Assessment of surface irrigation potential and crop water demand in Daramalo Wereda, southern Ethiopia

Abstract Assessing available water and land resources as well as their potential for surface irrigation use is vital for sustainable agricultural development and planning. Agricultural irrigation also plays a crucial role in ensuring food security and reducing poverty in Ethiopia. However, it is dominated by rain‐fed agriculture, with rainfall distribution and intensity vary spatially and temporally. Enhancing agricultural water management and irrigation has the potential to increase agricultural productivity. The objective of the study was to evaluate surface water potential and the irrigation water demand of Zage River sub‐watershed, which were estimated using hydrological model of Soil and Water Assessment Tool (SWAT) and CROPWAT8.0 software, respectively. Slope, soil type, drainage densities, land use/cover, and river proximity were the factors utilized to determine irrigation land suitability. A weighted overlay was completed, with 17.32% of irrigable lands found to be highly suitable, 41.29% moderately suitable, 37.61% marginally suitable, and 3.78% not suitable. The SWAT model result gave very good model performance indicator values of NE = 0.773 and R2 = 0.872 for calibration and NE = 0.771 & R2 = 0.945 for validation. The SWAT model result showed a total of 33.248 million m 3 of surface runoff generated annually. Compared with irrigation water demand of 21.068 million m 3 , this suggests the watershed has high surface water potential for surface irrigation for selected crop types of the watershed. The findings of this research are relevant to improving local water management policies and practices and enable stakeholders to make decisions that enhance agricultural productivity and sustainable agricultural practices and help ensure the food security of local farmers.