Groundwater lowering and stream incision rates in the Central Appalachian Mountains of West Virginia, USA

Abstract

Surface channel incision rates are of broad geomorphological interest because they set the boundary conditions for landscape change by affecting changes in local relief and hillslope angles. We report groundwater table lowering rates associated with subsurface Buckeye Creek and the surface channel of Spring Creek in southeastern West Virginia, USA. The mountainous watersheds have drainage areas of 14 km2 and 171 km2, respectively. The lowering rates are derived from U/Th-dating of stalagmites and the paleomagnetostratigraphy of clastic sediments in Buckeye Creek Cave. The oldest stalagmites have a minimum age of 0.54 Ma and we use a minimum age of 0.778 Ma for clastic cave sediments deposited during a period of reversed magnetic polarity. The water table at Buckeye Creek has lowered at a rate of ≤40 m Ma-1. Based on the relative elevations of Buckeye and Spring creeks, the water table at Spring Creek has lowered at a rate of ≤47 m Ma-1. These values are consistent with previously published rates obtained from caves in the region, although those rates were reported as surface channel incision rates, based on the assumption local groundwaters drained to the surface channel of interest. However, the rates we report are almost certainly not simple bedrock incision rates because of autogenic processes within the cave and surrounding, well-developed fluviokarst. Caveats aside, incision rates of ≤47 m Ma-1 now appear typical of landscapes of the Appalachian Mountains and Plateau.