Influence of Catchment Properties on Stability of Frozen...
Transcript of Influence of Catchment Properties on Stability of Frozen...
Cordilleran Section of the Geological Society of America 111th Annual Meeting – May 11-13, 2015
Alaska Department of Natural Resources Division of Geological & Geophysical Surveys
andUniversity of Alaska Fairbanks
Influence of Catchment Properties on Stability of
Frozen Debris Lobes
Ronald P.Daanen,MargaretM.Darrowand
TrentD.Hubbard.
Overview
• FrozendebrislobesintheDietrichRiverValley,southcentralBrooksRange
• Justification• Catchmentswithandwithoutlobes• Sedimentmovementfactors• Sedimentstabilizationfactors• Summary
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Frozen debris lobes
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Why are these features here? Why are they not in all catchments? What creates their dynamic nature?
Catchments without lobes
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This is why we need to know more
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40m
FDL‐A
270m
Dietrich River valley
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Glacier-filled Dietrich River valley
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Catchments draining into the valley
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Catchments
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Blue without frozen debris lobe Red with frozen debris lobe
Slope and sediment movement
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Slope comparison
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Blue marker = without frozen debris lobeRed marker = with frozen debris lobe
Aspect: Vegetation and permafrost
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North- versus south-facing slopes
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South‐facing North‐facing
Annual precipitation
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Annual discharge
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Channel morphology
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Summary
• Catchmentswithoutlobes• Steeperslopes• Higherelevation• Greaterdischarge
• Catchmentswithlobes• Mediumslopeswithabreakinslopewhereupperpartoflobestarts
• Sedimentstabilizationthroughvegetationandpermafrost
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Summary
• Whatwilllikelydestabilizefrozendebrislobes?• Lossofvegetation• Warmerground• Warmerclimate• Lossofpermafrost• Wetterclimate(warmergroundandlubricationoftheshearzone)
• Anthropogenicincreaseinslope
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The expected result
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Alluvial Fan
Current frozen debris lobe in transition
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Lobe 42
Thank you for your attention.Questions?
WewouldliketothanktheStateofAlaska,US‐DOT,andAlyeskafortheir
supportofthisresearch.5/11/2015 GSA–Cordilleran section – 111th Annual Meeting – Alaska Division of Geological & Geophysical Surveys 21