垂向入渗与河渠边界影响下潜水非稳定流参数的求解

Parameter estimation for semi-infinite phreatic aquifer subjected to vertical seepage and bounded by channel

在受垂向入渗影响及河渠边界控制的半无限含水层中,利用作者已推导出的潜水非稳定渗流模型的新Laplace解,建立不同水文地质条件下的模型参数求解方法。在垂向渗流和河渠水位变幅都不可忽略时,利用潜水位变动速度随时间变化曲线的拐点,给出参数求解的计算公式;在河渠水位变幅可忽略时,提出利用实测曲线与理论曲线进行配线的求解方法,并给出理论曲线的建立方法。以安徽省淮北平原中部的一个河渠-潜水含水层系统为例,阐述上述方法的求解过程与步骤。计算结果表明,关于导压系数计算,依据模型新解所提出的拐点法和配线法,计算结果与实际比较吻合,两方法之间的相对误差为5.3%。

A new analytic solution of unsteady flow for semi-infinite phreatic aquifer subjected to vertical seepage and bounded by a channel is deduced by applying the Laplace transformation. The methods for estimating the aquifer parameters corresponding to different hydrogeological conditions are proposed. In case of both the actions of vertical seepage and water level fluctuation cannot be neglected, the formulas for calculating the parameters can be established based on the turning point of the temporal variation curve of phreatic fluctuation speed. Whereas, if the water level fluctuation of the channel can be neglected, the parameter can be estimated by fitting the actual curve of groundwater fluctuation speed according to the theoretical curve, and the method for establishing the theoretical curve is also proposed. A phreatic aquifer stream system located in the Huibei Plain, Anhui Province, China, is taken as an example to demonstrate the application of the proposed method. The result shows that the calculated coefficients of groundwater diffusivity are in good agreement with the observation data.