On June 18, 2013, the Garonne unleashed its force and devastated everything in its path. A dozen towns in the Pyrenees succumbed to flooding and nearly 400 people had to be evacuated. An intense episode of rain, added to the melting of a significant layer of snow that had resisted since winter, overflowed its channel and flooded the Vall d’Aran region, in the province of Lleida, destroying bridges and roads and leaving thousands of people homeless. supplies.
These floods are not something exceptional in the region. In fact, approximately every 30 years, one of the rivers in this Pyrenean region overflows. This happened in 1907, 1937, 1940 and 1982. In total, more than 300 people died due to floods. The difference with the floods of 2013 is that eleven years ago, no one had lost their lives. And it is thanks to certain sensors that this region of Catalonia has installed in various river sources.
After the floods that devastated the Valencian Community and certain areas of Catalonia, and given the effectiveness of this system, the Camping Association and some Lleida Town Halls requested that the sensors be installed in all rivers. This way, these tourist facilities – most of which are in flood zones – would avoid having to close because they would have enough room to evacuate their facilities in the event of flooding. As already happened in 2013.
“These floods were special. We acted very quickly,” recalls Andreu Cortés, now mayor and then deputy mayor of Les, one of the most devastated towns. The bridge collapsed and the roads connecting this town – which constitutes the third border access point with France – remained impassable for days. In addition, 49.5% of houses in Les are built in a flood zone.
Source: Ministry of Ecological Transition, Land Registry
The Town Hall evacuated the 200 people who lived within 50 meters of the Garonne, a fifth of its total population, and transferred them to hotels far from the river just before it burst and took everything with it. As a result, only material damage was reported. “We knew what was going to happen for two days. The municipalities were warned,” recalls Jordi Gavaldà, geologist and technician from the Conselh Generau d’Aran (autonomous valley management body).
Prevention is essential in this place where disasters like this occur periodically. For this reason, in addition to the sensors that the ACA (Catalan Water Agency) and the CHE (Ebro Hydrographic Confederation) place in certain points of the rivers, the Conselh has had more complex and complete detectors for nine years in rivers. . They were placed just three months before the floods of 2013. “They were decisive,” says the Conselh.
Eisharc Jaquet is an engineer and founder of Arantec, the local company that designed them. “The problem with most sensors is that they function as water information systems and not as emergency systems,” he explains. On the other hand, those who have settled in the Aran Valley take into account the flow in real time, but are also analyzed the forecasts of rain and temperatures that can affect the snow cover, as well as the inclination of the terrain , river width and basin characteristics to determine when and where there is a risk of overflow.
“It is an ultra-personalized system which serves as an early warning of possible floods”, specifies Jaquet, who explains that “each basin is a world and has a different reaction time”. This depends on various factors such as the presence of vegetation. This acts like a sponge and gives more room to absorb than asphalt. It also depends on whether or not the river channel has been altered for development.
If the sensors detect that enough factors have been conspired, “alarms go off” and an SMS is sent to Conselh civil protection officials. Once there, politicians, technicians and security forces assess the situation and alert the municipalities. “It’s always better to warn, even if it’s a false alarm,” explains Gavaldà. Jaquet supports him. “The preventive technical tools are more than ready. What fails is human action, which sometimes does not react when it should.”
Incommunicado for days
The municipalities of Vall d’Aran knew that June 18 would be complicated. But they didn’t know it would be so bad. They expected that in addition to precipitation, a lot of water would come down from the thaw. What surprised them was that, as in Valencia with DANA, much more rain fell than expected and the accumulation became historic in cities like Vielha.
The river’s flow doubled in some places, causing hydraulic dams to overflow and burst. This caused “a domino effect” which multiplied the force of the water and washed away roads and bridges.
“We started to see that something was wrong in the morning, when we saw that the river was going higher than it should, even with the alert they sent us,” recalls- he of Andreu Cortés. It was 2:00 p.m. when they decided to evacuate its inhabitants. And it was just in time, because shortly after, water flooded Les, filling its streets with mud, leaving residents without services and destroying road access.
“It was a surreal sight. Fortunately for our culture of prevention,” explains the mayor, referring to the existence of drinking water wells, gas reserves and electric batteries which allow the entire city to survive for days. This was vital because, although other towns received help, they were completely isolated and could only be rescued by a few neighbors who acted as volunteer firefighters.
“The main accesses, which lead to France, were repaired in a few days, but the rest of the roads, like the bridge, took months to restore,” recalls Cortés. In fact, some consequences are still being paid today. “The city was filled with mud and people, with good intentions, pulled out the water hoses. But the mud, when drying, creates a clog worse than cement,” adds the mayor. This rendered most of the city’s sewers unusable and even today, ten years later, the municipality has still not issued a tender for the final repair works.
“We learned a lot from this episode,” we explain to the Conselh. All the sensors were torn out by the water but were replaced shortly after, with some improvements. In addition, they optimized the alert system and communication with the municipalities. “Since then, we have had a few alerts and we have been able to act quickly,” explains Jaquet.
They have been monitoring all the rivers in the valley for years and have also expanded to other communities such as Extremadura or Castilla y León, but this is a type of prevention that “is still in its early stages” , he laments.
This engineer believes that administrations should “get their act together”, especially since the most basic measurement systems, which take into account the flow of the river on the one hand and weather forecasts on the other, are becoming increasingly fail. And “the indicators are evolving”.
Climate change is changing trends and making forecasting methods, built from historical data, less accurate. This is why Jaquet is now working with devices integrating artificial intelligence and learning on the fly, generating “much more concrete and reliable” predictions.
More citizen awareness
In the days following disasters like those in the Aran Valley or Valencia, we talk a lot about prevention. But experts in the field, like the geologist Joan Manuel Vilaplana, regret that “even if now everyone has prevention in their mouths, in a few months we will forget about it.” Note that between this type of event there are long periods of calm that must be taken advantage of to work.
He emphasizes that the development of technical alert tools is important, but “it must be accompanied by awareness.” Vilaplana lacks good coordination of civil protection with administrations and political leaders and training for the population in risk areas. “Let’s do more drills, like for fires, so people know what to do and, more importantly, what not to do, in times of risk.”
It ensures that floods and floods cannot be avoided, but their impacts can be minimized. It is for this reason that the College of Geologists of Catalonia is committed to studying river basins and installing swimming pools or containment tanks like those that already exist in cities like Barcelona.
But for Vilaplana, the most important question is: “what do we do with urban planning?” The expert undertakes to “deconstruct” certain buildings and relocate those which are the most vulnerable, “even if people look bad”. The problem is that there are areas like the Aran Valley where many municipalities have a significant proportion of housing located in flood zones. From Les (49.5%), to Esterri d’Àneu (89.5%), via Llavorsí or Rialp (38.2%).
“We live in a valley. Homes are where they can be. We cannot build on slopes, that is why we live with a great culture of prevention and mutual aid,” explains Cortés. Residents of this town of fewer than 1,000 people spent days shoveling mud, sharing food and rebuilding streets. “Families who hadn’t spoken for a long time gave each other a helping hand.”
They had a common goal, which was not just to reclaim their city. Less than 10 days after the tragedy, Les celebrated its major holidays and the municipality had to be ready. “They were strange celebrations, but we were able to do them. It was the first step towards normality,” recalls the mayor.
