In 2021, unprecedented rainfall caused the Vesdre River to overflow and inundate the eponymous valley in southern Belgium. Thousands of people left—some temporarily, others definitively. Nearly three years later, the disaster’s damage is still felt and one question lingers: what role did climate change play?
By Morgane Anneix
A row of houses bordering the Vesdre in Chaudfontaine, March 1, 2024. 25 out of 27 would be destroyed only a week later as flood risks had been evaluated as too high© Cristina Coellen
CHAUDFONTAINE, Belgium ー Bernadette Leemans, a 50-year-old eco-consultant, knew she was moving to a flood-prone area when she rented a small, two-story brick house on the outskirts of Chaudfontaine, a former industrial town turned thermal resort, in 2018.
In July 2021, when water started rising after days of continuous rainfall, she wasn’t too worried at first. Small-scale overflows with little material damage were a common occurrence in this southern Belgian region. From locals, Leemans had learnt to treat them as an unpleasant nuisance, like a last-minute task at the end of a long office day: take the bins in so the water doesn’t knock them over and litter the street; move the car to higher ground; and get sandbags out, just in case. About 10 meters separated Leeman’s home from the Vesdre River, a usually peaceful stream running right across the main road. But as the heavy downpours persisted, the distance started shrinking.
“Still, there was this moment of initial denial. I don’t think anyone imagined the river would rise so high,” Leemans said. On the way back from parking her car on a nearby hill, she met a firefighter. “He told me we were only just receiving the water from 24 hours ago. That’s when I went ‘uh, oh,’ because I knew it was predicted to rain for another two days at least,” she said.
The weather forecast turned out to be accurate. Between July 13 and 15, an average of 150 liters per square meter—the equivalent of what typically falls during the whole of July and August combined—gushed down on the Vesdre Valley. An official report later estimated that, at its peak, the river roared through Chaudfontaine at a flow rate of 600,000 liters per second – enough to fill an Olympic swimming pool within less than five seconds. That first night, with her two cats, Bernadette Leemans took refuge on the first floor. Below her, the water almost reached the ground floor ceiling.
With 39 lives claimed, the 2021 floods were the deadliest natural disaster in recent Belgian history. In its immediate aftermath, the Internal Displacement Monitoring Centre (IDMC) recorded an estimated 16,000 displacements. For some, this was only temporary; others, like Leemans, permanently left. In Trooz, where the floods affected a record 45% of homes and public buildings, the population dwindled by nearly 500, or about 6% of inhabitants. Climate change rapidly emerged as a culprit to explain the event’s unprecedented scale.
“What struck me was how quickly people started defining themselves as Belgium’s first climate victims,” said Pierre Ozer, a geographer and professor in environmental sciences at the University of Liège. He was on the ground within 48 hours following the disaster. “For many, it was a wake-up call. Just like for Covid, we realized that this wasn’t just a ‘somewhere-else’ issue, but a global crisis that could also affect privileged European countries,” he added.
When, soon after the disaster, an attribution study drew a link between the floods and climate change, many felt validated. According to the team of 30 scientists, rising temperatures had made the rain dome that settled over a large part of Western Europe 1.2 to 9 times more likely and 3 to 19% more intense. A simple explanation lies behind the phenomenon: a warmer atmosphere can hold, and therefore suddenly release more water.
An seemingly abandoned house in the middle of Trooz. On the second floor, a sign indicated that it was for sale. © Cristina Coellen
“A lot of Europe doesn’t see itself in an extreme situation because so far, our socio-economic systems have protected people from having to move,” said Manuel Marques Pereira, who leads the climate action team at the International Organization for Migration (IOM). “But people tend to forget that this infrastructure is mostly only delaying environmental triggers of migration.”
Nevertheless, according to Ozer, the scale of the catastrophe could only be explained through the interaction of climate change with other human elements. “Climate change certainly was the trigger. But the floods only had such consequences because they happened on already fragile grounds,” said Ozer, who also serves as scientific advisor to the Hugo Observatory, a research institution on the climate-migration-politics nexus.
The floods came shortly after Belgium emerged from a Covid-19 lockdown, with mounting inflation further driving economic vulnerability in a region that is historically poor. “In the late 19th century, industrialisation led to a lot of construction in flood zones. Some houses literally have their foundations in the water,” said Jacques Teller, an urbanism and land use planning professor at the University of Liège. “Then, in the 1950s, a slightly richer population arrived and took to the plateaus and hillsides. This urbanization created pressure, and only further increased the risks for those who were stuck below, in the valley.”
“It all came down to the floods”
After the floods, and once the water had receded, Leemans rolled up her sleeves and, equipped with a simple shovel and wheelbarrow, started digging through the tons of mud that had invaded her home. For several weeks, her existence revolved around cleaning, scrubbing down the walls and saving what she could. “I wasn’t able to think further ahead than the next day,” Leemans said.
Ultimately, a sequence of chain reactions drove her to move. When the soft drinks factory across her home took up production again, the electricity generators it relied on emitted a constant, piercing buzz. “The noise was insufferable,” Leemans said. “It all came down to the floods,” she continued. “Without them, the electricity grid wouldn’t have collapsed, the plant would have continued to function normally, and the noise wouldn’t have become an issue.”
