LE3 .A278 2003

2003

Spooner, Ian

Acadia University

Master of Science

Masters

Geology

Earth & Environmental Sciences

Landslides are common in Nova Scotia, particularly within the highly-incised river valleys of the Cape Breton Highlands. These flows have resulted in the modification of habitat and may pose considerable risk as both industrial and recreational uses of this area intensifies. Research in the Cape Breton Highlands National Park focuses on: (a) investigation of thin-skinned debris flows, and (b) development of a slope assessment model for the rapid assessment of thin-skinned debris flows. Thin-skinned debris flows are complex events, which begin as thin translational slides or slumps and quickly evolve into debris flows. Failure has previously been recognised on steep slopes where colluvium directly overlies bedrock Site investigations revealed two stratigraphic relationships common to slopes prone to failure: (1) highly compacted, impermeable clay-rich lodgement till overlain by highly permeable colluvium, and (2) impermeable weathered bedrock in the form of saprolite overlain by permeable colluvium. Both boundaries act as a slip surface. Redirected surface and ground water accumulate at the colluvium/till interface within the activation zone producing an effective glide plane for initial translational movement. A Slope Assessment Model was developed through the implementation of the Infinite Slope Stability model, an empirical model that computes the relative stability of a slope through a Factor of Safety. GIS-based analysis through the Slope Assessment Model revealed areas of significant risk within the Cape Breton Highlands National Park. A total of 6 stability classes were identified, ranging from class 1 (chronically unstable) to class 6 (unconditionally stable). The resultant stability classification by the Slope Assessment Model was evaluated using aerial photographs on select sites. This evaluation indicated that the Slope Assessment Model was both precise and accurate in its classification of slope stability.

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