Alcanar has become the perfect storm, the Catalan epicenter of the climate emergency together with the Ebro delta. Action must be taken to mitigate the effects of the floods and it must be done quickly, agree the experts consulted. Intervene in the short but also in the medium and long term urbanistically in the flood zones near the ravines, including with expropriations, but with many other interventions.
It is necessary to apply concrete measures, some already in the study phase, to contain and laminate the large avenues of water launched from the Montsià mountain range through the ten ravines that flow into the sea passing through the inhabited centers of Alcanar Platja and The Houses of Alcanar. They are always the most affected by floods, with a terrible mix of water, stones, mud, branches and rubbish.
“It’s about reducing the risk of flooding, there will be floods whether yes or not, no one has any doubts about that, but they can be mitigated”, highlights Roger Sauquet, professor of Architecture at the UPC and member of the GREC-Bombers (Group of Collapsed Structures). 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 localities such as La Ràpita, Ulldecona or Santa Bàrbara, in the same area.
If no action is taken on the structural side, extreme weather phenomena, which are increasingly frequent, will continue to cause floods 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 is its own, 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, many times the only way to protect Les Cases d’Alcanar or Alcanar Platja is to tell the neighbors to go to high points of the houses, evacuation during the downpours is impossible”, reasons Rafael Prades, responsible for Civil Protection in the Terres de l’Ebre.
It is not by chance or by any atavistic curse that Alcanar has suffered three floods in five years (2018, 2021 and 2023). The causes and determining factors have been identified.
The orography, next to the sea, and with the Montsià mountain range (764 m.) behind. Terrible urban planning, with buildings close to the ravines through which the water rushing down the mountain seeks its exit to the sea. And the climate crisis, which explains why meteorological phenomena are becoming more frequent and more 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 to limit yourself to rebuilding the most affected areas, as has basically been done until now with the scarce and late public aid.
“It is necessary to act to give more space to the water, it will be necessary to rebuild in a different way and deconstruct in some cases, plan and make new legislation. There are many measures to implement, we need to rethink the coast”, says Carles Ibáñez, director of the Climate Change Hotline (Eurecat) and the Center for Climate Resilience (CRC).
More abundant public investments will be needed. It is a complex action, between the public and private spheres, with expropriations of houses and the exchange of private land that can now be developed in the area of ??influence of the ravines. Damaged owners will have to be compensated because the vast majority bought or built legally.
“We recommend as an urgent measure that the still empty spaces next to the barricades be used and that they be considered floodable green areas. They are a treasure for flood mitigation. But many of these areas are still qualified as urbanisable”, warns Sauquet (UPC and GREC-Bombers). It is also being studied to use agricultural estates to laminate the barrancades long before they reach the urban centers, with compensations for the affected farmers.
“It will probably be necessary to expropriate some houses, plots and equipment to restore the water circuit. It is the definitive solution, which must be studied by a technical commission with the involvement 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 is based, the location of Alcanar and its orography. Much of the municipal area is attached to the sea, at zero level, but it has right behind the Montsià mountain range, a few kilometers away, with the highest point at more than 700 meters.
When the torrential rains fall on the mountain, the water, turned into multiple torrents, seeks the natural exit to the sea through the ravines. The problem is that due to the non-existent urban planning of the sixties, seventies, eighties and even nineties, it has been built up next to the final stretch of some of the ravines. The three most destructive ravines are Sant Jaume (Els Cases d’Alcanar), Llop (Alcanar Platja and the Alfacs campsite) and Codonyol, between Alcanar and La Ràpita.
It aims to expropriate several dozen houses in these areas. Fifty has been given as a reference figure, but it is only an approximation. If other containment measures are applied, they will be fewer. “We plan to allow some houses to be raised one more floor, but oblige that no one can live on the lower floors in the most affected areas. In the most severely damaged houses, the water came back in through a door and took everything out and destroyed everything on the other side, leaving everything full of water and mud next to the Alfacs campsite”, adds Sauquet (UPC and GREC- Firefighters).
The sharp difference in level, of 700 meters from the mountain to the sea in barely 5 kilometers, multiplies the speed with which the water descends through the ravines and the probabilities of collapse.
“The occupation of ravines accelerates the speed of water and increases the capacity for destruction in urbanized areas near the coast”, adds Ibáñez (Eurecat). Ravines overflow and turn into raging torrents that cause floods also far from their course, as happened especially in 2021.
The particular coastal orography of Alcanar has a potentiating effect when the cold drops of late summer arrive. The sea water reaches its maximum temperatures between the end of August and September, when the DANA usually arrive. The perfect storm.
The mountain, next to the sea, retains the storms coming from the coast and anchors the disturbances near Alcanar, which amplifies the precipitation. “The mountain range of Montsià, very high and very close to the sea, is a key factor. Cloudiness remains anchored to the mountain, which acts as a barrier and lever; it feeds back into the clouds and the precipitation does not stop for hours”, says meteorologist Xavi Segura.
With the climate emergency, maritime storms are getting stronger and the sea level higher, a fact that punishes an increasingly fragile coastal front, as has been evidenced in the Ebro delta.
“We are playing with people’s lives, there is a real risk, investment must be focused on preventive measures for floods. The political discourse is exhausted, it has no further recourse, it is necessary to move once and for all to the technical discourse”, cries its mayor.
