Study area

Kentucky

Figure 4. Velocity data-collection points for Herrington Lake near the dam, April 8, 2010.

Figure 1. Location of the study area at Herrington Lake near Burgin, Ky.

Figure 5. Velocity vectors near top with bathymetric contours of Herrington Lake near the dam, April 8, 2010.

Figure 3. Bathymetric contours of Herrington Lake near the dam, April 6, 2010.

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EXPLANATION

Bathymetric contour—Shows elevation 

 of lake bottom. Contour interval 10 feet

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Outflow gates

Intake

Base from U.S. Geological Survey digital data, 2009.

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EXPLANATION

Velocity, feet per second

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Base from U.S. Geological Survey digital data, 2009.

Lambert Conformal Conic Projection NAD83

EXPLANATION

Velocity data-collection points

Transect numbers 000–013

0 100 200 FEET

0 25 50 100 METERS

Dam face

Intake

Outflow gates

000 001 002 003 004 005 006 007 008 009 010 011 012 013

Base from U.S. Geological Survey digital data, 2009.

Lambert Conformal Conic Projection NAD83

84°44' 84°42' 84°40'

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N

Kentucky River

Dix River

Dix Dam

Herrington Lake

Image produced by PhotoScience Inc. for Kentucky Division of Geographic Information, 2008.

Lambert Conformal Conic Projection NAD83

Figure 2. Bathymetric data-collection points for Herrington Lake near the dam, April 6, 2010.

Base from U.S. geological Survey digital data, 2009.

Lambert Conformal conic Projection NAD83

Intake

Dam face

Outflow gates

EXPLANATION

 Transect points

 Shoreline points

0 100 200 FEET

0 25 50 100 METERS

Prepared in cooperation with the Kentucky Utilities Company

Abstract

The U.S. Geological Survey (USGS) created bathymetric-contour 

and water-velocity vector maps for portions of Lake Herrington within 

600 feet of the face of Dix Dam near Burgin, Kentucky. The mapping 

was in support of a study of noninvasive acoustic technology for assessing structural integrity of dams, both as a routine inspection tool or as an 

emergency tool during hydrologic events, such as high water or flooding. 

In April 2010, scientists from the USGS used a boat-mounted transducer 

and echo sounder to obtain bathymetric data to characterize lakebed relief 

and sediment distribution under a closed-intake condition. Also in April 

2010, an acoustic Doppler current profiler was employed to measure water 

velocity and flow direction in the lake to locate velocities moving toward 

the dam face and, possibly, dam leakage. 

The bathymetric survey showed the present condition of fill in the 

reservoir since the dam was completed, as well as provided an outline of 

the lake floor. The velocity survey indicated no discernible flow pattern or 

direction within the study area; only one transect had shown a difference 

from the others that was noticeable. The noninvasive acoustic bathymetric and velocity surveys used during the case study showed promise in 

locating potential dam or intake maintenance areas. Additional case studies throughout the Nation are needed to more clearly define whether the 

methods for noninvasive bathymetric and velocity surveys for dam safety 

will be successful in a variety of settings. 

• The HYPACK TM navigation software package installed on a laptop computer was used to integrate 

the lakebed depths along with the DGPS horizontal position data and to display the location of the 

boat on a georeferenced aerial photo of the lake for navigation. 

• A laser rangefinder computed distance measurements and was used with a compass module, 

enabling determination of accurate azimuths and delineation of the shoreline. 

• The velocity survey was completed on April 8, 2010. The following equipment and software were 

used to collect the velocity data: 

• A 600-kHz Teledyne RD Instruments Rio Grande TM ADCP with a 0.7- to 75-m profiling range 

(Teledyne RD Instruments, 2010) was used to measure velocities. 

• A Trimble TM DGPS system was used for horizontal positioning during the survey. 

• The WinRiver II TM software package installed on a laptop computer was used to set configurations, 

collect data, and play back previous transects while integrating with a DGPS (Teledyne RD 

Instruments, 2006). 

• A laser rangefinder computed distance measurements and was used with a compass module, 

enabling determination of accurate azimuths and delineation of the shoreline.

