THE LAST FORTY YEARS OF KARST HYDROLOGY STUDIES ON THE CUMBERLAND PLATEAU ESCARPMENT IN TENNESSEE

After the pioneering work of Nicholas Crawford in the 1970s in the Sequatchie and Caney Fork basins, there have been relatively few published studies describing the karst hydrology of the Cumberland Plateau escarpment. Rather than basin delineation and hydrogeology, karst studies over the past four decades in plateau escarpment watersheds have focused more on speleogenesis, geochemistry, cave archeology and cave biology. Nevertheless, considerable information has been accumulated about the karst hydrology of plateau escarpment spring basins by those interested in cave exploration and conservation. The most detailed hydrologic information has come from water tracing with fluorescent dyes around Fall Creek Falls State Park and Spencer Mountain and from continuous spring gaging at Blue Spring in the Calfkiller Valley, but information on hydrology has been gathered in most major drainage basins on the Cumberland Plateau escarpment.

Straight-line subsurface flow paths documented through tracing studies do not exceed ten miles, but flow paths frequently cross under surface water divides. The limited flow observations that are available at major springs suggest that discharge during floods can be two orders of magnitude greater than baseflow, which is commonly less than 300 liters per minute. Extensive exploration of caves over the past forty years has resulted in a better understanding of geologic controls on hydrogeology. Divergent flow is common in this fluviokarstic terrain, with much of the baseflow that runs off Pennsylvanian clastic rocks sinking into cave streams in Mississippian carbonates while the majority of floodwater remains in surface channels. Major resurgences from cave streams are typically at limestone and chert contacts within the St. Louis limestone or at the contact between the St. Louis and Warsaw formations. Many of these discharges are at least partially submerged in surface streams and are located where access is difficult, complicating hydrology studies. Currently, a collaborative effort between cave explorers and the USGS is leading to a better organized effort to collect hydrology data in Cumberland Plateau escarpment watersheds.