Abstract: The simulation of the process and the effects of protection projects lays the foundation of its effective control and defence. A mathematical model of the problem and the upwind fractional step finite difference method are presented. Using this method, the numerical simulation of seawater intrusion in Laizhou Bay Area of Shandong Province is given. The numerical results turn out to be identical with the real measurements, so the prediction of the consequences of protection projects is reasonable.

Key words: seawater intrusion, protection project, model and algorithm, numerical simulation, theoretical analysis