, which are partially penetrating 

streams, to enter and exit the flow system. The Ohio 

and Kentucky Rivers are partially penetrating 

streams. The bedrock underlying the alluvial deposits 

is a mixture of shales and limestones and is 

considered impermeable, thus forming a no-flow 

boundary. 

The single-layer representation of the alluvial 

aquifer receives recharge from precipitation, 

discharge from the valley walls, and natural and 

induced infiltration from the Ohio River. Discharges 

from the ground-water-flow system include water 

withdrawn by production wells and natural discharge 

to the Ohio River. Two distinct flow patterns exist 

within the ground-water-flow system. Under natural 

conditions, regional flow patterns are predominantly 

horizontal, from points of recharge along the valley 

walls toward the Ohio River, a discharge zone; this 

pattern is interrupted by the effects of withdrawals at 

wells and well fields. Cones of depression formed in 

the potentiometric surface at the wells extend to the 

river; gradients are reversed and flow is induced from 

the Ohio River, thus making it a source of recharge. 

The Ohio River and other area streams may become 

additional sources of water to the alluvial aquifer 

during periods of high water. Floodwaters can 

percolate downward and contribute water to the 

ground-water-flow system. 

SIMULATION OF GROUND-WATER FLOW 

IN THE ALLUVIAL AQUIFER 

A finite-difference model was used to simulate 

ground-water flow in the alluvial aquifer at 

Carrollton, Ky., and the surrounding area. The 

objectives of the modeling were to test the conceptual 

model of the ground-water-flow system, generate the 

CONCEPTUAL MODEL OF THE GROUND-WATER-FLOW SYSTEM 25 
 

 

 

required data sets for particle-tracking analysis, and 

provide a regional-scale tool for water-resources 

investigations. The modular, finite-difference 

computer program, MODFLOW (McDonald and 

Harbaugh, 1988), was used to construct a regional, 

two-dimensional, steady-state model of the groundwater-flow system in the alluvial aquifer. Output from 

the MODFLOW program is used by the particletracking program, MODPATH (Pollock, 1989, 1994), 

to simulate ground-water-flow directions and travel 

times. The combination of the MODFLOW 

simulation and the application of the results through 

the MODPATH program provides an investigative 

tool for area water-resources managers. 

Equation Development 

The ground-water-flow model is formed from a 

set of partial-differential equations—governing 

equation, boundary conditions, and initial conditions. 

Numerical methods are used to solve a set of algebraic 

equations generated by approximating these 

equations. A general form of the partial-differential 

equation governing two-dimensional, steady-state 

ground-water flow in a heterogeneous, isotropic, 

unconfined aquifer is: 

  h   h -----T----- + -----T----- = W , (1) x x y y

where

h h T-----,T----- are the values of transmissivity along the x x y

 

and y axes, which are assumed parallel 

to the major axes of hydraulic conductivity (L2T-1), 

h is the hydraulic head (L), and 

W is a volumetric flux per unit volume representing sources and (or) sinks of water 

(LT-1). 

Boundary conditions and initial conditions 

were selected to represent hydraulic conditions as 

formulated in the conceptual model. The governing 

equation, boundary conditions, and initial conditions 

were combined in a set of finite-difference equations 

and solved numerically using the MODFLOW code. 

Model Assumptions 

The ground-water-flow model was designed in 

accordance with the following assumptions and 

simplifications: 

1.	 The shaley limestones beneath the alluvial 

deposits do not contribute flow to the alluvial 

aquifer; therefore, they are not included in the 

model design as an active layer. 

2.	 Ground-water levels during the months of 

November 1994 and 1995 approximate 

average water levels for the modeled area 

during periods of the least amount of 

changing hydrologic stresses. The groundwater-flow system is considered at steady 

state during this period, meaning no net gain 

or loss of water occurs. 

3.	 All simulated wells fully penetrate the alluvial 

deposits. 

4.	 Horizontal hydraulic conductivity is uniform 

throughout the study area.
 

5.	 Infiltration from precipitation is at a constant rate 

and does not vary areally. 

6.	 The Ohio River is hydraulically connected to the 

alluvial aquifer throughout its course in the 

study area. 

Model Grid 

The grid design used to represent the 

conceptual model of the ground-water-flow system is 

shown in figure 10. The grid comprises 36 rows and 

207 columns and simulates an area of 12,800 ft by 

74,900 ft, or approximately 34.1 mi2

. Cell sizes vary 

from 200 by 200 ft in areas within the industrial well 

fields to 1,000 by 1,500 ft for cells near the model 

boundaries. The grid rows are oriented parallel to the 

reach of the Ohio River within the study area and 

perpendicular to the regional ground-water-flow 

direction from the conceptual model. The alluvial 

aquifer is modeled as a single layer. 

