The Temporal Evolution Of Seawater Intrusion In The Laizhou Bay

The water samples of more than 60 observation wells of eleven profiles were measured their conductivity, chlorinity and salinity. The paper analyzed two years'data and studied their variation trends with time and space. Result showed that the seawater intrusion degree was more stable in time and the influence of months was small; the degree of seawater intrusion reduced gradually from the coast to the island.The variation of the groundwater chemistry could reflect the degree of seawater intrusion directly. They could provide the basis for prevention of seawater intrusion in the Laizhou Bay.Seven kinds of main ions in hundreds inspection wells were measured to study the ion concentration variations and hydrochemical characteristics of groundwater in the coast of the laizhou Bay. The effect of seawater instruction on the ion hydrochemical characteristics of groundwater on the coast of Laizhou Bay were studied through statistics analysis. Good correlation coefficient were found between sodium and chlorinity, potassium and chlorinity. However, the relationship between Ca2+, Mg2+, HCO3- were so poor that correlation coefficients were small. Seawater intrusion showed that the space varitaions of Ca2+, Mg2+, HCO3-, Na+, K+, Cl- from coastal areas to inland in space decreased regularly.On the basis of literatures and experimental data, this paper analyzes the grades of seawater intrusion. The study area is divided into three areas: salt-water area, transition region and freshwater area. The relation coefficient of salinity, conductivity and chlorinity shows a good empirical formula among salinity, conductivity and chlorinity. The major characteristics of seawater intrusion imply that the groundwater quality variation with time is less than 20%, and salinity, conductivity and chlorinity with space decrease from the coast to inland gradually. The area affected by seawater intrusion was estimated to be about 2484.4km2, the seriouse area was 1714.24km2. Comparied with the previous research, both the affected area and the trasition area were enlarged, indicating that the degree of the seawater intrusion was more and more serious.The influence region and extent of disaster of seawater intrusion were studied according to two year's experimental results. The Changyi, Hangting, Shouguang cities are the most serious areas of seawater instrusion in Shangdong coastal cities. The conclusion was got that over-exploitation of groundwater was the direct cause of seawater intrusion, such as agricultural irrigation, municipal water supply, et al. In addition, global warming and ion adsorption in sediment environment may lead to the intensified seawater intrusion in the Laizhou Bay.According to soil change in the Binhai area of Laizhou Bay, seawater instrusion lead to a lot of geological and environmental problems. The major damage included environmental degradation, soil salinization, etc. The preliminary prevention and controlling measures were suggested, including strengthen the management of the groundwater resource, construct transferring-water project, development of ecological agriculture.