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A new map showing the risk of flooding across France has been published to help combat the worsening issue, which is the country’s leading natural hazard in terms of property damage.

The – which have been compiled using data from the land, aerial images, satellite pictures, and artificial intelligence tools – is the first of its kind from geographic authority l’Institut national de l’information géographique et forestière (IGN).

One in four people live in areas that are at risk of flooding, with 16,000 communes having at least one zone inondable in them, and 11,000 communes in areas covered by prevention scheme le Plan de prévention des risques d'inondation (PPRI), the institute said.

The most at-risk areas, in terms of the percentage of residents, include:

• The Mediterranean coast 

• The Loire Valley

• Marne

• Avignon

• Some areas of the Lot-et-Garonne

The map uses new 3D mapping of the country which helps the authority to model rainfall patterns nationwide to better predict and manage flood risk.

Flooding is now the leading natural hazard in terms of the damage it causes and the number of municipalities at risk. Along with excess rainfall and overflowing rivers, flooding can also cause mudslides and damage to bridges and other important infrastructure.

“We wanted to show the extent of this flood risk, how it has changed over time with climate change, and how we can combat it,� said Sébastien Soriano, IGN director general, to the AFP.

“The risk of flooding is an unavoidable reality in France, which is preparing for a temperature rise of 4C by the end of the century. Faced with increasingly intense rainfall and a rise in the number of disasters, society is becoming aware that it must change,� the IGN states.

“This evolution marks the emergence of a culture of risk. It is no longer just a question of protecting ourselves, but of anticipating, adapting and reducing the vulnerability of the areas concerned in order to protect the population. 

“Map data is a key tool in this transition.�

Rising risk

Global warming is contributing to excess flood risk, the institute said, adding that rainfall increases by 7% for every 1C of atmospheric temperature rise.

A 15-30% increase in daily rainfall is expected across the majority of the country by 2100, the IGN said.

“In France, global warming has already led to a 12% increase in the intensity of extreme rainfall compared to the 1960s, and our climate models predict a further 10% to 15% increase in such intense rainfall by 2050,� said Benoît Thomé, director of institutional relations at forecaster Météo France, to Le Monde.

The new IGN map is therefore also aiming to help authorities “better manage waterways� and “rethink natural spaces and the role of natural solutions�, the IGN said in a press release.

“This 3D mapping [used for this map] will be incorporated into various models, such as [flood risk forecaster] Vigicrues, to predict runoff and flooding, and thus develop the country accordingly,� said Swann Lamarche, IGN partnership relations manager, to AFP.

Flood risk properties

In 2021, another interactive map was created, this time by climate science news organisation Climate Central. Based on peer-reviewed scientific papers and large datasets, it aimed to show how the world could be affected by climate change and rising water levels over the coming years and centuries.

In France, major cities including Calais, Dunkirk, and Bordeaux would be affected, as would the Mediterranean region.

Increased flood risk has not yet had a significant impact on the national property market, agents have said, particularly for homes that are near the coast, with people still choosing to overlook the risk if the home is in a sought-after location otherwise.

Check your property and insurance

Property purchasers and homeowners are also advised to check the geographical risks of an area (including flooding) on the , and check home insurance rules on issues such as flooding and natural disasters.

Water damage (dégâts des eaux) is covered in standard policies, but usually does not cover flooding, instead relating to damage from a burst pipe as opposed to heavy rainfall.

All home insurance policyholders can claim damage from exceptional weather events (évènements climatiques), including for rain, winds, ice, hail, etc. 

Specifically for storms, la garantie tempête sometimes additionally covers policyholders, depending on the insurer, which focuses more on the damage caused by strong winds. 

Certain conditions need to be met to benefit from these types of cover, such as buildings being of a ‘good construction’, and in some cases, certain safety measures being followed prior to the event. 

Some extreme weather events, including floods (as well as earthquakes, and drought damage), are not covered by standard policies. 

Instead, policyholders need to wait for a catastrophe naturelle (natural disaster) zone to be declared in their commune. 

This is usually done after government-appointed surveyors assess an area after such an event, but in some extreme cases the government or local authorities can immediately declare a natural disaster without this.

Once these communes have been listed in the Journal Officiel as natural disaster zones, homeowners have 30 days to claim (up from the standard five). In addition, insurers must pay out within three months.