Flood-prone Spain: more than one million homes built in high-risk areas

by Lorraine Williamson
flood risk areas

A study by Spanish newspaper elDiario.es shows that 4.3% of Spanish homes, most of them in the Mediterranean region, are at average risk of flooding from rivers or the sea. Furthermore, this percentage could start to increase due to climate change and more frequent torrential rains. 

The passage of DANA over the peninsula this weekend has brought back into the news the damage that can be caused by floods, which have so far killed three people. Areas hardest hit by the storm include Toledo, Madrid, Castellón and southern Tarragona. 

Furthermore, the number of buildings in Spain at risk from floods and rising seas includes at least 370,415 buildings. This is according to research carried out by elDiario.es. It used data from the Land Registry and the National Flood Mapping System. 

The system with map, which allows to consult flood-prone enclaves street by street and even house by house, analyses for the first time the situation of more than 12 million properties in Spain. It shows how entire villages lie within the perimeter of potential flooding, as well as kilometres and kilometres of new housing estates threatened by coastal flooding. 

Murcia stands out in flood-ravaged Spain 

Murcia is the city with the most houses at risk, according to calculations by elDiario.es, which assume the average or occasional probability of flooding. The figure is 60,775 homes, 28.6% of the total number of homes in the city. And newspaper archives confirm this: according to the available historical data, Murcia has experienced at least 60 periods of severe flooding in the last 100 years. It is the municipality with the most such periods recorded in official records. 

Cogesa Expats

Valladolid, Palma, Girona and Cartagena are the other major cities with more than 15,000 houses built in flood zones. And in relative terms, some 20 cities stand out, such as La Algaba, in Seville, Deltebre, in Tarragona, or Santoña, in Cantabria. These have more than 70% of their streets in flood-prone areas. The absolute record is shared by San Miguel del Pino – in Valladolid, on the banks of the Duero river – and Alfara del Patriarca – in Valencia, on the banks of the Carraixet river – both with 100% of their inhabitants in an area at risk. In Spain, there are a total of 200 places with one in five properties in this situation.  

By autonomous region, the ranking is led by the region of Murcia (17% of affected properties), followed by Cantabria (10%), Asturias (9%) and the Balearic Islands (8%). 

Building near rivers 

‘In Spain, there is a lot of building near rivers,’ says Ernest Bladé, professor at the School of Civil Engineering at the Universitat Politècnica de Catalunya (UPC) and director of the Flumen Institute. Areas adjacent to riverbeds are usually very attractive for urban development, Bladé explains. They are flat and therefore it is easier to build communication infrastructure there. ‘The problem is that we forget about floods because traditionally they have been infrequent, and for years construction has been done without taking floods into account,’ he explains.  

In Alcanar, on the coast of Tarragona, they know this all too well. After 218 litres per square metre fell on Sunday, houses and businesses were flooded for the third time in five years. ‘In the past, urban planning was not correct, with buildings in the middle of ravines and watercourses,’ complained the city’s mayor, Joan Roig, after the Llop ravine filled up and flooded. So much torrential rain is disastrous for the financial situation, the mayor said. 

Also read: Zaragoza – Ring road and school built on watercourse

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