Bathymetric Data Collection and Processing

Bathymetric data collection followed predetermined transect lines created in HYPACKTM (fig. 2) to 

ensure complete coverage of the lake study area. The area was photographed when the lake level was not 

gaged and was presumed higher than that on the day of the surveys; the water line in the figure 2 image 

therefore does not match with the survey water line. At the start of the bathymetric survey, the boat operator held the boat stationary on one side of the plan line near the shore. The echo sounder and DGPS were 

started, and depths and position data were simultaneously recorded within HYPACKTM. The operator of the 

laser rangefinder measured and recorded the distance and azimuth reading to the shoreline edge of water, 

shouting “mark” for the equipment operator to mark the edge in HYPACKTM. Subsequently, a distance 

and bearing were entered to define the shoreline point. The boat operator then proceeded across the lake, 

following the predetermined transect line to its opposite end. During the survey, the equipment operator 

took detailed notes to assist in data processing in the field and office. As the boat made its approach to the 

shoreline, the boat was stopped, held in position, and steadied to allow the operator of the laser rangefinder 

and equipment operator to mark the ending shoreline location. The recording was stopped, and the crew 

proceeded to the next transect to repeat the process (Hittle and Ruby, 2008). 

Raw bathymetric data were processed within HYPACKTM to filter (1) problems related to the echo 

sounder processing a multiple-return acoustic signal in shallow water, which causes the measured depth 

to be twice the actual depth; (2) invalid GPS positions; and (3) redundant areas along the banks caused by 

overlap of data collection at the ends of various cross sections. Analog printouts of the bottom profiles were 

produced during data collection and used as a quality-assurance measure in bathymetric data processing, 

because multiple-return errors can be identified in the analog printouts. The data were first reviewed and 

filtered within HYPACKTM and then were compared to all supporting field notes and analog printouts. The 

processed bathymetric data (including edge-of-water points) were next exported from HYPACKTM into a 

text file that included geographic coordinates and a corresponding depth (Hittle and Ruby, 2008). The water 

depths were then subtracted from the water-surface elevation to establish an elevation for the lakebed. 

HYPACKTM was finally used to produce a study-area map with 10-ft bathymetric contour intervals (fig. 3). 

This was accomplished by converting the dataset into a matrix and then building a Triangular Irregular 

Network (TIN) model for the final map product. 

Scientific Investigations Map 3198

Sheet 1 of 1

Conversion Factors, Abbreviations, and Datum Information

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 0.4047 hectare (ha)

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg)

SI to Inch/Pound

Multiply By To obtain

Length

meter (m) 3.281 foot (ft) 

meter (m) 1.094 yard (yd) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) 

as follows: °F=(1.8×°C)+32

Vertical coordinate information is referenced to the Kentucky Utilities Datum, which can be converted to the National Geodetic Vertical Datum of 1929 and the National Geodetic Vertical Datum 

of 1988 as shown below.

To convert from Subtract To obtain

Vertical datum

Kentucky Utilities Datum 13.81 NGVD 29

Kentucky Utilities Datum 14.31 NAVD 88

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

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

Methods for Noninvasive Bathymetric and Velocity Surveys for Impoundment Safety—A Case Study of Herrington Lake at Dix Dam near Burgin, Kentucky

By 

A. Thomas Ruby III

2012

Methods

USGS bathymetry surveys usually employ a hydroacoustic apparatus called an echo sounder. An echo 

sounder uses the frequency of sound to measure the distance from surface to bottom in a water body. 

USGS velocity surveys employ an acoustic Doppler current profiler (ADCP). ADCPs use Christian 

Doppler’s principle (published in 1842) that relates the change in frequency of a source to the relative 

velocities of the source and the observer. Use of an ADCP to measure velocities allows for unsteady, 

bidirectional flows to be more easily recognized than is possible with earlier types of current-measurement 

systems (Mueller and Wagner, 2009). 

Bathymetric and velocity surveys were made on April 6 and 8, 2010, respectively, by way of a 19-ft 

boat with a 2-inch pipe mount that was used to affix the acoustic equipment. A boat with direct-mounted 

equipment allowed for the best means for data collection. An initial visit to the site on March 30, 2010, 

was made to determine conditions at the site, safety allowances, and case study area. The case study 

area consisted only of the location near the dam and intake. As mentioned previously, the study area was 

approximately 800 ft wide and approximately 600 ft long, perpendicular to the dam face (fig. 2). The intake 

was shut down and was not discharging during the time of the surveys. The level of the lake was drawn 

down to minimum level so the survey could be done. The lake elevation for both surveys stayed constant 

at 720.5 ft. The weather on April 6, 2010, was clear and calm, with an average temperature of 23.8 degrees 

Celsius (°C). On April 8, 2010, the weather was still calm but overcast, with an average temperature of 

12.2°C.

