HR: 1340h
AN: H23C-1443    [Abstracts]
TI: Streamflow Generation on Small Forested Central Appalachian Watersheds
AU: Hicks, N S
EM: hicks@coshocton.ars.usda.gov
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ 08544 United States
AU: * Smith, J A
EM: jsmith@princeton.edu
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ 08544 United States
AU: Miller, A J
EM: miller@umbc.edu
AF: University of Maryland Baltimore County, Department of Geography and Environmental Systems, Baltimore, MD 21228 United States
AB: This study examines streamflow generation and extreme flood response for high-gradient, forested central Appalachian watersheds. Streamflow and rainfall observations are combined with observations from a network of 415 crest-stage piezometers on two headwater watersheds (0.30 and 0.14 km²) at the Fernow Experimental Forest near Parsons, WV, to examine the storm event response of forested Appalachian watersheds. Piezometer nests (piezometer depths of 25, 50, and 100 cm) were used to identify perched water tables and to distinguish between different runoff production mechanisms. A conceptual model of runoff processes in these watersheds includes the formation of localized perched water tables due to decreased macropores and increased flaggy stones with increasing depth in the soil column. This model is an extension of the variable source area. During small and moderate sized events, subsurface saturation observed in the swales supports the idea of expanding variable source areas; during extreme events, the development of perched water tables in the shallow subsurface and rapid progression of saturated conditions to the surface becomes increasingly important. Contributions from perched water tables are spatially and temporally variable and dependent upon preferential flow pathways and decreases in effective vertical hydraulic conductivity. This extension of the variable source area model of streamflow production is necessary to explain anomalously fast response times and large runoff ratios observed during extreme events on forested central Appalachian watersheds. Subsurface saturation over large portions of a watershed is infrequent in forested central Appalachian basins, but may play a central role in extreme flood response.
DE: 1817 Extreme events
DE: 1821 Floods
DE: 1850 Overland flow
DE: 1860 Streamflow
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005