Hydrology: Current Research

Runoff Sediment Yield Modeling and Development of Management Intervention Scenarios, Case Study of Guder Watershed, Blue Nile Basin, Ethiopia

Abstract

Behailu Nadew, Engidayehu Chaniyalew and Tibebu Tsegaye

Modeling Surface runoff and sediment loading provides important planning tools that can be used in management of land and water resources which can be used in the understanding of dynamic processes and prediction of the existing processes which have advance implication in the understanding of physical and biological processes of watershed.The objective of the study is to model runoff-sediment yield for Guder Catchment, characterizes the runoff from catchment and associated sediment yield, to evaluate spatial distribution of sediment source areas and identify hot spot areas, to assess the impact of different catchment management interventions on runoff and sediment yield and finally develop appropriate management options to control soil erosion and sedimentation problems in Guder watershed by using physical based SWAT model. SWAT model were calibrated and validated at Guder gauging station for both stream flow and sediment yield yielding reasonable results in monthly time step. The 17 years simulation result indicates that the simulated annual average suspended sediment yield by SWAT model was 4,842,000 ton/yr, which is 7.5 t/ ha /yr. The model prediction verified that about 9% of the watershed is erosion potential area contributing high sediment yield exceeding the tolerance limit (soil formation rate) in the study area and about 25% of the watershed area has high potential for soil erosion which produces above 10 ton/ha/yr sediment yield of the watershed. The simulation results showed that applying filter strips and parallel terrace/stone bunds scenarios reduced the current sediment yields by 48% and 53% respectively from the existing condition scenario both at the sub basins and the basin outlets i.e. sediment yield reduced to 3.908 t/ha/yr and 3.54 t/ha/yr by using filter strip scenario and conservation structure scenario respectively. Generally, studies like this in quantifying the total volume of runoff and sediment yields are urgently required for better land and water resources planning and management purposes.