[Impacts of lake lining on soil moisture variation in Vadose Zone]

For studying impacts of lake lining on soil moisture and groundwater recharge intensity, the scenarios analysis method was adopted, with bydrogeological concept modeling and 1D- and 2D-flow modeling for variably saturated porous media, to simulate and predict the variations of soil water content and groundwater recharge intensity before and after lake lining. Through a case of the Yuanmingyuan Ruins Park, the study was performed on the basis of in situ and laboratory experiments. The results showed that, during the low-water-level season, the distributions of soil moisture before and after the lake lining will be basically consistent with each other, and therefore, the lake lining will have little impacts on the soil moisture and groundwater recharge intensity. However, during the high-water-level season with 1 m depth of lake water, the modeling results showed that the groundwater table will rise quickly to the bottom of lake bed with a recharge rate of 18.0 mm/d, and the maximum impact width of the lake on the water content in vegetated zone will be up to 118 m. While after the lake lining, the groundwater recharge rate, and the impact width will decrease to 5.8 mm/d, and 14 m respectively. The vadose zone under the bottom of lake bed will be still unsaturated. Therefore, during high-water-level season, the lake lining will largely decrease the lake leakage, and also greatly reduce the soil moisture in large area.