截渗墙设计对水库海岸带预防海水入侵的影响

Influence of cutoff wall design on prevention of seawater intrusion of reservoir coastal zone

为探究海岸水库处于低水位时,不同深度与位置工况的截渗墙对滨海潜水层海水入侵的防治效果,在物模实验验证的基础上采用SUTRA模型建立了具有代表性的二维海岸模型,对有、无截渗墙、截渗墙底部到潜水层底部距离分别为14,12,10 m和截渗墙到海洋边界分别为70,65,60 m工况下的潜水层中水盐分布、水流运动特征、物质输移规律和地下水入侵动力情况进行模拟。结果表明:1)截渗墙能够显著减少海水入侵距离,且对于有海岸水库的滨海潜水层的海水入侵防治效果更加明显,减少幅度为19.5%;2)截渗墙越深入潜水层或越靠近海洋边界,对海水入侵的防治效果和潜水层淡水储量的增加效果越明显,内陆物质输移越慢,海侧物质输移越快;3)截渗墙能有效阻止潮汐的波动向内陆的传播,且截渗墙越靠近海洋、越深入潜水层,效果越明显。研究进一步明确了海岸水库地区截渗墙作用下海水入侵的特征与规律,其成果可为优化截渗墙空间设计提供模型参考和理论指导,并为海岸水库建设和科学管理提供科学依据。

In order to explore the prevention and control effect of cutoff walls with different depths and location conditions on seawater intrusion in the coastal diving layer when coastal reservoir is at low water level,a representative two-dimensional coastal model was established by SUTRA model on the basis of model experiment verification.The water and salt distribution,water flow movement characteristics,material transport rules and groundwater intrusion dynamics in the diving layer were simulated under the following conditions:whether there was the cutoff wall,the distance from the bottom of the cutoff wall to the bottom of the diving layer was 14,12 and 10 m,and the distance from the bottom of the cutoff wall to the ocean boundary was 70,65 and 60 m.The results show that:1)The cutoff wall can significantly reduce the seawater intrusion distance,and the prevention effect of coastal diving layer with coastal reservoirs is more obvious,with a reduction of 19.5%;2)The deeper the cutoff wall is in the diving layer or the closer it is to the marine boundary,the more obvious the prevention effect of seawater intrusion and the increase effect of fresh water reserves in the diving layer are;The slower the inland material transport is,the faster the marine material transport is;3)The cutoff wall can effectively prevent the tidal wave from spreading inland,and the closer the cutoff wall is to the ocean,the deeper to the diving layer,the more obvious the effect is.This study further clarifies the characteristics and laws of seawater intrusion under the action of the cutoff wall in the coastal reservoir area,and the results can provide model reference and theoretical guidance for optimizing the spatial design of the cutoff wall,and provide a scientific basis for the construction and scientific management of coastal reservoir.