Figure 1. An ADCP attached to a manned boat for use in 

measuring streamflow.

Side-mounted ADCP on U.S. 

Geological Survey work boat (photograph by James Duncker, USGS).

 GPS signal

Vessel-mounted

downward-looking

ADCP

 Velocity Acoustic beams

Slow Fast

 EXPLANATION

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2008–3096

February 2009

Acoustic Doppler Current Profiler Applications Used in 

Rivers and Estuaries by the U.S. Geological Survey

Printed on recycled paper

The U.S. Geological Survey (USGS) has collected streamflow information for the Nation’s streams since 1889. Streamflow information is used to predict floods, manage and allocate water resources, design engineering structures, compute 

water-quality loads, and operate water-control structures. The 

current (2007) size of the USGS streamgaging network is over 

7,400 streamgages nationwide. The USGS has progressively 

improved the streamgaging program by incorporating new 

technologies and techniques that streamline data collection while 

increasing the quality of the streamflow data that are collected.

The single greatest change in streamflow measurement 

technology during the last 100 years has been the development and application of high frequency acoustic instruments 

for measuring streamflow. One such instrument, the acoustic 

Doppler current profiler (ADCP), is rapidly replacing traditional 

mechanical current meters for streamflow measurement (Muste 

and others, 2007). For more information on how an ADCP works 

see Simpson (2001) or visit http://hydroacoustics.usgs.gov/. 

The USGS has used ADCPs attached to manned or 

tethered boats since the mid-1990s to measure streamflow in 

a wide variety of conditions (fig. 1). Recent analyses have 

shown that ADCP streamflow measurements can be made 

with similar or greater accuracy, efficiency, and resolution than 

measurements made using conventional current-meter methods 

(Oberg and Mueller, 2007). ADCPs also have the ability to 

measure streamflow in streams where traditional current-meter 

measurements previously were very difficult or costly to obtain, 

such as streams affected by backwater or tides.

In addition to streamflow measurements, the USGS also

uses ADCPs for other hydrologic measurements and applications, such as computing continuous records of streamflow 

for tidally or backwater affected streams, measuring velocity 

fields with high spatial and temporal resolution, and estimating 

suspended-sediment concentrations. An overview of these 

applications is provided below.

Streamflow Measurements

The first attempt to use an ADCP to measure streamflow 

was made in 1982 on the Mississippi River by Christensen and 

Herrick (1982) as part of work conducted for the USGS. In 

1985, the USGS purchased an ADCP and developed software 

for making streamflow measurements (Simpson, 2001). Since 

then, ADCPs have proven to be useful tools for measuring 

streamflow throughout the country. For many measurement 

conditions, the ADCP samples more of the flow (spatially), 

as compared to traditional 

mechanical current-meter 

measurements, resulting in 

more detailed streamflow 

information. Typically, it 

takes 45– 60 minutes to make 

a mechanical current-meter 

streamflow measurement 

using the two-point method 

(Rantz and others, 1982), a 

40-second velocity sampling 

interval, and approximately 

25 vertical measurement 

sections. An ADCP streamflow measurement can be 

made at the same section in 

15–20 minutes. This increase 

in efficiency results in cost 

savings with improved safety 

conditions, and more detailed streamflow data. ADCP streamflow measurements have been shown to have an uncertainty 

of 4.5 percent or less (Oberg and Mueller, 2007). Traditional 

current-meter measurements with a 40-second sampling 

interval and approximately 25 vertical measurement sections 

and uniform flow are estimated to have an uncertainty of about 

5.5 percent (Pelletier 1988). 

