Development of Suitable Water Harvesting Site Modelling and Suggest Corresponding Structure in Pastoral Community to Alleviate Water Scarcity: in Harorais Catchment, Somali Region, Jigjiga, Ethiopia

Abstract

Abstract The present study aims to identify suitable zones for water harvesting structures in Harorais Catchment by using a Geographic Information System (GIS) and Multi Criteria Evaluation (MCE). Multi-criteria evaluation is carried out in the Geographic Information system to help the decision-makers in determining suitable areas for water harvesting structures. Different layers that were taken into account for multi-criteria evaluation were; soil texture, slope, mean annual rainfall (2008–2019), land use/cover, mean annual runoff, infiltration rate, elevation, and evapotranspiration. A weighted overlay analysis (AHP) analytical method is applied to obtain a layer showing suitable areas for rainwater harvesting structures by rank. Hence, the Catchment is categorized as less suitable, moderately suitable, optimally suitable, and highly suitable. Accordingly, it was found that a small portion of about 0.36Km2 (1.41%) of the basin was highly suitable, 14.68Km2 (56.53%) moderately suitable, 6.93 Km2 (26.69%) optimally suitable and 3.99Km2 (15.37%) is less suitable from water harvesting suitability map. The suitable areas’ layer is integrated further with other structural considerations layers to determine spatial positioning for each rainwater harvesting structure. Finally, 8, 16, 20, and 21 locations in the entire Catchment are suitable and proposed for check dams, percolation tanks, farm ponds, and storage tanks respectively.