Integration of historical aerial photography and a geographic information system to evaluate the impact of human activities in a cypress-tupelo swamp

摘要

The Savannah River Site (SRS) is a 78,000 ha Department of Energy (DOE) facility that borders the Savannah River in the south-west portion of South Carolina. It includes a 3,800 ha cypress-tupelo swamp where commercial lumbering activities took place prior to the purchase of the land by the federal government in 1951. Since then, the DOE commenced nuclear production operations which resulted in the release of thermal effluent into the streams entering the Savannah River swamp system. The thermal effluent also had an impact on the swamp through the creation of sedimentation deltas. The purpose of this research is to identify areas of anthropogenic impact on the swamp and to delineate any areas that may still be considered pristine. Large-scale historical aerial photography of the swamp for 1938, 1943, 1951, and 1973 were photo-interpreted and used to develop a geographic information system (GIS) database. Logging features such as haul lines, drag points, harvest areas and roads were identified from black-and-white aerial photographs (1938-1973) and converted into a digital format. Sediment deltas were interpreted from 1976, 1981 and 1988 color aerial photography. Geometric transformations and GIS data analysis operations were performed to delineate areas impacted by man's activities over the 48-year time period. Only 1391 ha of swamp can still can be considered pristine. Approximately 63% of the swamp has been altered from its original state, either by logging practices or the effects of sediment loading from thermal effluent. This method of mapping the pristine areas of the swamp allows SRS environmental scientists the opportunity to have a priori knowledge about undisturbed swamp forest environments, which they may use as a baseline for restoration or wetland mitigation projects.