Synopsis of ADCP's and Their Use by the USGS Indiana District Office

Acoustic Doppler current profilers (ADCP's) transmit sound into the water and receive reflected sound (echoes) from particles suspended in the water. The frequency shift between the transmitted sound and echoes is used to compute the velocities of the particles and the water in which they are suspended. ADCP's have unique features that allow them to be deployed from moving boats. ADCP's track the river bottom by measuring boat speed and direction and, thus, are able to compensate for the boat movement in computation of water velocities. The ADCP beam number and geometry are designed for the measurement of three-dimensional velocity profiles. Because an ADCP can measure water velocities, depth, and platform path simultaneously, it can compute discharge. To make a discharge measurement with an ADCP, a portable computer loaded with the ADCP manufacturer's data-collection and processing software must be interfaced with the instrument.

In 1994, the USGS Indiana District office began using a 600-kilohertz (kHz) Broadband model ADCP  to routinely measure river discharges at 16 streamflow-gaging stations. Use of the ADCP increased the number of stations that could be measured in a week's time, compared to conventional methods. In addition, most of these measurements were made with greater accuracy and safety than was possible with conventional methods. For discharge measurements on Indiana rivers, the ADCP has been deployed from a 5-meter aluminum boat custom fitted for ADCP applications.  

The USGS Indiana District office has used various boats to deploy ADCP's for several other innovative applications: 

• bathymetric mapping of two large water-supply reservoirs near Indianapolis (read the report here=>  Bathymetric Surveys of Morse and Geist Reservoirs in Central Indiana Made with Acoustic Doppler Current Profiler and Global Positioning System Technology, 1996; Water-Resources Investigations Report 97-4099); and 
• surveying water velocities near the discharge-release gates of the Salamonie Reservoir near Wabash, Indiana, during two periods of high release (read the report here=>  Surveys of Water Velocities in the Vicinity of the Discharge-Release Gates of Salamonie Lake Dam, Northeastern Indiana, Spring and Winter 1998; Open-File Report 99-228).

In early 1998, the USGS Indiana District office purchased two new-model ADCP's, one with a 1200-kHz and one with a 600-kHz transducer assembly. The new ADCP model was smaller and lighter than the earlier Broadband model.

In 1999, the Indiana District office began working on a new project to refine this prototype tethered platform. The project is part of a joint effort by the Indiana and Kentucky District offices for the USGS Instrument Committee and Office of Surface Water. The Indiana District office is refining the tethered platform, and the Kentucky District office is refining the remote-controlled platform developed in that office. The major objectives of the project are to: 

• develop specifications based on a survey of user needs; 
• investigate various models of radio modems for wireless data telemetry;
• investigate commercial availability of boat hulls;
• test and evaluate prototype hulls;

Results for the tethered-platform part of the project.

U.S. Department of the Interior
U.S. Geological Survey
5957 Lakeside Boulevard
Indianapolis, Indiana
46278-1996
USA
Phone: (317)290-3333
Fax: (317)290-3313
URL: http://sunrise.er.usgs.gov/hydroacoustics/adcpuses.shtml
Last modified:Monday, 13-Aug-2007 15:58:46 EDT
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