Application of Remote sensing and GIS analysis to detect morphological changes in an artificial lake

Abstract In this study we have used remote sensing techniques inte-grated in GIS (Geographical Information System) environment to analyze the rapid morphological changes, spatially significant, occurred in an artificial lake, the San Giuliano Lake located in Basilicata Region (Southern Italy), generated by the damming of the Bradano River, in the period 1984 - 2004. The remote sensing data, derived from Landsat satellite imagery acquired in the same period, were processed using different enhancement techniques and classified with supervised algorithms widely used. The classification accuracy was assessed on the whole study area by estimating the Overall Accuracy (OA), Producer’s Accuracy (PA) and User’s Accuracy (UA). Data validation were performed with the aid of high resolution orthophoto means of random samples. The innovative approach lies in the way which the use of GIS geoprocessing data analysis and of the Digital Terrain Model (DTM) were integrated. They have allowed the creation of simulated water surfaces, called "false lake surface". A comparison between the false lake surfaces and the true ones, shows that the lacustrine area has experienced a dynamic evolutionary with plani-altimetric changes of water surface and volume stored. These physiographic changes are particularly evident in the subset imagery of years 1984, 1988, 1889, 1993, 1994 and 1995 and consist mainly of a substantial modification of the surface and perimeter of the artificial lake. These changes, related to erosion/sedimentation processes connected to the sedimentary dynamics of the main tributaries of the reservoir (Bradano River and Acquaviva Stream) and slopes overhanging the lacustrine area, are also confirmed by observations in the field. Finally, this study shows that the variations can adversely affect water volume stored with possible impact on the functionality of the reservoir in terms of risk and hazard for the local community.