Ground Water Potential Evaluation Based on Integrated GIS and Remote Sensing Techniques, in Bilate River Catchment: South Rift Valley of Ethiopia

A systematic evaluation of groundwater is essential for the proper utilization and management of this precious natural resource. Integrated GIS and remote sensing are efficient techniques in groundwater studies; in facilitate better data analysis and their interpretations of groundwater potential controlling parameters. In the present study, an attempt had been made to delineate and classify possible groundwater potential zones in the Bilate River catchment using integrated remote sensing and GIS techniques. The thematic layers considered in this study are lithology, geomorphology, drainage density, lineament density, rainfall, soil, slope and land use/ land cover were prepared using the Landsat ETM+ imagery and ArcGIS software. All the thematic layers were then assigned weights according to their relative importance in groundwater occurrence and the corresponding normalized weights were obtained based on the Saaty's analytical hierarchy process. These weights were applied in linear summation equation to obtain a unified weight map containing due weights of all input variables. The thematic layers were finally integrated using ArcGIS and IDRIS software to produce a groundwater potential zone map. Thus, four different groundwater potential zones were identified, namely 'high, 'moderate’,' low’ and 'poor'. The high potential zones correspond to alluvial plains, lacustrine sediments, the fracture valleys, and valley fills, which coincide with the low slope and high lineaments density areas .The eastern portion and valley escarpment of the study area fall under moderate groundwater potential zone. The low zones mainly comprise structural hills and an escarpment which contributes high run-off .On the other hand; Poor groundwater potential zones are present in the mountain peaks, plateaus and escarpments with steep cliff.The resulted groundwater potential zoning map validated based on existing water sources point data of the study area. Finally, it is concluded that the integrated GIS and remote sensing techniques are very efficient and useful for the identification of groundwater potential zones