RESISTIVITY SURVEYS AND INTERNAL FASCIES, HAYS, KANSAS

This study focuses on the application of surface resistivity surveys to characterize an incised valley-fill aquifer geometry in semi-arid Great Plains of the United States. In the Western U.S., the most significant single factor affecting groundwater management is the internal and external geometry of the aquifer, something that is commonly uncertain. Electrical resistivity is the most cost-effective way to characterize such geometry. The study site is a typical incised valley-fill aquifer composed of Late Quaternary silty alluvial terrace units hosting younger sandy channel deposits. Combining the resistivity survey results with existing water table, well logs, and pumping test results, we were able to map aquifer boundaries and high-productivity aquifer facies in three-dimensional. Transmissivity and resistivity usually have strong positive correlation. Locally calibrating the correlation of transmissivity and resistivity, the estimated hydraulic conductivity and transmissivity can be computed from resistivity results. Given these information, the aquifer can be conceptualized as a natural storage tank, allowing detailed optimization of wellfield development and management in time of climate stress. Considering the convenience, simplicity and cost-effectiveness, this study successfully shows resistivity surveys are the favorite survey method to characterize aquifer geometry.