HR: 0830h
AN: H31C-0481    [PDF]
TI: Catastrophic Flooding From an Orographic Thunderstorm in the Central Appalachians
AU: * Hicks, N S
EM: nsbates@princeton.edu
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 21250 United States
AB: An orographic thunderstorm in Pendleton County, West Virginia, produced 125 - 150 mm of rainfall during a period of less than 30 minutes on 9 August 2003. The most severe fluvial impacts were concentrated in the 2.2 $km^2$ Saul's Run watershed. According to long-time residents, the August 2003 flood was the largest in Saul's Run since the June 1949 flood, which stimulated Hack and Goodlett's study of catastrophic flooding in the central Appalachians (approximately 20 km east of Saul's Creek). Hydrometeorological analyses of the storm are based on WSR-88D radar reflectivity observations and rain gage observations. Peak discharge estimates at three locations on Saul's Run are based on hydraulic computations, using surveyed high-water marks and channel cross-sections. Longitudinal profiles of the channel bottom and high-water surface were surveyed for a 2.4 km reach of Saul's Creek. The Saul's Run drainage basin contains a mixture of forest and pasture. The agricultural portions of the basin had a uniform vegetation cover. Anecdotal evidence indicates that Hortonian overland flow was prevalent over vegetated pastureland and that saturated soil columns did not develop. No first-hand observations were available for forested portions of the watershed. A large debris dam, consisting of trees, boulders and gravel deposits, formed in Saul's Run at a drainage area of approximately 1.0 $km^2$. Abrupt changes in the extent of incision and channel widening are seen along the 2.4 km reach. Large geomorphic impacts are present despite the short duration of the event, and in some places the channel is incised to bedrock. At a drainage area of 0.5 $km^2$ the stream was incised 2.0-2.5 meters to a depth of near 3 meters with a width of 2 meters at the bottom and approximately 6 meters at the top of the banks. Unlike the study site of Hack and Goodlett, this area did not sustain major slope failures or debris flows.
DE: 1821 Floods
DE: 1824 Geomorphology (1625)
DE: 1854 Precipitation (3354)
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2003 Fall Meeting