GIS-BASED ASSESSMENT OF RAINWATER HARVESTING POTENTIAL AREAS OF HARSHIN DISTRICT, SOMALI REGION, ETHIOPIA

Abstract

In Somali Region (SR), water has always been a critical resource. It has been in short supply for many years. Since 1996, the Somali Region has been either in a state of drought, recovering from a drought or moving into a new drought. Similarly, 90% of Harshin district communities dwell in the rural area depending mainly on livestock production for their livelihood; where the water supply in Harshin is totally from surface water system through rainwater harvesting (RWH). Thus, a systematic identification of areas suitable for RWH is essential to ensure its effectiveness, mitigate dry spells and better target investments in RWH. Therefore, the objectives of this study were to develop a GIS-based approach for identifying suitable sites for pond rainwater harvesting in Harshin District of Somali Region and to integrate factors for locating and mapping suitable areas for RWH interventions. This study used a GIS-based suitability model to generate suitability map for pond RWH by combining different criteria through Multi Criteria Evaluation (MCE) process. The suitability criteria considered were soil, climate, topography, land cover and rainfall. Maps for each criterion were prepared using ArcGIS and assigned weights according to their relative importance in prioritizing potential areas suitable for pond RWH. Accordingly, the spatial distribution of the suitability map showed that about 45.69% of the Harshin land falls under highly to very highly suitable category which covers around 1,968.90 Km2 of land, the moderately suitable class is about 54.29% which covers about 2,239.49 Km2 areas. The less and non-suitable land of this district for pond RWH is 0.01% which accounts for 0.61Km2 of land. It is concluded that suitability modelling using GIS was a flexible, time efficient and cost effective method for accurate identification of potential areas for RWH that facilitates decision-making in RWH.