26 Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

42 

42 

227 

71 

Base from U.S. Geological Survey 

Carrollton 1:24,000, 1994 

Sanders 1:24,000, 1987 

Florence 1:24,000, 1981 

Vevay North 1:24,000, 1981 

Vevay South 1:24000, 1980 0 2 4 6 8 10 MILES 

0 2 4 6 8 10 KILOMETERS 

EXPLANATION 

Active cells 

River cells Inactive cells 

Calibration cells (points) 

Study Area 

KENTUCKY 

Figure 10. Extent of finite-difference model grid and location of model-calibration cells. 

SIMULATION OF GROUND-WATER FLOW IN THE ALLUVIAL AQUIFER 27 
Page 28 - BLANK - (back of figure 10 page) 
 

Model Boundaries 

Conceptually, the bedrock forms the sides and 

bottom of the ground-water container—the alluvial 

aquifer. The bedrock beneath the alluvial aquifer is 

assumed to be a non-contributor of water to the flow 

system and simulated as a no-flow boundary. The 

sides of the container, or the bedrock valley walls, 

however, are considered contributors to the flow 

system and are modeled as general head boundaries. 

Flow across general head boundaries depends upon 

the head difference between an active model cell and 

an adjacent external source. 

Precipitation infiltration forms a specified-flux 

boundary for the top of the model layer, which is 

simulated with the recharge package of the 

MODFLOW code. 

Input Parameters 

Initial input parameters for the ground-waterflow model were derived from reviews of previous 

studies, available records from area ground-water 

users, and data-collection activities conducted as part 

of this investigation. Input parameters included 

recharge from precipitation, hydraulic conductivity of 

the alluvial deposits, boundary conditions of the 

bedrock and valley walls, and initial ground-water 

levels and reported pumpage. Input parameters also 

included characteristics of the Ohio River such as 

river stage, altitude of the riverbed, and the hydraulic 

conductivity of the riverbed deposits. Input 

parameters were systematically varied over respective 

ranges of acceptable values until simulated water 

levels for the alluvial aquifer approximated the water 

levels from the November 1995 synoptic 

measurement. 

Recharge to the alluvial aquifer was simulated 

as leakage across the fine-grained alluvial deposits. 

Rorabaugh (1956) estimated the recharge to the 

alluvial aquifer in Louisville to be 6 to 12 percent of 

the annual precipitation; this range was assumed to be 

reasonable for the Carrollton area because the study 

areas are similar. The annual precipitation for 

Carrollton during the period July 1994 to June 1995 

was 42.05 in., which resulted in a test range of 2.52 to 

5.05 in. recharge; during calibration, the amount of 

recharge from precipitation was varied over this 

range. The best approximation of recharge to simulate 

the November 1995 water levels was 4.63 in/yr. The 

recharge was distributed evenly throughout the model 

area for the simulation. 

The altitude of the Ohio River stage was 

simulated at 421 ft on the basis of data from the USGS 

gaging station at the Markland Locks and Dam and 

measurements from an auxiliary gage on the 

Kentucky River just above its confluence with the 

Ohio River. Riverbed altitude was held constant at 

385 ft. The hydraulic conductivity of the riverbed 

material was held at 0.65 ft/d based on estimates from 

Grubb (1975). Streambed conductance varied 

because of the area of the cells representing the river. 

River stage, hydraulic conductivity, and elevation of 

the riverbed were not varied as part of the calibration 

process. 

The hydraulic conductivity of the alluvial 

deposits was assumed to range from 300 to 350 ft/d 

based on area aquifer tests conducted for previous 

investigations or by private industry. Because 

measurements of anisotropy were not available, a 

lateral isotropy was assumed for the simulation. A 

horizontal hydraulic conductivity of 350 ft/d provided 

the best simulation of the measured water levels. 

The valley walls, which form boundaries for the 

ground-water-flow system, were simulated as headdependent flux boundaries because of the potential for 

flow from the limestone beds. An external boundary 

head altitude of 600 ft was assumed for each cell of 

the boundary. Conductance between the external 

source and the aquifer was held at 10 ft/d. The model 

simulation was not very sensitive to changes in the 

conductance during the calibration process. 

Other input parameters used for the simulation 

(but not varied) included altitude of the bedrock 

surface and ground-water pumpage. Available depthto-bedrock measurements and additional data 

collected during this investigation revealed a fairly 

flat bedrock surface (ranging in altitude from 340 to 

350 ft) beneath the alluvial aquifer. Ground-water 

pumpage was simulated for 29 wells at 6 installations 

in the study area; locations and pumpage amounts 

were verified for November 1995. 

