Three-Dimensional Numerical Simulation Of Pollutant Diffusion In The Three Gorges Reservoir And Its Application

The three-gorge project is an extremely large hydraulic project which draws attention of the whole world, whose establishment will make great contribution to comprehensive aspects including flood control, electric power generation and river shipping, and will be profoundly influential to the ecology and environment of the reservoir area. So the water environment of three-gorge dam area becomes one of the focuses of environmentalists of the whole world when the dam is in use.This thesis aims to make technological research on the diffusion of the point-source pollutions at the three-gorge reservoir. Through establishing double equation turbulent model based on the body-fitted grid, diffusing the computing area according to the volume-control method, and solving the diffusion equation with simple method, to set Three-Dimensional steady and dynamic equation turbulent model based on the computing parameter of standard model, roughness coefficient n and prandtl of typical river section of three-gorge calculated by other researchers and the comparatively reasonable attenuation coefficient.the steady-state simulation and model calibration of current water quality and identification on the typical river section of wanzhou city section of three-gorge reservoir demonstrates that this model is applicable to the numerical simulation of hydraulic power and water quality of large-size river in complicated terrain condition areas, and can provide reference to the quantitative analysis of steady state mathematical simulation on hydraulic power and water quality of changjiang section of three-gorge reservoir. In addition, water quality couples well with flow field, and the simulation of the changes of water quality and the facts are almost the same in this dynamic calculation model, this demonstrates that this model could perfectly expose the movement of contamination.Having made simulation with this model on the steady-state computing of hydraulic power and water quality of pollution sources under typical hydrological conditions of wanzhou section of three-gorge reservoir when it becomes a reservoir, we have two points to demonstrate:â‘ As the water level of three-gorge reservoir gets higher, the water flows slower, and vertical flow turbulence ability gets weaker and the contamination in the water diffuses more negatively along vertical direction and much more actively along horizontal direction, and the polluted zone still distributes as belt pattern. So convection diffusion which is controlled by the pace of water flow still plays the dominant role in the movement of contamination in a shaped reservoir.â‘¡In the before-and-after comparative study of the same reservoir with the same pollution load, we discover: the water quality becomes better after the reservoir comes into being because of more contour water flow and longer time that the water stays in the reservoir. But at the city sections, especially around some waters near the sewage draining exits, water flows slower and diffuses less actively along horizontal directions, the water quality becomes worse and the polluted areas become larger. So if the polluted water is not forbidden, the pollution along the river banks will be more and more obvious during dry seasons.