VARIATIONS IN A TYPICAL LOWER JINGJIANG RIVER REACH BELOW THE THREE GORGES PROJECT: A PRELIMINARY STUDY

摘要

Simulation results of the FLUVIAL-12 Model are presented in this paper. The model is calibrated and tested for fluvial processes of the OuCK-JianL reach of the typical lower Jingjiang River during the period from 1987 to 1991. Based on calculated results, future tendencies have been predicted and analyzed regarding river channel aggradation and degradation, cross-section configuration and water stages within a 60-year operation period of the Three Gorges Project (TGP). The FLUVIAL-12 Model achieved reasonable agreements with observations in terms of flood stages, sediment transport rates, erosion-deposition processes, river-bed deformation and cross-section configurations. Simulation shows that within the 60-year period of TGP operation, the OuCK-JianL reach will experience 4 sequent fluvial periods, which are slight deposition, substantial degradation, transient equilibrium, and slow recovery, respectively. The maximum erosion volume will be (7.1-11.2)x10~8 t around the 55th year of TGP operation and the average scouring depth will be 3 m-9 m. The maximum reduction in flood stage will be 3.13 m-4.71 m for a discharge of 5000m~3 • s~(-1) and 0.42 m-2.77 m for 30000m~3 • s~(-1), respectively.