No abstract

HYDROGEOPHYSICSCross-borehole geophysical data can provide valuable information concerning hydrologic properties of the unsaturated zone. Such data are most often used sequentially, where images of soil physical properties are obtained through numerical inversion and then converted to hydrologic state properties using petrophysical relationships. If not accounted for, inversion artifacts are transferred to the resulting hydrologic images. We propose a framework in which multiple geophysical data sets can be incorporated using an integrated data fusion approach. Th e geophysical data collected are integrated in a forward modeling approach to evaluate a series of plausible hydrologic models. Th e approach permits an evaluation of the sensitivity of geophysical data for constraining hydrologic model parameters. We illustrate the approach using geophysical data collected during a dual water and solute tracer experiment in the unsaturated zone. Cross-borehole ground penetrating radar and electrical resistivity tomography, measuring electromagnetic travel time and electrical transfer resistances, respectively, were collected during a 20-d period. As a fi rst approximation, one-dimensional fl ow was considered and three models (one, two, and fi ve layers) of the subsurface were evaluated. Th e fi ve-layered model was found to be the only model capable of mimicking the infi ltration pattern satisfactorily. Th e results showed that only the hydraulic conductivity and one of the parameters (empirical parameter n) describing the soil moisture release curve for three of the fi ve layers could be constrained by the data, illustrating the nonuniqueness of the problem. Th e data fusion approach proved, however, that application of multiple geophysical methods may reduce hydraulic parameter uncertainty.

No abstract

No abstract

Resistivity and induced polarization methods are used for a wide range of near-surface applications, including hydrogeology, civil engineering and archaeology, as well as emerging applications in the agricultural and plant sciences. This comprehensive reference text covers both theory and practice of resistivity and induced polarization methods, demonstrating how to measure, model and interpret data in both the laboratory and the field. Marking the 100 year anniversary of the seminal work of Conrad Schlumberger (1920), the book covers historical development of electrical geophysics, electrical properties of geological materials, instrumentation, acquisition and modelling, and includes case studies that capture applications to societally relevant problems. The book is also supported by a full suite of forward and inverse modelling tools, allowing the reader to apply the techniques to a wide range of applications using digital datasets provided online. This is a valuable reference for graduate students, researchers and practitioners interested in near-surface geophysics.