Complex geology and pressure tests

Identification of groundwater flow parameters using reciprocal data from hydraulic interference tests

“…Drawdowns governed by (1) follow the so-called Lorentz reciprocity (Lorentz, 1896). This implies that a signal w b a ðtÞ=Q a monitored in a well located in x b while withdrawing the flow rate Q a in x a coincides with the signal w a b ðtÞ=Q b observed in x a while pumping Q b in x b (Bruggeman, 1972;Raghavan, 2009;Hariga et al, 2010;Delay et al, 2011Delay et al, , 2012. In the case of a model simulation of hydraulic tomography performed through (1) by considering a set of wells, each of them being pumped sequentially while observing at the others, vectors w…”

“…On these basis, it is clear that considering jointly reciprocal drawdowns w b a , w a b , w b;Ã a , and w a;Ã b within any (inverse) modeling approach based on (1) would correspond to exploiting multiple times the same information content. As such, one might consider w a b and/or w a;Ã b to constitute a set of redundant entries to model inversion with respect to w b a and/or w b;Ã a (e.g., Raghavan, 2009;Bohling and Butler, 2010). Note that this type of redundancy would still be present even if the terms in vectors w were not normalized by the pumped flow rate, because they would only differ by a multiplicative constant.…”

“…2a clearly illustrates the principle of reciprocity for flow in a single continuum, i.e., forward simulations of drawdowns w b a strictly coincide with w a b , rendering the two signals indistinguishable. Note that the reciprocity principle has already been employed by, e.g., Raghavan (2009), as a check on the accuracy of numerical codes, by simply stating that a reciprocal equation should render reciprocal numerical solutions. Fig.…”

“…A critical point which is often raised when considering applications of hydraulic tomography (e.g., Leven and Dietrich, 2006;Raghavan, 2009;Bohling and Butler, 2010;Delay et al, 2012;Jiménez et al, 2013) is the assessment of the number of available independent (and/or redundant) drawdown observations and their impact on the solution of the inverse problem. The issue arises when interpretation and inverse modeling are based on mathematical formulations of the classical single-continuum approach to three-dimensional flow grounded on Darcy's law.…”

Impact of model complexity and multi-scale data integration on the estimation of hydrogeological parameters in a dual-porosity aquifer

“…Mansour et al, 2011;Raghavan, 2004;Schad and Teutsch, 1994;Thorbjarnarson et al, 1998). Pumping tests have been simulated with finite difference (Barrash and Dougherty, 1997;Cheng and Chen, 2007;Halford and Yobbi, 2006;Kaleris et al, 1995;Lee et al, 2007;Leven and Dietrich, 2006;Mohamed and Rushton, 2006;Raghavan, 2009Raghavan, , 2006Schroth and Narasimhan, 1997), finite elements, and hybrid finite elements -finite difference models (Chen and Jiao, 1999;Lebbe et al, 1992). Radial flow models based on cylindrical coordinate grids are particularly appropriate for the simulation of pumping tests since they provide a more precise representation of the flow field around the pumping borehole (e.g.…”