咸淡水界面位置确定的综合方法（TEcG）及其应用

Comprehensive Method(TEcG)of Determination of the Location of Freshwater and Saltwater Interface and Its Application

准确确定咸淡水界面位置是评价咸水入侵范围的前提。对于咸淡水界面位置的确定,传统研究以水化学法和物探法为主。为克服单一使用传统方法造成的人力、物力和财力的大量浪费,以莱州湾西南岸广饶县小清河以南咸水入侵区为研究对象,在综合分析研究区地下水开采现状、水化学监测结果的基础上,选择3个典型断面,采用水化学法中的野外现场电导率法,快速判断咸淡水界面大致位置(某两眼监测井之间);再在一咸一淡的两眼监测井之间,采用高密度电阻率法快速、准确地确定咸淡水界面的空间分布。结果表明:该地区的地下水电导率若大于1.61mS/cm,即可认为此处受到咸水入侵;咸淡水界面位置的视电阻率特征值为11~13Ω·m,咸淡水界面附近咸水体呈舌状入侵并主要发生在地表以下13m内的浅层地下水中。

Accurate determination of the location of freshwater and saltw ater interface is the premise of evaluation of saltw ater intrusion.Hydrochemical analysis method and geophysical investigation method are the main methods to determine the location of freshwater and saltw ater interface.In order to overcome the huge waste of hum an,material and financial resources caused by using only one traditional m ethod,take the saltw ater intrusion area south of Xiaoqing River in Guangrao C ounty,southw estern coast of Laizhou Bay as the research object.Based on comprehensive analysis of the current situation of groundwater exploitation and the results of hydrochemical monitoring in the area,three typical sections were selected,and field electrical conductivity method in hydrochemical method was used to rapidly determine the approximate location of the freshwater and saltwater interface.T h en,high-density resistivity method was used to rapidly and accurately determine the spatial distribution of freshwater and saltwater interface between saltwater and freshwater monitoring wells.Results show that if the electrical conductivity of underground water in this area is greater than 1.61 mS/cm,it can be considered that the area is intruded by saltw ater.The apparent resistivity of the freshwater and saltwater interface is 11-13 Ω·m.The saltw ater body near the freshwater and saltwater interface is tongue-shaped and mainly occurs in shallow groundwater within 13 m below the surface.