INNOVATION May-June 2017

p ract i ce

Design Flood Hydrology Under a Changing Climate

Brian Chow, P.Eng., Dr. Dave Spittlehouse, P.Ag., Dr. Francis Zwiers, Kathy Hopkins, RPF, Harshan Radhakrishnan, P.Eng., Lee DesLauriers, P.Eng., Dr. Matthias Jakob, P.Geo., Megan Hanacek, RPF, RPBio, Dr. Paul Whitfield

resource-industry practices. They also discussed possible changes to design f low requirements under the Forest and Range Practices Act and dealing with hydrologic non-stationarity. Information, Tools and Guidance Needed Participants identified information, tools and guidance needed to effectively address changing climate in structure design. These included more LIDAR data to understand the geomorphology, climate change–based intensity– duration–frequency (IDF) curves, a tool for quantifying risk of debris floods, policy, practice guidelines, rules of thumb for scaling culvert designs, metrics for changes to run-off coefficients, information about experimental basins, and watershed models. Next Steps It became clear that best-available science includes a great deal of climate information to help advance understanding of the potential effects of climate change on design flood hydrology. Close collaboration between hydrologists, geomorphologists, meteorologists, climatologists, and owners of natural

British Columbia’s hydrological cycles are changing, and many resource professionals are grappling with the implications for design of bridges, culverts and other structures. Design flood hydrology is already complex, but climate change will make it more so. APEGBC recently hosted a workshop on design flood hydrology for BC’s natural resource professionals. Funded by Ministry of Forests, Lands, and Natural Resource Operations and supported by the Association of BC Forest Professionals, the workshop addressed climate change–induced variations in precipitation patterns, resulting flood hydrology, and steep- creek processes. More than 140 professionals explored issues related to terrain stability and the design and maintenance of natural resource infrastructure. They viewed presentations, reviewed case studies and discussed strategies for improving the robustness of natural resource infrastructure in a changing climate, gaining insight into current understanding of possible future changes to hydrology and potential impacts to natural resource infrastructure, as well as into current

resource infrastructure is critical to determining the design, operations and maintenance strategies that will be useful in addressing risks, costs and benefits in infrastructure design. Climate change will add one additional component of uncertainty for the design of structures on small and typically steep creeks. Reliably quantifying other uncertainties inherent in ungauged basins is also important. In this context, changes in hydroclimatic extremes, rather than annual means, are key. Updates to the Climate Change Information Portal APEGBC has updated its Climate Change Information Portal to include more resources for professional engineers and geoscientists in the natural resources sector who are actively involved in design flood hydrology. In addition, APEGBC offers members professional development opportunities and guidelines to support members in their consideration of climate change in their professional practice. Visit the Climate Change Information Portal, apeg.bc.ca/climateportal, for more information about the workshop.

6 0 M A Y/J U N E 2 017

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