Geospatial techniques amalgamated with two-dimensional electrical resistivity imaging for delineation of groundwater potential zones in West Guji Zone, Ethiopia.

Abstract

Pressure on groundwater resources is continuously increasing day by day in West Guji Zone, Southern Ethiopia due to urbanization. So, this research introduces the integration of various methods like Geographical Information System (GIS), Remote Sensing (RS), Analytical Hierarchy Process (AHP) and Two-Dimensional Electrical Resistivity Imaging (2D ERI) technique for assessing the accurate and reliable sources of groundwater in the study area. To delineate groundwater potentiality, seven main criteria like lithology, drainage density, lineament density, soil texture, geomorphology, slope and land use/cover were identified based on the regional characteristics, field surveys, local information and literature review. Weightage for each thematic layer was consequently done by GIS based AHP weighted overlay analysis techniques and classified into three categories which represent high (247.69 km2), moderate (1314.79 km2) and low (4883.61 km2) respectively. High potential zones are mainly found in escarpment areas due to the presence of highly weathered and fractured rocks. At last, results were validated with borehole yield data and 2D ERI survey. The coordinates of each borehole yield data have been transferred to GIS platforms and it clearly shows that 4 out of 5 sample points were matching with >5 L/s in high potential zones. 2D ERI was conducted in the high potential zone for cross-validating the results and it indicates that the area was covered by water bearing formation with resistivity values of 30 Ωm to 162 Ωm respectively. Therefore, these tools are very effective for groundwater sustainable development and indispensable for planning and utilization of groundwater.