Water Stewardship Information Sources

Citation Spry, C. 2013. Understanding extreme precipitation behaviour in British Columbia's lower mainland using historical and proxy records. MRM Thesis, SFU.
Organization SFU
URL http://rem-main.rem.sfu.ca/theses/SpryChristie_2013_MRM527.pdf
Abstract/Description or Keywords In British Columbia, Pineapple Express storms can lead to flooding, slope failures and
negative impacts to water quality. Mitigating the impacts of extreme weather events in a
changing climate requires an understanding of how local climate responds to regional-toglobal
climate forcing patterns. In this study, I use historical and proxy data to identify the
distinguishing characteristics of Pineapple Express storms and to develop a tree ring
oxygen isotope record (1960-1995) of local climate conditions in the Lower Mainland of
British Columbia. I found that high magnitude Pineapple Express storms have
significantly higher precipitation and streamflow than other storms types, which result in
relatively high contributions of Pineapple Express storms to the annual water budget. As
well, Pineapple Express precipitation is characterized by an enriched δ18O isotopic
signature when compared to precipitation originating from the North Pacific Ocean.
However, differences in source water do not appear to be driving the variability in tree
ring δ18O ratios. Instead, tree ring isotopic values exhibit a regional climate pattern that is
strongly driven by latitudinal temperature gradients and the Rayleigh distillation effect.
Therefore, future warmer conditions may decrease the temperature gradient between
the equator and the poles, which can be recorded in the tree ring isotope record. The
results also suggest that warmer temperatures due to climate change could result in
more active Pineapple Express storm seasons, with multiple PE storms happening over
a short period of time. Concurrent storms significantly increase the risk to society
because the resulting antecedent saturated soil conditions can trigger precipitationinduced
natural hazards.
Keywords: extreme weather; stable isotopes; Pineapple Express; British Columbia;
climate change; tree rings
Information Type thesis
Regional Watershed Lower Fraser
Sub-watershed if known
Aquifer #
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Project status complete
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