Reduced runoff and sediment loss under alternative land capability-based land use and management options in a sub-humid watershed of Ethiopia

Abstract

Study region: Laguna watershed of the Upper Blue Nile basin, which is representative of drought-prone tropical sub-humid watersheds of Ethiopia. The river of the watershed drains into Lake Tana, one of the largest lakes in Ethiopia. Study focus: This study evaluated the impacts of five alternative land capability-based land use and management options in reducing runoff and sediment loss by integrating observed plot- and watershed-scale data with the Soil and Water Assessment Tool. New hydrological insights: We modified flow- and sediment-sensitive model parameters based on six best-performing plot-scale land management practices to simulate the runoff and sediment loss of the watershed under five alternative options. The results revealed that alternative land use options could reduce runoff and sediment loss by about 21–30% (from 740 to 517 mm) and 32–83% (from 101 to 18 t/ha), respectively, compared to the baseline data. The simulations of best alternative land management options also decreased runoff by 10–41% and sediment loss by 40–89%. Runoff and sediment loss reductions were estimated to be as high as 72% (from 740 to 210 mm) and 95% (from 101 to 5 t/ha), respectively, when land use and land management options are combined. These results indicate that implementing suitable land use and management practices has the potential to rehabilitate degraded watersheds in the sub-humid Ethiopian highlands and similar environments elsewhere.

Keywords

• Drought-prone
• Land degradation
• Land use plan
• Land rehabilitation
• Upper Blue Nile basin
• SWAT