Estimation of sedimentation in reservoirs helps in the management and design of the reservoir's useful capacity.This research was done on the Awash River basin at the Koka Dam Reservoir in Ethiopia.The method applied was the loose integration of the Soil and Water Assessment Tool(SWAT)model and Hydrologic Engineering Center-River Analysis System(HEC-RAS)model for the estimation of the sediment load reaching the reservoir.The SWAT model was used for the estimation of erosion at the catchment level,and the HEC-RAS model was applied to estimate the sediment transport in the river channel.The implemented method allows sedimentation in the floodplains and bed shear stress to be considered in the sediment modeling,which cannot be considered in the SWAT model.In addition,the river cross sectional properties and the hydrodynamic processes in the rivers were considered in the modeling process.The data used in this study are a combination of i)observed data collected by government agencies,ii)data available online in data repositories,and iii)data extracted from remote sensing in the Shuttle Radar Topographic Mission(SRTM)Digital Elevation Model(DEM).The calibration and validation of the SWAT model was done by using Sequential Uncertainty Fitting(SUIF-2)calibration and validation tools.The HEC-RAS model was calibrated by adjusting the roughness factor.The output from the integrated approaches gives better estimates of flow and sediment near the inlet to the reservoir,with coefficients of determination of 0.85 and 0.67,respectively,and Nash Sutcliffe coefficients of model fit efficiency of 0.90 and 0.62,respectively,for daily simulations.
International Journal of Sediment Research
the National Key Research and Development Program of China (Grant no. 2016YFC0402501)
the National Natural Science Foundation of China (NSFC) (Grant no.51479071)
the 111 Project (Grant nos. B12032 and B17015)
the Priority Academic Program Development of Jiangsu Higher Education Institutions (Grant no.3014-SYS1401).
Corresponding author:Wenhong Dai,E-mail address:firstname.lastname@example.org(W.Dai).