A view toward the future of subsurface characterization: CAT scanning groundwater basins

First, we advocate that recently developed tomographic surveying is an effective and high-resolution approach for characterizing the field-scale subsurface. Fusion of different types of tomographic surveys further enhances the characterization.

A basin is an appropriate scale for many water resources management purposes. We thereby propose the expansion of the tomographic surveying and data fusion concept to basin-scale characterization. In order to facilitate basin-scale tomographic surveys, different types of passive, basin-scale, CAT scan technologies are suggested that exploit recurrent natural stimuli (e.g., lightning, earthquakes, storm events, barometric variations, river-stage variations, etc.) as sources of excitations, along with implementation of sensor networks that provide long-term and spatially distributed monitoring of excitation as well as response signals on the land surface and in the subsurface.