SIMULATION OF GROUND-WATER FLOW IN THE ALLUVIAL AQUIFER 29 
 

 

 

Model Calibration and Water Budget 

The calibration of a model is the procedure used 

to reduce the difference between simulation results 

and observed data by adjusting input parameters of 

the model until an acceptable range of differences is 

achieved. For this simulation, three input parameters 

were adjusted to meet the predetermined calibration 

criteria: the recharge rate from precipitation, 

hydraulic conductivity of the alluvial deposits, and 

the conductance value for the general head-boundary 

configurations. Rorabaugh (1956) determined a range 

of infiltration from precipitation for the alluvial 

aquifer at Louisville of 6 to 12 percent of the annual 

precipitation. This range of values was used to 

determine the extent to which the recharge rate could 

vary because the study area at Carrollton is similar to 

the region around Louisville. Less is known about the 

variations in conductance values for the riverbed and 

valley-wall configurations. 

The root-mean-square error (RMSE) of the 

measured and simulated heads was used to determine 

the effect of an adjustment. The RMSE is calculated 

as: 

 N hcali 

– hmi 2 

  RMSE =  -------------------------------- , (2)   N i = 1

where 

hcali 

is the simulated head, 

h is the measured head, and mi 

N is the number of measurements used in 

error computations. 

Decreases in the RMSE as a result of the 

calibration process indicated an improvement in the 

overall fit of the simulation to the observed 

conditions. Flow paths were checked to ensure 

compliance with the conceptual model. 

The calibration criteria were based on an 

observed range of ground-water levels assuming 

steady-state conditions. The steady-state simulation 

of the alluvial aquifer at Carrollton represents a period 

during which the ground-water-flow system was in 

equilibrium, meaning that the rate of recharge to the 

system is equal to the rate of discharge from the 

system. True steady-state conditions probably never 

exist for the aquifer because of various and almost 

continual changes in recharge (river stage, 

precipitation, and flow from the valley wall) and 

discharge (river stage and ground-water 

withdrawals). But ground-water-level synoptic 

measurements, continuous ground-water-level 

records, and Ohio River stage hydrographs indicate 

that the alluvial aquifer was generally near steadystate conditions during November 1994 and 

November 1995. For the purposes of this 

investigation, it was assumed that the aquifer was at 

steady-state during these periods and the groundwater-flow conditions during November 1995 were 

chosen as the target levels for calibration of the 

model. The hydrograph from recorder 2 (fig. 4) 

shows the ground-water levels at the beginning of 

November 1994 and 1995 to be stable, showing no 

significant changes to any system stresses. 

The calibration criteria were dependent on 

water levels measured in 48 observation wells. The 

average difference of water levels for the 48 wells was 

1.43 ft from November 1994 to November 1995; the 

differences ranged from 0.0 to 4.46 ft. Based on these 

measurements, the calibration criteria selected were a 

maximum difference of 4.46 ft and an average 

difference of 1.43 ft between simulated and observed 

water levels for November 1995. 

After calibration, the maximum difference 

between simulated and observed water levels for 

November 1995 is 4.43 ft. The simulated and 

observed water levels differed by less than 4 ft in 

98 percent of the wells, less than 3 ft in 88 percent, 

less than 2 ft in 77 percent, and less than 1 ft in 

48 percent of the wells. The average difference in 

water levels for the 48 wells was 1.43 ft; the RMSE 

for the simulation was 1.80. Figure 11 shows the 

comparison between observed and simulated heads 

for the model calibration. 

30 Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

42 

42 

227 

71 

Base from U.S. Geological Survey 

Carrollton 1:24,000, 1994 

Sanders 1:24,000, 1987 

Florence 1:24,000, 1981 

Vevay North 1:24,000, 1981 

Vevay South 1:24000, 1980 0 2 4 6 8 10 MILES 

0 2 4 6 8 10 KILOMETERS 

EXPLANATION 

Alluvial aquifer >4 

2 to 4 

0 to 2 

-2 to 0 

-4 to -2 

Difference in simulated - observed Study Area 

KENTUCKY 

SIMULATION OF GROUND-WATER FLOW IN THE ALLUVIAL AQUIFER 31 

Figure 11. Model calibration by use of root-mean-square-error (RMSE) results. 
Page 32 - BLANK - (back of figure 11 page) 
 

 

 

 

 

The simulation also provided a ground-water 

budget for the aquifer. In terms of volume of water, 

the model calculated a total water budget of 

3,034,800 ft3. The simulation indicated that, of the 

total recharge to the alluvial aquifer, induced 

infiltration of water from the Ohio River provided 

approximately 32 percent (983,900 ft3), water from 

area streams provided 25 percent (752,500 ft3), flow 

from the bedrock valley wall contributed 24 percent 

(723,000 ft3

), and recharge from precipitation 

provided about 19 percent (575,400 ft3

). The portion 

of recharge attributed to infiltration of water from the 

Ohio River could be greater during times of flooding. 

