Geospatial identification of potential rainwater harvesting sites for agricultural sustainability in the Gurnd Watershed, North Wollo, Ethiopia

Rainfall in the North Wollo zone of Ethiopia is irregularly distributed in space and time, leading to frequent crop failures and droughts that threaten food security for rural populations. While rainwater harvesting (RWH) has been promoted by the Ethiopian government and NGOs to enhance agricultural resilience, its adoption remains low due to operational challenges and a lack of site-specific suitability assessments. The objective of this study is to use a GIS-based methodology to find possible rainwater gathering locations for agriculture in the Gurnd watershed. Analytical Hierarchy Processes (AHP) and Multi Criteria Decision Analysis (MCDA) were utilized to find appropriate RWH sites based on five physical parameters. The assigning weight of each component was consistent, as seen by the consistency ratio of 0.086 for assigning values for each factor. A GIS-based integrated Soil Conservation Service-Curve Number (SCS-CN) model was utilized to estimate the depth of runoff potential based on annual rainfall. The study's findings indicate that, of the watershed's 525.3 hectares, 14% are unsuitable, 28.0 percent are less suitable, 28.2 percent are moderately suitable, 18.1% are suitable, and 11% are extremely suitable for a possible RWH site. Validation was done using installed structures to determine the work's dependability. On the final suitability map, the locations of both operational and non-operational Rain Water Harvesting sites were superimposed. According to the results, 65.2% of rainwater harvesting structures are non-functional and just 34.8% of them are operational. A class of suitable potential rainwater harvesting sites included about 25% of functional rainwater harvesting facilities, and 75% of these functional sites fell under the category of moderately acceptable rainwater harvesting sites. 53.3% of non-functional rainwater harvesting structures were found to be in the moderately acceptable class of possible rainwater harvesting locations, while around 40% of non-functional rainwater harvesting structures were found to be in the less to a not suitable class. Among the appropriate class of possible rainwater harvesting locations, the remaining 6.7% of non-functional sites were found.