Study On The Dynamic Changing Laws Of Seawater Intrusion In The North-east Coastal Area Of Laizhou Bay

Sea-level rise due to global warning and over-exploitation of groundwater resources in coastal areas will induce salt water intrusion into inland,namely seawater intrusion(SWI).SWI can cause some ecological environment problems,including the deterioration of groundwater quality,the soil salinization and so on,which may seriously hinder the development of regional economy.Choosing the north-east coastal area of Laizhou Bay as the study area,namely adjacent coastal areas of Longkou City and Zhaoyuan City,this paper made the integrated use of the numerical simulation method and mathematical evaluation model to do the system research on dynamic changing laws of SWI in this region.Then,we found some important laws of SWI based on research results and main research contents of this paper are as follows:1.Analyze the characteristics of SWI process in the aquifers by single factor numerical simulation method.Choose Cl-as the simulation factor,which can sensitively reflect the process of SWI in the aquifers,and then make numerical simulation of Cl-migration process in the aquifers by combining the theory of groundwater dynamics and the theory of groundwater numerical simulation.According to the concentration distribution of Cl-,analyze the characteristics of SWI process in the aquifers in the study area.2.Assess and predict the degree and the range of SWI in the study area by multiple factor mathematical evaluation model.Firstly,build the mathematical evaluation model of SWI degree in the study area based on fuzzy mathematics and analytic hierarchy process.After that,choose Cl-,Br-,SO42-,K+ and SAR as evaluation indicators,and then apply the model to study the degree and the range of SWI in the study area.3.Study dynamic changing laws of SWI in this area under different groundwater exploitation conditions.Change the conditions of groundwater extraction in the study area and then simulate the migration and diffusion process of Cl-in the aquifers under different groundwater level conditions.According to the concentration distribution of Cl-,analyze the dynamic changing laws of SWI under different groundwater exploitation conditions in the study area.4.Study dynamic changing laws of SWI in this area under different precipitation conditions.Based on the analysis data of groundwater quality from groundwater monitoring wells in the flood season and the non-flood season,apply the mathematical evaluation model built in this paper to assess the degree and the range of SWI in this area.According to evaluation results,analyze dynamic changing laws of SWI during flood season and non-flood season in the study area.5.Summarize research results made by the numerical simulation method and the mathematical evaluation model,and then divide the study area into the pure salt water region,the salt-fresh water mixed region and the pure fresh water region.