It shares common borders with nine countries. The climate of Sudan varies from continental in the northern parts, through savannah in the centre, to equatorial in its most southern parts. Water used in Sudan derives almost exclusively from surface water resources, as groundwater is used in only very limited areas, and mainly for domestic water supply. There are large areas in Sudan where exploitation of groundwater has been hampered by cost, as the water table is very deep.
Surface water is provided mainly by the Nile river.
Spate irrigation area 3. Equipped wetland and inland valley bottoms 4. Other cultivated wetland and inland valley bottoms 5. Elements in the water balance of Sudan Ethiopian plateaus, while the White Nile originates from the Equatorial Lakes. Apart from the Nile system, there are also the seasonal rivers of Gash and Baraka in eastern Sudan.