way of advancing socio-economic development in the region and protecting biodiversity and land resources. See also Lake Ptolemy African humid period References Bibliography Essay and Maps: Groundwater Resources of the Nubian Aquifer System Dahab, K.A., El Sayed, E.A. Study of Hydrogeological Conditions of the Nubian Sandstone Aguifer in the Area Between Abu Simbel & Toschka, Western Desert, Egypt. American Geophysical Union, Spring 2001 Aquifers Aquifers of Africa Springs of Africa Sahara Geography of Libya Geology of Libya Springs of Libya Springs of Chad Springs of Egypt Springs of Sudan