Identification of groundwater potential zones using geospatial analysis and frequency ratio model: the case of Kulfo-Hamassa watershed, Rift Valley, Ethiopia

Groundwater potential mapping is crucial for ensuring the sustainable use of groundwater resources. This study aims to identify groundwater potential zones in the Kulfo-Hamassa watershed, located in the Rift Valley, Ethiopia, using geospatial and frequency ratio (FR) approaches. A training set (70%) and a testing set (30%) were created from water well inventory data. Factors such as elevation, slope, curvature, topographic wetness index (TWI), stream power index (SPI), lithology, soil texture, land use/land cover, rainfall, lineament density, and drainage density were selected based on data availability, literature review, and expert consultation. The FR method was used to analyze the statistical relationships between these factors and groundwater occurrence. Groundwater potential zones were identified and categorized into three zones, including low (5.03 km2, 5.03%), moderate (950.21 km2, 40.61%), and high (1272.04 km2, 54.36%) potential zones. Validation using receiver operating characteristic (ROC) curves produced an area under the curve (AUC) value of 0.831, indicating high model accuracy. The quantitative validation showed a 76.3% agreement between predicted and actual well yields. This groundwater potential map provides a practical tool for site selection and sustainable water management, benefiting decision-makers, practitioners, and local communities involved in water resource planning in the watershed.