A HYDROLOGICAL STUDY OF THE AREA AROUND THE BLUE NILE BETWEEN KAMLIN AND WAD MEDANI

Abstract

This study was carried out around the Blue Nile between Kamlin and Wad Medani in the Gezira State, Central Sudan, to characterize the hydrogeology and hydrochemistry of studied area. In this study field data from 200 boreholes were analyzed to assess the hydrogeological and hydrochemical properties of the study area. The main geological sequences in the study area are: Basement Complex, the Nubian Sandstone Formation, Gezira formation, Buried Chemical deposits Alluvium deposits and the superficial deposits. The main aquifer in the area is the Nubian Sandstone formation which overlies unconformably the Basement Complex and crop out at the eastern part of the study area. The Hydraulic properties of this aquifer are moderate (T = 397m2/d, K = 163m/d at Butana area and T = 331m2/d, K = 16m/d at Gezira area). The hydrochemical properties indicate that the water quality is acceptable according to standard parameters (average TDS = 386 ppm at Butana area and 332 ppm at Gezira area) .It is classified as predominately fresh water with isolated pockets of brackish water and calcium sodium bicarbonates water type, class S1C2for irrigation at Butana area, while at the Gezira area fresh water is classified as sodium bicarbonates water type and class S1C2 for irrigation purposes. The Gezira formation is the main aquifer west of the Blue Nile River, and it rests unconformably over the Nubian sandstone formation erosional surface with a thickness ranging from zero to 80m. The groundwater occurs under semi confined condition in the Gezira aquifer water is of good quality (TDS = 380ppm), and can be classified as sodium bicarbonate water type and class S1C2 for irrigation purposes. The general groundwater flow directions are from Blue Nile towards east and northeast at Butana area, and north, northwest at Gezira area with average hydraulic gradient 0.00288 and 0.00072 in Butana and Gezira area respectively. Estimated groundwater storage capacity of the Nubian Sandstone is 68.5X109 m3, at Gezira area 29.1X109 m3 at Butana area while in the Gezira aquifer is 42.4X109m3.