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Track: Water Distribution, Wastewater, Sewer
Tim Leonard
Duke Power Company
13339 Hagers Ferry Road
Huntersville, NC 28078
Telephone: 704-875-5247
Fax: 704-875-5038
E-mail: tjleonard@dpcmail.dukepower.com
David Coughlan
Reservoir Bathymetry-Mapping the Pitfalls
Defining Issue: In a reservoir, processes are constantly at work changing the bottom morphology into something much different than when first impounded. In order to make proper management decisions, current information is necessary but too often lacking. Typical surveying techniques are too costly to provide this information. GIS Solution: Coupling GIS with GPS and modern hydroacoustic technologies has enabled Duke Power to develop maps of its reservoir bottoms much more quickly and cheaply than before. Methodology: Real-time differentially corrected GPS and highly accurate hydroacoustic gear are mounted on a boat that travels across the reservoir collecting longitude, latitude, and depth. The full pond elevation for the time of sampling is used to convert the depths to elevations above mean sea level. GIS is used to model the bottom surface, calculate volumes and areas of different depth layers, create contour maps, and determine the location and amount of sedimentation that has occurred.
Techniques were developed in order to assure the use of the most accurate depth measurements. The methods were tested by comparing the volume calculated with this method of a thirty-four acre pond with the volume calculated by surveyors using typical techniques. Some shortcomings and surprising and unexpected legal obstacles were discovered. Software: BioSonics Visual Acquisition and Visual Analyzer software was used to collect and process the depth data. ArcInfo, ARCTIN, ARCGRID, ArcView and Spatial Analyst were used to perform the GIS functions. This paper demonstrates the ease of integrating these technologies and also problems that a user may face.
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