Physical Features

Coweeta Hydrologic Laboratory is located in the Nantahala Range of the southern Appalachian Mountains approximately 200 km north of Atlanta, Georgia, and 119 km southwest of Asheville, North Carolina. The laboratory comprises two adjacent, east-facing, bowl-shaped basins. The Coweeta Basin encompasses 1626 ha and has been the primary site for watershed experimentation, whereas the 559-ha Dryman Fork Basin has been largely held in reserve for future studies. More than 50 km of streams drain the area, including first- through fifth-order drainages. Ball Creek and Shope Fork are fourth-order streams draining the Coweeta Basin; they join within the laboratory boundary to form Coweeta Creek, a fifth-order tributary that flows 9 km east to the Little Tennessee River. Elevations range from 675 m in the administrative area to 1592 m at Albert Mountain. The diverse topography, including various aspects and slope positions distributed across the elevational gradient within the Coweeta Basin, creates a complex mosaic of environmental conditions that influence hydrologic, climatic, and biological characteristics of forest and stream ecosystems.

Since Coweeta Hydrologic Laboratory was established, numerous weirs have been installed on streams within the laboratory; currently 18 are operational. Stream gaging was initiated on most watersheds between 1934 and 1938. Relief in the watershed (weir to ridge top) averages 300 m on smaller catchments and 550 m on larger watersheds. Side slopes average about 50% and a variety of aspects are present within the basin. Eight Coweeta watersheds have remained relatively undisturbed since the establishment of the laboratory and serve as reference watersheds in paired watershed experiments. Over the 68-year history of Coweeta, a variety of watershed experiments have produced a diverse array of forest and stream ecosystems with respect to composition, structure, productivity, and suc-cessional state.

Eight long-term (60+ years) climatic stations are distributed across the basin, and bulk precipitation chemistry has been measured weekly at each station since 1971. In addition, stream water inorganic chemistry has been measured weekly for many of the watersheds since 1971. Over 400 permanent plots, established in 1934, remain undisturbed and provide a basis for assessing forest successional trends. This network of forested plots has been periodically resampled in 5- to 15-year increments to document changes in species composition, tree density, and tree basal area. Other long-term research on processes is facilitated by a five-site environmental gradient, canopy gap sites, riparian focused studies, and stream litter exclusion studies, to name a few.

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