Porto Floods
After the flood: image: Rui Manuel Farinha/ Lusa

Porto’s devastating floods: 2020 report highlighted flooding risk posed by Metro works

… but suggested flooding would be “small in magnitude and negligible”

After all the talk of “climate change” and extreme weather phenomenon being behind  apocalyptic scenes of flooding in downtown Porto last weekend, it appears the risk of flooding due to Metro works in the area was identified more than two years ago.

Says Lusa today: “The Execution Project Environmental Conformity Report (RECAPE) of the construction project for the Porto Metro Pink Line identified the possibility of floods due to the deviation of pipelines”.

The possibility was described as a “vulnerability“, but with reduced impact, says the State news agency.

The document, dated February 2020, points out the “temporary obstruction of the rainwater drainage network and temporary diversion of runoff, in particular resulting from the Vila river diversion project (with a more expressive intervention in the rainwater drainage network).

“This situation represents a vulnerability due to the possibility of originating localised floods, in situations of intense precipitation” – which is exactly what happened on Saturday: intense, if not unprecedented, precipitation. Estimates pointed to 25 litres of water having fallen per square metre in 20 minutes.

The 2020 document considered the situation represented “a negative impact, temporary, reversible, not certain but only possible, of small magnitude and negligible“.

These “additional impacts” were not mentioned in the Preliminary Study phase, in which “impacts on water lines were not mentioned”, the document adds.

And this is where things may have ‘unravelled’: had this risk been mentioned at Preliminary Study phase, the havoc wreaked last weekend may have been avoided, or at least reduced.

The municipality of Porto registered as many as 250 requests for help because of flooding in homes and public roads in less than two hours on Saturday – mainly in downtown Porto.

Deputy mayor, Filipe Araújo was one of the first who suggested works underway at the Metro in the area may have been the cause, but at the time Minister for Interior Administration José Luís Carneiro appeared more inclined to blame climate change, extreme weather phenomenon and ‘possibly’ unregulated building.

Engineers from the National Laboratory of Civil Engineering (LNEC) are now leading a study into what exactly went wrong.

Works on the city’s Pink Line taking in the stations of São Bento, Hospital Santo António, Galiza and Casa da Música, are expected to be finished by the end of 2024, says Lusa.

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