Leeman’s case illustrates well how complex and entangled migration is. Researchers still grapple to understand what prompts people to stay or leave, notably when disaster hits. For millennia, humans have moved in reaction to environmental changes, in search of better, more hospitable conditions elsewhere. But they have also adapted—or at least tried to—whilst staying rooted. A study on 516 households in the German Ahrtal, which was also heavily affected by the 2021 floods, found that place attachment and house or flat ownership significantly influenced inhabitants’ decision to stay and rebuild. As a tenant who had moved to Chaudfontaine only three years before the floods, neither applied to Leemans.
In Chaudfontaine, many houses featured “phantom messages” from people who had seemingly left the area. Text left: “Goodbye since 1968. I’ll miss you. Fabienne.” Right: “They tried to bury us. They didn’t know we were seeds.” © Cristina Coellen
But having worked in the environmental sector for over twenty years, Leemand knew that—whether climate change was involved or not—the consequences of the floods presented an opportunity. She joined climate marches, holding up a simple, black-and-white printed sign with a provocative slogan. “I’m a climate refugee,” the banner read.
“I wanted to draw attention to the hypocrisy of migration and asylum policies,” Leemans explained. “Whether in Verviers [a nearby Belgian city] or Bangladesh, we’re all in the same boat when it comes to global warming. Yet, I can freely move, whilst others have to risk their lives to escape even worse conditions.”
Although experts are cautious about establishing a causal link between climate and migration, a growing body of research attempts to quantify how rising temperatures might affect human mobility in the future. Only two months after the devastating floods, in September 2021, the World Bank released a report projecting that “climate change could force 216 million people to migrate within their own countries by 2050.” (The number doesn’t account for cross-border displacement.) Other estimates are even starker: the Intergovernmental Panel on Climate Change (IPCC) calculates that, by the end of the decade, climate-fuelled water stress might displace 700 million people on the African continent alone.
A constant question - stay, or move?
In the Vesdre Valley, nearly three years after the floods, traces of destruction are still omnipresent. It’s a world of contrasts: in Trooz, one of the worst-affected municipalities, empty homes with overflowing letter boxes and crackling façades sit next to shiny, newly renovated flats. “See that garage shop with the broken window panes? Everything was flooded, and so the owners left,” said Joséphine, an 80-year-old resident who asked only to share her first name. “I’ve lost track of where everyone went,” she said. “For sale” and “sold” signs decorated many windows, like phantoms of their former inhabitants.
The collapsed roof of a farmshed in Trooz © Cristina Coellen
There’s also the emotional scars. “It’s like for 9/11: everyone remembers what they were doing the day the floods hit,” said Valérie Constant, a warder at the local tourist office. The images haunt her to this day: cows, dead and alive, floating by in the currents; her neighbors’ wooden terrace; and cars in which she thinks people might have been trapped. “You just felt so powerless,” she said.
Constant’s home was spared; the water stopped a few meters from the front porch. Still, she now casts a worried glance at the sky every time it clouds before a rainstorm. “My son, who was eleven at the time, will look at me and ask: ‘Are the floods coming back,’” she said. “We adults might not speak it out loud, but honestly, many have the same fear.”
Climate models project that, in the future, a flood similar to the 2021 event could strike the Vesdre Valley every decade or two. The return rate for the 1.2°C cooler, pre-industrial era, was around 350 years. “The various scenarios presented by the IPCC suggest that this type of precipitation will repeat over the next ten to thirty years,” said climatologist Xavier Fettweis during his audition to the parliamentary commission on the 2021 floods. “After that, summers will be too dry and we'll face other challenges, including heatwaves and forest fires."
Valérie Constant scrolls through pictures she took in the aftermath of the floods © Cristina Coellen
For now, Constant plans to stay in Goffontaine, a neighborhood of Pepinster, where she has lived all her life.
Whereas most towns in the region are slowly recovering from the post-disaster population loss, censuses in Pepinster remain on a slight downward trajectory. To reduce future risk, the municipality has voted to build flood expansion zones, where the river can naturally flow when it rises from its banks. But this also means destroying homes and reducing housing availability, sometimes at the risk of losing more inhabitants.
Constant’s cousin Christelle belongs to those who painstakingly rebuilt after the floods. “We invested a lot to make it even nicer and more adapted than before,” said Constant, who suffers from muscular problems. But in June 2023, after new risk evaluations, the family of five learnt their house was among those set to be demolished.
“It’s like a bombshell. You reconstruct everything, and then you’re told to start all over again somewhere else,” she said. Since housing prices soared after the floods, Constant doesn’t know whether she can stay in the region.
Missing data
Today, retracing the itineraries of those who moved after the July 2021 floods remains difficult. “No one has a precise view of the areas that are still abandoned and, most importantly, where the people have gone,” said Ozer, the geographer from the Hugo Observatory. “In a way, it’s as if they had disappeared. They’ve become invisible.”
According to the Internal Displacement Monitoring Centre, this lack of monitoring is a recurring problem in Europe. “We don’t see much displacement data published systematically or in a centralized way,” said Ricardo Fal-Dutra Santos, the IDMC’s regional coordinator for Europe and Central Asia.
Although the figures for Europe are much lower than in other regions, Fal-Dutra Santos insisted on the need to put them into perspective. “We don’t know if it’s because there’s actually little displacements happening, or them just not being counted. So in a certain sense, the data is skewed,” he added.
Leemans, for her part, moved to the nearby city of Liège, some 10 kilometers from her former home in Chaudfontaine. From her flat, she can still see the same waters. Among the tributaries of the Meuse canal, which her flat overlooks, is the Vesdre. But this time, it’s all from the safety of the seventh floor.
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