Investigation of groundwater resources in highland Ethiopia using a geospatial technology

Abstract

Because of the rapid growth of human population combined with a decline in quality and quantity of surface water, the demand for groundwater has been rapidly increasing in Ethiopia. It is also highly anticipated that climate change-induced variations in hydrometeorological parameters will make groundwater more indispensable and scare resource in Ethiopia at some point. It is, therefore, essential to well understand the characteristics and potential areas of groundwater for proper management and use. In this study, an attempt has been made to identify groundwater potential zones in the Rib watershed, north-western highland Ethiopia. The thematic layers of the main factors that control the occurrence and movement of groundwater in hard rock regions were ranked, weighted and aggregated in a linear combination equation in ArcGIS Raster Calculator to generate the groundwater potential zone map. The generated map was then classified into five categories which represent very poor to very good groundwater potential zones. It was found that the downstream areas comprising gentle slope, alluvial deposits, and floodplains have very good groundwater potential zone which cover approximately 294 km2 (14.87% of the watershed). The upstream areas in the eastern and south-eastern parts of the watershed fall into low (either poor or very poor) groundwater potential zone due to high runoff and low infiltration. The generated groundwater potential zone map was finally validated using borehole points, which showed a good correlation. The results of this study will be helpful for better planning and management of local groundwater resources.