Simulation Of Freshwater Lens Formation And Water Conservation Of Coastal Areas

To solve the problem of shortage of land resources, the coastal region hasincreasingly become the focus of urban development. But in the process ofdevelopment, soil salinization becomes the bottleneck which constraining economicgrowth in coastal areas. Tianjin Eco-City is located in the Binhai New Area, wheresoil is sodium-saline soil which salinity is usually about1to3%. Higher salt contentneed not meet the plant growth. Therefore, we are urgent to study the characteristicsand relationship between water and salt of salinization soil at the coastal areas inconditions of lack water, and build water retention and soil salinity control function.To meet the needs of plant growth, salinization soil in the region need comprehensivetreatment. The study of coastal saline ecological restoration research has practicalsignificance and of great significance.This paper made a detailed test of the particle size, composition, permeability bycombined on-site sample testing with indoor supplementary experiment. We analyzedwater characteristic curves of the saline soil with various soil factors above and madea preliminary judgment on water retention properties of the soil. According to theprinciple of geometric similarity, we built the physical simulation device in the lab toestablish the Groundwater-Vadose zone system, which was similar with the system ofthe simulated area. We made measures of the changes of soil moisture, temperatureand salinity, and focused on the characteristics of water and salt movement insalinization soil at different conditions. We built freshwater lens simulation system tostudy generation and degeneration of the freshwater lens by controlling soil structureand recharge rate. The conductivity value from the observation holes and the seawateris used as the means to character the shape of freshwater lens in the experiment.Under no recharge situation we simulated exploiting freshwater lens resources byextraction wells. The results showed that when the exploitation rate reached29.6ml/min, inverted cone came into the pumping well, and the lens body was brokedown.When we generalized the indoor physical models and boundary conditions, gothydrogeological parameters and their source and sink terms conditions, we build thecorresponding vertical two-dimensional coastal groundwater flow equation and thefreshwater lens equation mathematical model. We solve the mathematical modelusing the finite difference method. And the process used Visual MODFLOW software to achieve visualization. The influence of generation and degeneration of thefreshwater lens on soil and water conservation was able to provide a theoretical basissolving the water shortage in saline areas.