| Water is an essential natural resource of the survival and development of human society,and is also an important guarantee for social economic sustainable development. As animportant part of the natural water cycle, groundwater resources are the indispensableresources for human survival. In recent years, with the rapid development of the economicand social and the accelerating process of urbanization and increasing population, waterdemand are increasing year by year. With the accelerating of groundwater development, aserial of serious environmental problem are caused. Seawater invasion that is a geologicaldisaster with powerful potential, high harmfulness, and eliminated difficultly, threatenseriously the survival and development of human society.Coastal areas of Dalian are seriously affected by seawater intrusion. Recently, sea wateris polluted by offshore oil field leak cause. While fresh water stalinization by seawaterintrusion, it also carry the polluted seawater into groundwater, cause groundwater qualitydeterioration, and endanger the economic and social development and human health. It hastheoretical and practical value that we should immediately analyze the water quality of theseawater intrusion areas and propose the solutions.This study takes the regions of seawater intrusion of Dalian as the research field, allgroundwater sample are collected and the conventional ion composition are analysized byusing Hydrochemistry components analysis method, and groundwater quality indexes areobtained. Firstly, the physiographic and hydrological condition and groundwater qualityevaluation method are introduced. Then Single-factor analysis has been used to preliminarilyevaluate the chloride ion in the groundwater and analysis the seawater intrusion of Dalian.Furthermore, the grading method has been used to analysis the groundwater quality in droughtperiod and rain period of Dalian in2008. The seven excessive elements of total dissolvedsolid, total hardness, chloride, sulfate, nitrate, fluoride, ammonia are choosed, and fuzzy setpair analysis model based on entropy coefficient assessment of water quality is used toanalysis the seawater intrusion of Dalian. The main results are as follows:(1) Goundwater quality of four areas in Dalian from2005to2008are evaluated by asingle factor (chloride) evaluation method. And the results show the water quality levelinfluenced by chloride ion and the status of seawater intrusion. On the whole, the numbers ofgroundwater samples belonging to the grade of II was the most, and the grade of IV and Vwas few. The range of chlorine ion concentrations more than250mg/L from2005to2008has annual volatility, most has decreased, part of the stage has increased in Dalian. (2) The evaluation process of comprehensive evaluation method can show groundwatermain indexes of the four areas in Dalian including ammonia nitrogen, chloride, nitratenitrogen, total hardness, total dissolved solid. During dry period the worst indexes areammoniea nitrogen and chloride, the worse are total dissolved solid and nitrate nitrogen.During rain period the severe pollution indexes are total hardness and ammonia nitrogen.(3) Fuzzy set pair analysis evaluation model based on entropy considers the evaluationindex weights and the uncertainty of the boundary values about groundwater evaluationstandards, so the result is more reasonable. The results of confidence judgment is moreaccurate than that of the maximum value criterion. Evaluation results indicated that thegroundwater quality of Zhongshan district was the best, Ganjingzi district was the worst, andShahekou district, Xigang district were in the middle.Lastly, some countermeasures for seawater intrusion are put forware. |
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