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Depth of conduit flow

Bedrock dissolution resulting in channels occurs in a zone that often extends for tens, and sometimes for hundreds or even thousands of meters below the water table. The abstract below is from a paper which explains the depth to which this high-permeability zone extends.

Depth of conduit flow in unconfined carbonate aquifers
Stephen R.H. Worthington

ABSTRACT

The locus of formation of cave conduits in carbonate aquifers is dependent on hydraulic, structural, and solubility factors, and these can facilitate flow deep below the water table. Geothermal heating results in increasing temperatures and decreasing viscosity with depth. This favors deep conduit development for flow paths with lengths >3 km. Steeply dipping strata aid the flow of undersaturated water to depth along bedding planes. These factors indicate that flow deep below the water table should be associated with steep dips and long flow paths. Empirical evidence strongly supports this model and demonstrates that the flow depth of conduits is directly proportional to flow-path length and stratal dip.

Published in Geology: Vol. 29, No. 4, pp. 335–338, by Geological Society of America, P.O. Box 9140, Boulder, CO 80301-9140 USA (http://www.geosociety.org). The full text can be found at www.gsajournals.org