Modeling best management practices to reduce future sediment yield in the Fincha watershed, Ethiopia

Abstract

Severe socio-environmental pressures and land degradation are substantially impacting Ethiopia, eventually leading to low agricultural productivity, with a consequent very high rate of poverty and food insecurity. The current study investigates the future effect of four management practices on reducing sediment yield in the Fincha sub-watershed, Ethiopia, by developing a soil and water assessment tool (SWAT) model over the next three decades (2019–2050). Four best management practices (BMPs) largely applied in the region were considered here. It was found that filter strips can decrease the sediment yield by 65.64 and 58.77, soil or stone bund by 76.37 and 73.07, contour farming by 79.79 and 75.86, and terracing by 84.9% and 76.32% for the years 2019 and 2050, respectively. The impact of these BMPs on various hydrological processes also was evaluated using SWAT. It was found that BMPs are effective in reducing surface runoff and water yield and in increasing groundwater and lateral flows, while they have a reduced effect on evapotranspiration, lateral flow and water yield. The findings presented here point out that all the simulated management practices significantly lower surface runoff and consequently sediment yield across the watershed, but they are not effective enough to reduce soil erosion below a critical threshold that assures crop production. Therefore, to achieve tolerable soil loss, additional soil and land management strategies, such as biological measures and a combination of BMPs are needed and should be considered in future investigations. In summary, the current study offers evidence for managing river basins in semi-arid regions, and can help in ensuring sustainable management of natural resources.