A study of factors impacting landslide displacement rates was conducted on the Ripley Landslide within the Thompson River valley in British Columbia, Canada for the International Programme on Landslides’ project #202. Seasonal and multiyear changes in atmospheric factors cause cyclic fluctuation of matric suction in the vadose zone through changes to the in situ water content. The ingress of moisture is shown to contribute to multiyear and seasonal loss of stability causing increasing landslide displacement rates, often disregarded in slope stability calculations. However, the water content in the unsaturated zone is important, especially in semi-arid to arid climates where the water table is low and large portions of the slope are unsaturated. Additional tools for studying long-term variations in climate and seasonal changes in water content are presented. These tools are used to characterize historical climate and compare several factors that have resulted in changing landslide displacement rates and magnitude. Infiltration of precipitation and snowmelt directly contributes to matric suction loss in the head scarp and is exacerbated by the presence of tension cracks. While groundwater levels are often correlated to changing displacement rates, changes in matric suction can also influence the rates of displacement. Climatic trends over subsequent years alter the long-term soil water accumulation which impacts rates of landslide displacement. By accounting for additional strength, or potentially a loss in strength due to increasing water content, it is possible to develop a more complete understanding of the mechanisms of climate change which drive displacement rates in the translational, metastable earthen slides that dominate the Thompson River valley. These mechanisms can be applied to comparable river valleys around the world.
Bibliographical noteFunding Information:
The authors received continued financial support and resources from Transport Canada (TC), the (Canadian) Railway Ground Hazard Research Program (RGHRP), the Canadian Rail Research Laboratory (CaRRL) and Clifton Engineering Group. These entities are supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), CP and CN.
Access to the Ripley Landslide for the research programme was graciously provided to the authors by CP and CN. Installation and monitoring of these instruments would not be possible without their ongoing support. Productive collaboration and data sharing with the Geological Survey of Canada and the British Geological Survey have been greatly appreciated as we work towards the common goal of protecting railway infrastructure. Holmes, Wilkinson, Chambers and Meldrum publish with permission of the Executive Director of the BGS (UKRI).
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- Retrogressive landslides
- Soil moisture deficit
- Variable matric suction
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology
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Supervisor: Sivakumar, V. (Supervisor), Donohue, S. (Supervisor) & Chambers, J. (External person) (Supervisor)
Student thesis: Doctoral Thesis › Doctor of Philosophy