Study On Numerical Simulation For Control Of Seawater Intrusion Through Barriers

The seawater intrusion in coastal areas has been a focus of world common concern. Irrationally exploiting groundwater results in seawater intrusion directly. Therefore utilizing groundwater efficiently is a radical way of controlling seawater intrusion. And efficient measures should be brought into effect in areas where serial seawater intrusion has been happened to prevent seawater intrusion from getting deteriorated.Comprehending the seawater intrusion theory is the first step to prevent seawater intrusion from getting deteriorated. According to transition zone width, the theory of salt-fresh water interface for seawater intrusion includes abrupt interface theory and transition zone theory. Basic equations of seawater intrusion, mathematics models and numerical simulation methods are figured out with the two theories fully studied. The result shows that the transition zone model of nouniform density is more applicable and will be a major research target.The purpose of the research is preventing and controlling seawater intrusion. Actualizing barriers is the primary measure of preventing seawater intrusion. Before actualizing barriers, numerical simulation analysis is of vital importance. First, a numerical model is set up by two-dimension sectional transition zone model of nouniform density. Second, the numerical model is calculated by Galerkin finite element method and the solution is proved valid by compared with the classical solution of numerical value and the experimental results.In 1989 seawater intrusion happened in Beihai city. The model is applied to simulate the migration of the salt-fresh water interface after exceedingly exploiting groundwater, adopting different conditions such as anti-seepage wall, extraction, injection and extracting-injecting water. The results with these conditions were compared, and the conclusion is that injection is optimal operation for control of seawater intrusion in Beihai city.A lot of freshwater is found wasted through extraction when controlling of Beihai seawater intrusion. Therefore the extracted water can be partly used to inject into the aquifers. Effect of controlling seawater intrusion is simulated after adopting extraction-injection accordingly in Longkou city, Shandong. And in the model, injection concentration was 0.5 times of that of extraction. The Results shows that...