GIS-Based Multi-criteria Approach Surface Irrigation Potential Assessment for Ethiopian River Basin: in Case of Upper Awash River Basin

Agriculture plays a significant role in the economy of Ethiopia. However, Ethiopian agriculture is vulnerable to rainfall, with minimal irrigation for agricultural production. The primary issue associated with rainfall-dependent agriculture is the instability and unreliability of rains. The main problems in this study area are that available water resources, potentially irrigable sites, and irrigation water demand for crops grown are not explicitly known. Therefore, the study’s main aim was to assess suitable lands in the upper Awash watershed for surface irrigation using a GIS-based multicriteria approach and computation of crop water requirement of dominant crops grown in the study area. The main essential factors used for land suitability assessment are land slope, soil physical characteristics, distance from the water source, and land use land cover. All the factors are weighted using ArcGIS to get the overall suitable area of the study area. The irrigation water demand of the dominant crops was assessed using metrological station data with the support of CROPWAT8.0 software. The dominant crops identified in the study area are potatoes and tomatoes. The study result revealed that the area is dominated mainly by moderately suitable land, covering 488,337.1 ha (48.4%). The highly suitable area covers 284,220.31 ha (28.17%), the marginally suitable area covers 147,221.205 (14.6%), and not a suitable area covers 89,121.23 ha (8.83%) for surface irrigation. The potentially suitable lands for surface irrigation in upper Awash subwatersheds, namely, Melka Kunture, Akaki, Mojo, and below Koka dam, are also identified. The finding signifies that gross irrigation water demand was more significant in almost all subwatersheds than the available streamflow. As a result, the government should work hard and develop various irrigation projects to use the upper Awash watershed’s potential irrigated lands by utilizing various irrigation water storage structures.