Modeling Long-Term Fluvial Processes Between The Three Gorges Dam And The Gezhouba Dam

This thesis presents a numerical simulation of sediment transport anddegradation process between the Three Gorges Dam and the Gezhouba Dam.A one-dimensional model is used which simulates the water flow andnon-equilibrium sediment transport processes. The 1-D model has beencalibrated and verified against observed hydrological data and topographicalchanges from 1997 to 1999 in the river section between the two dams. Anumerical simulation based on this model has been made to predict the fluvialprocess between the two dams and the sediment concentration upstream theGezhouba Dam in the first 20 years (2003-2022) from the operation of ThreeGorges Projects. The results show that the deposit between the two dams willbe washed out about 46 million m3 and the scour will be happened mainly inthe first two years, 2003 and 2004.Secondly, the results of two methods for evaluation of the suspended loadtransport capacity for each grain size group are compared, in which themethod by Li Yitian considers the influence of bed material distribution whilethe other one by Han Qiwei considers the effects of the incoming sedimentconcentration. The comparison shows that the equation of Han Qiwei is moresuitable for the calculation of bed scour downstream of the reservoirs.Finally, the mathematical model for unsteady open channel flow has beenapplied to the river channel between Yichang to Wuhan, with a total length of626km. It was also used to calculate rill flow and to establish the criticalcondition for rill initiation.