U.S. Geological Survey
Water Resources of Indiana

Collection of Water-Velocity and Bathymetric Data along a 5,000-Foot Reach of the Wabash River near New Harmony, Posey County, Indiana, March 2006

The U.S. Geological Survey (USGS), in cooperation with the Indiana Department of Natural Resources (IDNR), collected water-velocity and bathymetric data along a 5,000-foot reach of the Wabash River near the town of New Harmony in southwestern Indiana (fig. 1). The east and south river banks along this reach have been armored with limestone rip rap to protect New Harmony from damage caused by river-bank erosion. The USGS evaluated an innovative approach to collect the water-velocity and bathymetric data, using hydroacoustic instrumentation, and developed new methods of creating three-dimensional data-visualization products so that the IDNR could analyze the hydrodynamics and channel configuration along the reach.

The USGS used an acoustic Doppler current profiler (ADCP) (fig. 2) to collect the velocity and bathymetric data. ADCPs are acoustic instruments that the USGS uses to measure streamflow. To compute streamflow, ADCPs also measure water velocities, boat velocities, and water depths. Water-velocity measurements are made by transmitting sound at a known frequency into the water and measuring the Doppler shift, or change in sound frequency, from signals reflected off particles in the water (Oberg, Morlock, and Caldwell, 2005). Measurement of the Doppler shift of signals reflected from the river bottom determines the boat speed, and the ADCP on-board compass determines the boat direction (Wilson, Morlock, and Baker, 1997). The signals reflected from the bottom also are used to compute the depth of water. Although it has become commonplace for the USGS to use ADCPs for streamflow measurements, the collection of water-velocity and bathymetric data for use in three-dimensional data-visualization products is an innovative use of the technology.

All data were collected March 27 to March 29. During this period, Wabash River water levels were at or near the top of the armored bank. The ADCP was deployed from an 18-foot aluminum boat (fig. 3). The ADCP was interfaced with a real-time differential GPS (DGPS) unit to reference all collected water-velocity and bathymetric data to earth coordinates. All ADCP data were collected in real time on a laptop computer as binary files. Data were collected along boat paths that formed a grid (fig. 4), with the highest density of data collected near the armored bank.

The USGS quality assured the ADCP binary data files and output the water-velocity and bathymetry data in a text-file format. Computer programs were written to screen the text files for erroneous data and to format the data so they could be imported into ARC-GIS software and into three-dimensional data-visualization software called Earth Visualization Software (EVS). ARC-GIS was used to create files (called “covers”) of the water depths; the covers were used to create contour maps of river-bottom elevations (fig. 5). EVS was used to create three-dimensional plots of the river reach, showing river-bottom elevations (fig. 6) and water-velocity vectors (fig. 7).

Figures

Click any of the thumbnails below to see a larger version of the figure.

Figure 1. Aerial map showing the town of New Harmony (outlined with a white border), the study reach, and river-bottom elevations within the study reach.

Figure 2. Two acoustic Doppler current profilers commonly used by the U.S. Geological Survey (Oberg, Morlock, and Caldwell, 2005).

Figure 3. USGS jet boat used to collect water-velocity and bathymetry data.

Figure 4. Plot showing boat paths along which data were collected (because the river channel has changed since the aerial photograph was taken, boat paths cross outside the channel banks as shown in the photograph).

Figure 5. Contour map of river-bottom elevations, with a contour interval of 10 feet.

Figure 6. Three-dimensional plot of the river reach, showing river-bottom elevations.

Figure 7. Three-dimensional plot of the river reach, showing water-velocity vectors and river-bottom elevations.

Related Information Available from the World Wide Web

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: report describing bathymetric mapping of two large water-supply reservoirs near Indianapolis.

Quality-Assurance Plan for Discharge Measurements Using Acoustic Doppler Current Profilers, U.S. Geological Survey Scientific Investigations Report 2005-5183: report describing the quality-assurance measures implemented by the USGS for streamflow measurements using ADCPs.

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: report describing surveys of water velocities near the discharge-release gates of the Salamonie Reservoir near Wabash, Indiana, during two periods of high release.

References

Oberg, K.A, Morlock, S.E., and Caldwell, W.S., 2005, Quality-assurance plan for discharge measurements using acoustic Doppler current profilers: U.S. Geological Survey Scientific Investigations Report 2005-5183, 35 p.

Wilson, J.T., Morlock, S.E., and Baker, N.T., 1997, Bathymetric surveys of Morse and Geist Reservoirs in central Indiana made with acoustic Doppler current profiler and global positioning system technology, 1996: U.S. Geological Survey Water Resources Investigations Report 97-4099, 49 p.

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