KWRRI Research Reports


Limestone groundwater flows mainly in openings it has solutionally enlarged, thus an understanding of the water's state of saturation relative to calcite (the principal mineral component of limestone) is fundamental to an understanding of the nature and evolution of the limestone aquifer. This study investigated the Mammoth Cave-Sinkhole Plain (MCSP) and Cave Hollow (CH) aquifers in Kentucky, both in Missippian limestones.

Both aquifers were always undersaturated with calcite. Except for completely ventilated vadose flows (usually) and some vadose seepage (occasionally), all recharges sampled (sinking streams, vadose flows, and vadose seepage) were also undersaturated. The lack of saturation in the MCSP aquifer was due to the introduction of carbon dioxide into the water in amounts difficult to explain by the carbon dioxide content of the above recharges. In both vadose flows and seepage, undersaturatlon tended to correlate directly with flow volume, and there was an inverse correlation between the amount of carbon dioxide and calcite saturation in most of the waters sampled. In vadose seepage this relationship was so strong as to suggest seasonal invariance of carbon dioxide content of the water prior to out gassing.

Results suggest solutional enlargement is greatest near recharge points in "ventilated" aquifers (CH) but the carbon dioxide introduction phenomenon (MCSP) allows solution over wide areas in "unventilated" aquifers.

Publication Date


Report Number


Digital Object Identifier (DOI)

Funding Information

The work upon which this report is based was supported by funds provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Research Act of 1964.