An example of how personnel from the USGS Indiana 

Water Science Center were able to make more streamflow 

measurements with fewer personnel using ADCPs during a 

recent flood in central Indiana is given in table 1. Because 

ADCPs can be used to make streamflow measurements within 

minutes, they often are used to measure unsteady flows, such as 

tidally affected streams, or unsteady flows near dams or other 

control structures (Simpson, 2001). ADCPs also are able to 

measure extreme low-flow conditions that could not have been 

measured by using conventional methods. 
A

A

Plan view

Profile view

Streamflow

Echo

Beam

angle

Ping

x-component

Water-surface

elevation gage

Sidewardlooking 

ADCP 

Sideward-

 looking ADCP

Velocity measured

 along acoustic beam

Piling

y-component

00:00 04:48 09:36 14:24 19:12 00:00 04:48 09:36 14:24 19:12 00:00

12,000

10,000

8,000

6,000

4,000

2,000

0

–2,000

–4,000

–6,000

–8,000

–10,000

–12,000

Lostmans Creek

Broad River

Harney River

Shark River

North River

STREAMFLOW, IN CUBIC FEET PER SECOND

TIME, IN HOURS AND MINUTES

Flood

tide

Ebb tide

bin

bin bin

bin bin

bin

bin

bin

bin

bin

Beam

Ensemble

Bottom

unmeasured

zone

Top

unmeasured zone

River bottom

Water surface

ADCP

Bottom mount

Measured zone

y = 0.7345x + 0.0864

R2= 0.994

–2.0

–1.5

–1.0

–0.5

0

0.5

1.0

1.5

2.0

–3.0 –2.5 –2.0 –1.5 –1.0 –0.5 0 0.5 1.0 1.5 2.0

04/19/2001

Measurement date

10/26/2001

02/05/2002

03/13/2002

10/03/2002

02/27/2003

INDEX VELOCITY, IN FEET PER SECOND

MEAN VELOCITY, IN FEET PER SECOND

Table 1. Resources used to measure a flood in central Indiana 

with mechanical current meters and with ADCPs.

Flood/method

Number of 

streamflow 

measurements 

during 10 days

Average time 

per streamflow 

measurement, 

in minutes

Number 

of 

hydrographers

January 1991/Current meter 52 96 11

July 2003/ADCP 62 18 6

In 2007, 21 percent of all USGS streamflow measurements were 

made with ADCPs, this includes 71 percent of all streamflow measurements made from a boat, cableway, or bridge. During this same 

period, approximately 250 ADCPs were used for making streamflow and velocity measurements in USGS water science programs.

Index-Velocity Method

With ADCPs, measuring and computing continuous 

records of streamflow can be conducted in challenging environments. Until the advent of ADCPs, it was difficult or impractical 

to accurately compute streamflow records on tidally affected 

rivers or rivers affected by backwater. Two-beam ADCPs can 

be attached to a fixed structure, such as a pile or bridge pier, 

and used to measure velocity horizontally for a portion of 

a channel cross section (fig. 2). The measured velocity at a 

fixed point in the cross section can be used to compute continuous streamflow records. When a site is subject to periods 

of vertically stratified bidirectional flow, an ADCP can be 

mounted at the bottom of the streambed in a vertically oriented 

or “up-looking” position, and velocities can be measured at 

multiple points or “bins” throughout the water column (fig. 3).

Figure 3. Schematic diagram of a bottom-mounted ADCP 

(Wall and others, 2006).

Figure 5. Typical instantaneous streamflow cycle for five stations along 

the southwest coast of the Everglades National Park (Levesque, 2004).

Figure 4. An example index-velocity rating (Hittle, 2005).

Figure 2. Installation of a fixed ADCP for use in measuring 

index velocity (Ruhl and Simpson, 2005).

Measured velocity and stage or water-surface elevation data 

are used with the index-velocity method (Ruhl and Simpson, 

2005) to compute continuous records of streamflow. In the indexvelocity method, two ratings (or relations) are developed and 

maintained—a stage-area rating and an index-velocity rating. The 

stage-area rating is developed by surveying a stable cross section 

in the stream near the permanently mounted ADCP. The channel 

area for a given stage then can be determined from the surveyed 

cross section. An index-velocity rating (fig. 4) is developed by 

using the relation between the measured mean cross-sectional 

velocity at the surveyed cross section and the simultaneous 

index velocity measured with the permanently mounted ADCP. 

