GIS data integration for SRTM -Landsat ETM<sup>+</sup>-RADARSAT-1 images to delineat subsurface paleolakes, Wadi Watir area, Egypt

Abstract

The present research aims at using remote sensing data, including ETM+, SRTM DEM and Radarsat-1 for year 2000 to delineate subsurface paleolakes in Wadi Watir area. Mapping ancient surface water paths and accumulation (in lakes) can help significantly in groundwater exploration efforts at the concerned site. Data fusion of Radarsat-1 and the ETM+ satellite images for year 2000 were conducted to classify the texture roughness of wadi deposits. The SRTM data and radar images, particularly, proved to be an excellent tool in mapping ancient desert fluvial features that are presently concealed beneath a sand cover, without direct field measurements. The watershed of Wadi Watir and its drainage patterns were extracted from the DEM (SRTM) data. The shuttle radar topography mission (SRTM) data, with ~90 m horizontal resolution, were used to delineate and map the subsurface paleolakes. Sinks are formed if a cell is surrounded by higher elevation cells; the water is trapped in that cell and cannot flow. The results show existence of several disconnected subsurface paleolakes at upstream of Wadi Watir. Its fluvial systems developed in depressions surrounded by highlands, prior the uplifting. This study illustrates the capability of the SRTM and RADARSAT-1 data integration to penetrate surfaces and map ancient lakes, which allows a better understanding of the magnitude of the hydrological processes that acted upon the region in the past.