Fusion of hydrologic and geophysical tomographic surveys

Abstract

In this paper, we argue the need for high-resolution characterization of the subsurface and discuss difficulties of traditional characterization approaches to meet this need. Necessary and sufficient conditions are then presented for well-posedness of groundwater inverse problems associated with identifying spatially distributed parameters. Non-uniqueness and large uncertainty in model calibration are subsequently attributed to difficulties in collecting information to meet these conditions. Using an example, we show that a tomographic survey can make problems of identification of spatially distributed parameters better posed. We subsequently present some recent advances in hydrologic/geophysical characterization of the subsurface using information fusion based on tomographic survey concepts. This paper includes hydraulic and electrical resistivity tomographic surveys as well as fusion of hydraulic and resistivity tomography and fusion of hydraulic and tracer tomography.

An Extended Trajectory Mechanics Approach for Calculating the Path of a Pressure Transient: Derivation and Illustration

“…The use of transient pressure and hydraulic head data to infer aquifer properties has a long and varied history (Bohling et al, 2002;Brauchler et al, 2003Brauchler et al, , 2010Butler et al, 1999Butler et al, , 2003Cardiff & Barrash, 2011;Cardiff et al, 2013aCardiff et al, , 2013bCarrera & Neuman, 1986;He et al, 2006;Hsieh et al, 1985;Hu et al, 2011;Jacquard & Jain, 1965;Karasaki et al, 2000;Oliver, 1993;Paillet, 1993;Vasco et al, 2000;Vasco & Karasaki, 2001;Yeh et al, 2008;Yeh & Liu, 2000). One advantage of approaches based on pressure and hydraulic head is the rapid propagation of pressure transients in comparison to methods such as tracer transport and multiphase flow, leading to faster experiments and better turn-around times.…”

Structure-coupled joint inversion of geophysical and hydrological data

“…But, reliable modeling of groundwater flow and solute transport requires detailed quantitative information about the distribution of hydraulic conductivity, which geophysics alone cannot provide (e.g., Yeh et al, 2008). Classical geophysical imaging hence provides high-resolution images of structures that may be essential for predictive numerical groundwater modeling, but generally fails to produce the numerical values of the hydrological parameters of interest.…”

Effect of the spatial distribution of physical aquifer properties on modelled water table depth and stream discharge in a headwater catchment

“…But, particular parameters like hydraulic conductivity are already highly variable within one soil or geological unit, so we can hardly use this information to represent absolute differences among the areas. Only a combination of water table measurements (or other spatial observations, such as soil moisture, if other processes are studied) and an appropriate spatial model, together with discharge observations, can provide the necessary information to parameterise a distributed model (Yeh et al, 2008). As can be seen for the studied hillslope, the predictions based on the different spatial models are rather different from each other and different from predictions without a spatial model.…”