Flooding in British Columbia is more of a human failure than a natural disaster


Opinion: Dikes give a false sense of security, and for decades governments ignored warnings that almost all CBs were on the verge of failure.

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As British Columbians have tragically learned over the past few weeks, catastrophic flooding is not just too much rain falling too quickly. It is a confluence of factors, not the least of which is human failure.

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Long before climate change, people began to massively alter landscapes and disrupt water flows with dykes, dams, diversions and improvements. In a mountainous province like this, there is no choice but to build in valleys and river basins with the corollary that when this man-made infrastructure fails, it often fails dramatically.

Dike ruptures were the most obvious and completely preventable cause of the current flooding which has forced nearly 15,000 people to evacuate, put 7,400 more on evacuation alert and resulted in the death of an estimated 628,000 chickens, 12,000 pigs, 420 dairy cows and bees with 110 urticaria.

“Dikes give us a false sense of security,” said Brent Ward, co-director of the Natural Hazards Research Center at Simon Fraser University. “They are supposed to protect us. But they always fail.

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Until recently, the geology professor said, “Strong engineering solutions were the way to go… We thought we could control nature.

More than 200 dikes cover more than 1,100 kilometers. They are supposed to protect 160,000 hectares of land, some of the most valuable. In the Lower Mainland alone, there are 600 km of dikes, 400 flood chambers and 100 pumping stations.

But worse than the thought of the masters of the universe is the fact that for years engineers have warned governments that systems are on the verge of collapse or have already failed.

More recently, the warning came from the Fraser Basin Council. In March, he concluded that most dikes do not meet provincial standards and predicted their failure during relatively weak storms, not to mention three successive atmospheric rivers.

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Six years earlier, the summary of the 2015 Lower Mainland Dyke Assessment for the Government of British Columbia got right to the point.

“The dikes generally do not meet current provincial standards and none fully meet or exceed the standards,” he said. “Fifty-four percent have ridge profiles below design flood levels. One would expect 71% of the dikes to fail when they flow.

And, just in case you were wondering what could happen in an earthquake, engineers said none of them meet seismic standards along their length and 53% are unstable from the point of. seismic view.

This 233 page report from Northwest Hydraulic Consultants and Thurber Engineering made an equally straightforward and correct prediction. Nothing would likely be done to address these shortcomings.

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“Given the high cost of land, raising dikes can be prohibitively expensive, even in places where improvements are feasible from a geotechnical and land use standpoint… larger improvements.

In addition to the recent failure of the Fraser Valley dikes, those meant to protect Merritt from flooding every 200 years only lasted a few hours before the Coldwater River broke free. He rushed to the floodplain, flooded the sewage treatment system, and made a new path.

“I’ve never seen anything like it,” Ward said of the changes downstream from Merritt to Spences Bridge. “There is very little road left. The river has become really wide and wide, and the erosive power of the river can cause it to migrate sideways.

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As the water recedes, he expects the river to settle into a new permanent channel. What does this mean for the roads, bridges, power lines, houses and everything else built along the old canal? Will they have to be moved?

“That’s the $ 64,000 question,” he said. “We still don’t know how climate change is evolving. People are talking about a new normal, but it is not yet normal. We still haven’t reached equilibrium, so it’s hard to predict the size of a culvert to install, the amount of rip-rap that will keep the river from digging roads or even flows.

The problem with dikes is that they leave swollen rivers with nowhere to go because they were almost always built on top of the river banks. Then, once the water pours out, it gets trapped in the floodplain with no way to retreat.

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“What we have to start thinking about is that in some areas the levees will have to be pushed back and houses and properties will have to be purchased,” Ward said. “And I don’t know if we have the political will to do it.”

These may be more like $ 64 billion or $ 64 billion questions, especially since just five years ago the Fraser Basin Council estimated that the damage alone caused by a flood every 200 years could reach $ 30 billion.

As for political will, perhaps this flood was the tipping point after years of governments ignoring scientists and engineers. When it came to choosing between paying now or paying later, most had stuck to the electoral calendar, hoped for the best, and continued to underfund the construction, maintenance and repair of all kinds of infrastructure. essential.

All the while, they also continued to bow to development pressures, paving aquifers and waterways, and increasingly approving the construction of everything from airports and hospitals to high-density housing. in the floodplains.

For decades, political calculation has favored all levels of government.

But, now in British Columbia, the bills are finally coming due.

[email protected]

twitter: @bramham_daphne

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