Evidence for a large extended paleolake in the Eastern Sahara as revealed by spaceborne radar lab images

Recently processed radar images from the two flights of the space shuttle Endeavour by the spaceborne imaging radar-C/X-band synthetic aperture radar instrument in 1994 give a clear view, of widely distributed sediments of a palaeolake in todayʹs hyperarid eastern Sahara (NW Sudan). Although a few of the sites of lacustrine sediments were previously examined in the field, their extent now visible on the images yields a new perspective on the Early-to Mid-Holocene wet phase that affected northern Africa. Freshwater wetlands across an area exceeding 15,000 km2 existed between 8800 and 4500 B.P. owing to a significant increase in rainfall. The phenomenon called the West Nubian Lake constitutes the largest-scale hydrographic evidence in the eastern Sahara for a northward shift of the tropical rain belt. Given that the region now receives less than 15 mm of precipitation per year on average, the former open water body and its vegetated catchment may have acted as a modifier of the regional climate. In connection with the detection of a buried major palaeodrainage system near Kufra (SE Libya), the West Nubian Lake confirms the new multifrequency and multipolarization radar imaging as a powerful tool for the reconstruction of arid land palaeohydrology.