Paris, France – Operation Sequana: What Would Happen if the Seine Burst Its Banks

Two videos have been released online showing the extent of flood damage if the Seine bursts its banks. The shocking footage shows water rising to heights of three metres, and chronicles the expected destruction, including 435,000 homes flooded, increased health risks and expected damage costs as high as 30 billion Euros.

The last devastating floods in Paris occurred in 1910, but the threat of flooding in Île-de-France is near constant and has prompted Parisian officials to fully test the city’s preparedness and response to flooding from the River Seine in an 11 day exercise called “Operation Sequana”.

Half a Million Homes Flooded, Damage Costs of €30 Billion

The videos have been released by the Institut d’Aménagement et d’Urbanisme (IAU), and show even tall buildings almost completely submerged in flood waters. The IAU predict that 435,000 homes will be flooded if the river bursts its banks, creating lakes that will cover urban areas. This means that twenty percent of social housing will be devastated, and the costs may run as high as 30 billion Euros. Two areas in particular, Hauts-de-Seine and Val-de-Marnem, will be the worst affected.

Warning Systems

The upside at present is that, if flooding does occur, Paris will have a few days to prepare because of warning systems that are presently working well. This will give officials time to move civilians to safer areas before the waters hit.

Operation Sequana

In order to fully prepare themselves for the floods and the consequences, Parisian officials are running an exercise between the 7th and 18th March 2016 called Operation Sequana. This test will allow police and public services to better anticipate the damage, and fully assess the systems that are currently in place, and work on response times.

The operation will be tested to the highest level. The European Union will be included in the decisions of the operation, as well as the Interministerial Crisis Centre, down to local authorities and private institutions.


Flood Map

The IAU have released an interactive map which goes into detail each area that will be hit, and how bad the floods will be. Ninety eight percent of Alfortville will be covered in flood waters, and the city centre itself will be swamped three metres deep. The IAU are calling the event a “100-year flood”, with the northernmost parts of the city being the worst areas hit.


The IAU have also predicted that the bridges along the Seine from Gennevilliers to La Défense will be completely submerged, which will affect flood response and rescue times. Staff at Libération have said that they would be under a meter of water, and that electricity in the city will be gone. Clean water facilities will be compromised and rubbish treatment systems will be damaged.

The other health risk of this level of flooding in this area will be the emergence of approximately one million rats from cellars and sewers. The trains in the Métro will also be marooned. Efforts have already been put in place to protect older buildings and valuable artefacts. Staff at the Louvre have an evacuation plan for the most prized pieces of artwork to be relocated.

The videos and maps of the predicted flooding can be found on the local authority websites. Residents in each area are advised to research their respective areas – what the damage will be and what the evacuation plan is for when the floods occur.

Videos – Simulation of What Would Happen if The Seine Burst its Banks