Continuous records of stage and index velocity are converted to a channel area and mean velocity using the respective 

ratings. The channel area then can be multiplied by the mean 

velocity over time to compute a continuous record of streamflow as illustrated in figure 5. 
EASTINGS, IN FEET

1,031,500 1,032,000 1,032,500

323,000 323,500 324,000

NORTHINGS, IN FEET

WATER DISCHARGE, IN CUBIC FEET PER SECOND

SUSPENDED SAND CONCENTRATION,

IN MILLIGRAMS PER LITER

40,000 100,000

10,000

1,000

100

10

1

Colorado River at river mile 61

20,000

4 6 8 10 12 14 16 18

JANUARY 2005

0

Water discharge

Sand concentration computed from acoustic backscatter

Sand concentration measured by the equal-width increment method

FALSE RIVER AT SAN JOAQUIN RIVER

GRID SIZE = 580 X 940 METER

CONTOUR INTERVAL = 0.8 METER

BACKSCATTER INTENSITY, IN DECIBELS

50 54 58 62 66 70 74 78 82 86 90

Figure 6. Visualization of two-dimensional velocities measured with 

an ADCP (Dinehart and Burau, 2005; cm/s, centimeter per second).

Figure 7. Velocities measured with an ADCP, which are overlaid (red) 

on velocities calculated by using a model (Wagner and Mueller, 2004).

Measuring Velocity Fields

The USGS has used two-dimensional horizontal water 

velocity measured by an ADCP to map velocities in a stream 

or estuary as shown in figure 6. This figure illustrates how 

Dinehart and Burau (2005) used successive surveys with an 

ADCP and a differential global positioning system (DGPS) 

to analyze the flow dynamics of a section of a tidal river. 

The application of multidimensional numerical hydraulic 

models is often facilitated with velocity data collected with 

ADCPs and a DGPS. Wagner and Mueller (2004) used ADCPs 

to collect depth-averaged velocity data to both calibrate and 

validate a two-dimensional (2-D) flow model of the Ohio 

River near Olmsted, Illinois. A single ADCP dataset for 

model calibration or validation, consisting of repeated ADCP 

measurements at 15 cross sections, could be collected in 

1–2 days. Collecting the equivalent data using current meters 

would have required more than 1 week. Depth-averaged 

velocity measured by means of an ADCP and DGPS are shown 

in figure 7, along with simulated velocities from the 2-D model. 

Estimating Suspended Sediment

For each of the acoustic beams, the ADCP measures the 

acoustic intensity of signals backscattered to the ADCP by 

suspended particles in water. After correcting for the effects 

of temperature and voltage supplied to the ADCP and signal 

attenuation in the water column, the intensity of the acoustic 

backscatter is mainly a function of the suspended particles in 

the water. If the bulk of the suspended particles is composed 

of suspended sediment, then the backscatter intensity is mainly 

a function of suspended sediment and can be used as a spatial 

indicator of suspended-sediment concentration (fig. 8). USGS 

researchers are investigating and developing new methods for 

using acoustic backscatter as a surrogate for suspended-sand 

concentrations, as illustrated in figure 9. 

Figure 8. Backscatter intensity as an indicator of suspendedsediment dynamics along a boat track (Gray, 2005).

Figure 9. Comparison of estimated and measured 

suspended-sand concentration (Topping and 

others, 2007).
A

B

C

Summary

The emergence of hydroacoustic instruments, especially 

ADCPs, has allowed the USGS to adapt the technology for a 

variety of hydrologic measurements. The USGS uses ADCPs 

to make accurate streamflow measurements. Often these 

measurements can be made more efficiently than when using 

conventional methods. ADCPs permanently mounted in streams 

and tidal rivers are being used to compute continuous records 

of streamflow, and research is being conducted to use the same 

instruments and installations to estimate suspended-sediment 

concentrations. Calibration and validation of numerical models 

of flow and transport are facilitated by the rapid measurement 

of velocity fields using ADCP and DGPS technology. The 

USGS is leading the way in the implementation of the ADCP 

for riverine applications. As the technology evolves, the USGS 

tests ADCPs, develops new methods for measurement and 

analysis, and prepares guidance for ADCP applications to 

assure that high-quality data are collected.

References Cited

Christensen, J.L., and Herrick, L.E., 1982, Mississippi River test, v. 1., 

Final Rep. DCP4400/300, prepared for the U.S. Geological Survey: 

AMETEK/Straza Division, El Cajon, Calif. 

