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| Indiana's Lost River and Bluespring Cavern |
The U.S. Geological Survey (USGS), in cooperation with the Indianapolis
Museum of Art (IMA), Ohio River Valley Water Sanitation Commission (ORSANCO),
and Bluespring Caverns collected bathymetric data along two reaches of the Lost
River within the Bluespring Cavern near Bedford, Indiana. The two reaches,
designated as "upstream reach”, and “downstream reach”, had lengths of
approximately 200 feet and 300 feet, respectively. These data were collected in
support of an artwork commissioned by the IMA.
The USGS used an acoustic Doppler current profiler (ADCP) (fig. 1) to collect
the bathymetric data. ADCPs are acoustic instruments commonly used by the USGS
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 bathymetric data
within a cavern for use in three-dimensional data-visualization products is an
innovative use of the technology.
All data were collected on July 10, 2007. The ADCP was deployed from a small
tethered flotation platform. All ADCP data were collected in real time on a
laptop computer as binary files. 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 three-dimensional
data-visualization software. This software was used to create three-dimensional
plots of the river reaches that showed river depths (fig 2).
Figure 1. Two Acoustic Doppler current profilers commonly used by the U.S. Geological Survey (Oberg, Morlock, and Caldwell, 2005).
Figure 2. Three-dimensional plot of the river reaches, showing river depths.
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Indianapolis Museum of Art: http://www.ima-art.org/
Ohio River Valley Water Sanitation Commission: http://www.orsanco.org/
Bluespring Caverns: http://www.bluespringcaverns.com/
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.
Go to the USGS Indiana Water Science Center
Home Page.
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