Satellite-based assessment of the dynamics of new lakes in southern Egypt

Lakes in arid landscapes are indicators of environmental change and important sources of water for human use. In regions without in situ hydrologic measurements, remote sensing may provide the only means to monitor longterm changes in water storage. We used a synergistic combination of multiple satellite remote-sensing methods to provide the first comprehensive assessment of the dynamics of a newly formed chain of large lakes in the hyper-arid Toshka Depression of southern Egypt. A total of 145 MODIS and AVHRR satellite images were used to monitor changes in lake surface area, which increased to a maximum of 1740km(2) before declining to 900km(2). Two methods were tested for satellite-based measurement of lake levels and volumes, one based on analysis of a digital elevation model and one using data from the ICESat GLAS laser altimeter. This study shows the power of satellite remote sensing for long-term monitoring of regional-scale hydrologic transformations.