Skip to Main Content
Precipitation-snowmelt timing and snowmelt augmentation of large peak flow events, western Cascades, OregonAuthor(s): Keith Jennings; Julia A. Jones
Source: Water Resources Research
Publication Series: Scientific Journal (JRNL)
Station: Pacific Northwest Research Station
Download Publication (1.0 MB)
DescriptionThis study tested multiple hydrologic mechanisms to explain snowpack dynamics in extreme rain-on-snow floods, which occur widely in the temperate and polar regions. We examined 26, 10 day large storm events over the period 1992–2012 in the H.J. Andrews Experimental Forest in western Oregon, using statistical analyses (regression, ANOVA, and wavelet coherence) of hourly snowmelt lysimeter, air and dewpoint temperature, wind speed, precipitation, and discharge data. All events involved snowpack outflow, but only seven events had continuous net snowpack outflow, including three of the five topranked peak discharge events. Peak discharge was not related to precipitation rate, but it was related to the 10 day sum of precipitation and net snowpack outflow, indicating an increased flood response to continuously melting snowpacks. The two largest peak discharge events in the study had significant wavelet coherence at multiple time scales over several days; a distribution of phase differences between precipitation and net snowpack outflow at the 12–32 h time scale with a sharp peak at p/2 radians; and strongly correlated snowpack outflow among lysimeters representing 42% of basin area. The recipe for an extreme rain-on-snow event includes persistent, slow melt within the snowpack, which appears to produce a nearsaturated zone within the snowpack throughout the landscape, such that the snowpack may transmit pressure waves of precipitation directly to streams, and this process is synchronized across the landscape. Further work is needed to understand the internal dynamics of a melting snowpack throughout a snowcovered landscape and its contribution to extreme rain-on-snow floods.
- Visit PNW's Publication Request Page to request a hard copy of this publication.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationJennings, Keith; Jones, Julia A. 2015. Precipitation-snowmelt timing and snowmelt augmentation of large peak flow events, western Cascades, Oregon. Water Resources Research. 51(9): 7649-7661.
- Extreme flood sensitivity to snow and forest harvest, western Cascades, Oregon, United States
- Climate variability, snow, and physiographic controls on storm hydro graphs in small forested basins, western Cascades, Oregon
- A simple snowmelt lysimeter
XML: View XML