B.C.’s West Coast has always been prone to earthquakes. But as the floods, wildfires and record-breaking heat wave of 2021 underscored, it’s also increasingly at risk of catastrophic damage from extreme weather.
Those natural weather cycles, which have been amplified in scale and frequency by global warming, combine with a growing population that puts more people and infrastructure in the way of raging rivers, fires and ocean tides.
Between Nov. 13 and Nov. 15, 2021, an atmospheric river dumped 252 millimetres (10 inches) of rain on Hope, nearly as much on the Coquihalla Summit and 172 millimetres in Abbotsford.
That caused the Sumas River to burst its banks, overtop dikes, swamp drainage systems and flood the Fraser Valley and the TransCanada Highway that runs through it.
The deluge came after a record summer heat wave that dried out soil and increased wildfires, which likely exacerbated the flooding and landslides.
The deluge wiped out highways, bridges and railway lines, leaving the Lower Mainland cut off from the rest of the world for several days, and killed five people travelling the Duffey Lake Road (Highway 99) south of Lillooet when their vehicles were washed from the road in a major landslide.
It has been alleged that the fatal landslide on Highway 99 may have been triggered by steep slopes destabilized by old abandoned logging roads.
The flooding resulted in a three-week precautionary shutdown of the Trans Mountain pipeline, which supplies the Lower Mainland with most of its gasoline and diesel.
The flooding required major road and bridge repairs in 10 critical areas, including the Coquihalla Highway, where seven bridges were cut and 20 sections of highway severely damaged in a 130-kilometre stretch between of Hope and Merritt.
It took 35 days for temporary repairs to the Coquihalla Highway to allow commercial and emergency vehicles through, and two months to reopen it to general traffic on January 19, 2022.
Nearly a year later, work on permanent repairs to restore the highway to full four-lane capacity is still underway.
Canadian Pacific Raillway (TSX:CP) reported 30 sections of track in B.C.’s Thompson and Cascade subdivisions were damaged by flooding. CP managed to restore rail service between Kamloops and Vancouver by Nov. 23.
The Ministry of Transportation currently estimates the cost of rebuilding Highways 1, 5 and 8 to be $1 billion.
It may be that the November floods were a once in 100-year event unlikely to be repeated again in anyone’s lifetime. Or, they could become more frequent, as climate change drives greater severity and unpredictability of extreme weather events, in which case the provincial government will need to harden transportation infrastructure as part of its climate adaptation plans.
One way to harden transportation infrastructure against flooding is to replace culverts that divert streams under roads with bridges or at least make the culverts wider. Culverts can become choked with runoff, mud and debris, causing streams to flood highways. Bridges provide more space for streams to swell.
“It’s initially a more costly solution to put in a bridge or something like that, but you wouldn’t necessarily have those issues in the future,” said Kees Lokman, associate professor of landscape architecture at the University of British Columbia.
He laments the fact that $5 billion in emergency funding from the federal government only allowed for roads to be repaired to current standards.
“I think that’s a major mistake,” Lokman said. “We saw a lot of damage to highways and railroads because culverts were under-sized and they were basically blown out and then took out major parts of the road as well. If we don’t want to see that in the future, what we should do is replace many of these culverts with bridges.
“In recovery mode, you’re just trying to put some Band-Aids on a wound. You’re not preventing yourself from getting hurt again.”
Joanna Eyquem, managing director for climate-resilient infrastructure at the Intact Centre on Climate Adaptation (University of Waterloo), said hardening infrastructure against future damage from flooding isn’t really the solution.
“I think we learned we cannot necessarily engineer ourselves out of flood risks,” she said.
She pointed to Resilient Pathways, a recent report that urges the B.C. government to come up with a new model for managing watersheds.
“I was happy to see in the Resilient Pathways report there’s very much a recommendation to go to a more strategic level for flood management – not just looking at patching things and building things higher and bigger and stronger, but actually looking at the mechanisms of why it’s flooding and seeing whether we can work with the natural systems of the watershed to reduce flood risks.
“What we found is, B.C. really doesn’t have a good governance structure for watershed management, whereas other provinces have a much better governance system,” Eyquem said. “The Fraser Basin Council does a good job of bringing people together in facilitation and education, but they don’t have any power.”
Resilient Pathways concludes that the current “governance mechanism and budgeting for disaster risk management in all hazards is built on emergency response and recovery approaches of the past. As a result, the design of policies, funding and programs are mostly reactive – including to the most recent disaster events in B.C.”
When assessing all the various risks to B .C . from climate change, the risk of catastrophic flooding was ranked a “low likelihood” in the government’s 2019 Preliminary Strategic Climate Risk Assessment. The report deemed severe wildfires, seasonal water shortages, ocean acidification and long-term water shortages to be higher climate change-related risks.
“Severe riverine flooding and severe coastal storm surge risk events would have among the highest overall consequences, but their relatively low likelihood reduces their overall risk relative to other events,” the 2019 report noted.
In addition to a better governance model for water management, Lokman and Eyquem said B.C. forestry practices also need to be considered as part of longterm adaptation. Clearcuts and logging roads can weaken mountain slopes above highways and railways, setting them up to slip in heavy rains.
B.C.’s 2022 budget commits $500 million to a Climate Preparedness and Adaptation Strategy, which includes “new standards for design and construction of resource roads that include future climate considerations” and “significant investments in nature-based solutions.”
It also includes:
- a flood strategy and flood resilience plan;
- increased funding for the River Forecast Centre; and
- increased investments in flood mapping.
In its 2021 budget, the Canadian government committed $1.4 billion over 12 years for a Disaster Mitigation and Adaptation Fund, with $64 million over three years to complete flood maps in high-risk areas. ■
