Water Stewardship Information Sources
| Citation | Schwab, JS. 1998. Debris avalances-flows on British Columbia's north coast. In: Hogan, D.L., P.J. Tschaplinski, and S. Chatwin (Editors). B.C. Min. For., Res. Br., Victoria, B.C. Land Manage. Handb. No. 41. |
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| Organization | FLNRO |
| URL | https://www.for.gov.bc.ca/hfd/pubs/docs/Lmh/Lmh41.htm |
| Abstract/Description or Keywords | Heavy rainfall is the dominant environmental factor contributing to rapid debris avalanches-flows on British Columbia’s North Coast. The legacy of events triggering slope failures is carved onto hillsides as linear strips of vegetation. The location of large failures is readily identified on air photographs. In selected study areas, slope failures were identified on air photographs and mapped. The identification of failures was repeated for each available photo coverage to determine the year of photography when the failure first appeared. The oldest photography available on the Queen Charlottes was from 1936 to 1937 and near Prince Rupert in 1947. A field sampling program was undertaken in the Rennell Sound, Pivot Mountain (northwest Graham Island), and Prince Rupert area. Failures that were greater than 1 ha in size or large enough to extend into the valley bottom were sampled in the field to determine the possible date of the event. Tree sampling was done on slide deposits in the depositional zone or on levees within torrent channels. Generally, 10–15 core samples were obtained for each slide. Scarred trees located along the edge of a slide, and trees showing vigorous or suppressed growth, were also cored or a cross-section disk taken. A search for storm and landslide events recorded in newspapers, journals, technical reports, ship logs, diaries, and company documents was also undertaken. The ages of trees sampled on landslides were then compared and linked to known events. A vegetation description of field-sampled landslides made it possible to group landslides viewed from a helicopter in a way that showed various canopy structure characteristics linked to specific events. |
| Information Type | abstract |
| Regional Watershed | Coast Region |
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| Project status | complete |
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