Megech Dam Reservoir Sediment Estimation Using Swat Model
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Date
2016-09
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Addis Ababa
Abstract
Erosion is a major watershed problem causing significant loss of soil fertility and productivity. Increased sediment loads that shorten the useful life of the reservoir, the lives of other water related structures, and increase the cost of maintenance and sediment remediation are off-site impacts of erosion. The main objective of this study is to predict the sediment yield to Megech dam reservoir. In this study Soil and Water Assessment Tool (SWAT 2012) having an interface with ArcView GIS software was used to estimate sediment yield and identify spatial distribution of sediment yield in the watershade. The hydro-meteorological data were collected from the nearby stations and the quality of those data was checked. Weather generator was also created to fill-in missing gaps and generates climate data .The detail land use data was updated by the current land use/cover data and the soil map were used as per FAO classification. The SWAT model is calibrated and validated at the Azezo gauging station.Flow calibration gives coefficient of determination (R2) and Nash-Sutcliffe model efficiency (ENS) 0.8 and 0.74 respectively and validation test gives R2 and ENS 0.87 and 0.86. Sediment calibration gives R2 and ENS 0.97 and 0.98 respectively and validation test gives R2 and ENS 0.97 and 0.97 respectively. This indicated that the observed values show good agreement with simulated value for both flow and sediment yield. The model prediction result shown that the annual sediment yield leaving the watershed was found to be 13.48 ton/ha/Yr. This result is within the sediment yield estimates given by the studies in the basin such as BCEOM (1999), USBR (1964) and studio Pietrangeli (2005), which is in the range of 12 ton/ha/Yr to 16 ton/ha/Yr. This study also shows that 47% of the watershed has high erosion potential and this is a real threat of reducing the operational life of the dam due to decreasing its active storage. Management and conservation practices are recommended to be applied for the sub-basin with high quantities of erosion and sediment yield.
Key Words: Sedimentation, SWAT model, Megech Dam Reservoir
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Keywords
Sedimentation, SWAT model, Megech Dam Reservoir