Overview of the Hydrogeology and Groundwater Occurrence in the Lake Tana Basin, Upper Blue Nile River Basin

Abstract

The Blue Nile (Abay) River is originating in the Lake Tana basin where many perennial and seasonal streams feed the largest lake of Ethiopia (Tana). The basin is characterized by different volcanic formations covered by thick alluvial and residual Quaternary sediments at the center of the basin around Lake Tana. In this study, an attempt was made to outline the hydrogeology of the basin based on limited information from well lithologic logs and previous relevant works. The Lake Tana basin is considered as a potential area for surface water and groundwater development corridors. The hydrogeology and groundwater occurrence is complex due to tectonism and existence of different volcanic rocks covered with thick alluvial sediments at the center of the basin. The shallow aquifer systems in the middle of the basin from the alluvial sediments are tapped by local communities using shallow wells fitted with hand pumps. The volcanic aquifers are multi-layer and tapped from different volcanic layers. The latter are highly productive depending up on the degree of fracturing and weathering. In few cases, as in the case of Kola Diba area there are artesian wells. The groundwater system converges towards the center of the basin. The Lake Tana basin leaks groundwater to the adjacent Beles basin and through the Blue Nile outlet.