Coweeta, North Carolina, USA, 1934 -
Location and Scale
The Coweeta Hydrologic Laboratory is located in the Nantahala Mountain Range of western North Carolina within the Blue Ridge Physiographic Province, latitude 35°/03TSl, longitude S3°25'W (Figure 1.1). The2185 ha Laboratory is comprised of two adjacent, east-facing, bowl-shaped basins. Coweeta Basin encompasses 1626 ha (Figure 1.2) and has been the primary site for watershed experimentation, while the 559 ha Dryman Fork Basin has been held in reserve for future studies. Ball Creek and Shope Fork are fourth-order streams draining the Coweeta Basin and they join within the Laboratory boundary to form Coweeta Creek, a tributary that flows 7 km east to the Little Tennessee River.
1934 - present
Coweeta's climate is classed as Marine, Humid Temperate.
Annual Average Precipitation estimates in the sub-basins range from 1772 to 2457 mm, with discharge from 854 - 1737 mm, giving a range of runoff coefficients from 0.48 to 0.75.
Geology and soils
The northern part of the basin is underlain by Granite-Gneiss, the southern part by Mica-schists. There are significant depths of colluvium in the valley bottoms.
Soils within the Laboratory fall within two orders: imn Inceptisols and older developed Ultisols. The Inceptisols found at Coweeta fall seven "Great Groups." Umbric Dystrochrepts of the Porters series are found on rocky faces at high elevations on the north- and south-facing aspect of the Laboratory. The Typic Dystrochrepts, as represented by the Chandler gravelly loam series are found on south-facing slopes underlain by the Tallulah Falls formation. The Haplumbrepts as represented by the Spivey-Tusquitee complex, are formed in alluvium of long narrow areas associated with watershed hollows and coves.
The Ultisols are represented by Typic Hapludults and Humic Hapludults. The Hapludults are the largest soil group in areal extent at Coweeta and fall into two geomorphic settings: the Cowee-Evard gravelly loam series is found on strongly sloping very steep ridges and sideslopes, and the Fannin sandy loam series is found on sloping sideslopes. Both soil series are formed in residuum weathered from gneiss, or granite. Humic Hapludults include the Trimont gravelly loams, whi found on cool, steep north-facing slopes.
Elevations range from 675 m at the catchment outlet to 1592 m at Albert Mountain.
Vegetation / Land Use
Land use and basin manipulation histories can be found in Swank and Crossley (1988).
Charles R. Hursh, an ecologist, was hired by the Forest Service in 1926 to begin research in forest influences at the appalachian forest experiment station (later the Southeastern Forest Experiment Station and currently the Southern Research Station). Hursh was the principal individual responsible for the selection of the Coweeta basin as a research site and for development of an interdisciplinary research program with am emphasis on quantifying the processes of the hydrological cycle. Hursh led the analysis of erosion, runoff, and soil processes on the catchments in relation to forest management.
By summer of 1936, there were 16 stream gages, multiple groundwater wells, and ten weather stations. By 1939, 25 weirs were in operation, and this was increased to 30 by 1943. Data were collected for only a short time on many of the larger multiple watersheds because of maintenance requirements, while other gaging sites were discontinued after study objectives were achieved. The most recent weir installation was constructed in 1981. In 2001 there are 17 active, permanent stream-gaging sites.
In the period 1939 - 1942 various sub-basin scale land use manipulations were carried out. These were kept going during the war years by Martin Hoover, only with great difficulty, but provided a data set that proved invaluable for later analysis. In 1948 the site was renamed the Coweeta Hydrologic Laboratory. The work continued after the war and by the mid-50s 14 different manipulation experiments had been completed.
In the early 1960's John D Hewlett organized the program to address basic research questions on plant water, soil water, stream flow, and atmospheric relations. This was a fulfillment of Hursh’s original plan for forest hydrology research at Coweeta. The work was progressed by Hewlett together with J. E. Douglass, L. W. Swift, Jr., A. R. Hibbert, J. D. Helvey, J. H. Patric, and W. T. Swank and produced major insights into the functioning of forested catchments with a predominantly subsurface response. This included some interesting experiments on artificially constructed hillslope sections.
From the late 1960s more ecological and biogeochemical cycling work was started at Coweeta, led by Eugene P Odum and Philip Johnson. This later included studies on ecosystem perturbations. A 59-ha, south-facing watershed (WS 7) was selected for a commercial clearcut, cable-logging treatment. Following two years of pretreatment study, the cable logging commercial clear-cut took place in 1977.
Cowed became one of the first tranche of basins selected for the Long Term Ecological Research (LTER) programme in 1980. The 50th anniversary of research at Coweeta was celebrated by a symposium that led to the book edited by Swank and Crossley (1988)
Further information on the history of Coweeta may be found in Douglass and Hoover (1988), Swank et al. (2001) and Swank and Webster (2014).
Hydrological Knowledge Gained
- Importance of variable contributing areas on stream hydrography in forest catchments of high infiltration capacities
- Understanding of translatory flow effects in subsurface storm flow
- Importance of channel and riparian precipitation in storm response of catchments with low runoff coefficients
- Changes in water yield after deforestation
- Relationship of peak rainfalls to rainfall intensity on forested catchments
- W. T. Swank and D. A. Crossley Jr., editors. Forest Hydrology and Ecology at Coweeta. Ecological Studies, Volume 66. Springer-Verlag, New York, New York, USA.