The bathymetric survey was completed on April 6, 2010. The following equipment and software were 

used to collect the bathymetric data: 

• A 210-kilohertz (kHz) AirmarTM transducer and a NavisoundTM 210 Reson echo sounder were used. 

The NavisoundTM 210 Reson echo sounder had a depth range from 0.6 to 600 meters (m) (Reson, 

Inc., 2005). 

• A Trimble TM Differential Global Positioning System (DGPS) was used for horizontal positioning 

during the survey. 

the study area. The independent water temperature check was done by using a YSI 30 temperature meter 

that was checked during a yearly five-point temperature inspection (Wagner and others, 2006). The compass calibration resulted in an error of 1.2 degrees. 

Survey Results 

The noninvasive acoustic bathymetric and velocity surveys used in this case study show promise in 

locating potential dam or intake maintenance areas; however, additional case studies throughout the Nation 

are needed to more clearly define whether the methods for noninvasive bathymetric and velocity surveys 

for dam safety will be successful in a variety of settings. The bathymetric survey results from the case study 

can be used to help determine how much sediment has filled the reservoir since the dam was completed, as 

well as provide an outline of the lake floor. The velocity survey indicated that there is no discernible flow 

pattern or direction within the study area. For this particular case study, only transect 012 showed a slightly 

varied flow pattern from the other transects across the lake (not visible in figure 5 because the velocity 

vectors are averaged and the slightly varied flow pattern is obscured as a result). Further testing at the same 

study area at different conditions (higher levels in the lake, intake releasing at half open and also at full 

open) would help confirm differences at transect 012. 

References Cited 

Hittle, C.D., and Ruby, A.T., III, 2008, Bathymetric surveys of Lake Arthur and Raccoon Lake, 

Pennsylvania, June 2007: U.S. Geological Survey Data Series 357, p. 3, 4, 9. 

Interagency Committee on Dam Safety, 2004, Federal guidelines for dam safety: Accessed November 15, 

2011, at http://www.fema.gov/library/viewRecord.do?id=1578.

Mueller, D.S., and Wagner, C.R., 2009, Measuring discharge with acoustic Doppler current profilers from 

a moving boat: U.S. Geological Survey Techniques and Methods 3A–22, 72 p., available at http://pubs.

water.usgs.gov/tm3a22.

Oberg, K.A., and Mueller, D.S., 1994, Recent applications of acoustic Doppler current profilers, in

Fundamentals and advancements in hydraulic measurements and experimentation, Buffalo, N.Y., 1994, 

Proceedings: Hydraulics Division/American Society of Civil Engineers (ASCE), p. 341–350.

Reson, Inc., 2005, NaviSound 200/400 users guide: Navisound TM 100, 200 & 400 series operator’s 

manual, version 4.01, 177 p. 

Teledyne RD Instruments, 2006, WinRiver II quick start guide: San Diego, Calif., Teledyne RD 

Instruments, P/N 957–6230–00, 3 p. 

Teledyne RD Instruments, 2010, Workhorse Rio Grande ADCP: Accessed Nov. 5, 2010, at http://www.

rdinstruments.com/rio.aspx.

U.S. Army Corps of Engineers, 2002, Engineering and design—Hydrographic surveying: Washington, 

D.C., manual no. 1110 2–1003, 510 p. 

U.S. Environmental Protection Agency, 2010, U.S. Environmental Protection Agency Action Memorandum 

(AM) fact sheet on selected Engineering Evaluation/Cost Analysis (EE/CA) Alternative Kingston Fossil 

Fuel Plant Release Site, Harriman, Roane County, Tennessee: 4 p., accessed Dec.12, 2011, at http://www.

epa.gov/region4/kingston/FINAL_TVA_EECA_Fact_Sheet051810.pdf.

U.S. Geological Survey, 2008, Facing tomorrow’s challenges—An overview: U.S. Geological Survey Fact 

Sheet 2008–3008, 4 p.

Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A., 2006, Guidelines and standard procedures 

for continuous water-quality monitors—Station operation, record computation, and data reporting: U.S. 

Geological Survey Techniques and Methods 1–D3, 51 p. + 8 attachments; accessed September 30, 2011, 

at http://pubs.water.usgs.gov/tm1d3.

U.S. Geological Survey

U.S. Department of the Interior

Suggested citation: 

Ruby, A.T., III, 2012, Methods for noninvasive bathymetric and velocity surveys for impoundment safety—A case study of Herrington 

Lake at Dix Dam near Burgin, Kentucky: U.S. Geological Survey Scientific Investigations Map 3198, 1 sheet.

