Research On Coupling Simulation Of Surface And Groundwater In Inner Row Section Of The Middle South-to-North Water Diversion Project

The middle route of South-to-North Water Diversion is a massive cross-basin water transfer engineering project, which for the purpose of solving uneven distribution and enforcing reasonable configuration of water resources in our country. Ensuring the water quality safety during diversion is the premise that promote the project produce water diversion benefits, and the important basis to evaluate it is successful or not. During the design and construction, to relief the influence from the uplift pressure of ground water to the main canal, we use the one-way no-return type discharge system to make the hydraulic connection exist between ground water and main canal. The contaminated ground water directly imperil the water quality safety of main canal, and this kind of main canal is about 400 kilometers. Thus, developing the study of surface water-ground water coupling simulation has the important meaning to protect the water quality safety of main canal.In this paper, the western mountains of Bao Ding, He Bei is chose as the study area, basing on the surface water-ground water coupling model that made by Excel, we have made the quantitative analysis of the water exchange and solution transport between ground water and main canal trough the no-return valve. Considering the main canal and ground water separately as a complete system, and according to the water dynamics and contaminant migration characteristic of the main canal, we established an one-dimensional hydrodynamic model(the de Saint-Venant system of equations) and an one-dimensional convection diffusion water quality model. Considering the hydrogeological conditions of the study area, established an one-dimensional steady ground water flow model and an one-dimensional solute transport model. According to the situation of check valves installation, treat the water level difference as variable to solve the surface water-ground water coupling model, by utilizing Extensible Markup Language and Visual Basic Application compiled the general numerical simulation model, it’s proved that the accuracy of this model content the actual quest.In the study area, by analyzing the ground water environment of both sides of the whole main canal, considering the typical contaminant of Xiao Wang Jing village as research object, combining with the local geological conditions, and using the established coupling numerical simulation model, it figures out that the variation of ground water quality effect the main canal water quality at different situation. The results is:(1) At the rate of flow of main canal being 150 m3/s,the yields that the ground water flow to the main canal through the check valves is 663 m3/d, having little influence on the main canal hydraulic dynamics;(2) The highest concentration of NO3- in ground water around the main canal is 479 mg/L, as ground water through the check valves, the NO3- concentration value of the main canal is 0.47 mg/L;(3) By simulating the suddenly pollution accident, the time that contaminant moves to the water pouring aqueduct is 3960 s.