give the minimum number of the wells. And we offer a method to determine the interval of sampling by significance test. Using the density-time relationship of the monitoring wells, we can also calcu- late the approximate amount of the pollutant by volume integral This model is simple to use but is accuratc enough in practice Assumption Because the factors that affect the environment are very com plex, we give the following assumptions to simplify our model In a certain small area, the geologic terrain and geologic structure is considerably stable The geologic materials dispersion property is isotropic and the hydraulic conductivity is also the same. Model Design We consider the pollutants are materials and energy that cause the natural water's quality to becme bad and unable to be used And if the pollutants infiltrate into the groundwater, which over the water self-purification ability, the waters quality will become lower. We call this phenomena groundwater pollution Model of pollutants transferring When the pollutants enter the groundwater, they will be trans ferring with the groundwater in the aquifer. The thickness of aquifer is small, so the transport will be modeled as a two-dimen sional-flow problem. In the homogenic aquifer, the density of pollu tants will satisfy this advection-dispersion equation ac aC In this equation, i is the curvilinear coordinate direction of thc streamline; v is the mean linear velocity of the groundwater stream and C is the density of the pollutants PDF文件使用" pdffactory"试用版本创建w, fineprint,com,cnPDF 文件使用 "pdfFactory" 试用版本创建 www.fineprint.com.cn