Why is northern France so vulnerable to treacherous flooding?

Two months after unprecedented rains submerged parts of northern France, thousands of residents whose homes had just dried out have been hit once again. Outdated water management systems are proving no match for the deluge brought about by rising sea levels and other climate impacts.

The flooded town hall square of Arques, in northern France, on January 4, 2024. AFP - DENIS CHARLET

All eyes are on the Aa river in the department of Pas-de-Calais. It's close to bursting its banks as it reaches the same record levels as last November.

Areas surrounding the river have been give France's highest flood alert warning, with rain that started on Sunday continuing to devastate low-lying communities.

While no large-scale evacuations are planned, businesses have been closed as the streets of some towns are transformed into mini rivers accessible only by boat. Some 10,000 homes are without electricity.

The local prefecture said rescue workers have carried out 450 interventions, with more than 370 people evacuated as of Thursday morning.

Flooding, again

As water levels rise, so too does the anger of people in communities whose homes are still drying out from the massive November floods and who are still negotiating insurance claims.

In Blendecques, a small town some 50 kilometres inland from Calais, RFI reporter Natanael Vittan visited a flooded street with a sign proudly announcing the creation of a basin to manage rainwater.

The Aa Delta region is below sea level and depends on a system of pumps, canals and ditches, known as wateringues, to manage flooding.

But heavy rains and rising sea levels due to climate change have overwhelmed the drainage network, causing even areas that are far from waterways to flood.

The regional auditor said the sea level around Dunkirk had increased by 9 centimetres between 1957 and 2017.

And with a growing population in the region and new developments, riverbanks have been built up and inlets closed off – depriving rivers of natural outlets.

All options on table

To address the immediate flooding, four extra pumps have been brought to the region from elsewhere in France. A further eight are on route from the Netherlands, the Czech Republic and Slovakia.

Local officials are calling for the renovation of the wateringue system.

Meanwhile Environment Minister Christophe Bechu, who toured the flooded areas on Thursday, said every option was on the table for discussion, including revoking building permits for flood-prone areas.