Abstract:
Sedimentation is a major problem of reservoir operation in Ethiopia. Deforestation,
overgrazing and poor land management practices are some that accelerate the rate of
erosion. The topography of Ethiopia in general and TDW in particular is undulating and
local farmers commonly cultivate on the hilly sides causing easy topsoil wash away. This
study aims to determine the sediment yield at Tendaho dam reservoir, identify the high
sediment source sub-basins and check the applicability of SWAT model in the area. To
achieve these goals, the hydro-meteorological, sediment, topographic, land use and soil
map data were used as inputs for the model. The model was successfully calibrated and
validated for measured stream flow and sediment yield of AR at Wonji, Melka Werer and
Tendaho stations. It was thus found applicable in this watershed with acceptable
performance evaluation statistics values. From the model simulated output, sub-basins
27, 34, 29 and 50 were found to be the top four severely eroded sub-basins with average
annual sediment yield of 26.66t/ha, 24.22t/ha, 23.79t/ha and 19.13t/ha, respectively.
While, sub-basins 31, 18 and 21 were found to be the least sediment sources with annual
averaged sediment yield of 0.02t/ha, 0.04t/ha and 0.04t/ha, respectively. In general, the
results found in this study are very important inputs in selecting appropriate watershed
management strategies and the methodologies used can also be valuable guides for the
researchers in similar studies.
