中文摘要：

运用数理统计方法获取秦皇岛洋戴河平原地下潜水和海水的水化学统计特征,据此优选出4项海水入侵评判指标,建立各评判指标的背景值及指标等级体系,并将模糊数学综合评价法和地理信息系统结合起来评价研究区潜水含水层的海水入侵程度。研究结果表明：氯离子Cl-、电导率EC、溶解总固体TDS和潜在盐度是指示本区潜水含水层海水入侵程度的最佳指标,其判别海水入侵发生的下限值分别为250 mg/L、1 250μs/cm、700mg/L和8.5 meq/L;洋戴河平原潜水含水层的海水入侵程度总体上为中等水平,洋、戴河间浦河一带的潜水含水层海水入侵程度最为强烈。

英文摘要：

Analyzing the distribution map of seawater intrusion degree can increase the knowledge of seawater intrusion mechanism, which is not only the important reference for water supplies of production and daily life but also the core content of seawater intrusion survey and research. In this article, four effective indicators for seawater intrusion of Qinhuangdao Yangdai River Plain which is located in the northeast of Hebei Province were selected out according to the different hydrochemical characteristics of fresh groundwater, brackish groundwater and seawater using the method of mathematical statistics. And then, the background values and in- dex system of those seawater intrusion indicators were built to carry on seawater intrusion degree evaluation work based on the approach of fuzzy synthetic evaluation and geographic information system. The research re-suits can be showed as follows： The chloride ion （CI-）, electric conductivity （EC）, total dissolved solids （TDS） and potential salinity are the optimal seawater intrusion indicators which can help to distinguish the intruded samples from all groundwater samples. The background value of study area for chloride ion concentration, EC, TDS and potential salinity are 83.06-243.8 mg/L,600-1 222 μs/cm,341.82-679.14 mg/L and 2.92-8.05 meq/L, respectively. The lower limit value of chloride ion concentration, EC, TDS and potential salinity are 250 mg/L, 1 250 μs/cm, 700 mg/L and 8.5 meq/L, respectively, which can manifest the occurrence of seawater intrusion. The groundwater samples identified seawater intrusion degree as rank Ⅱ and rank Ⅲ, make up 74% of all sam-ples, which reveals that seawater intrusion degree of study area generally belongs to the medium level. On the basis of the distribution map of seawater intrusion degree, the seawater intrusion degree of the alluvial aquifers around Pu River between the Yang River and Dai River is the highest.