Fusion of hydrologic and geophysical tomographic surveys

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.