Dynamics of surface runoff and sedimentation leading to extensive transformation in land use land cover in Megech dam watershed of Ethiopia

Abstract

Land use land cover (LULC) modification affects the surface runoff and sediment output in the Megech dam watershed in Abay River Basin of Ethiopia. ERDAS Imagine 2015 with a supervised maximum likelihood classifier was used to perform the change analyses during 1985, 2000, and 2018. Stream flow had Nash–Sutcliffe efficiency (NSE), square of regression coefficient (R²), observations standard deviation ratio (RSR), and percent bias (PBIAS) values of 0.70, 0.71, 0.54, and 11.7 during calibration and 0.72, 0.77, 0.83, and 14.4 during validation, respectively. NSE, R², RSR, and PBIAS values for sediment yield were 0.75, 0.78, 0.55, and − 9.60 during calibration and 0.79, 0.82, 0.46, and 13.6 during validation, respectively. Changes in land use from forest to agriculture and habitation between 1985 and 2018 contributed significantly to 14.95% rise in average annual surface runoff during the simulation period. Annual sediment yields assessed from land use maps increase by 25.46% between 1985 and 2018. The use of filter strips and terracing and sediment yield reduction in the mean annual base was 36.71% and 63.93%, respectively. Terracing was more effective than filter strip conservation methods for reducing sediment production. A program combined with runoff and sedimentation together on the dam site generated a novel approach to the research.