运用三维变密度潮汐效应模型确定滨海含水系统的海底等效边界——山东烟台夹河中下游地区为例

Determination of Seaward Boundary with Three-Dimensional Density-Dependent Tidal Effect Model: By Example of Coastal Aquifers in Jiahe River Basin, Shandong Province

确定咸淡水界面的位置是滨海地区海水入侵研究的主要任务之一 .对于天然条件承压含水层而言 ,含水层顶板向海底延伸的距离直接影响了咸淡水界面的位置 ,它可以通过承压含水层中地下水的潮汐效应信息来确定 .考虑到咸淡水之间密度的差异 ,建立了山东省夹河中下游地区滨海含水系统地下水三维变密度潮汐效应模型 .通过反复对比潮汐效应观测中的地下水水头波动与模型计算出的水头波动 ,确定了滨海承压含水系统的海底边界 .同时 ,也初步估计出海区与近海陆区含水层的水文地质参数 .

One of the main tasks in studying saltwater intrusion into coastal aquifer system is to determine the position of the saltwater-freshwater interface. For a natural confined aquifer, this position is related to the roof length of the aquifer extending under the sea. This information can be obtained from fluctuations of confined groundwater level caused by tidal effect of the sea. In the paper, taking account to the density difference between freshwater and seawater, a three-dimensional density-dependent tidal-effect model is developed in the Jiahe River basin, Shandong Province, China. The position of the aquifer roof extending under the sea, which is called the equivalent boundary toward sea, is determined by converging hydraulic head fluctuations data observed in the tidal-effect observation experiment. The aquifer parameters near the sea side are also estimated according to tidal fluctuation information.