Bankfull hydraulic
geometry relationships, also called regional curves, relate bankfull stream
channel dimensions and discharge to watershed drainage area. This paper
describes results of bankfull curve relationships developed for the temperate
rainforests of the Southern Appalachian Mountains primarily on Western
North Carolina Mountain streams in the Southeastern United States. Gauge
stations for small and larger catchments were selected with a range of 10 to
50 years of continuous or peak discharge measurements, no major
impoundments, no significant change in land use over the past 10 years, and
impervious cover ranges of <20%. Cross-sectional and longitudinal surveys
were measured at each study reach to determine channel dimension,
pattern, and profile information. Log-Pearson Type III distributions were
used to analyze annual peak discharge data for nine small watersheds sites
gauged by the United States Department of Agriculture (USDA), Forest
Service, Southern Research Station, Coweeta Hydrologic Laboratory and for
eleven larger watersheds gauged by the United States Geological Survey
(USGS). Power function relationships were developed using regression
analyses for bankfull discharge, channel cross-sectional area, mean depth,
and width as functions of watershed drainage area