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any 

copyrighted material contained within this report.

Bathymetric Survey Quality Assurance/Calibration

The bathymetric survey was quality assured by using the echo sounder and a bar-check method. The 

NavisoundTM 210 Reson echo sounder has an accuracy of 0.03 ft at 210 kHz (Reson, Inc., 2005). A built-in 

bar-check utility enabled depth verification by using a correction for the speed of sound. The U.S. Army 

Corps of Engineers suggests performing the bar-check procedure to ensure the adequate calibration of 

an echo sounder (U.S. Army Corps of Engineers, 2002). Multidepth bar checks of the echo sounder were 

conducted by lowering a 2-ft by 4-ft plate to known depths between 5 and 30 ft at 5-ft increments. The echo 

sounder always reported within plus or minus 0.1 ft of the bar check. A bar check was also conducted at a 

depth of 100 ft by using a boat mounted crane with a motorized crank equipped with a 100-pound sounding 

weight to lower the plate. A counter mounted within the boom unit that was incremented to tenths of feet 

measured the actual depth. The vertical accuracy of the echo sounder was conservatively estimated to be 

plus or minus 0.1 ft. The bar-check process was repeated four times throughout the day to ensure accurate 

data collection (Hittle and Ruby, 2008). The survey was completed on a calm day to minimize the effects of 

wave action on the accuracy of the depth data. 

Lake-elevation stage readings were documented by using staff plates fastened to the west side of the 

dam intakes, which is the primary reference for Herrington Lake’s elevation, at the beginning and end of 

each survey day to determine any changes in the lake-surface elevation. The elevation of the lake was constant during the bathymetric survey. The echo sounder recorded the depth data both digitally and by analog 

signal via a built-in thermal paper recorder that was used for comparison to the digital data during processing in the office. 

The accuracy of the distance measurements from the transducer location to the shoreline point data 

was enhanced by equipment configurations and operator locations. The equipment on the boat was configured so that the transducer was mounted on the starboard side, and the DGPS was mounted directly above 

the transducer. Readings taken from the laser rangefinder from this position would correlate the lakeshore 

with the boat/transducer position. The equipment operator sat on the port side to offset the boat operator on 

the starboard side, reducing the roll of the boat during surveys (Hittle and Ruby, 2008). 

Velocity Survey Quality Assurance/Calibration

A series of pre-measurement field procedures are mandated by USGS to ensure the ADCP will perform accurately for the conditions present, and procedures were conducted in accordance with these documented USGS methods (Mueller and Wagner, 2009). The procedures were an instrument diagnostic check, 

water temperature measurement, and compass calibration. The ADCP equipment on the boat was configured such that the ADCP was mounted on the starboard side and the DGPS was mounted directly above it. 

As with the bathymetric survey, the equipment operator sat on the port side to offset the boat operator on 

the starboard side to reduce pitch and roll. The three pre-measurement field procedures (instrumentation 

diagnostics check, water temperature measurement, and compass calibration) were done in the middle of 

Velocity Data Collection and Processing

Advances in velocity-measurement technology allow three-dimensional velocities to be measured 

from a moving boat by using an ADCP (Oberg and Mueller, 1994; Mueller and Wagner, 2009), and all 

velocities in this study were measured with an ADCP. Three-dimensional velocities were measured from 

approximately 2 ft beneath the water surface to within 6 percent of the depth to the bottom. Depths ranged 

from 80 to 160 ft during the survey. The locations for velocity data collection were determined by the number of expansion joints on the face of the dam (fig. 4). The locations were chosen because of potential areas 

of concern on the dam face where the expansion joints aligned, and the velocity data collected would serve 

as a tool to locate velocities moving toward the dam face and, possibly, dam leakage. Velocity data were 

collected along transects that were perpendicular to the bathymetric transects. Each transect was started 

at the warning buoys, which were approximately 600 ft upstream from the dam. The first transect was 

initiated on the west side of the dam near the overflow gates, and following transect started in succession 

from the previous. The ADCP and DGPS were started simultaneously by use of the WinRiver IITM software 

(Teledyne RD Instruments, 2006) on the west side of the dam near the overflow gates, and the boat was 

then navigated directly toward the adjacent expansion joint. Field notes were kept to document any errors, 

anomalies, or issues experienced during each transect. Fourteen transects were collected during the velocity 

survey. 

Each transect was processed with WinRiver IITM software, in accordance with established USGS techniques (Mueller and Wagner, 2009). Three-dimensional velocity data were exported from WinRiver IITM 

into a Geographic Information System (GIS) to create an example illustration of the mean vector velocities 

from the top 10 ft of the lake near the dam (fig. 5). 

