Document Type

Article

Publication Date

11-20-2007

Abstract

North-western Sudan, as a part of the castern Sahara, is among- the driest places on earth. However, the region underwent drastic climatic changes through the alternation of dry and wet conditions in tho past, During humid phases;"when the rain was plentiful over prolonged time period, the surfacc was veined by rivers and dotted by large lakes. The new Shuttle Radar Topography Mission data (SRTM ~90 m) revealed a large endorheic drainage basin, which is centred by a large terminal palacolake, in the northern Darfur State, The use of GIS methods allowed the delineation of the drainage basin and its associated palacorivers, The SRTM data along with the Landsat (ETM+) and Radarsat-l images oroborate the presence segments of palaeoshorelines associated palacolake highstands, These constitute a convincing argument of the long-term the cxistence of a possible pre-Holocene large water body in the region in the past. The rcmains of the highest palacoshoreline have a constant altitude of 573 1 3 m asl. At its maximum cxtent, the mega Lake occupied an arca of about 30 750 km² (the samc sizc as the Grcat Bear Lake, Canada's largest lake), which would have contained approximately 2530 km" of water. This, ancestral lake, which we named the Northern Darfur Megalake (ND Mcgalakc), represents indisputable evidence of the past pluvial conditions in the castern Sahara. The discovered palacoshorelines will have significant consequences for improving our knowledgc of continental climate changel and regional palaeohydorology, and should be taken into consideration in studies of past buman habitation in the resion. Much of the water carried by the Northem Darfur palacorivers and the ND Megalake would have percolated into the underlying rocks feeding the Nubian Sandston aquifer. These findings show that the used approach ol space-data integration can help significantly in the groundwater exploration efforts in the Darfur region, wherc freshwater access is essential for refugec survival, and can be successfully adopted in other parts of Sudan and arid lands in general.

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