Identification of Suitability Sites for Water Harvesting Technologies in Upper Danakil and Upper Tekeze Basins, Ethiopia

The growing global demand for water, outpacing population growth, coupled with the increasing challenge of food security, necessitates innovative water resource management strategies. In the study area, communities face acute water shortages for crop production during dry seasons, highlighting the critical role of rainwater harvesting. This study aimed to identify suitable zones for rainwater harvesting by integrating socioeconomic and biophysical factors using Geographic Information Systems (GIS), the Soil and Water Assessment Tool (SWAT), fuzzy logic, the Fuzzy Analytical Hierarchy Process (FAHP), and the Analytical Hierarchy Process (AHP). Key parameters considered included rainfall, drainage density, surface runoff, soil texture, vegetation cover (NDVI), land use/land cover, slope, lithology, hydrogeology, population density, lineament density, and proximity to settlements, wells, and roads. The Soil Water Assessment Tool model was used to compute run-off, Fuzzy Analytical hierarchy process and Analytical hierarchy process was used to drive the weight of each influential factor, fuzzy membership to standardize the input factor, and gamma fuzzy overlay weighted was used to aggregate factors together for both basins. Statistical performance of the Soil Water Assessment Tool model was revealed with R2 of 0.77 and NSE of 0.76 for Upper Tekeze Basin and R2 of 0.79 and NSE of 0.75 for Upper Danakil Basin for monthly calibration and R2 of 0.75 and NSE of 0.75, and R2 of 0.78 and NSE of 0.76 for Upper Tekeze, and Upper Danakil Basin respectively for monthly validation periods. Rainwater harvesting potential suitability class coverage of the Upper Tekeze Basin for surface water harvesting was very highly Suitable (2.32%), highly suitable (14.45%), moderately suitable (59.22%), low suitable (9.92%), not suitable (9.48%), and constraints (4.59%). Finally, ground water recharge (percolation tank) suitability class coverage in the Upper Danakil Basin was very highly suitable (12.4%), highly suitable (16.22%), moderately (18.512%), low suitable (22.74%) and unsuitable (30.151%). The study's findings offer valuable insights for policymakers and planners to support the development of sustainable irrigation projects and improve water security across both basins.