ANALYSIS OF A HEADWATERS STREAM SYSTEM IN THE SOUTHERN APPALACHIANS, CULLOWHEE, NC. PART A: SETTING AND STREAM GEOMORPHOLOGY

The Long Branch watershed, located in Cullowhee, NC is planned to be established as a hydrologic research station as part of the NC Department of Environment and Natural Resources (NCDENR), Groundwater Resource Evaluation Program (REP). This site is being developed in collaboration with and on the property of Western Carolina University (WCU). A primary objective of this station is to document groundwater-stream water interaction in streams of different scales in different geomorphic settings. WCU is located in the Blue Ridge Mountains, where there is little research on interactions among geology, hydrology, and geomorphology in headwater streams. The purpose of this study is to determine the relationship of different geomorphic zones to hydrology and stream processes within a small basin. Such data would support NCDENR’s efforts to protect groundwater resources during the development of a mountainous region.

A nested study design was used to examine stream reaches in three different geomorphic zones: Gribble Gap Creek (0.44 km²)--a colluvial reach, flows into Long Branch (4.39 km²)--an alluvial-colluvial reach, which flows into Cullowhee Creek (62 km²)--an alluvial reach. Geologic studies include lineament and fracture analysis, and soil borings with textural analysis adjacent to channels. Data collected for stream analyses included discharge, stage, velocity, total suspended solids, longitudinal and cross–section profiles, and bed material size distribution. Gaging stations were established on two reaches; one site with an automated water sampler. Some hydrologic modeling was completed with WinXS Pro to determine bankfull flow, stream power, and bed shear stress.

Data show that stream paths (lineaments) correlate with dominant foliation trends in bedrock. Preliminary sediment analysis shows a general correlation of texture with slope and distance from the channel. Stream hydrology and channel type progress from a baseflow dominated, colluvial reach at Gribble Gap to a runoff dominated riffle-pool channel in Cullowhee Creek. Stream power, suspended and bedload transport show some correlation with reach type. Determining stream traits associated with different geomorphic zones should allow results of this study to be applied to similar settings in the Southern Appalachians.