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Kansas Geological Survey, Open-file Report 1998-31


Approximate Analysis of Groundwater Mineralization Due to Local Discontinuity in an Impermeable Layer

Part 1: Direct Contact between Fresh and Saltwater

by
Hillel Rubin and Robert W. Buddemeier

KGS Open File Report 1998-31
July 24, 1998

Abstract

This manuscript represents a basic study carried out within a framework of comprehensive research on the major mechanisms and phenomena involved in the mineralization of groundwater of the Great Bend Prairie aquifer in Kansas by saltwater originating from a deeper Permian bedrock formation. The conceptual model for this study assumes that mineralization of the aquifer is attributed to local discontinuities in the impermeable layers, which allow direct contact between the fresh and saline water.

Calculations are made for a single discontinuity in the impermeable layer. Salinity penetrating into the freshwater aquifer through that discontinuity is subject to advection and dispersion. A boundary layer (BL) method developed in the framework of this study provides a simple but robust approach for the initial evaluation of mineralization processes taking place downstream of the local discontinuity in the impermeable layer. It was shown that downstream of the discontinuity, the salinity profiles incorporate two BLs: an inner BL adjacent to the bottom of the aquifer, and an outer BL, which develops on top of the inner one. The horizontal penetration of the salinity is characterized by two regions extending along the aquifer: the steady state region and the spearhead region. The latter represents the salinity front, which varies as a function of the discontinuity exposure length, distance from the discontinuity, and the aquifer characteristics.

The method developed in this study has been applied to practical issues concerning mineralization of groundwater in south central Kansas.

The complete text of this report is available as an Adobe Acrobat PDF file.

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Kansas Geological Survey, Geohydrology
Placed online Oct. 17, 2013
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