Landslide Risk to Railway Operations and Resilience in the Thompson River Valley near Ashcroft, British Columbia

• Author / Creator

  Tappenden, Kristen M

• This thesis investigates the hazard frequency and associated risk posed by twelve large landslides in the Thompson River Valley south of Ashcroft, British Columbia, which are collectively referred to as the Ashcroft Thompson River landslides. The Canadian National and Canadian Pacific railways operate busy main lines within the subject 10 kilometer corridor south of the village of Ashcroft, traversing the lower portions of many of the landslides. These landslides have resulted in significant, recurring disruptions to Canada’s Class 1 railways, and affect numerous other groups located within the valley, including First Nations communities, residents of the villages of Ashcroft and Spences Bridge, salmonid populations within the Thompson River, and owners/operators of upland agricultural areas. While the Ashcroft Thompson River landslides are typically inactive or very slow moving, numerous periodic reactivations have been documented in the past 150 years, some of sufficient magnitude to temporarily dam the Thompson River. The objectives of the research are to characterize the risks posed by the Ashcroft Thompson River landslides to the Canadian railway network and to the numerous stakeholders in the Thompson River Valley, and to investigate strategies for managing the risks and improving the overall resilience of the system. The research methodology includes an examination of the history and ongoing activities of the landslides, with an emphasis on the dynamic climatic and anthropogenic factors which have contributed to the slope movements over time. Recent landslide activity in the corridor is correlated to snow pack and stream flow in the Thompson River basin. Trends in the discharge of the Thompson River over the past century are, in turn, related to the phase of the high-level climate phenomenon termed the Pacific Decadal Oscillation (PDO). An awareness of the interannual and interdecadal fluctuations in climate regimes and their hydrologic implications is presented as an essential component for contextualizing historic landslide frequency and future landslide risk. The anticipated hydrologic impacts of climate change and their potential effects on landslide activity in the corridor are also discussed. The qualitative risk assessment which follows distinguishes the different modes of failure which have been demonstrated by the landslides in the corridor, to elucidate the unique causal factors, consequences and associated risk scenarios. A risk management strategy is presented which integrates an understanding of climate factors which may portend landslide activity in the corridor, a kinematic understanding of the landslide failure modes, and an observational approach to geotechnical monitoring and inspection. It is recommended that contemplated risk reduction measures favor flexible options which would be suited to a range of future climate conditions, improve adaptive capacity through more effective anticipation and forward planning, and integrate active monitoring and regular site inspections of slope movements with effective strategies for the documentation, communication and dissemination of hazard and risk information. The economic consequences of a landside which impacts the railway infrastructure in the Thompson River Valley can grow exponentially with the duration of the outage; given the diverse cross-section of stakeholders involved, the consequences of a rapid landslide in this corridor may also include significant safety, environmental, and cultural impacts. The application of a resilience paradigm for managing critical infrastructure and enhancing a community’s ability to cope with disruptions is presented in the context of the Ashcroft Thompson River landslides. The high-consequence, low-probability nature of a rapid landslide necessitates a flexible, resilient response by all stakeholders. To this end, case studies summarizing and evaluating the risk communication and public involvement efforts in the District of North Vancouver, British Columbia, and Canmore Alberta, are presented to convey lessons learned and highlight current best practices stakeholder involvement in risk management and decision making. It is hoped that the research contributions in the area of risk management and system resilience will impact how Canada’s railway industry and its regulator will monitor and mitigate landslides along the Thompson River Valley, with broader implications for the risk management of natural hazards interacting with the built environment.

• Subjects / Keywords

  • Railway
  • Landslides
  • Risk management

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3Z31P30K

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.