US Army Corps of Engineers

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Impact of Beetle Infestation on Hydrology

Dr. Christopher A. Hiemstra

Cold Regions Res. and Engr. Lab. (CRREL)U.S. Army Corps of EngineersFort Wainwright, AK

Christopher.A.Hiemstra@usace.army.miloffice: (907) 361-5488 mobile: (907) 347-1028

November 2010

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Favorable Conditions for Beetles

Even-aged forests Drought-stressed trees Warmer winters (higher beetle survival)

Lodgepole pine trees are experiencing high mortality, as seen by their red coloration. In this August 2007 aerial image of the Fraser Experimental Forest, Colorado, dead reddened trees cover vast areas.

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Widespread Impact

Raffa et al. 2008

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Kelly Elder

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Snow

Interception

Litter

TranspirationSnow MeltInfiltrationRunoff

InterceptionInterception

PrecipitationThroughfallWind SpeedSublimation

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Potential Impacts Pre-disturbance

► Canopy intercepts ~20-36% of snow► transpiration is ~38% of precipitation► higher shading, slower spring melt

Post-disturbance► lower interception► higher sublimation, evaporation, and radiation► faster runoff, earlier hydrograph peak

Unknowns► Transpiration (forest floor compensation?)► Runoff (greater or lower; spatially variable?)

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Watershed Research (Uunila et al. 2006)

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Snow Modeling (Bewley et al. 2010)

Baker Creek, BC, Canada (1570 km2) Lodgepole pine with 50-80% mortality 10-20% increase in peak SWE 10-15% faster melt rate