Scientists push for swift intervention to shield coasts from storm surges and rising seas

With sea levels expected to rise between 50 and 100 centimeters by 2100 and violent storms to become ever more frequent, swift intervention is needed to minimize the risk of flooding along the Catalan coast.

That is the warning from researchers at the Blanes Center for Advanced Studies (CEAB-CSIC) and UPC Barcelona Tech, speaking to the Catalan News Agency (ACN) five years on Storm Gloria, which caused widespread flooding in Catalonia in 2020.

Scientists have identified in particular "hot spots" that require action, namely the Ebre, Llobregat and Tordera deltas, the Maresme coastline and urban beaches, including those in Barcelona.

They propose combining natural solutions – such as dunes or wetlands – with concrete structures, and deem it "essential" to conduct a study on coastal flood risk.

Storm Gloria

January 20 marks five years since the start of Gloria, one of the strongest storms to hit Catalonia in recent years.

For three days, there were winds of up to 80 kilometres per hour, waves seven metres high, and heavy rain and snowfall.

The effects on the population were devastating.

Four people lost their lives in Catalonia, numerous seafront promenades and piers were damaged or submerged, and farmers experienced significant crop losses.

Several rivers burst their banks – including the Ter, the Fluvià and the Tordera – and in southern Catalonia, seawater pushed several kilometers inland into the Ebre delta, leading to the disappearance of the Trabucador Bar, a narrow sandbar six kilometers long located at the mouth of the river.

'Urgency faded'

"In the first years after the event, it seemed there was a great sense of urgency and a need to take action, but shortly after, seeing that the phenomenon did not recur, the urgency faded," Jordi Pagès, researcher at the Centre for Advanced Studies of Blanes (CEAB-CSIC), told ACN.

Agustín Sánchez-Arcilla, director of the UPC's Maritime Engineering Laboratory, stated that although "work has been done, "it is not enough.

"We will never be sufficiently prepared for the acceleration of climate change that will take place in the second half of this century," he said.

Increasingly violent storms, rising sea levels

Experts have pointed out that although the three days of Storm Gloria were exceptional, United Nations climate change reports reveal that such events will continue to occur in Catalonia.

In fact, Pagès noted that studies show the "magnitude and intensity" of these phenomena will increase in the coming years.

"What’s most concerning is the strength of these storms," said Pagès, who predicts much "more intense hailstorms, rain, and marine storms."

As if that weren't enough, Pagès stated that due to global warming, sea levels are expected to rise by half a meter by 2100. "It will be much easier for the sea to push further inland with any storm or small swell, causing flooding," he said. 

Sánchez-Arcilla provided further details, pointing out that UPC is working with two possible scenarios: one intermediate and one more pessimistic.

"The range of average sea levels we are considering is 30 centimeters by 2050 in both models, but it varies for 2100, ranging from 80 centimeters to a meter," he explained.

"If we wait until the risk level rises enough that the average sea level affects the entire coastline, we won’t have the workforce, the funding, the sand, or the stones to restore everything.

Therefore, we need to act now. And we are behind," said the UPC researcher.

Ebre delta and Maresme coast

The researchers highlighted engineered coastlines – such as those along the Maresme – urban beaches, and the Ebre, Llobregat, and Tordera river deltas as areas that require urgent intervention.

"The Catalan government knows this, the Spanish government knows it too, but the problem is that there are differences of opinion between the two," Pagès said.

He pointed out that the "regression" of the Maresme coastline is "very evident," but acknowledged that "the amount of population and infrastructure that would be affected has been exaggerated."

In terms of solutions, Sánchez-Arcilla said that in areas with "enough space," the most efficient option would be to rely on nature.

"We are using dunes with vegetation for the exposed beach, a proposal currently being tested in the Ebre delta with Spain's environment ministry; wetlands and coastal lagoons for intertidal beaches near the waterline, and seagrass meadows for submerged beaches," he explained.

In the specific case of Maresme, he acknowledged that the solution most likely involves moving the railway and the road inland.

Pagès warned that the deadly floods in Valencia last year have to act as a warning, that "emergency systems and infrastructure need to be prepared."