内陆单斜构造内咸水入侵淡水含水层三维数值模拟——以山西柳林泉区柳林电厂水源地为例

A Three-dimensional Numerical Simulation for Salt Water Intrusion into Fresh Water Aquifers in an Inland Monoclinal Structure——A case study of the water supply centre of Liulin Power Plant in the Liulin spring area, Shanxi

本文建立了内陆单斜构造内咸水入侵淡水含水层的三维可混溶溶质运移模型。同时,为了尽可能提高模拟精度,还建立了区域二维水流模型和水质模型,为三维模型提供边界条件。模型应用于描述柳林电厂水源地成—淡水界面运移特征,模拟效果良好,还据此预报了咸水入侵的可能性并探讨了淡水流的强弱对咸—淡水界面运移的影响。

This paper presents a three-dimensional miscible solute transport model for salt water intrusion into fresh water aquifers , in an inland monoclinal structure. The following two equations are necessary for the description of salt water intrusion in aquifers with a transitional zone:The first equation is used to describe the flow of variable-density fluid (a mixture of fresh water and salt water). The second equation is used to describe the transport of dissolved salt. The above two equations together with the relevant initial and boundary conditions and the motion e-quation constitute a complete three-dimensional model for the description of salt water intrusion in an monoclinal structure. In order to improve the simulation precision as far as possible, a telescopic mesh refinement technique is used. Using this technique, a coarse grid is used to model a large problem domain (2727 km2) bounded by the physical limits of the aquifer system. The solution is used to define sub-regional boundaries, which then define the smaller new problem domain, the spring area (about 90 km2). These models are used to describe the motion of a salt water-fresh water interface. The simulated values of the concentration of Cl- in groundwater and the hydraulic head agree very well with the field data. Then these models are used to predict the possibility of salt water intrusion into fresh water aquifers when the Liulin spring is used as a water supply centre for a power plant.