The Study Of Electrical Methodin The Test Of Seawater Intrusion In Quanzhou

With the development of coastal cities, groundwater resources what is necessaryfor human beings are exploited seriously. It results in the seawater intrusion in thesecities. With the result of the seawater intrusion, the groundwater resources will bepolluted by the seawater. In order to provide scientific basis for making the controlmeasures, it is necessary to research the law of seawater intrusion.Based on reading document widely, this paper summarizes the precious methodsand tools. What’s more it shows the advantages and disadvantages. Then, it decides touse outside testing, laboratory test and numerical simulation to study the seawaterintrusion. Firstly, it analyzes the identification index for seawater intrusion. On thebasis of the result, it uses electrical conductivity and resistivity as the index foroutside and laboratory test respectively. The electrical conductivity is1700us. Theresistivity of sand and clay are50·m and20·m. It shows the map of seawaterintrusion on the basis of researching the status quo in Quanzhou.Secondly, it completes the laboratory test by using high density electrical technique.In the experiment, it shows the conclusion that seawater intrusion occurs first andthen begins to roll back; the rate of seawater intrusion in the sand is quicker than thatin clay, but the rate is different in the same soil; the distance of intrusion is more inthe second tide because of the cumulative effect.Then it makes up for the experiment by numerical simulation and points that themain elements what effects the results are the saturated hydraulic conductivity,moisture volume percentage, dispersion coefficient, diffusion coefficient. Thedispersion coefficient is most important factor. Saturated hydraulic conductivity anddispersion coefficient are less important, but the moisture volume percentage is notimportant contrasted to other factors. The result of numerical simulation shows thatthe water head has influence to the rate of seawater intrusion. The rate will be higherwith the bigger water head. And the intrusion rate of the soil which is below the sealevel is higher than what is above the sea level. But the rollback rate is opposite. Last, it forecasts the contaminated degree of coastal aquifers in a specific area forthe next three years though the previous numerical simulation. Therefore, it willprovide guidance for the prophylaxis and treatment of Quanzhou.