HR: 1330h
AN: H12B-0984    [PDF]
TI: Modeling Episodic Surface Runoff in an Arid Environment
AU: * Waichler, S R
EM: scott.waichler@pnl.gov
AF: Pacific Northwest National Laboratory, MSIN K9-36 P.O. Box 999, Richland, WA 99352 United States
AU: Wigmosta, M S
EM: mark.wigmosta@pnl.gov
AF: Pacific Northwest National Laboratory, MSIN K9-36 P.O. Box 999, Richland, WA 99352 United States
AB: Methods were developed for estimating episodic surface runoff in arid eastern Washington, USA. Small (1--10 km$^{2}$) catchments in this region with mean annual precipitation around 180 mm produce runoff in about half the years, and such events usually occur during winter when a widespread cold snap and possible snow accumulation is followed by warmer temperatures and rainfall. Existence of frozen soil appears to be a key factor, and a moving average of air temperature is an effective predictor of soil temperature. The watershed model DHSVM simulates snow accumulation and ablation reasonably well at a monitoring location, but the same model applied in distributed mode across a 850 km$^{2}$ basin overpredicts runoff. Inadequate definition of local meteorology appears to limit the accuracy of runoff predictions. However, runoff estimates of sufficient quality to support modeling of long-term groundwater recharge and sediment transport may be found in focusing on recurrence intervals and volumes rather than hydrographs. Usefulness of upland watershed modeling to environmental management of the Hanford Site and an adjacent military reservation will likely improve through sensitivity analysis of basic assumptions about upland water balance.
DE: 1815 Erosion and sedimentation
DE: 1833 Hydroclimatology
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2003 Fall Meeting