2024-01-04 18:59:05
A flooded street in the town of Arques, in Pas-de-Calais, on January 4, 2024, due to the flooding of the Aa river. DENIS CHARLET / AFP
After historic rains in November 2023 and an unprecedented rise in water levels, Pas-de-Calais is once again prey to floods. Like a scenario that repeats itself tirelessly, 169 municipalities are affected by these new floods, 500 homes are deprived of electricity and 2,000 residents have no access to drinking water, declared the prefect of Pas-de-Calais. , Jacques Billant. The department remains on red alert for floods.
Wateringues, a water evacuation system, created almost a thousand years ago in France, are nevertheless supposed to prevent flooding and protect agricultural land. But their effectiveness has been called into question since recent episodes of severe weather.
A system specific to Flanders
As ingenious as they are fragile, watering machines are best known in Belgium and the Netherlands. In France, this system covers the Calais – Dunkirk – Saint-Omer triangle, in order to protect the approximately 450,000 inhabitants from the floods of the Aa and Liane rivers. Because this area is a polder: land reclaimed from the sea and therefore located below the level of high tides.
Concretely, it is a network of 1,500 kilometers of ditches and canals which communicate with each other in order to regulate the water level of the lowlands, and if necessary, evacuate excess water towards the sea, as the remember the Intermunicipal Watering Institution (IIW). At low tide, the locks are opened in order to discharge these surpluses into the North Sea – gravity thus doing its work – while at high tide they are closed to prevent flooding of the land. In the event of excess water in the watering stations, the pumps come into action to speed up evacuation.
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Inadequacy and lack of maintenance
In September 2023, a report from the Regional Chamber of Accounts pointed “the fragility of the hydraulic system accentuated under the effects of climate change” and was concerned about the increase in population (INSEE projects more than 500,000 inhabitants in 2050), the increase in urbanized areas, the waterproofing of soils, runoff and volumes of water to be evacuated .
Also, the obsolescence of the system is pointed out: “Channels to transfer [qui peuvent être des wateringues mais aussi des voies à naviguer] are in poor condition (…). A limited number of them are likely to overflow and cause flooding., observes the court, which recommended restoration or cleaning work. An argument taken up by Allan Turpin, mayor of Andres, an affected Pas-de-Calais commune, and president of the Stop Floods Pas-de-Calais association, who deplores on LCI “banks sinking”.
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“We can no longer find the parts” for the pumps
A problem which, if resolved, is not sufficient for the councilor due to a “lack of pumping” and pumps, some of which have not been changed since “around forty years” – in November 2023, two Dutch pumps were sent as reinforcements. “Unfortunately, watering holes are difficult to maintain. Some pumps, for example, are so old that we can no longer find the parts”, declared Bertrand Ringot to France 24 in November 2023. The mayor of Gravelines and president of the IIW specifies that he has increased the institution’s budget sevenfold since 2017.
Who is responsible for this lack of maintenance? Three main players share the management of the watering holes. At the most local scale, these are the wateringue sections, small areas cut up by ditches, responsible for maintaining the wateringues. The main arteries of the network are managed by the Voies navigables de France, while the IIW is responsible for carrying out the major evacuation works and ensures their operation and maintenance.
Beyond the structural problem posed by watering holes in the event of heavy flooding, the priority, for elected officials and residents, is the immediate evacuation of the water. The Minister of Ecological Transition, Christophe Béchu, promised “exceptional responses” during a visit on Thursday to Pas-de-Calais.
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