AN UPDATE ON KARST HYDROLOGY STUDIES ON THE CUMBERLAND PLATEAU ESCARPMENT

There have been few academic studies describing the karst hydrology of watersheds on the western escarpment of the Cumberland Plateau in Tennessee since the pioneering work of Nicholas Crawford on the Caney Fork River and of William and Elizabeth White on the Obey River. Nevertheless, considerable information has been accumulated about plateau escarpment spring basins in the interim forty years by those interested in cave exploration and conservation. The most extensive work has been water tracing with fluorescent dyes around Fall Creek Falls State Park and Spencer Mountain, but information on the hydrology in almost all the major basins that drain the western escarpment of the Cumberland Plateau has been gathered. Flow paths crossing significant watershed divides have been identified, and a better understanding of geologic controls on hydrology is developing.

Straight-line flow paths through the subsurface seem to be limited to about ten miles or less. Limited spring flow data are available, but observations suggest that discharge during floods at major springs tend to be one to two orders of magnitude greater than baseflow, which is commonly less than 300 liters per second. Many major springs discharge directly into surface streams in this fluviokarstic terrain, and frequently are not even shown on topographic maps. Divergent flow is common, with much of the baseflow that runs off Pennsylvanian clastic caprocks sinking into cave streams in Mississippian carbonates, while the majority of floodwaters remain in the surface channels. Two years of continuous stage data have now been collected at Blue Spring in White County, Tennessee, where the spring exit channel is well suited to establishing a rating curve for flow. Sporadic dye tracing work continues with support from the caving community in an attempt to better delineate the spring basin.