A Study on the Water-Soil Interaction in the Process of Sea Water Intrusion

The field observed and the laboratory experimental results of water-soil interaction in the process of sea water intrusion are presented. Results of the field observed and the laboratory experiments show that there exist significant cations exchange of Na⁺ and Ca²⁺, and moderate cations exchange of Mg²⁺ and Ca²⁺ between water and soil in the process of sea water intrusion. On the basis of the above work, a new three-dimensional mathematical model for sea water intrusion in aquifer is presented. This model considers not only many important factors( Such as the existence of transition zone, the effect of variable density and viscosity on fluid flow, the effect of phreatic surface fluctuation on the process of sea water intrusion, etc.), but also the cations exchange of Na⁺ − Ca²⁺ and Mg²⁺⁻ Ca²⁺ between water and soil during sea water intrusion. It can simulate simultaneously the transport behavior of Ca²⁺, Na⁺ and Mg in aquifer in the process of sea water intrusion. This model is used to describe the transport behavior of Ca²⁺, Na⁺ and Mg²⁺ in the process of sea water intrusion in Huangheying of Longkou City, Shandong Province, China. The simulated values agree very well with the field data(e.g., the total mean values of the absolute errors of Ca²⁺, Na⁺ and Mg²⁺ concentrations are 6.48mg/l, 11.53mg/l and 2.72mg/l, respectively, and that of the hydraulic head is 0.19m).