- Swank, WT, and JR Webster (eds.). 2014. Long-Term Response of a Forest Watershed Ecosystem: Clearcutting in the Southern Appalachians 247 pp. Oxford University Press, New York
- Douglass, J.E. and Swank, W.T., 1975, September. Effects of management practices on water quality and quantity: Coweeta Hydrologic Laboratory, North Carolina. In Municipal watershed management symposium proceedings (pp. 1-13). USDA Forest Service Gen. Tech. Report NE-13, Northeastern Forest Experimental Station.
- Douglass, J. E., and M. D. Hoover. 1988. History of Coweeta. Pages 17-31 in W. T. Swank and D. A. Crossley Jr., editors. Forest hydrology and ecology at Coweeta. Ecological Studies, Volume 66. Springer-Verlag, New York, New York, USA.
- Hewlett, J.D., 1961. Soil moisture as a source of base flow from steep mountain watersheds (p. 11). US Department of Agriculture, Forest Service, Southeastern Forest Experiment Station.
- Hewlett, J.D. and Hibbert, A.R., 1961. Increases in water yield after several types of forest cutting. Hydrological Sciences Journal, 6(3), pp.5-17.
- Hewlett, J.D. and Hibbert, A.R., 1963. Moisture and energy conditions within a sloping soil mass during drainage. Journal of Geophysical Research, 68(4), pp.1081-1087.
- Hewlett, J D and Hibbert, A R, 1967, Factors affecting the response of small watersheds to precipitation in humid areas, in Sopper, W E and Lull, H W (Eds) Forest Hydrology, Pergammon Press: Oxford, 275-290.
- Hewlett, J.D. and Helvey, J.D., 1970. Effects of forest clear‐felling on the storm hydrograph. Water Resources Research, 6(3), pp.768-782.
- Hewlett, J.D., 1974. Comments on letters relating to ‘role of subsurface flow in generating surface runoff: 2, upstream source areas’ by R. Allan Freeze. Water resources research, 10(3), pp.605-607.
- Hewlett, J.D., Fortson, J.C. and Cunningham, G.B., 1977. The effect of rainfall intensity on storm flow and peak discharge from forest land. Water Resources Research, 13(2), pp.259-266.
- Hewlett, J.D., Cunningham, G.B. and Troendle, C.A., 1977. PREDICTING STORMFLOW AND PEAKFLOW FROM SMALL BASINS IN HUMID AREAS BY THE R‐INDEX METHOD. JAWRA Journal of the American Water Resources Association, 13(2), pp.231-254.
- Hoover, M.D. and Hursh, C.R., 1943. Influence of topography and soil‐depth on runoff from forest land. Eos, Transactions American Geophysical Union, 24(2), pp.693-698.
- Hursh, C. R., and E. F. Brater. 1941. Separating storm-hydrographs from small drainage-areas into surface- and subsurface-flow. Transactions, American Geophysical Union. Part 3: 863-871.
- Hursh, C.R. and Fletcher, P.W., 1942. The soil profile as a natural reservoir. In Proceedings of Soil Science Society of America (Vol. 6, pp. 414-422).
- Johnson, P. L. and W. T. Swank. 1973. Studies on cation budgets in the Southern Appalachians on four experimental watersheds with contrasting vegetation. Ecology 54: 70-80.
- Johnson, D.W., Kelly, J.M., Swank, W.T., Cole, D.W., Van Miegroet, H., Hornbeck, J.W., Pierce, R.S. and Van Lear, D., 1988. The effects of leaching and whole-tree harvesting on cation budgets of several forests. Journal of Environmental Quality, 17(3), pp.418-424.
- Steenhuis, T.S., Parlange, J.Y., Sanford, W.E., Heilig, A., Stagnitti, F. and Walter, M.F., 1999. Can we distinguish Richards' and Boussinesq's equations for hillslopes?: The Coweeta experiment revisited. Water Resources Research, 35(2), pp.589-593.
- Swank, Wayne T.; Meyer, Judith L.; Crossley, Deyree A., Jr. 2001. Long-term ecological research: Coweeta history and perspectives. In: Barrett, Gary W.; Barrett, Terry L. Holistic Science: The Evolution of the Georgia Institute of Ecology (1940-2000). Ann Arbor, MI: Sheridan Books: 143-163.
- Swank, W. T. 1988. Stream chemistry responses to disturbance. Pages 339-357 in W. T. Swank and D. A. Crossley Jr., editors. Forest hydrology and ecology at Coweeta. Ecological Studies, Volume 66. Springer-Verlag, New York, New York, USA.
- Swank, W. T., and J. B. Waide. 1988. Characterization of baseline precipitation and stream chemistry and nutrient budgets for control watersheds. Pages 57-79 in W. T. Swank and D. A. Crossley Jr., editors. Forest hydrology and ecology at Coweeta. Ecological Studies, Volume 66. Springer-Verlag, New York, New York, USA.
- Swank, W.T. and Vose, J.M., 1997. Long‐term nitrogen dynamics of Coweeta Forested Watersheds in the southeastern United States of America. Global Biogeochemical Cycles, 11(4), pp.657-671.
- Swank, W.T., Vose, J.M. and Elliott, K.J., 2001. Long-term hydrologic and water quality responses following commercial clearcutting of mixed hardwoods on a southern Appalachian catchment. Forest Ecology and Management, 143(1-3), pp.163-178.
- Webster, J.R., Golladay, S.W., Benfield, E.F., Meyer, J.L., Swank, W.T. and Wallace, J.B., 1992. Catchment disturbance and stream response: an overview of stream research at Coweeta Hydrologic Laboratory. River conservation and management, 15, pp.232-253.