Channel-forming discharge based on the extreme value identification of sediment-carrying capacity index

Abstract

Abstract Channel-forming discharge (D cf) is an important parameter in river management and reservoir flood regulation. Applying the methods for calculating D cf to reaches downstream reservoirs characterized by drastic changes in water and sediment conditions and long-term scouring status is difficult. Based on the riverbed-shaping principle of sediment-laden water flow, while simultaneously considering the active action of water flow and response of the riverbed, this study proposes a new method for calculating D cf by identifying the extreme value of the suspended sediment-carrying capacity index. The application of this method to the middle and lower reaches of the Yangtze River showed that after the impoundment of the Three Gorges Reservoir, D cf in this section was reduced by an amplitude between 2500 and 4700 m3/s. The results can be used to guide the operation of the Three Gorges Reservoir and the management of the middle and lower reaches of the Yangtze River, thus providing reference for other river channels downstream of the reservoir.

Keywords

• channel-forming discharge
• Suspended sediment-carrying capacity
• Three Gorges Reservoir
• Flood regulation of reservoirs
• The middle and lower reaches of the Yangtze River