Introduction 

Throughout history, impoundments have been built for purposes of water supply, power generation, 

storage of waste materials, and recreation. As is the case with all retaining objects, dams or dikes that 

form impoundments are subject to forces from the contents inside, which can lead to erosion of the materials, seepage, and eventual destruction. One such instance of destruction happened in 2008, a failure of 

the northwest side of a dike used to contain fly ash at the TVA Kingston Fossil Fuel Plant, Roane County, 

Tennessee. The release extended approximately 300 acres outside of the fly ash storage areas of the plant 

into the main Emory River channel (U.S. Environmental Protection Agency, 2010). Although dam and dike 

failures cannot always be foreseen, inspections of impoundments can provide snapshots of current conditions and identify potential problems. Periodic inspections of dams, reservoirs, and appurtenant structures 

typically involve use of divers for visual underwater inspections and drilling crews to sample cores of dam 

and dike materials in areas of concern (Interagency Committee on Dam Safety, 2004).

There is a need to collect accurate georeferenced bathymetric and velocity data of impoundments 

throughout the Nation through use of noninvasive techniques in order to supplement traditional inspection 

methods and provide dam and reservoir managers with adequate tools to make decisions. Noninvasive techniques using acoustic instrumentation allow for minimal disturbance and improved safety conditions within 

a study area. The capabilities of acoustic technology can supply background data for future construction as 

well as focused data needed for routine inspection or emergency repair work. 

On April 6 and 8, 2010, the U.S. Geological Survey (USGS), in cooperation with Kentucky Utilities 

Company (KU), conducted noninvasive bathymetric and velocity surveys as a case study at Herrington 

Lake at Dix Dam near Burgin, Kentucky. The goal of the data collection was to evaluate acoustic technology in an impoundment environment near the dam and intake and to start developing a methodology for 

using bathymetry and velocity surveys as components of an overall engineering strategy for assessing dam 

safety. This work supports the USGS mission “to provide the Nation with reliable, impartial information 

to describe and understand the Earth. This information is used to minimize loss of life and property from 

natural disasters; manage water, biological, energy, and mineral resources; enhance and protect the quality 

of life; and contribute to wise economic and physical development.” Given this mission, USGS researchers 

have collected accurate bathymetry data at many sites throughout the country to provide partner organizations with useful information and assist them in managing their facilities. Specifically, this research falls 

in line with the USGS science strategies “A Water Census of the United States” and “A National Hazards, 

Risk, and Resilience Assessment Program” (U.S. Geological Survey, 2008).

Purpose and Scope

This report details the case study at Herrington Lake at Dix Dam on April 6 and 8, 2010. Three goals were 

targeted for the study:

1. Acquire accurate georeferenced bathymetry and velocity surveys at a case study site.

2. Collect data at a constant low level with no discharge of water.

3. Produce findings that demonstrate whether acoustic technology may be utilized as a tool for 

impoundment safety.

KU impounded the Dix River behind Dix Dam to create Herrington Lake in the 1920s, mainly for 

hydropower generation. Dix Dam is approximately 2 miles upstream of the confluence of the Dix River 

with the Kentucky River (fig. 1). Dix Dam is a rock-filled dam with one water intake. The intake is approximately 300 feet (ft) southwest of the dam face and approximately 700 ft southeast of the spillway. The 

dam and intake pipes are regularly inspected as part of dam safety procedures. Regular inspections of the 

impoundment are conducted to ensure the structure is safe. A typical dam-safety inspection at Dix Dam 

would consist of a diver team looking below the water surface to inspect the dam and intake structures 

to identify areas of concern. A drilling team would then be used to explore the areas of concern. Voids or 

holes, if identified, would be investigated and repaired.

During the case study, the area of concern was approximately 800 ft wide and 600 ft long, perpendicular to the dam face. The water intake was closed during the case study, and overflow gates were not in 

use because the lake level was lower than the gates. The elevation of the lake level was 720.5 ft, and the 

weather was calm with no precipitation. 

Read-me files and the extensive data files from the bathymetry and velocity can be downloaded from 

http://pubs.usgs.gov/sim/3198/.

Acknowledgments 

The USGS thanks Kentucky Utilities Company for granting access to their property for the survey. 

The author also thanks Shawn LeMaster, Ed Puckett, and Ellen Barringer from the Louisville USGS office 

for their work in collecting, filtering, and processing the data.