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<div class="column"><p class=""><i class="">WATER RESOURCES RESEARCH</i>, VOL. 48, W10503, doi:10.1029/2012WR012449, 2012
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<div class="column"><p class=""><font size="4" class="">A paradigm shift in understanding and quantifying the effects of
forest harvesting on floods in snow environments
</font></p><p class="">Kim C. Green<span style="vertical-align: 5pt;" class=""> </span>and Younes Alila<span style="vertical-align: 5pt;" class=""><br class="">
</span>Received 25 May 2012; accepted 23 August 2012; published 2 October 2012.
</p><p class="">Abstract <b class="">[ bold emphasis added ]</b></p><p class="">A well-established precept in forest hydrology is that any reduction of forest cover will always have a progressively smaller effect on floods with increasing return period. The
underlying logic in snow environments is that during the largest snowmelt events the soils
and vegetation canopy have little additional storage capacity and under these conditions
much of the snowmelt will be converted to runoff regardless of the amount or type of
vegetation cover. Here we show how this preconceived physical understanding, reinforced
by the outcomes of numerous paired watershed studies, is indefensible because it is
rationalized outside the flood frequency distribution framework. We conduct a
meta-analysis of postharvest data at four catchments (3–37 km<span style="vertical-align: 5pt;" class="">2</span>) with moderate level of
harvesting (33%–40%) to demonstrate how harvesting increases the magnitude and
frequency of all floods on record (19–99 years) and how such effects can increase
unchecked with increasing return period as a consequence of changes to both the mean
(þ11% to þ35%) and standard deviation ( 12% to þ19%) of the flood frequency
distribution. <b class=""><font face="Arial" class="">We illustrate how forest harvesting has substantially increased the frequency of
the largest floods in all study sites regardless of record length and this also runs counter to
the prevailing wisdom in hydrological science.</font></b> The dominant process responsible for these
newly emerging insights is the increase in net radiation associated with the conversion from
longwave-dominated snowmelt beneath the canopy to shortwave-dominated snowmelt in
harvested areas, further amplified or mitigated by basin characteristics such as aspect
distribution, elevation range, slope gradient, amount of alpine area, canopy closure, and
drainage density. Investigating first order environmental controls on flood frequency
distributions, a standard research method in stochastic hydrology, represents a paradigm
shift in the way harvesting effects are physically explained and quantified in forest
hydrology literature.
</p><p class="">Citation: Green, K. C., and Y. Alila (2012), A paradigm shift in understanding and quantifying the effects of forest harvesting on
floods in snow environments, Water Resour. Res., 48, W10503, doi:10.1029/2012WR012449. </p>
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