Alcanar has become the perfect storm, along with the Ebro Delta, the Catalan epicenter of the climate emergency. Measures must be taken to mitigate the effects of the floods, and quickly, experts interviewed agree. In the short, but also medium and long term, intervene in the floodplains near the ravines with urban development, including expropriations, but also with many other interventions.
It is necessary to take concrete measures, some of which are already in the study phase, to contain and isolate the major waterways that flow from the Montsià mountains through the ten gorges that pass through the inhabited centers of Alcanar Platja and The Houses flow into the sea from Alcanar. They are always the most affected by flooding, with a terrible mix of water, rocks, mud, branches and debris.
“It’s about reducing the risk of flooding. Whether yes or not, there will be floods, no one doubts that, but they can be mitigated,” emphasizes Roger Sauquet, professor of architecture at the UPC and member of the GREC Bombers (Collapsed Structures Group). Sauquet intervened in the last floods in Alcanar (2018 and 2021) and led a UPC study to find solutions.
The most urgent are the urban centers of Alcanar by the sea, but without forgetting other places such as La Ràpita, Ulldecona or Santa Bárbara in the same area.
Without structural measures, the increasingly frequent extreme weather phenomena will continue to cause flooding and millions of dollars in damage to public and private properties. It’s not just homes, businesses and infrastructure that are at risk.
“The water takes what belongs to it, both Alcanar and other municipalities are heirs to an urban development of the seventies without the planning tools of today.” No matter how much we warn the population, often the only option is Les Cases d’Alcanar or Alcanar The way to protect Platja is to tell the neighbors to go to the highest points of the houses. Evacuation during the downpours is impossible,” explains Rafael Prades, responsible for civil protection in the Terres de l’Ebre.
It is not a coincidence or an atavistic curse that Alcanar has suffered three floods in five years (2018, 2021 and 2023). The causes and determining factors are identified.
The orography, right by the sea and with the Montsià mountain range (764 m) behind it. Terrible urban planning, with buildings near the ravines through which the water flowing down the mountain seeks its exit to the sea. And the climate crisis, which explains why meteorological phenomena are becoming more frequent and extreme (DANA).
There is hope because there are ways to intervene, with route actions, according to experts in emergencies, architecture or the climate crisis. Of course, it is enough to put more patches or limit ourselves to rebuilding the most affected areas, as has essentially been done so far with public aid, which is scarce and delayed.
“It will be necessary to act to give more space to water, it will be necessary to convert in other ways and in some cases to dismantle, to plan and to enact new laws.” There are many measures to be implemented, we must Rethink the coast,” says Carles Ibáñez, director of the Climate Change Hotline (Eurecat) and the Center for Climate Resilience (CRC).
Greater public investment will be required. It is a complex operation between the public and private spheres, with the expropriation of houses and the exchange of private land that can now be built within the area of influence of the ravines. Injured owners must be compensated since the vast majority bought or built legally.
“As an urgent measure, we recommend using the still empty areas next to the barricades and viewing them as floodable green spaces.” They are a treasure for flood protection. But many of these areas are still considered urbanizable,” warns Sauquet (UPC and GREC-Bombers). Consideration is also being given to bringing down the barricades on agricultural land long before they reach urban centers, with compensation for affected farmers.
“It will probably be necessary to expropriate some houses, land and equipment in order to restore the water cycle.” It is the final solution that will have to be examined by a technical commission with the participation of the central government and the Generalitat,” says Joan Roig (ERC), Mayor of Alcanar.
As if they were the foundations on which this serious problem rests, the location of Alcanar and its orography. A large part of the municipal area is located directly on the sea and is at sea level, but lies directly behind it, just a few kilometers away, with the highest point at more than 700 meters above sea level.
When the torrential rains fall on the mountain, the water, which turns into several torrents, seeks its natural outflow towards the sea through the gorges. The problem is that due to the non-existent urban planning of the sixties, seventies, eighties and even nineties, it was built next to the last section of some ravines. The three most destructive gorges are Sant Jaume (Els Cases d’Alcanar), Llop (Alcanar Platja and the Alfacs campsite) and Codonyol, between Alcanar and La Ràpita.
The aim is to expropriate several dozen houses in these areas. Half a hundred was given as a guideline, but this is only an approximation. If other containment measures are applied, these will be less severe. “We plan to allow some houses to be raised by one floor, but we are committed to ensuring that in the most affected areas no one will be allowed to live on the lower floors.” In the most damaged houses, the water came back through a door and ripped everything apart with it and destroyed everything on the other side, so that next to the Alfacs campsite everything was full of water and mud,” adds Sauquet (UPC and GREC – Firefighters). .
The stark difference in elevation of 700 meters from the mountain to the sea in just under 5 kilometers multiplies the speed at which the water sinks through the gorges and the likelihood of collapse.
“The occupation of the ravines accelerates the speed of the water and increases the destructive capacity in urban areas near the coast,” adds Ibáñez (Eurecat). Gorges overflow and turn into torrential torrents, causing flooding even far away from their course, as was particularly the case in 2021.
Alcanar’s particular coastal topography has an amplifying effect when the cold drops of late summer arrive. Seawater reaches its maximum temperatures between late August and September when the DANA usually arrive. The perfect storm.
The mountain by the sea holds back the storms coming from the coast and anchors the unrest near Alcanar, increasing the rainfall. “The Montsià mountain range, very high and very close to the sea, is a key factor. The cloud cover remains anchored to the mountain, which acts as a barrier and lever; “It feeds back into the clouds and the precipitation doesn’t stop for hours,” says meteorologist Xavi Segura.
There are private settlements in flood areas that can still be built today
With the climate emergency, ocean storms are increasing and sea levels are rising, putting strain on an increasingly fragile coastline, as the Ebro Delta shows.
“We are playing with people’s lives, there is a real risk, and investments must be focused on preventive measures against floods.” The political discourse is exhausted, there is no further way out, it is necessary to go to the technical discourse once and for all to pass over,” shouts its mayor.
