Application Research Of GIS Technology In Numerical Simulation Of River Water Quality Model

In today's world, people's health and survival has been seriously affected by environmental pollution, so it carries great significance for the research activities to analysis,forecast and control the environmental pollution, with comprehensive utilization of relevant theoretical knowledge and the scientific method.It regards predicting the change in the quality of the shallow river water as the goal in this thesis. Two-dimensional water quality model is chosen,and the river flow velocity field can be solved by finite difference method for discrete water controlling equations, then based on the flow velocity field, the contamination concentration field of river can be solved by finite difference method for discrete water quality equations. Due to the twists and turns of the river borderlines, when the river is divided by rectangular grid, the grids' borderline hardly comes in line with the natural river borderline, and then the accuracy of the results is affected. In this thesis, river is divided by body-fitted grids, and the computation proceeds in the body-fitted coordinate system, so water controlling equations and water quality equation must be transformed into the corresponding format in the new coordinate system. The computing process is simplified by fractional step method, and the stability and accuracy of result is insured by Alternative Direction Implicit (ADI) method.Finally Geographic Information System (GIS) technology is used for application development. According to the function, the whole numerical solution process is divided into the data exporting module, the grid subdivision module, flow velocity generation module and concentration generation module, the basic data that is involved in the solution is stored and managed in the format of GIS geospatial data, such as the river borderline, the river bed topography, hydrology of the river, pollution location, discharge amount of pollutants and so on. The color ramp is made use of to bring a visual representation of the result of contamination concentration. The whole research process in the GIS system, takes advantage of GIS technology on spatial information and attributes information to collect, store, analyze, display, etc, so it is valuable for application.