Item: Effects of the Thermal Characteristics of Snow Entrainment in Avalanche Run-Out at Bird Hill, South Central Alaska
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Title: Effects of the Thermal Characteristics of Snow Entrainment in Avalanche Run-Out at Bird Hill, South Central Alaska
Proceedings: International Snow Science Workshop 2014 Proceedings, Banff, Canada
Authors:
- Katreen Wikstroem Jones [ Alaska Pacific University, Anchorage, AK, USA ]
- David Hamre [ Alaska Railroad Corporation, Anchorage, AK, USA ]
- Perry Bartelt [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
Date: 2014-09-29
Abstract: Snow entrainment has a large impact on avalanche flow regime. It adds mass to the moving avalanche body which can amplify a fluidized or lubricated flow regime. Recent studies have demonstrated the importance of the thermal characteristics of the entrained snow for avalanche rheology. Fluidization and lubrication, typical for dry respectively wet avalanches, lead to increased run-out distance, velocity and impact pressure. At Bird Hill, located south-east of Anchorage, Alaska, along the Seward Highway and the Alaska Railroad, small avalanches have historically produced unexpectedly large and fast avalanches with long run-out distances. Deposition of large debris piles on the highway and the railroad indicate significant snow entrainment. Bird Hill is unique for its maritime sub-arctic snowpack, small release zones, consistent steep slopes and minimal transition zones. In this project we will implement the 2-D dynamical run-out model RAMMS in order to examine the impact that the thermal snow cover properties in the avalanche path have on avalanche flow regimes after entrainment. In agreement with current research, our early simulation results, presented in this paper, show that for avalanches to starve at the steep slopes of Bird Hill, snow cover temperature and density is equally or even more critical than the amount of entrained mass along the avalanche track. Snow cover characteristics can be correlated to weather data and monitored from weather station data. Our final project results may explain particular avalanche behaviors at Bird Hill that can improve run-out assessments and thereby support decision-making of road closures at this dangerous highway and railroad corridor.
Object ID: ISSW14_paper_P2.25.pdf
Language of Article: English
Presenter(s):
Keywords: snow entrainment, snow temperature, avalanche run-out, flow regimes, fluidization,lubrication
Page Number(s): 781-788
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