Assessment of Karst Features Underlying Lake Seminole, Southwestern Georgia and Northwestern Florida, Using Orthorectified Photographs of Preimpoundment Conditions and Hydrographic Maps
Torak, Lynn J.
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Surface expression of karst-dissolution features in limestone units of the Upper Floridan aquifer underlying Lake Seminole, southwestern Georgia and northwestern Florida, is evident in preimpoundment aerial photographs and recent hydrographic maps of the lake bottom. Orthorectification of preimpoundment aerial photographs with U.S. Geological Survey Digital Raster Graphics files corresponding to 1:24,000-scale topographic maps allowed construction of a map of karst features in the impoundment area. This map provides a necessary tool to assess the likelihood of increased limestone dissolution and to evaluate the potential for sinkhole collapse and high rates of vertical leakage (lake outflow) beneath the lake. Comparison of aerial photographs with recent hydrographic maps prepared by the U.S. Army Corps of Engineers and with maps showing navigation channels and locations of inlake springs indicates that the orthorectified photographs contain details of karst features that can be used to enhance knowledge of lake-bottom hydrography and further understanding of lake-aquifer interaction.