Computation of recharge that would be derived from 

the Ohio River during flooding was not considered as 

part of the calibration of a steady-state model. 

Simulation results indicate that a seemingly large 

percentage of the system’s recharge originates from 

the bedrock-valley wall. Rorabaugh (1949) estimated 

that as much as 28,600 ft3

/d of recharge per mile of 

bedrock-valley wall is contributed to the groundwater-flow system at Louisville. The average amount 

calculated from this simulation of the Carrollton area 

is 27,800 ft3

/d per mile of bedrock-valley wall. 

Withdrawals from area wells accounted for 

83 percent (2,511,400 ft3

) of the total discharge from 

the alluvial aquifer, with the remaining 17 percent 

(520,800 ft3

) discharging to the Ohio River. 

Sensitivity Analysis 

Sensitivity analysis is a procedure used to 

assess how responsive the calibrated model is to 

systematic changes in each input parameter. The 

analysis determines which parameters exert the most 

control over the model solution and possibly generate 

the largest error when varied over their respective 

range of test values. Parameters that were varied in the 

sensitivity analysis include the hydraulic conductivity 

of the alluvial deposits, recharge, river stage, river 

conductance, and terms associated with general head 

boundaries. Each input parameter was varied a 

specified amount from the calibrated value used in the 

steady-state simulation. The amount of variance was 

determined by estimates of the probable range of data. 

Because each change in parameter value was tested 

separately, the additive effects of changes for different 

combinations of parameter values were not 

considered. 

Simulated hydraulic heads at 49 wells were 

compared statistically to the water levels measured in 

November 1995. Head responses are reported as the 

RMSE of residuals. The results of the sensitivity 

analysis in terms of percentage of change in RMSE 

are shown in figure 12. An increase in the percentage 

of change in RMSE indicates that the match between 

measured and simulated heads from a sensitivityanalysis run is worse that the match of the calibrated 

model. The magnitude of the percentage of change in 

RMSE indicates the relative sensitivity of the model 

to that change in the model parameter. 

The sensitivity of the model to changes in 

hydraulic conductivity was evaluated by varying the 

conductivity (350 ft/d) within a range of 

+/- 50 percent. The results of the analysis indicate that 

the head residuals are slightly more sensitive to 

decreases in hydraulic conductivity than to increases. 

Recharge to the ground-water-flow system 

from precipitation was estimated at 4.63 in/yr 

(0.00106 ft/d), or approximately 11 percent of the 

annual precipitation, for the calibrated model. For the 

sensitivity analysis, the amount of recharge was 

varied from 4 to 16 percent of the annual 

precipitation. Hydraulic heads simulated by the model 

were not very sensitive to changes in the amount of 

recharge from precipitation infiltration. 

The Ohio River is the dominant hydrologic 

feature in the study area. It is a constant source of 

recharge for nearby pumping wells and a point of 

discharge for the alluvial aquifer in areas unaffected 

by pumpage. For the calibrated model, the river stage 

altitude was 421 ft. Even though the river stage is 

monitored closely and the accuracy of the 

measurements is known, stage was varied +/- 10 ft to 

evaluate the sensitivity of the model. As shown in 

figure 12, the model is very sensitive to changes in the 

river stage, emphasizing the river’s importance in the 

hydrologic system. 

The hydraulic conductivity of the riverbed 

material was varied from +/- 10 percent of the 

calibrated value (0.65 ft/d). The hydraulic heads 

simulated by the model were very sensitive to this 

change in river characterization. 

