GROUNDWATER POTENTIAL ASSESSMENT USING GIS AND REMOTE SENSING: A CASE STUDY IN MANTHA WATERSHED, OMO-GIBE RIVER BASIN, ETHIOPIA

Abstract

In the current study area, the demand for groundwater is increasing. Therefore, the ultimate purpose of this study was to map groundwater potential zones in Mantha watershed using geographic information system and remote sensing. Ten groundwater controlling factors (geology, rainfall, lineament, soil, land use/land cover, geomorphology, slope, and distance to river, elevation, and drainage density) were used to map the groundwater potential zones of the study watershed using remote sensing data. Among these, three layers (geology, geomorphology, and soil) of the study watershed were extracted from existing data, and five layers (slope, drainage density, elevation, lineament, and distance to river) were developed using DEM of 30m*30m spatial resolution. 20 years precipitation data obtained from National meteorology Agency of Ethiopia were converted into areal rainfall using inverse distance weight interpolation method integrated with ArcGIS 10.8 to develop rainfall layer of the study watershed. Landsat8 of the year 2020 was used to map the land use/land cover of the study watershed using supervised image classification with maximum likelihood algorism in ERDAS 2015. Then, all thematic layers were reclassified using literatures and Jenks methods and finally rated in analytical hierarchy process. The results of ten thematic layers data rated in in analytical hierarchy process indicated that the most dominant thematic layers that hold high weight relative to others were- geology (28%), rainfall (16.6%), lineament density (12.9%), and soil (10.3%). Groundwater potential map of the study watershed was obtained by using weights derived from AHP and overlay analysis conducted in arc GIS10.8_ platform. There were four groundwater potential zones mapped in the Mantha watershed, namely, very high, high, moderate, and low. The map result was verified by well data and the result showed strong agreement in each category with 85.7%, 83.33%, 90%, and 100% respectively. The finding of this study indicates that the geographic information system and remote sensing model approach are reliable and can be a reliable prospecting method of groundwater potential zone