HR: 0800h
AN: H51C-0648    [Abstracts]
TI: Rapid Streamflow Generation from Subsurface Flow
AU: * Seyfried, M
EM: mseyfrie@nwrc.ars.usda.gov
AF: USDA-ARS, 800 Park Blvd, Boise, ID 83712, United States
AB: Traditional streamflow forecasting from snowmelt-dominated basins has been based on snowpack dynamics. A weakness of this approach is a failure to accommodate the increasingly common mid-winter rainfall events, which are often responsible for major flooding. We recently combined a snowmelt and soil water balance model in order to predict the spatial and temporal distribution of water flow through the root zone (through flow) in a snowmelt-dominated watershed (Reynolds Mountain in Idaho, USA). No attempt was made to calculate subsurface flow through the underlying fractured bedrock. We found: 1) a measurable soil water storage component and 2) extremely rapid streamflow response to through flow input even when the water source (snow drift) is hundreds of meters from the stream channel. The implication is that subsurface water throughout the watershed is interconnected and that streamflow response is insensitive to the spatial location of inputs. At present, it is difficult to know how far the second observation can be generalized, except to say that it is consistent with widespread observations that flooding events are often dominated by old, subsurface water that must be similarly interconnected.
DE: 1847 Modeling
DE: 1860 Streamflow
DE: 1863 Snow and ice (0736, 0738, 0776, 1827)
DE: 1866 Soil moisture
DE: 1879 Watershed
SC: Hydrology [H]
MN: 2007 Fall Meeting