What Goes Down, Must Come Up

A groundwater recharge area is the land area where surface waters infiltrate into the underlying aquifer and supply flow to karst features, such as caves and springs. Recharge in karst landscapes can occur through sinkholes, losing streams, and solutionally widened fractures in the bedrock.

Tumbling Creek is the name of the underground stream that flows through the cave. Over 100 groundwater traces using fluorescent tracer dyes have been conducted to delineate the 9.02 square mile recharge area that contributes water to the cave. While all mapped cave passages are in the Big Creek topographic basin, about 70% of the recharge area for the cave lies to the west in the Shoal Creek topographic basin.

The cave stream responds quickly to rainstorms and flow rates of as much as 100 million gallons per day have occurred within the cave. Under low flow conditions, all the flow emerges from a few springs tributary to Big Creek. Under high flow, the cave stream feeds 20 to 25 springs located along Big Creek and Bear Cave Hollow.

The Karst Window is exactly that, a window into the subsurface conduits that drain waters from Tumbling Creek Cave to springs along Big Creek. The ceiling of this conduit has collapsed, giving us a view into the karst plumbing below. In wet conditions, the Karst Window is a spring, discharging water to the surface. In dry conditions, there is no surface discharge and water continues it path down the subsurface conduit to springs along Big Creek.

The Karst Window on TCCF land between the cave and Big Creek.

Recharge area boundary for Tumbling Creek Cave.

Much of the flow of Tumbling Creek is derived from losing streams on the surface. These streams only flow appreciable amounts of water during major storms. Mean straight-line groundwater travel rates of nearly 1000 feet per hour have been observed in the recharge area. The longest distance groundwater trace into the cave was from a losing stream 5.3 miles away.

Introduction of tracer dye into Bear Cave Hollow, a losing stream that recharges waters in Tumbling Creek.