This thesis examines the influence of lithology on debris torrent occurrence. The analysis
covers a thirty-year period in 80 supply-limited basins distributed in the 400 km2 Tsitika River
watershed, on northern Vancouver Island, British Columbia. Two bedrock types occur in the
watershed, the Igneous Intrusive and the extrusive Karmutsen formations, covering forty-nine and
fifty-one percent respectively. The debris torrent source basins are unlogged.
The frequency data were obtained in the field using dendrochronological evidence of debris
torrents. Field data were compared with data derived from air photographs, the latter were found
to be unrepresentative of debris torrent occurrence and were not used. All study basins were digitised
from 1 : 20 000 Terrain Resource Inventory Maps (TRIM), and were characterised by selected
morphometric parameters.
Results show that geology exerts significant control over the temporal and spatial occurrence
of debris torrents in the Tsitika watershed; the Karmutsen formation is more prolific. Geology also
was found to exert significant control over the runout area and volume of debris torrents. Climate,
morphometry and surficial materials do not appear to be confounding parameters.
Differences in weathering rates, infiltration patterns and detrital grain-size distribution
associated with the two bedrock types are believed to account for the differences in debris torrent
behaviour.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/6563 |
| Date | 05 1900 |
| Creators | Sterling, Shannon M. |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Relation | UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] |
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