SIMULATION OF GROUND-WATER FLOW IN THE ALLUVIAL AQUIFER 33 
25
 400 

20
 

0 5 10 15 20
 

PERCENT OF ANNUAL PRECIPITATION
 

FOR INFILTRATION
 

SEMR OF CHANGE IN 

300
 

LS 

LS 

SIDUA 15
 

DUAIS

 RE

ER20

D

D 

E 

A

OF CHANGE IN RMSE

0
 

E

E 

G

10
 

NTA

OF H

G

OF HEA

RCE

CENTA

100
 

E

5
 P

PER

0 0 

-15 -10 -5 0 5 10 15
 

PERCENTAGE OF CHANGE IN RIVERBED
 

CONDUCTANCE
 

250
 25
 

E

E

 IN RMS

RMS

S 

S 

NGE

AD RESIDUAL

NGE IN 

NTAGE OF CHA

CHA

SIDUAL

NTAGE OF 

READ 

OF HE

OF HE

RCE

RCE

PE

EP

E	IN RMSE 

ALS	

E OF CHANG

DU RESI

RCENTAG

OF HEAD

PE

-60 -40 -20 0 20 40 60
 

PERCENTAGE OF CHANGE IN
 

HYDRAULIC CONDUCTIVITY
 

200
 20
 

150
 15
 

100
 10
 

50
 5
 

0 

-30 -20 -10 0 10 20 30
 

PERCENTAGE OF CHANGE IN BOUNDARY
 

CONDUCTANCE
 

600
 

500
 

400
 

300
 

200
 

100
 

0 

0 

EXPLANATION 

Calibration wells 

RMSE = Root mean square error 

-15 -10 -5 0 5 10 15
 

CHANGE IN RIVER STAGE, IN FEET
 

Figure 12. Sensitivity of simulated heads to changes in precipitation infiltration, riverbed conductance, hydraulic conductivity, 

boundary conductance, and river stage, Carrollton area, Kentucky. 

34	 Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 
APPLICATION OF THE GROUND-WATER-FLOW MODEL 35 

 

 

 

 

The valley walls on both sides of the Ohio River 

were simulated as general head boundaries. Hydraulic 

conductivity of the interface between the aquifer cell 

and the boundary was varied 

+/- 20 percent for the sensitivity analysis. The effects 

of these changes did not vary greatly, generally less 

than 20 percent change in RMSE. 

Limitations of the Model 

Limitations of the ground-water-flow model 

and the interpretation of subsequent simulation results 

must be known and fully considered for appropriate 

application of the model and accurate simulation of 

the natural flow system. The amount and detail of 

hydrogeologic knowledge of the natural flow system, 

the initial scale of the ground-water-flow model, and 

the inherent limitations of numerical models restrict 

applications of the model. With proper application 

and an understanding of the limitations, however, the 

ground-water-flow model is a useful investigative 

tool capable of simulating regional ground-water flow 

through the alluvial aquifer. 

Grid design, boundary conditions, and 

calibration all rely on knowledge of the 

hydrogeologic characteristics of the natural flow 

system. For this assessment of hydrogeologic 

conditions, a series of synoptic water-level 

measurements were made for model calibration. 

Boundary conditions and surface-water/ground-water 

interaction, particularly regarding the Ohio River, 

were based on published data, county/project file 

data, continuous water-level recordings, and the 

conceptual model. The grid design was based on the 

anticipated ground-water flow as formulated by the 

conceptual model and on the spatial distribution of 

available control points. Hydrogeologic 

characterization of the natural flow system will 

improve with the incorporation of additional data. 

Scale limitations also should be considered 

when using the model to predict the response of the 

ground-water-flow system to changes in applied 

stresses or hypothetical situations such as the 

migration routes of hazardous-material releases. The 

response of the ground-water-flow system to largescale changes, such as a 50-percent increase in 

pumpage or the addition of 1 in. of recharge from 

precipitation infiltration, can be simulated with a 

limited degree of accuracy. The response of the 

ground-water-flow system to small-scale changes, 

such as rearranging withdrawals within a well field, 

could not be accurately simulated; a more sitespecific model would be required for this type of 

application. 

The ground-water-flow model is an attempt to 

represent numerically the natural flow system. Userdefined numerical approximations and convergence 

tolerances—the predetermined error criterion for 

model solutions—allow the model to simulate the 

natural flow system and its response to changes in 

stresses within a predetermined range of accuracy. No 

ground-water-flow model can completely recreate the 

natural flow system in a numerical representation. 

APPLICATION OF THE GROUND-WATERFLOW MODEL 

The calibrated ground-water-flow model was 

used to delineate recharge and discharge boundaries 

and to estimate flowpaths and travel times of particles 

placed in the flow system. The cell-by-cell flow terms 

from the calibrated steady-state model were used as 

input to MODPATH, a particle-tracking program 

(Pollock, 1989, 1994). The MODPATH program 

computes particle locations and travel times in three 

dimensions based on advective flow in a uniformly 

porous medium. MODPATH can track particles 

forward in time and space in the direction of groundwater flow or backward toward recharge areas 

(Robinson and others, 1997). 

