Water resource allocation in the Abaya Chamo sub-basin, Ethiopia: a scenario-based SWAT-WEAP modelling approach

This study integrates the SWAT and WEAP models to address water allocation challenges in Ethiopia’s Abaya Chamo sub-basin. SWAT simulated water availability, while WEAP allocated water to the domestic, irrigation, industrial, and environmental sectors. Baseline (2020) water demands were analysed, and four scenarios were explored: reference (2021–2035), high population growth, irrigation expansion, and irrigation efficiency improvement. The SWAT model estimated the annual water potential at 4.38 ×109m3. In 2020, total water demand was 1.22 ×109m3, with an unmet demand of 0.17 ×109m3. Projections to 2035 revealed persistent unmet demand across all scenarios. The irrigation expansion scenario resulted in a critical water deficit of 0.65 ×109m3. In contrast, improving irrigation efficiency from 50% to 60% alleviated water shortages. The findings underscore the importance of developing water storage infrastructure and promoting efficient water-use practices. This study emphasizes the role of advanced modelling tools in guiding sustainable water management in the region.