ABSTRACT The Ashebeka River, the primary drinking water source for Assela City, is increasingly threatened by sediment and pollutant loads from its 107 km2 upstream catchment. Few studies integrate biophysical modeling with socio-institutional evidence within a water safety plan (WSP) framework. This study applied a mixed-methods approach to identify and evaluate best management options (BMOs) for the Ashebeka catchment in Ethiopia. The Soil and Water Assessment Tool was developed using a digital elevation model, land use/land cover datasets, soil maps, long-term climate records, and observed sediment measurements. Model calibration and validation showed strong performance (Nash–Sutcliffe efficiency ≥0.83; R2 ≥ 0.84, percent bias ≤ ±10%), with annual soil loss of 18, 29, and 35 t/ha/year in sub-basins 2, 1, and 3. Household surveys, key-informant interviews, and focus groups were conducted with farmers, water-utility personnel, and local authorities. Stakeholder inputs guided the prioritization of sub-basin-specific BMOs, including contour farming, terracing, agroforestry, vegetative strips, and reforestation. Scenario analysis demonstrated that these measures reduced sediment yield by 87–90% (p 0.001). Integrating these technically robust and socially supported BMOs into a catchment-scale WSP provides a cost-effective, scalable strategy for safeguarding drinking-water sources in Ethiopia and other erosion-prone regions with similar agro-ecological and governance contexts.
Meka et al. (Fri,) studied this question.