IN IMAGES, IN PICTURES. Five months after suffering a “heat dome”, western Canada is ravaged by flooding

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After the “heat dome”, make way for “atmospheric river”. In mid-November, the province of British Columbia in southwestern Canada suffered from extraordinary precipitation, resulting in flooding, landslides and the evacuation of thousands of people. This extreme weather phenomenon comes less than six months after the spectacular heat wave that caused the thermometer to climb to 49.5 ° C and sparked destructive fires, such as the one that ravaged the small town of Lytton, in the same province. .

As was the case in early July, a state of emergency was declared there on Wednesday, November 17, and the army was deployed the next day to help residents stranded by bad weather. “With climate change, we must respond to more frequent and intense internal emergencies “, leading to a “strong demand” assistance from the army, ruled General Wayne Eyre, quoted by AFP.

Franceinfo takes a look back at this passage from one extreme to the other, “140 days apart”, as noted on Twitter a meteorologist specializing in the region.

Rainfall records

Several records for rainfall were recorded on Sunday along the Fraser River, which starts from Vancouver and sinks east before climbing north towards Lytton: the city of Abbotsford (150,000 inhabitants) recorded 100 mm of precipitation in a day. The previous record, which dated from 1998, was 51 mm, details Canadian geologist John J. Clague, in an article published by The Conversation *. The District of Hope (where the film was shot Rambo in 1981), meanwhile, received 174 mm in one day, five times the amount received … throughout 2018. Another record was broken in the city of Chilliwack: 154.6 mm.

Faced with these data, the Canadian meteorologist Armel Castellan, quoted by Global News *, found the qualifier adapted to the situation: “Mind-boggling”. “We will probably analyze these figures in the days and weeks to come because they are truly extraordinary”, she added.

Abbotsford is 30 km from the Pacific Ocean. A video posted by a reporter for the CBC, the national television, shows that small waves are forming on the surface of the water.

These torrential rains are the result of an “atmospheric river”, a meteorological phenomenon that the magazine Science et vie described in 2019 as a “hidden climate monster”. To know “windy corridors gorged with ultra-dense water vapor which spread over approximately 400 km in width and at least 2,000 km in length, all suspended at an altitude of 1.5 km”.

According to a study published in 2020 * in the journal Nature and cited by The Weather Network *, “the formation of atmospheric rivers has increased since 1948, [ce qui] is possibly related to the warming of the sea surface temperature in the western Pacific, [lequel est] due to climate change caused by human activity. ” She estimates that the number of days marked by this phenomenon has increased by 20%.

Floods and destruction

The flooding caused by the torrential rains is visible from space, tweeted (from Earth), Canadian astronaut Chris Hadfield, sharing images from NASA.

The rainfall in recent days has caused numerous landslides, blocking access to roads and highways.

A destroyed road east of the town of Chilliwak, along the Fraser River, in British Columbia (Canada) on November 14, 2021. & nbsp; (BRITISH COLUMBIA MINISTRY OF TRANSPORTATION / AFP)

In late June and early July, the town of Merritt had welcomed survivors from the village of Lytton, 100 km further west, then ravaged by flames. This time, it is the turn of the 7000 inhabitants of Merritt to have to leave their homes, as of Monday, after the floods knocked out. the wastewater reprocessing plant.

The infrastructure has suffered particularly on the outskirts of the town. In several places, the Coquihalla Highway was washed away, British Columbia road services reported. Authorities have identified five particularly affected areas just between the towns of Hope and Merritt, some 100 kilometers away.

In August, this section of highway that connects Hope and Merritt had already had to be closed for a few days. Three months before the area was hit by floods and mudslides, two forest fires had joined on either side of this busy road. In an article devoted to bad weather, the Canadian geologist John J. Clague establishes a possible link between this first exceptional event and the severity of the damage observed this summer. Charred soils don’t absorb water as usual, he explains in The Conversation *. “It is possible that on these scorched lands, the runoff was aggravated by this phenomenon of soil hydrophobicity”, he writes.

If the torrential rains have caused rivers to rise from their beds, local meteorologists add that the rain has also helped to melt snow at high altitude in these mountainous regions, this water further swelling the rivers. At last, Canadian meteorologist Armel Castellan, cited by Global News, recalls for its part that abundant precipitation observed since mid-September has contributed to saturating the meadows with water, unable to absorb more.

Evacuations and casualties

Rescue workers were still looking for three missing people near Pemberton, north of Vancouver, which had been hit by a landslide on Thursday. There, the body of a woman was found.

After the evacuation of some 7,000 residents of Merritt on Monday, 200 people were evacuated from Hope, thanks to a specially chartered train to reach the greater suburbs of Vancouver, when the community was isolated by the rising waters and the storms. landslides. In Abbotsford, nearly 600 people were also evacuated out of the 150,000 inhabitants of the city.

Images filmed at Abbotsford, posted on Wednesday, showed farmers rescuing cattle, sometimes using jet skis. In this rural region, herders have lost all their animals.

In Merritt, Global News devoted a report Thursday to the rescue of dozens of horses, also trapped in flooded fields.

Also at Merritt, theAnimal Lifeline Emergency Response Team, a rescue service specializing in animals, managed to shelter 600 pigs stranded on the highway, local press reported.

* All links marked with an asterisk refer to articles in English.


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