Analyses of optical images and radar data reveal structural features and predict groundwater accumulations in the central Eastern Desert of Egypt

The North African Sahara is currently dominated by arid to hyperarid climate. In the central part of the Eastern Desert of Egypt, Wadi Matula is a dry stream course much like those in the rest of the Sahara. It covers an area of about 7,500 km(2). Radarsat-1 images, Shuttle Radar Topography Mission (SRTM), and Advanced Land Observing Satellite (ALOS)/Phased Array type L-band Synthetic Aperture Radar (PALSAR) data revealed paleodrainage systems and fault/fracture zones. Its trends display cross-cutting relationships. Interrupted surface runoff connections are inferred from block movements, tectonic capture processes, diverted valleys, and paleodrainage. The movements of the blocks led to newly formed drainage and caused disturbances in drainage orientations, topography, fractures, and stream density. Paleodrainage and the more recent drainage lines are superposed on weakness zones of major fractures and faults. These zones facilitated the hydrologic processes that caused erosion and downcutting. The intersection points of paleochannel courses, fracture/fault systems, and active streams must have increased the possibilities of groundwater accumulations. Accordingly, several exploration wells are suggested, which they represent the best abstraction sites of groundwater potentials. These predicted sites are consistent with the high potential zone of the groundwater prospect map. Thick fluvial deposits support that past pluvial events recharged the underlying aquifers. It is concluded that locations of paleodrainage, fractures/faults, and stream intersections are the best sites for groundwater resources; thus, radar images are powerful tools for mapping multi-temporal near-surface features in arid regions.