Spatial Analysis of Groundwater Potential Using GIS Based Multi Criteria Decision Analysis Method in Lake Tana Basin, Ethiopia

Groundwater resource development for various uses is increasing in the Lake Tana basin, as surface water became limited in quantity and quality. Assessment of the groundwater potential (GWP) in the basin is crucial for sustainable use of water resources. This study aims at assessing the GWP in the basin using remote sensing and GIS-based Multi Criteria Decision Analysis (MCDA). Seven factors (lithology, lineaments, drainage density, rainfall, slope, land use/land cover and soils) that affect groundwater distribution were considered. Analytical Hierarchy Process (AHP) approach were used to compute each layer weight. Thematic weighted layers were overlaid in ArcGIS to identify GWP are-as in the basin. The result indicated that, 15% (1765 km2) classified as “very high”, 26.5% (3151 km2) as “high”, 31% (3592 km2) as “medium”, and 27.5% (3224 km2) were classified as “low” GWP zones in the basin. The GWP map was validated using observed borehole and springs data in the basin, and it indicated that 76% of agreement. It was found that GWP was highly sensitive to lithology and rainfall with mean variation index of 2.7% and 2.0%, respectively. High GWP is available at the southern and eastern side of the Lake Tana.