Dinehart, R.L., and Burau, J.R., 2005, Repeated surveys by acoustic 

Doppler current profiler for flow and sediment dynamics in a tidal 

river: Journal of Hydrology, v. 314, 21 p.

Gray, J.R., ed., 2005, Proceedings of the Federal Interagency Sediment Monitoring Instrument and Analysis Research Workshop, 

September 9–11, 2003, Flagstaff, Arizona: U.S. Geological 

Survey Circular 1276, 46 p. plus extended abstracts, available 

only online at http://water.usgs.gov/osw/techniques/sediment/

sedsurrogate2003workshop/listofpapers.html

Hittle, Clinton, 2005, Hydrologic characteristics of estuarine river systems 

within Everglades National Park: U.S. Geological Survey Fact Sheet 

2004-3129, 4 p., available online at http://pubs.usgs.gov/fs/2004/3129/

By Anthony J. Gotvald and

 Kevin A. Oberg

For more information contact:

U.S. Geological Survey

Office of Surface Water

415 National Center

Reston, Va. 20192

(703) 648-5301

U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

Or visit online at: 

http://hydroacoustics.usgs.gov

http://www.usgs.gov

ADCPs are used on a variety of measurement platforms. (A) Manned boats 

(photograph by Paul Baker, USGS). (B) Tethered boats. (C) Remotely controlled boat.

Levesque, V.A., 2004, Water flow and nutrient flux from five 

estuarine rivers along the southwest coast of the Everglades 

National Park, Florida, 1997–2001: U.S. Geological Survey 

Scientific Investigations Report 2004-5142, 24 p., available online 

at http://pubs.usgs.gov/sir/2004/5142/

Muste, M., Vermeyen, T.R., Hotchkiss, R., and Oberg, K.A., 2007, 

Acoustic velocimetry for riverine environments: Journal of 

Hydraulic Engineering, v. 133, no. 12, p. 1297–1298. 

Oberg, K.A. and Mueller, D.S., 2007, Validation of streamflow 

measurements made with Acoustic Doppler Current Profilers:

Journal of Hydraulic Engineering, v. 133, no. 12, p. 1421–1432.

Pelletier, P.M., 1988, Uncertainties in the single determination of river 

discharge—A literature review: Canadian Journal of Civil Engineering, 

v. 15, no. 5, p. 834–850.

Rantz, S.E., and others, 1982, Measurement and computation of 

streamflow: U.S. Geological Survey Water Supply Paper 2175, 

v. 2, 631 p.

Ruhl, C.A., and Simpson, M.R., 2005, Computation of discharge using the 

index-velocity method in tidally affected areas: U.S. Geological Survey 

Scientific Investigations Report 2005-5004, 31 p., available online only 

at http://pubs.usgs.gov/sir/2005/5004/

Simpson, M.R., 2001, Discharge measurements using a broad-band 

acoustic Doppler current profiler: U.S. Geological Survey Open-File 

Report 01-1, 134 p.

Topping, D.J., Wright, S.A., Melis, T.S., and Rubin, D.M., 2007, Highresolution measurements of suspended-sediment concentration and grain 

size in the Colorado River in Grand Canyon using a multi-frequency 

acoustic system: Proceedings of the Tenth International Symposium 

on River Sedimentation, August 1–4, 2007, Moscow, Russia, v. 3, 

p. 330–339.

Wagner, C.R. and Mueller, D.S., 2004, Results of a two-dimensional 

hydrodynamic and sediment-transport model to predict the effects of the 

phased construction and operation of the Olmsted Locks and Dam on 

the Ohio River near Olmsted, Illinois: U.S. Geological Survey WaterResources Investigations Report 03-4336, 31 p., available online at 

http://pubs.usgs.gov/wri/wri034336/

Wall, G.R., Nystrom, E.A., and Litten, S., 2006, Use of an ADCP to 

compute suspended-sediment discharge in the tidal Hudson River, 

New York: U.S. Geological Survey Scientific Investigations Report 

2006-5055, 26 p., available online at http://pubs.usgs.gov/sir/2006/5055/