REMOTE SENSING TO SUPPORT A BETTER HYDROGEOLOGICAL UNDERSTANDING OF THE NUBIAN AQUIFER SYSTEMS IN THE WESTERN DESERT OF EGYPT

Synthetic Aperture Radar and multispectral images are used in conjunction with topographic and groundwater data to understand heterogeneities of the Nubian aquifer between 20-24.5°N and 25-32°E in SW Egypt. This includes El-Oweinat and the southern Tushka region. New fluvial and structural interpretations emphasize the desert landscape was produced by fluvial action, including: newly-mapped alluvial fans, fed by eastward-flowing dendritic drainage; braided channels in central locations some being spatially aligned with a NE structural trend; and dendritic drainage to the east where the direction of flow is predominantly northward. The alluvial fans, the structurally-enclosed channels and the dendritic channels coincide with gentle slopes and optimal recharge conditions (1-5%) as derived from a SRTM generated slope map, indicating that these areas have high groundwater potential. Agricultural development of these areas then will improve the chances of more sustainable development. Further, with respect to El-Oweinat, the remote sensing interpretations are correlated with anomalies observed in groundwater data. Results suggest a relationship between the spatial organization of fluvial and structural features and the occurrence of low-salinity groundwater. Low-salinity water exists adjacent to the alluvial fans and in SW reaches of the structurally-enclosed channels. Wells in the vicinity of structures contain low-salinity water, emphasizing that knowledge of structural features is essential to understand groundwater flow paths. Advanced electromagnetic and electrical geophysical profiling will now be employed in the field to provide information about the aquifer depth and distribution, and the subsurface distribution of faults. The approach described here can be applied throughout the Great Sahara to assist in resource management decisions and support the much needed agricultural expansion.