Application Of New Data Processing Techniques To Hydrogeophysical Survey Data From The Netherlands

The determination of aquifer characteristics from surface geoelectrical measurements is a difficult nonlinear<br>inverse problem. In routine data analysis, this problem can be addressed by time-consuming forward<br>modelling and automated iterative inversion or recently by the faster approach of direct inversion. A major<br>draw-back of these standard approaches is that in the absence of accurate a priori information, there is no<br>guarantee that the constructed model represents the true subsurface structure. A simple and effective<br>alternative scheme for approximate direct resistivity-depth transformation of geoelectrical data is combined<br>with standard numerical modelling techniques and applied to well-known transient electromagnetic and dc<br>resistivity survey data from the Netherlands in order to evaluate its usefulness in this geological setting.<br>The resulting models of the subsurface are found to be in excellent agreement with borehole lithological and<br>permeability distribution data and demonstrate that dc resistivity and TEM methods are an essential<br>combination for accurate geoelectrostratigraphic characterisation. The results also suggest that the rapid<br>scheme for simultaneous TEM and dc resistivity data analysis is a powerful tool for hydrogeophysical<br>studies in the region.