To delineate discharge areas, one particle, 

representing an infinitesimal volume of ground water, 

was placed at the center of all active cells in the model 

grid. Each particle progressed forward in time and 

space through the ground-water-flow system until a 

discharge boundary was encountered. Cells 

discharging to the same boundary were grouped to 

produce a map identifying the contributing areas 

(fig. 13). Discharge boundaries include area groundwater-withdrawal wells and the Ohio River. Likewise, 

particles were placed at the center of all active cells 

and allowed to progress backward in time and space 

to recharge boundaries (fig. 14). 
Page 36 - Blank 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

1 

22 24 

3 

4 

5 

6 7 8 

11 10 

12 

17 16 

19 

20 21 

23 

25 

26 

27 

42 

2 42 

9 13 14 

15 28 

18 

227 

71 

Base from U.S. Geological Survey 

Carrollton 1:24,000, 1994 

Sanders 1:24,000, 1987 

Florence 1:24,000, 1981 

Vevay North 1:24,000, 1981 

Vevay South 1:24000, 1980 0 2 4 6 8 10 MILES 

0 2 4 6 8 10 KILOMETERS 

EXPLANATION 

Contributing area to discharge boundary 

of Ohio River and Kentucky River 

Shaded areas (1-28) are contributing 

areas to ground-water withdrawal wells 

Study Area 

KENTUCKY 

Figure 13. Simulated contributing areas to discharge boundaries of the alluvial aquifer. 

APPLICATION OF THE GROUND-WATER-FLOW MODEL 37 
Page 38 - BLANK - (back of figure 13 page) 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

42 

42
 

227
 

71
 

Base from U.S. Geological Survey
 

Carrollton 1:24,000, 1994
 

Sanders 1:24,000, 1987
 

Florence 1:24,000, 1981
 

Vevay North 1:24,000, 1981
 

Vevay South 1:24000, 1980
 0 2 4 6 8 10 MILES
 

0 2 4 6 8 10 KILOMETERS
 

EXPLANATION 

Study Area Areas of recharge to the Ohio Alluvial aquifer River and Kentucky River 

KENTUCKY Recharge boundary for 

modeled area 

APPLICATION OF THE GROUND-WATER-FLOW MODEL 39
 

Figure 14. Simulated recharge areas and boundaries of the alluvial aquifer. 
Page 40 - BLANK - (back of figure 14 page) 
APPLICATION OF THE GROUND-WATER-FLOW MODEL 41 

 

 

Recharge boundaries for the model include the valley 

walls, surface streams, and the Ohio and Kentucky 

Rivers. Typical ground-water velocities ranged from 

about 0.025 to 31.43 ft/d. The average residence time 

is about 2,044 days. Ground-water velocities for 

particles simulating induced infiltration from the 

Ohio River ranged from about 0.313 ft/d in lightly 

pumped areas such as downtown Carrollton to about 

15.30 ft/d for well fields servicing industrial plants. A 

porosity of 0.20 was used for the particle-tracking 

analysis (Bell, 1966). 

To estimate flowpaths and travel times for a 

specific well, particles were placed at the center of the 

model cell representing a public water supply in near 

Ghent, Ky. The particles were traced backward in 

time and space to delineate the possible contributing 

area for this particular well. Figure 15 shows the 

extent of the modeled contributing area and the 

calculated times of travel contours. Estimations of 

contributing areas to wells, the delineation of 

flowpaths, and the calculation of time of travel for 

particles are subject to error. The limitations of 

particle tracking are directly related to the uncertainty 

in parameter estimations and incorrect model design. 

Contributing areas to wells are approximated because 

assumptions are made in estimating parameters 

characterizing the alluvial deposits, and a limited 

number of particles are used for the traces. 

Particle-tracking analysis also can be used to 

delineate the extent and travel times for a plume 

originating from a potential contaminant source 

within the study area. For illustrative purposes, 

particles were placed in a cell to represent a potential 

contaminant source and allowed to progress forward 

in time and space, thus delineating the extent of the 

contaminant-plume migration (fig. 16). Time-oftravel estimates can then be plotted on the trace of the 

plume to predict breakthrough times at different 

points along the flowpaths. Physical, chemical, and 

biological processes that attenuate chemical 

constituents in ground water are not considered, and 

the dissolved contaminant is assumed to not 

appreciably alter the density of the ground water. 

MODPATH cannot be used to predict solute transport 

(Robinson and others, 1997). 

