时变补给条件下潜水运动模型的参数敏感度分析

Parameter Sensitivity of Phreatic Water Movement Model under Time-varying Recharging

参数敏感度分析是地下水数值模拟过程中的一个重要步骤。以河间地块潜水含水层为例,基于MODFLOW程序建立了正弦形式补给条件下的二维模型,根据局部敏感度分析方法设计了2组数值试验,对渗透系数和给水度进行了敏感度分析。研究表明,渗透系数和给水度与观测孔水位振幅分别呈对数反比和线性反比关系;地下水位对补给的响应存在明显的滞后,渗透系数与滞后时间呈对数反比关系,而给水度与滞后时间则呈线性正比关系。研究结果可为类似水文地质条件的地下水模型校正、参数敏感度分析和不确定性分析提供理论依据。

The parameter sensitivity analysis is an essential step in all groundwater modeling applications. Taking account of a time-varying recharging process as a sine function, the phreatic water between two parallel ditches is studied. Based on the local sensitivity analysis, two numerical tests are carried out to estimate the sensitivities of the hydraulic conductivity （HC） and specific yield （SY） of aquifer. The observations show that the groundwater level amplitude is inversely proportional to HC fitted to a logarithmic function, and the relationship between amplitude and SY is inversely linear ratio. The time lag of response of water table to recharge fluctuation is determined by using cross-correlation coefficients. The results suggest that the relationship between HC and time lag is the same to amplitude. However, the time lag is directly linear proportional to SY. This research is helpful to modeling calibration and sensitivity and uncertainty analysis if the hydrogeological conditions are similar.