Andrew Binley October 27th Seminar

Dr. Andrew Binley ~ Lancaster University, Environmental Science “Hydrogeophysics: Opportunities and Challenges” Wednesday, October 27, 2010, 4:00 pm Harshbarger Building ~ Room 206 Detailed knowledge on the extent, hydraulic properties, and vulnerability of groundwater reservoirs is necessary to enable sustainable use of groundwater resources. Hydrogeophysical methods can allow, for example, large scale aquifer characterisation, previously unobtainable through conventional hydrogeological techniques. In addition, time-lapse deployment of appropriate methods can give useful insight into complex subsurface processes, aiding hydrological model development and the assessment of groundwater restoration strategies. New regulatory water policies, for example the European Water Framework Directive, demonstrates the demand for new technology to assist in water resource management, with clear opportunities for hydrogeophysical method development and application. Geophysical methods have been widely used to support groundwater investigations for many years. Geophysical borehole logging is commonly used within hydrogeological studies to provide data to support the development of conceptual models of groundwater processes. Much of these established methods, however, offer only qualitative information about hydrogeological parameters and processes and during the 1990s a re-emergence of geophysics in hydrology occurred as attempts were made to provide more quantitative information about subsurface hydrology. The field hydrogeophysics emerged as a multi-disciplinary subject that focuses on the use of geophysical methods for characterising subsurface features, determining hydrogeological properties and monitoring processes relevant to soil and groundwater processes. Over the past decade hydrogeophysics emerged due to the availability of new (or developing) geophysical techniques and the potential value in addressing the hydrological challenges that had emerged from recent research. Many geophysical methods may provide solutions to the problems above but it is essential that the expectations of the hydrologist are consistent with what the geophysicist can provide. Geophysical methods will be limited in what they can offer but provided these limitations are accepted at the outset then there may be enormous potential value to a hydrological study. Imaging of hydrological structure and processes are potentially valuable hydrogeophysical tools, however, in hydrological investigations one is often faced with subtle contrasts in some geophysical property. In such cases the application of conventional geophysical inversion approaches may have limited value due to limited resolution and effects of inappropriate regularisation schemes. In addition, there is a need to link the imaged geophysical property to some useful hydrological variable or parameter. This requires reliable petrophysical models, developed at an appropriate scale. The resulting image will be subject to uncertainty, the extent of which should be understood before any hydrological value can be drawn from the image. Recent attempts have been made to tackle some of these problems. Here we outline the limitations of current hydrogeophysical methods, identify specific challenges facing the community and exciting opportunities in this field.