Additional applications of the model include 

hypothetical pumping situations to determine the 

development potential of the aquifer for current users, 

the addition of new pumping centers and the potential 

effects of these new stresses on water availability, and 

the overall “safe yield” of the aquifer for resource 

management. Such issues and situations may be 

addressed with proper application of the model and 

understanding of the model assumptions, but are 

beyond the scope of this investigation. 
Page 42 - Blank 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

42 

42
 

227
 

71
 

Base from U.S. Geological Survey
 

Carrollton 1:24,000, 1994
 

Sanders 1:24,000, 1987
 

Florence 1:24,000, 1981
 

Vevay North 1:24,000, 1981
 

Vevay South 1:24000, 1980
 0 2 4 6 8 10 MILES
 

0 2 4 6 8 10 KILOMETERS
 

EXPLANATION
 

Contributing areas
 Study Area and time of travel 

5 years Ground-water withdrawal well Alluvial aquifer 10 years KENTUCKY 15 years 

20 years 

APPLICATION OF THE GROUND-WATER-FLOW MODEL 43
 

Figure 15. Simulated contributing area and time of travel to a withdrawal well near Ghent, Kentucky. 
Page 44 - BLANK - (back of figure 15 page) 
CARROLL COUNTY

GALLATIN COUNTY

85∞10′ 85∞10′

85∞

85

38

∞

∞45′

38∞45′

38∞40′

38∞40′

42 

42 

227 

71 

Base from U.S. Geological Survey 

Carrollton 1:24,000, 1994 

Sanders 1:24,000, 1987 

Florence 1:24,000, 1981 

Vevay North 1:24,000, 1981 

Vevay South 1:24000, 1980 0 2 4 6 8 10 MILES 

0 2 4 6 8 10 KILOMETERS 

Alluvial aquifer 

EXPLANATION 

2 years 

4 years 

6 years 

8 years 

10 years 

Areas discharging to a 

simulated ground-water 

withdrawal well and 

simulated time of travel 

2 years 

4 years 

6 years 

8 years 

10 years 

Areas discharging to the 

Ohio River and simulated 

time of travel Study Area 

KENTUCKY 

Ground-water withdrawal well 

APPLICATION OF THE GROUND-WATER-FLOW MODEL 45 

Figure 16. Simulated flowpaths and time of travel for a simulated contaminant release from a hypothetical hazardous-materials storage facility. 
Page 46 - BLANK - (back of figure 16 page) 
 

 

 

SUMMARY AND CONCLUSIONS 

The alluvial aquifer at Carrollton, Ky., consists 

of glacial-outwash deposits of Wisconsin Age 

underlain by shales and limestones of Ordovician 

Age. The glacial outwash is composed of medium- to 

coarse-grained sand with lenses of gravel in the lower 

part capped by a thick layer of fine-grained sand and 

silt. A layer of silt and clay covers the glacial-outwash 

deposits throughout the study area. The direction of 

ground-water flow in the aquifer is predominantly 

from the bedrock valley walls toward the Ohio River 

and pumping wells. 

The alluvial aquifer receives natural recharge 

from the following sources: (1) direct infiltration of 

precipitation; (2) subsurface flow from the 

consolidated rocks along the valley walls; (3) flow 

from small streams; and (4) flow from the Ohio River 

to the aquifer when the stage of the river is higher than 

the adjacent ground-water levels. Additional recharge 

to the alluvial aquifer occurs as pumping wells close 

to the Ohio River induce flow from the river to the 

aquifer. Water discharges from the alluvial aquifer by 

flow to the Ohio River and to pumping wells. The 

aquifer was assumed to be at or near steady-state 

conditions in November 1995. 

A two-dimensional, single-layer, finitedifference model of the alluvial aquifer was calibrated 

by comparing the computed hydraulic heads with 

corresponding measured water levels in 49 area wells 

for steady-state conditions. The model simulation 

indicates that ground water enters the system 

primarily from induced infiltration from the Ohio 

River (32 percent), and from smaller streams 

(25 percent), flow from the valley walls (24 percent), 

and infiltration of precipitation (19 percent). The 

water exits the system through pumped wells 

(83 percent) and by flow to the Ohio River 

(17 percent). A sensitivity analysis of the model 

indicated it is most responsive to changes in the stage 

of the Ohio River and changes in the conductance of 

the riverbed material. 

Recharge and discharge boundaries for the 

model area were identified and contributing areas to 

ground-water withdrawal wells and time of travel for 

particles were estimated on the basis of head gradients 

and ground-water velocities as simulated by the 

model. 

The ground-water-flow model of the Carrollton 

area is an attempt to numerically represent the natural 

flow system. The simulations in this report were 

designed on the basis of general hydrologic 

conditions. Results of the simulations provide only an 

estimate of the components of the ground-water 

budget in the alluvial aquifer and are not intended for 

well-field design or placement. The accuracy of the 

simulations would be improved by the acquisition and 

incorporation of more information characterizing and 

quantifying boundary conditions, surface-water/ 

aquifer interaction, and hydraulic conductivity 

estimations. Additional study to quantify the water 

quality of the alluvial aquifer and to characterize 

solute-transport mechanisms would be beneficial to 

water-resource managers. 

