Propagation characteristics of the flow and suspended sediment peaks in the three gorges reservoir, China: Insight from numerical simulations and measured data

Effective management of reservoir sedimentation necessitates the characterization of flood events, especially in relation to the propagation of the flow peak (Qpeak) and the suspended sediment concentration peak (SSCpeak). This study, based on a one‐dimensional river network hydro‐sediment model together with field data, presents an exploration of the flood events in the Three Gorges Reservoir (TGR) with focus on the propagating characteristics of Qpeak and SSCpeak. The findings reveal that the main flood season (from July to September) contributed over 80% of the annual sediment load into the TGR, with the mainstream Yangtze and its tributary, the Jialing River, being the primary sediment sources. After the impoundment of the TGR, the propagation time of Qpeak decreases with the raise of the water level in front of dam (WLdam). The increases in Qpeak discharge extends the range of river reach dominated by kinematic wave, resulting in an increase trend in Qpeak propagation time. The propagating speed of SSCpeak is closely related to the ratio of sediment concentration to flow discharge and WLdam. Finally, the propagating durations of Qpeak and SSCpeak in the TGR are compared, and empirical formulas are proposed for quantifying their difference. The findings reveal that the flood season contributed over 80% of the annual sediment load into the TGR. Raising the exit water level could accelerate the flow peak (Qpeak) but slow down the suspended sediment concentration peak (SSCpeak). The propagating speed of SSCpeak is also closely related to the ratio of sediment concentration to flow discharge. The propagating durations of Qpeak and SSCpeak in the TGR are compared, and empirical formulas are proposed for quantifying their difference.