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The gash is a seasonal river that originates in the Ethiopian highlands and flows to the eastern parts of the Sudan covering a river basin of 200km length. The annual river discharge fluctuates between 400x103 m3 to 1200x103 m3.Ocasionally the higher discharge rates of the river lead to over bank flooding that cause severe damage t o buildings and farms of the Kassala town and the river gash delta agricultural area in addition to loss of lives. On the other hand, the agricultural activities lead to a drastic continuous decline of the ground water level. The alluvial deposits of quaternary age of the river gash basin form the ground water aquifers in the kassala region having thicknesses 27-54 m .They consist mainly of sands, silts with intercalations of. clays and local occurrences of gravel The deposits overly a basement rocks terrain of presumably Cambrian to Precambrian age.
Geophysical studies showed that a number of palaechanells of the gash river exist within the basin. Two distinct paleochanells occur in the upstream of the river. Estimation of hydrgeological parameters from pumping tests gave values of transmisivities ranging between 300-1854 m2/day and hydraulic conductivities ranging between 11-142 m/day. Ground water budget indicated that the annual inflow of water to the upstream area is of the order of 67.5x106 m3 while the outflow amounts to 69.0x106 m3. This indicates a ground water loss of -1.5x106 m3.The water quality of the gash aquifer is generally good and TDS values are in the range of 150-500 ppm.
On the basis of this study an integrated management programs for both surface as well as ground water resources are recommended. It is suggested that groundwater of the river gash aquifer is recharged through directing excess surface water during flood seasons to palaeochanels of river gash ,thus reducing hazards brought about by floods and increasing aquifer storage.
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