Numerical simulation of seawater intrusion caused by ground water extraction inlayered heterogeneous aquifers
In coastal areas with layered heterogeneous aquifers,over-exploitation of the groundwater resource has led to serious seawater intrusion.Based on previous physical model tests in coastal areas with layered heterogeneous aquifers,a two-dimensional numerical model of saltwater rising caused by pumping wells was established by applying the scientific modelling package OpenGeoSys to investigate the behavior of seawater intrusion.With the verified model,the heterogeneity of layered heterogeneous aquifer,the thickness of lower permeability aquifer and the influence of pumping well location on criti-cal pumping rate and seawater intrusion were analyzed.The numerical results indicated that the critical pumping rate of the pumping well in heterogeneous aquifers was lower than that in homogeneous aqui-fers,and the difference of the critical pumping rate between the two types of aquifers was larger for deep wells and wells near the seawater boundary.In layered heterogeneous aquifer,the influence of seawater intrusion was greater when the thickness of low permeability aquifer was thicker.With the in-crease of pumping rate of pumping wells,the influence of seawater intrusion was more obvious.The horizontal distance between the pumping well and the seawater boundary was closer,the pumping well depth was deeper and the critical pumping rate was lower.Furthermore,the critical pumping rate of the pumping well was more sensitive to the change of the well depth.This research provided scientific theoretical basis for rational exploitation and planning of groundwater resources in coastal areas with layered heterogeneous aquifers.
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