Identifying rainwater harvesting sites using integrated GIS and a multi-criteria evaluation approach in semi-arid areas of Ethiopia

Abstract

In recent years, East Africa has been suffering from severe droughts. The availability of water is crucial to socioeconomic development and ecosystem services in the region. In order to address the pressing issue of water scarcity in the Wag Himra zone, a study will identify viable rainwater harvesting (RWH) sites. Geographical Information System with a multi-criteria evaluation system was used to identify suitable RWH sites based on land use and cover, soil texture, runoff depth, slope, drainage density, and considering road and town constraints. The runoff depth was estimated using the soil conservation service curve number model, and the land use/cover image classification was undertaken using ArcGIS. By using weighted overlay analysis, sites that are potentially suitable for RWH were identified. Based on the hydrological and socioeconomic characteristics of the study area and available literature, the weight of the criteria was determined using the Analytical Hierarchical Process. The findings of the study indicate that only 0.02% of the study area is considered highly suitable, 2.59, 12.26, 61.76, and 21.1% are rated as moderately suitable, marginally suitable, less suitable, and not suitable for RWH, respectively, and 2.29% is labeled a constraint for RWH. It is possible to harvest and store rainwater in the study area to meet increasing water demand. These findings aim to assist decision-makers, planners, and managers to find sites, invest in water resources, and use RWH as an alternative water source.