Kansas Geological Survey, Open-file Report 1998-34
by
Hillel Rubin and Robert W. Buddemeier
KGS Open File Report 1998-34
September 1998
This report concerns mineralization of groundwater resources in the Great Bend Prairie aquifer, south central Kansas, where saltwater originates from a deeper Permian bedrock formation. Based on field as well as theoretical studies it is assumed that the aquifer mineralization process occurs due to upward migration of salinity through various types of discontinuities in the impermeable layers separating the freshwater aquifer from the formation saturated with saltwater. A simplified conceptual model is adopted, in which the saltwater seeps into the aquifer through a discontinuity representing a semi-confining layer.
A top specified boundary layer (TSBL) approach is employed to describe and characterize the mineralization process. According to this approach various types of boundary layers (BLs) develop in the discontinuity region. They are termed bottom, inner, and outer BLs. It is predicted that in cases of high rates of saltwater seepage and low values of transverse dispersivity, a saltwater mound develops at the bottom of the aquifer. Downstream from the impermeable layer discontinuity the saltwater mound thickness decreases. The TSBL approach is also applied in this region to simulate changes of salinity distribution in the domain. Numerical simulations indicate that similar salinity profiles develop throughout the mineralized domain. Power coefficients typical of salinity distributions in the various BLs are determined, and calibration of the TSBL approach is achieved by comparison of the TSBL predictions to those provided by rigorous numerical simulations.
The study provides a set of definitions and terminology that are very convenient and helpful in visualizing the development of saltwater mounds in aquifers subject to mineralization. The TSBL approached is a simple and robust tool for initial characterization of the aquifer mineralization process. It can also be useful for the interpretation and evaluation of field monitoring results.
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Kansas Geological Survey, Geohydrology
Placed online Oct. 18, 2013
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