Scale dependence of the hydraulic properties of a fractured aquifer estimated using transfer functions. Issue 7 (2nd July 2016)

• Record Type: Journal Article
• Authors: Pedretti, D.; Russian, A.; Sanchez‐Vila, X.; Dentz, M.
• Is Part Of: Water resources research. Volume 52:Issue 7(2016:Jul.)
• Page Start: 5008
• Page End: 5024
• Publication Date: 2016-07-02
• Subjects: scaling -- transmissivity -- storativity -- transfer function uncertainty -- nonlocal; Hydrology -- Periodicals; 333.91
• DOI: 10.1002/2016WR018660
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: We present an investigation of the scale dependence of hydraulic parameters in fractured media based on the concept of transfer functions (TF). TF methods provide an inexpensive way to perform aquifer parameter estimation, as they relate the fluctuations of an observation time series (hydraulic head fluctuations) to an input function (aquifer recharge) in frequency domain. Fractured media are specially sensitive to this approach as hydraulic parameters are strongly scale‐dependent, involving nonstationary statistical distributions. Our study is based on an extensive data set, involving up to 130 measurement points with periodic head measurements that in some cases extend for more than 30 years. For each point, we use a single‐porosity and dual‐continuum TF formulation to obtain a distribution of transmissivities and storativities in both mobile and immobile domains. Single‐porosity TF estimates are compared with data obtained from the interpretation of over 60 hydraulic tests (slug and pumping tests). Results show that the TF is able to estimate the scale dependence of the hydraulic parameters, and it is consistent with the behavior of estimates from traditional hydraulic tests. In addition, the TF approach seems to provide an estimation of the system variance and the extension of the ergodic behavior of the aquifer (estimated in approximately 500 m in the analyzed aquifer). The scale dependence of transmissivity seems to be independent from the adopted formulation (single or dual‐continuum), while storativity is more sensitive to the presence of multiple continua. Key Points: Scale‐dependent transfer functions can used to evaluate scaling in fractured aquifers The method is inexpensive, able to sample statistical hydrogeological properties Single‐porosity and dual‐porosity formulations show different scaling behavior of selected variables