利用滨海地下水系统对双频潮汐的响应识别含水层压力传导系数

Utilizing the Response of Coastal Groundwater System to Dual-frequency Tides to Identify Hydraulic Diffusivity of Aquifer

含水层的压力传导系数是地下水溶质运移及扩散的重要参数,通常压力传导系数由抽水试验确定,即通过抽水给地下水系统一个扰动,然后监测地下水水位的响应,进而计算压力传导系数。对滨海地区含水层来说,潮汐波动就是天然的抽(注)水试验。潮汐由不同频率的分潮构成,前两项主频潮汐基本可代表潮汐主要特征。利用地下水水位对潮汐的响应,识别含水层压力传导系数。在推导出地下水对双频潮汐响应的解析解的基础上,提出了潮汐信号衰减法识别压力传导系数,并做了敏感性分析。通过对数值解叠加高斯噪音信号进行参数估算,证明该方法估算压力传导系数具有较高的可靠性和实用性。

The hydraulic diffusivity of aquifer is an important parameter of groundwater solute transport and diffusion.Traditionally,the hydraulic diffusivity is determined by pumping test,and the response of groundwater level are monitored.For coastal aquifers,tidal fluctuations are natural test of pumping and injection.Tides are composed of multi-frequency tidal constituents.Basically,the first two major frequencies of tides could reflect their characteristics.This paper collected the data of tides and groundwater responses to calculate hydraulic diffusivity.Based on the analytical solutions of these data,it proposed a tide signal attenuation rate method to identify the hydraulic diffusivity,and conducted sensitivity analysis.The method was proved to have higher reliability and accuracy to estimate the hydraulic diffusivity of aquifer by estimating the parameters of Gaussian noise signal.