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Post-wildfire debris flows in southern British Columbia, Canada

Author(s): Peter Jordan
Year Published: 2015

Several post-wildfire debris flows and other landslides occurred after the extreme wildfire season of 2003 in the southern interior of British Columbia. Such events had not been previously reported in Canada, although they are common in lower latitudes. Severe wildfire seasons also were experienced in 2007 and 2009, and additional events were observed in four fires. Post-wildfire landslides have occurred in spring, summer and fall (autumn); events have been triggered by spring snowmelt, high-intensity summer rainstorms and low-intensity fall rainstorms. Of a total of 36 documented events, 23 were debris flows, and the most common initiating mechanism was high peak flow in channels. Most sediment in these events was derived from the channels, not from erosion in burned areas. Seven of the events were infiltration-triggered debris slides, and six events were debris floods. A variety of hydrologic changes can contribute to the prevalence of post-wildfire landslides and floods, including an increase in snowmelt rate. High-severity burn in catchment headwaters above steep channels is a topographic factor favouring debris flow occurrence. These observations demonstrate that the likelihood of debris flows and other mass-movement events in susceptible terrain is significantly increased following severe wildfire in this snow-dominated environment.

Citation: Peter, Jordan. 2015. Post-wildfire debris flows in southern British Columbia, Canada. International Journal of Wildland Fire, http://dx.doi.org/10.1071/WF14070.
Topic(s): Fire Effects, Ecological - Second Order, Soils, Water
Ecosystem(s): Montane wet mixed-conifer forest, Montane dry mixed-conifer forest
Document Type: Book or Chapter or Journal Article
Hot Topic(s): Post-fire Debris Flows
NRFSN number: 12886
Record updated: Jun 30, 2016