Research On Environmental Modeling Supported By GIS

The study of environmental modeling supported by GIS has been paid more attention by experts who engaged in the fields of environment and GIS, and become a focus in those fields. The integration of both was mainly drived by the endeavor from environmental experts who took advantage of GIS in model's data preparation, simulation result visualization, and interactive modeling. Principle and general process of environmental modeling supported by GIS were introduced, and the application of GIS technology to the process of tide-current and pollutant dispersion numerical modeling, including computational domain delineation, computational mesh generation, and model parameters extraction, was also discussed in the paper. Water depth data(main parameters), which was matching to model's grid structure, was obtained by using the function of GIS digital elevation model(DEM) to linear-interpolate the isobath of chart.Based on two-dimensional shallow water circulation principle, condition of water depth, and the domain of pollutant dispersion in Meizhou Gulf, M2 tide and tidal current numerical model and two-dimensional depth-averaged advection-dispersion numerical model of soluble liquid chemicals pollutant were constructed. In the models, location of variables was Platzman interleaving grid, which was good at spatial central difference, and numerical method was finite difference ADI method. In the later model, the advection was treated with "windward" difference format to avoid occurrence of negative concentration. Current field and tidal value from the simulation were consistent well with relative references.Tight integration of GIS and two-dimensional depth-averaged advection-dispersion numerical model was realized through the technology of integration of GIS and environmental model, so that the visualization of environmental pollutant transport and dispersion which had spatial distributed characteristic was fulfilled. The problems of result's poor visualization andnon-friendly system interface for environmental simulation have been well solved.Through the tight integration of GIS and soluble liquid chemicals pollutant advection-dispersion model, the result of simulation for different spill spot, time of taking place, and spill mode, took out reasonable spatio-temporal distribution of pollutants' concentration in Meizhou Gulf. The results also indicated that the numerical simulation was steady and doable. At last, the general rule of pollutants dispersion in gulf was presented.