British Columbia is on the verge of a major environmental and economic disaster if a major flood on the coast or Fraser River happens between now and the year 2100. A recently published flood strategy report suggest such an event could lead to between $20 billion and $30 billion in economic losses.
Phase 1 of the Lower Mainland Flood Management Strategy was released in 2016 and points to a “significant risk” of such a large flood occurring in B.C.’s Lower Mainland. Over the next 85 years, the risk of an event happening will increase due to environmental impact and climate change. Flood frequency will increase as sea levels rise.
Speaking to Canadian Underwriter this week, Steve Litke, senior program manager, watersheds and water resources with the Fraser Basin Council, said the study took into account localized and heavy rainfall, sewer backup, and large and regional scale flooding probabilities along Fraser River and the coast.
In the economic loss estimate, Litke says the study looked at potential impact on infrastructure, agriculture, buildings, and vehicles. He also says even the upper $30 billion loss is “a fairly conservative estimate” and the study does not “look very deeply at indirect economic losses related to damage and disruption of critical infrastructure.”
Litke is participating in this week’s Friday Forum webinar at the Institute for Catastrophic Loss Reduction (ICLR) where he will talk about the Phase 1 report. He will also share some details about the ongoing Phase 2 study, which includes floodplain modelling and flood mitigations for the Lower Mainland in British Columbia.
In the region, Fraser River presents a clear risk. “For some of the floodplain areas of the Fraser, people might experience two or three or four metres of floodwater,” Litke said.
Among the mitigation topics in the webinar will be:
- Diking systems and flood proofing: guiding growth out of flood-prone areas or building habitable building space above predicted floodplain levels. “So if there is a flood, there is reduced damages,” Litke said;
- Sediment management;
- Upstream storage (the upstream floodplain may store a significant amount of water so that downstream dikes may not fail); and
- Nature-based solutions, such as setting back dikes to leave more room for the river.