REFERENCES CITED 

Bell, E.A., 1966, Summary of hydrologic conditions of the 

Louisville area, Kentucky: U.S. Geological Survey 

Water-Supply Paper 1819-C, 36 p., 6 pl. 

Gallaher, J.T., and Price, W.E., Jr., 1966, Hydrology of the 

alluvial deposits in the Ohio River Valley in 

Kentucky: U.S. Geological Survey Water-Supply 

Paper 1818, 80 p. 

Grubb, H.F., 1975, Simulated drawdown for selected well 

fields in the Ohio River alluvial aquifer: 

U.S. Geological Survey Water-Resources 

Investigations Report 2-74, 38 p.
 

Grubb, H.F., and Zehner, H.H., 1973, Aquifer diffusivity of 

the Ohio River alluvial aquifer by the flood-wave 

response method: U.S. Geological Survey Journal 

Research, v. 1, no. 5, September–October 1973, 

p. 597-601. 

Hall, F.R., and Palmquist, W.N., Jr., 1960, Availability of 

ground water in Carroll, Gallatin, Henry, Owen, and 

Trimble Counties, Kentucky: U.S. Geological Survey 

Hydrologic Investigations Atlas HA-23, 3 sheets, 

scale 1:125,000. 

Kentucky Cabinet for Economic Development, 1996, 

Kentucky Resources for Economic Development, 

Carrollton: Frankfort, Ky., Division of Research, 28 p. 

SUMMARY AND CONCLUSIONS 47 
McClain, D.L., Byrd, F.D., and Brown, A.C., 1997, Water 

resources data, Kentucky, water year 1996: 

U.S. Geological Survey Water-Data Report KY-96-1, 

286 p. 

McDonald, M.G., and Harbaugh, A.W., 1988, A modular 

three-dimensional finite-difference ground-water 

flow model: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 6, chap. A1, 

528 p. 

Pollock, D.W., 1989, Documentation of computer 

programs to compute and display pathlines using 

results from the U.S. Geological Survey modular 

three-dimensional finite-difference ground-waterflow model: U.S. Geological Survey Open-File 

Report 89-381, 188 p. 

_____1994, User’s guide for MODPATH/MODPATHPLOT, version 3—A particle tracking post-processing 

package for MODFLOW, the U.S. Geological Survey 

finite-difference ground-water-flow model: 

U.S. Geological Survey Open-File Report 94-464, 

249 p. 

Price, W.E., Jr., 1964, Geology and hydrology of alluvial 

deposits along the Ohio River between Ethridge and 

the Twelvemile Island, Kentucky: U.S. Geological 

Survey Hydrologic Investigations Atlas HA 97, 

2 sheets, scale 1:24,000. 

Robinson, J.L., Carmichael, J.K., Halford, K.J., and Ladd, 

D.E., 1997, Hydrogeologic framework and simulation 

of ground-water flow and travel time in the shallow 

aquifer system in the area of naval support activity, 

Memphis, Millington, Tennessee: U.S. Geological 

Survey Water-Resources Investigations 

Report 97-4228, 56 p. 

Rorabaugh, M.I., 1949, Progress report on the groundwater resources of the Louisville area, Kentucky, 

1945-49: City of Louisville and Jefferson County, Ky., 

64 p. 

_____1956, Ground water in northeastern Louisville, 

Kentucky, with reference to induced infiltration: 

U.S. Geological Survey Water-Supply Paper 1360-B, 

169 p. 

Swadley, W.C., 1973, Geologic map of parts of the Vevay 

South and Vevay North quadrangles, north-central 

Kentucky: U.S. Geological Survey Geologic 

Quadrangle Map GQ-1123, scale 1:24,000. 

_____1976, Geologic map of part of the Carrollton 

quadrangle, Carroll and Trimble Counties, Kentucky: 

U.S. Geological Survey Geologic Map GQ-1251, 

scale 1:24,000. 

Walker, E.H., 1957, The deep channel and alluvial deposits 

of the Ohio Valley in Kentucky: U.S. Geological 

Survey Water-Supply Paper 1411, 25 p., 6 pls. 

Whitesides, D.V., and Ryder, P.D., 1969, Effects of 

pumping from the Ohio River Valley alluvium 

between Carrollton and Ghent, Kentucky: Kentucky 

Geological Survey Information Circular 18, 20 p. 

48 Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky 

Hydrogeology and Simulation of Ground-Water Flow in the Ohio River Alluvial Aquifer 

Near Carrollton, Kentucky / Water-Resources Investigations Report 98-4215 U.S. Geological SurveyLouisville, KY 40299-1906 9818 Bluegrass ParkwayWater Resources Division

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