Tree Rings reveal the history of severe drought in British Columbia

Friday, May 6, 2016

LTRR postdoctoral researcher Bethany Coulthard is the lead author on a recent paper “Is worst-case scenario streamflow drought underestimated in British Columbia? A multi-century perspective for the south coast, derived from tree-rings” just published in the Journal of Hydrology (with Dan Smith from the University of Victoria and the LTRR's David Meko as co-authors). Their results are not good news for water managers on the coast of southwestern Canada, showing that droughts more severe than any observed in historical times have occurred sixteen times since the year 1658. Although much more rain falls in this area than in the semi-arid regions that are the subject of other recently highlighted reconstructions, it has limited capacity to store water, and ecosystems that are sensitive to relative drought. The reassurance of knowing that the area has recovered from past droughts is offset by knowing that the present human uses of the water are greater, and that projected climate change makes future droughts more likely. Although reconstructing stream flows from tree-ring data is a well-established technique, the researchers successfully overcame some technical difficulties to produce an accurate reconstruction, including not having trees whose growth was directly affected by low stream flows, and working with small and hydrologically complex catchments.