Groundwater prospect zonation using the analytical hierarchy process technique in Mekelle area, Tigray, northern Ethiopia

Abstract

This study is aimed to delineate groundwater prospect zones of Mekelle area using Analytical Hierarchy process techniques. Eight thematic layers including geomorphology, geology, lineament density, slope, drainage density, soil, land use/cover and precipitation were used for the groundwater prospect zone mapping. The weighted sum overlay Analysis method in the ArcGIS environment was used to map the groundwater prospect zones of the study area. The results of the groundwater prospect zone were validated using yields of 42 deep wells, 29 shallow wells and 29 springs. Accordingly, the groundwater prospect of the area classified into four zones as poor, moderate, good and very good with respective area coverage of 185 km2, 252 km2, 243 km2 and 358 km2. The correlation of the geology and the prospect zones shows that areas covered with the deep massive dolerite aquifers represent poor groundwater prospect zones, while the shallow, weathered and fractured dolerite and shale-marl-limestone intercalations correspond to the moderate groundwater prospect zones. Whereas, the lower sandstone formation is correlated with good prospect zones as well as the marl-limestone and limestone-marl formations with intensive lineament concentrations are corresponded with the very good prospect zones. Validation of the groundwater prospect zones against the corresponding yield variations of the groundwater point’s results in a fit of about 94%.