单井捕获地下水污染羽的优化方法

Optimal method of groundwater pollution plume capture by single well

针对不同抽水井捕获半径及驻点获取方法存在局限性和误差的问题,以潜水、承压水2个类型污染场地为例,分别采用实测法、解析解公式法、数值模拟法3种方法计算单井捕获半径及驻点值;通过对比分析,研究了不同条件下3种方法的局限性及精确度;探讨了不同类型污染场地获取捕获半径及驻点的最适宜方法。结果表明:对于承压水类型,解析解计算值与实际观测值误差较小,为3.2%;对于水位降深相对于含水层厚度不可忽略的潜水类型,解析解计算值与实际观测值误差较大,为80.7%;在充分掌握水文地质条件时,数值模型模拟结果与实际观测误差值不超过10%。因此,当场地水文地质情况符合解析解公式假设条件时,可采用解析解公式法获取单井捕获半径及驻点,否则须利用数值模拟方法或实测法获取相关参数。研究成果为不同类型污染场地选择合适方法获取捕获半径及驻点提供了参考。

In view of the limitations and errors in the acquisition methods of capture radius and stagnation points of different pumping wells,two types of contaminated sites,such as unconfined aquifer and confined aquifer,were taken as examples.Subsequently,the capture radius and stagnation point of a single well are calculated by using the measurement method,the analytical solution formula method and the numerical simulation method,respectively.Through comparative analysis,the limitations and accuracy of the three methods under different conditions were studied.The optimum methods for obtaining the capture radius and stagnation point of different types of contaminated sites were discussed.The results show that for the type of confined aquifer,a low error of 3.2%between the calculated value of analytical solution and the measured value occurred.For the type of unconfined aquifer,its groundwater level drawdown could not be ignored with respect to aquifer thickness,a relatively high error of 80.7%between the calculated value of analytical solution and the measured value occurred.When the hydrogeological conditions were fully mastered,the error between the numerical model simulation result and the measured value did not exceed 10%.Therefore,when the hydrogeological conditions in the field met the assumed conditions of the analytical solution formula,the analytical solution formula could be used to obtain the capture radius and stagnation point of a single well,otherwise,the numerical simulation or field measurement method should be used to obtain the relevant parameters.This study provides a reference for selecting suitable methods to obtain the capture radius and stagnation point of different types of contaminated sites.