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Trickle-down ecohydrology : complexity of rainfall interception and net precipitation under forest canopies

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dc.contributor.advisor Bond, Barbara J.
dc.contributor.advisor McDonnell, Jeffrey J.
dc.creator Allen, Scott T. (Scott Thomas)
dc.date.accessioned 2012-06-28T17:45:14Z
dc.date.available 2012-06-28T17:45:14Z
dc.date.copyright 2012-06-12
dc.date.issued 2012-06-12
dc.identifier.uri http://hdl.handle.net/1957/30309
dc.description Graduation date: 2013 en_US
dc.description.abstract Rainfall interception is a primary control over the moisture input to a forested ecosystem through the partitioning of precipitation into throughfall, stemflow, and an evaporated component (i.e. the interception loss). Rainfall interception is a spatially and temporally varying process at multiple scales, but heterogeneity in interception processes are poorly understood and poorly described in the literature. We need to know how net precipitation varies in ecosystems because natural systems are driven by non-linear ecohydrological processes where mean values cannot capture localized effects or the cumulative consequences associated with an extremely heterogeneous input. In this thesis, we present two studies that investigate the heterogeneity of interception loss and throughfall in a forested catchment in the western Cascades range of Oregon. In one study, we examined the spatio-temporal patterns among point measurements of throughfall depth and isotopic composition to determine the cause of isotopic differences between throughfall and rainfall. Our results indicated that the residual moisture retained on the canopy from previous events plays a major role in determining the isotopic composition of the next event's throughfall. Differences between the isotopic composition of throughfall samples could indicate further partitioning of throughfall into various flow-paths from the canopy. The second project examined the question of how vegetation variability and terrain complexity drive interception loss heterogeneity at the whole-catchment scale. We applied a simple interception model to a watershed gridded at a 50 m resolution to investigate the relative importance of topographic and vegetative controls over the spatial variability of interception loss. We found that storm characteristics are crucial regarding the impact of spatial heterogeneities in vegetation and evaporation rates. In the Pacific Northwest climate, interception loss is not highly variable for the majority of the year because the annual precipitation is dominated by large storms with low interception losses. However, the net precipitation input to a watershed becomes extremely heterogeneous in the summer due to high interception loss variability. Summer interception loss could be an important control over the spatial variability of the availability of moisture, coinciding with when vegetation is most water-limited. en_US
dc.language.iso en_US en_US
dc.relation Forest Explorer en_US
dc.subject Interception Loss en_US
dc.subject Forest Hydrology en_US
dc.subject Throughfall en_US
dc.subject Evaporation en_US
dc.subject.lcsh Ecohydrology -- Cascade Range en_US
dc.subject.lcsh Forest hydrology -- Cascade Range en_US
dc.subject.lcsh Forest influences -- Cascade Range en_US
dc.subject.lcsh Throughfall -- Cascade Range en_US
dc.subject.lcsh Forest canopies -- Cascade Range en_US
dc.subject.lcsh Evaporation (Meteorology) -- Cascade Range en_US
dc.title Trickle-down ecohydrology : complexity of rainfall interception and net precipitation under forest canopies en_US
dc.type Thesis/Dissertation en_US
dc.degree.name Master of Science (M.S.) in Water Resources Engineering en_US
dc.degree.level Master's en_US
dc.degree.discipline Graduate School en_US
dc.degree.grantor Oregon State University en_US
dc.contributor.committeemember Brooks, J. Renee
dc.contributor.committeemember Harmon, Mark E.
dc.description.peerreview no en_us


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