Debris Flows from Forest Landscapes Along the Mainland British Columbia Coast
College of Liberal Arts and Sciences
More than 1800 distinct debris flows along the Inside Passage of mainland coastal British Columbia have been documented and analyzed. The largest of these debris flows exceeds 24 ha but the average is 3 ha. More than 66% occur on slopes with southern aspects where biomass accumulation is maximal and decomposition is minimal. Approximately 50% of the debris flows are bounded by latitude 51° N with an average drop of 279 m, a run of 538 m and slope angle of 27 degrees. The flows overwhelmingly take place in mature conifer forests and appear to be triggered by storm events. 94% originate within undisturbed forest areas. On average 90 debris flows occur /year; they occur primarily in winter months when precipitation adds to hill slope mass, causing the soil to become supersaturated and unstable. During such conditions almost any disturbance can trigger a debris flow and its subsequent cascading avalanche.
Geological Society of America Annual Meeting
Cole, Kevin, "Debris Flows from Forest Landscapes Along the Mainland British Columbia Coast" (2011). Faculty Scholarly Dissemination Grants. 183.