Soil erosion, ground subsidance, and structural damage to a public square occurred just shoreward of a retaining seawall in Alert Bay after high rainfall events.
Observation by Tom Okey:
Soil erosion, ground subsidance, and structural damage to a public square occurred just shoreward of a retaining seawall in Alert Bay after high rainfall events. This seawall and public square has has been in place for decades, as indicated by installed memorial dedications in this public square just north of the Alert Bay Visitor's Centre. This surface and underground erosion and land subsidence was likely caused by underground material movement that occurred when high volumes surface runoff and groundwater pooled behind the retaining wall during these rainfall events.
High rainfall events are increasing at this location due to climate change as illustrated at climatedata.ca [https://climatedata.ca/explore/location/?loc=JBOIS&location-select-temperature=tx_max&location-select-precipitation=r20mm&location-select-other=frost_days].
Modelling by Jacob and Owen (2021) [https://doi.org/10.1016/j.geomorph.2021.107921] indicated, "Up to almost 400% increases in the frequency of shallow landslides under the RCP 8.5 scenario by the 2080s." In this coastal rainforest region with steep slopes, high levels of erosion of all types should be expected during this century and beyond including types of erosion that damage infrastructure, as observed in the present contribution.
Literature cited
Matthias Jakob and Trevor Owen. 2021. Projected effects of climate change on shallow landslides, North Shore Mountains, Vancouver, Canada. Geomorphology, Volume 393, 15 November 2021, 107921
Comment from LEO.ai:
The observation of erosion and land subsidence in Alert Bay following a high rainfall event is a stark reminder of the increasing vulnerability of coastal infrastructure to extreme weather events, which are becoming more frequent and intense due to climate change. The damage to the public square and the potential threat to the retaining seawall highlight the need for communities to reassess the resilience of existing structures in light of these changing conditions. It is important for local authorities and planners to consider adaptive measures that can mitigate the risks associated with soil erosion and landslides, such as improving drainage systems, reinforcing or redesigning seawalls, and implementing early warning systems. Additionally, the integration of green infrastructure, which utilizes natural processes to manage water and create more resilient landscapes, could be a valuable strategy in coastal areas like Alert Bay. The use of vegetation, permeable surfaces, and other natural features can help absorb rainwater, reduce runoff, and stabilize soil, thereby reducing the potential for erosion and landslides. As we continue to witness the impacts of climate change on our environment, proactive and innovative approaches to infrastructure design and land management will be crucial in safeguarding communities and preserving the natural beauty of places like Alert Bay.
