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 chara...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 discharges are 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 by comparing 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.展开更多
Jing River is a tributary of the Wei River which is the largest tributary of the Yellow River. Sediments eroded from the upland of the Jing River basin are one of the major contributors of sediment entering the lower ...Jing River is a tributary of the Wei River which is the largest tributary of the Yellow River. Sediments eroded from the upland of the Jing River basin are one of the major contributors of sediment entering the lower Wei River(LWR). The Dongzhuang reservoir is designed to be constructed on the lower Jing River for flood control and water resources regulation, and this may change the sustainable management of the LWR as changed channel deposition by trapping sediments and releasing concentration-limited flow. Its effects on the LWR, especially the deposition distribution, should be analyzed. The steady quasi-two-dimensional dynamic model was adopted to estimate the deposition processes in the LWR. Then, the qualitative effects of the Dongzhuang reservoir on channel deposition were evaluated and compared with historical data, including capacity loss in other reservoirs and measured deposition in the LWR. Analyses indicated that the annual deposition in the LWR will decrease by approximately two-thirds due to the reservoir’s operation. After 15 years of operation, the effects of the Dongzhuang reservoir on the lower channel will decrease gradually. Moreover, its effects on lateral distribution in different sub-reaches are different. After the reservoir’s operation, the floodplain of the Xianyang–Lintong(XY-LT) sub-reach will change its sediment regime from deposition to erosion. For the Lintong–Huaxian(LT-HX) sub-reach, deposition in the main channel will be more serious during the first 30 years of operation. For the Huaxian–Tongguan (HX-TG) sub-reach, the reservoir will have almost no effects on the lateral distribution. All these analyses may benefit the sustainable management of the Wei River and the Yellow River.展开更多
基金funded by the National Natural Science Foundation of China(Grants No.2011CB403305,51579230,51109198,41571005,and 51479179)
文摘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 discharges are 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 by comparing 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.
基金The research reported in this manuscript is funded by the National Natural Science Foundation of China(Grants No.51979264 and 51479179)。
文摘Jing River is a tributary of the Wei River which is the largest tributary of the Yellow River. Sediments eroded from the upland of the Jing River basin are one of the major contributors of sediment entering the lower Wei River(LWR). The Dongzhuang reservoir is designed to be constructed on the lower Jing River for flood control and water resources regulation, and this may change the sustainable management of the LWR as changed channel deposition by trapping sediments and releasing concentration-limited flow. Its effects on the LWR, especially the deposition distribution, should be analyzed. The steady quasi-two-dimensional dynamic model was adopted to estimate the deposition processes in the LWR. Then, the qualitative effects of the Dongzhuang reservoir on channel deposition were evaluated and compared with historical data, including capacity loss in other reservoirs and measured deposition in the LWR. Analyses indicated that the annual deposition in the LWR will decrease by approximately two-thirds due to the reservoir’s operation. After 15 years of operation, the effects of the Dongzhuang reservoir on the lower channel will decrease gradually. Moreover, its effects on lateral distribution in different sub-reaches are different. After the reservoir’s operation, the floodplain of the Xianyang–Lintong(XY-LT) sub-reach will change its sediment regime from deposition to erosion. For the Lintong–Huaxian(LT-HX) sub-reach, deposition in the main channel will be more serious during the first 30 years of operation. For the Huaxian–Tongguan (HX-TG) sub-reach, the reservoir will have almost no effects on the lateral distribution. All these analyses may benefit the sustainable management of the Wei River and the Yellow River.
