中文摘要：

为研究湖泊防渗对地下水水质的影响，在现场和室内试验的基础上，运用二维包气带溶质运移模型进行防渗对地下水中氨氮污染物的浓度影响的模拟。分析结果表明：当湖水氨氮浓度保持目前的0．14mg／l时，无防渗时，地下水中氨氮平均浓度由0．43mg／l下降到0．23mg／l，有防渗时，则下降至0．29mg／l；当湖水中氨氮污染物浓度为1mg／t，无防渗时，在计算期末地下水中氨氮平均浓度由0．43mg／l上升到0．77mg／l，有防渗时，则上升至0．53mg／l。因此，在湖水水质好于地下水时，湖底防渗将降低地下水环境质量改善的速度；而在湖水水质较差时，湖泊防渗将显著降低地表水污染物向地下水的扩散强度，有利于地下水水质的稳定。

英文摘要：

On the basis of in-situ and laboratory experiments the hydrogeological conceptual model was applied to study the variation of pollution concentration in groundwater for different scenarios in the Yuanmingyuan Ruin Park in case the lake is lined. The groundwater quality was studied by using 2D fluid flow model and solute transport model for variable saturated porous media. The results show that if the lake water maintains the present NH3-N concentration 0.14mg/l, the NH3-N concentration of groundwater will be reduced from 0.43mg/l to 0.23mg/1 for unlined lake bed, and the concentration will be 0.29mg/1 for lined lake bed. If the NH3-N concentration is very high, such as 1mg/l, the average concentration of NH3-N in groundwater will increase from 0.43mg/l to 0.77mg/l for unlined lake bed, and will be 0.53mg/1 for lined lake bed. It may conclude that the lining of lake bed will retard the improvement of groundwater quality if the lake water quality is better than the groundwater. The lining will remarkably reduce the discharge intensity of surface water to groundwater and is in favor of stabilizing the quality of groundwater, if the lake water quality is poor.