A field assessment of site-specific correlations between hydraulic and geophysical parameters

In this study the potential of combining high-resolution hydraulic tomographic and geophysical tomographic measurements to define site-specific relationships between geophysical and hydraulic parameters was investigated. We exploit the high-spatial resolution of hydraulic and geophysical tomographic images to define a representative and reliable site-specific relationship, if it exists, over an area, where geophysical and hydraulic tests are performed. The parameters involved in this study were: seismic P-wave velocity derived from seismic tomography; resistivity and electrical conductivity derived from electrical tomography (ERT); diffusivity, hydraulic conductivity and specific storage derived from hydraulic tomography. We derived a site-specific correlation function between the parameters P-wave velocity and diffusivity that shows the highest correlation of all hydraulic and geophysical parameter combinations. The transformation of the P-wave velocity field into a diffusivity field using the estimated site-specific correlation function allowed us to increase the significance of hydraulic tomographic as well as seismic tomographic measurements with respect to the spatial diffusivity distribution in the near subsurface.