Vol15 No.5: 1057-1070
【Title】Application of numerical model in evaluating the effects of a planned reservoir on reach-scale bankfull discharge of the lower Wei River
【Addresses】Key Laboratory of Water Cycle and Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
【Corresponding author】HE Li
【Citation】He L (2018) Application of numerical model in evaluating the effects of a planned reservoir on reach-scale bankfull discharge of the lower Wei River. Journal of Mountain Sciences 15(5). https://doi.org/10.1007/s11629-017-4657-8
【Abstract】Predicting the responses of an alluvial channel to changes in flow and sediment supply is essential for engineering design. Many methods have been developed in the last few decades to describe sectional bankfull characteristics (elevation and discharge); however, studies on long-term reach-scale bankfull discharge are still limited. In this study, a hydraulic model is built to calculate the reach-scale bankfull discharge,and the effects of reservoir building on downstream bankfull dischargesare discussed. The studied river reach is located at the lower Wei River (WR), where the planned Dongzhuang Reservoir would be built on its largest tributary, the Jing River. A quasi-two-dimensional numerical model coupled with a bankfull discharge estimating method is put forward to calculate the reach-scale bankfull discharge. The soundness of the model is verified. Results show that the temporal variation of reach-scale bankfull discharge of the lower reach of the WR would be highly influenced by the planned reservoir, especially during the first 20 years of operation. The effect of the planned reservoir on bankfull discharge may reach its maximum when the total trapped sediment load reaches approximately 75% of the reservoir capacity. Our results show that after the first 17 years of operation, the effect of the planned reservoir on bankfull discharge of the river reach may decrease gradually. The soundness and predictive capability of the coupled model have also been calibrated bycomparing with existing reservoirs. All analyses indicate that the numerical model can be used to predict the changed reach-scale bankfull discharge of the lower WR.
【Keywords】Wei River; Bankfull discharge; Reservoir; Numerical model; Flow change; Sediment supply