HR: 0800h
AN: H51D-1181    [Abstracts]
TI: Increases in Stream Flow at Stream Crossings on Forest Roads in Western Oregon, USA
AU: * Toman, E M
EM: elizabeth.toman@oregonstate.edu
AF: Oregon State University, Department of Forest Engineering 215 Peavy Hall, Corvallis, OR 97331-5706 United States
AU: Skaugset, A E
EM: arne.skaugset@oregonstate.edu
AF: Oregon State University, Department of Forest Engineering 215 Peavy Hall, Corvallis, OR 97331-5706 United States
AB: The hydrologic impacts of forest roads on a watershed are uncertain despite decades of research. There is consensus, however, that roads can alter hydrologic pathways by intercepting subsurface flow and by producing overland runoff. Where a forest road crosses a stream the road can channel runoff, via a roadside ditch, directly to the stream. At these stream crossings the peak flow and runoff volume of the stream may be increased. This study monitored ditch flow and stream flow at fifteen stream crossings within an 824 ha watershed in western Oregon. Ditch flow and stream flow at each crossing were matched in time. Stream flow increases were calculated for five storms that occurred during the winter of 2002-2003. Nine of the fifteen streams consistently had greater than a five percent increase in peak flow and stream runoff at the stream crossing. For these nine stream crossings, the average increase in peak flow was 42 percent and the average increase in stream runoff was 77 percent. Ditch flow, on average, contributed the most volume on the rising limb of the stream hydrograph at the stream crossing. Stream flow increases have management implications for flooding and road drainage features.
DE: 1803 Anthropogenic effects
DE: 1821 Floods
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting