Geology and geophysics of the West Nubian Paleolake and the Northern Darfur Megalake (WNPL–NDML): Implication for groundwater resources in Darfur, northwestern Sudan

The recent delineation of a vastly expanded Holocene paleo-lake (the Northern Darfur Megalake which was originally mapped as the West Nubian Paleolake and here will be referred to as WNPL–NDML) in Darfur in northwestern Sudan has renewed hopes for the presence of an appreciable groundwater resource in this hyper-arid region of Eastern Sahara. This paleolake which existed within a closed basin paleo-drainage system might have allowed for the collection of surface water which was subsequently infiltrated to recharge the Paleozoic–Mesozoic Nubian Aquifer. However, the presence of surface exposures of Precambrian crystalline rocks in the vicinity of the paleolake has been taken as indicating the absence of a thick Paleozoic–Mesozoic sedimentary section capable of holding any meaningful quantity of groundwater. This work integrates surface geology and gravity data to show that WNPL–NDML is underlain by NE-trending grabens forming potential local Paleozoic–Mesozoic aquifers that can hold as much as 1120 km of groundwater if the sedimentary rocks are completely saturated. Nevertheless, it is advised here that recharge of the Nubian aquifer under WNPL–NDML is insignificant and that much of the groundwater is fossil water which was accumulated during different geological times much wetter than today’s hyper-arid climate in Eastern Sahara. Excessive extraction will lead to quick depletion of this groundwater resource. This will result in lowering of the water table which in turn might lead to the drying out of the oases in the region which provide important habitats for humans, animals and plants in