In response to ongoing concerns about landslides on the steep slopes above Cowichan Lake, the Cowichan Valley Regional District has released updated landslide hazard mapping in the Youbou area.
In 2019, the CVRD completed a number of natural hazard risk assessments as part of its Climate Adaptation Program.
One of these assessments identified high risks to both people and property from landslides on the steep slopes above Cowichan Lake.
While the assessment identified a number of properties in potential hazard areas, site-level geotechnical assessments were recommended for future development.
The CVRD worked with Palmer Environmental Consulting Group and Stantec Consulting to refine and update the landslide hazard mapping.
Through modeling over 68,000 simulated landslides, the consultants mapped the likelihood and damage from such landslides and were able to identify a limit of modeled run out, beyond which the risk of a landslide causing damage is very low.
The updated mapping has resulted in a reduced hazard rating for a number of properties previously identified in the 2019 assessment.
The debris flow modelling was made possible through the acquisition of high-resolution LiDAR imagery, and shows the furthest down slope a landslide would travel.
The updated landslide hazard mapping will be used to inform planning and development in the Youbou area.
Going forward, proposed development within identified hazard areas would require additional geotechnical analysis before development can proceed.
The CVRD is exploring the potential to extend this mapping to other areas of potential landslide hazard within the region.
The Youbou landslide hazard mapping report is available on the CVRD website at www.cvrd.bc.ca/hazards, as well as other information and resources for a variety of natural hazard awareness and preparedness.
Affected property owners are receiving direct correspondence by mail from the CVRD, and are encouraged to contact CVRD Environmental Services division with questions or concerns.