Aux Antilles, les inondations brutales vont s'intensifier, comme les déplacements de familles [Planète Outre-mer] - Outre-mer la 1ère

Aux Antilles, les inondations brutales vont s’intensifier, comme les déplacements de familles [Planète Outre-mer] – Outre-mer la 1ère

“It is estimated that 6% of the Guadeloupe coastline currently occupied by man could become uninhabitable. We will therefore have to prepare to abandon areas in which populations will not be able to maintain themselves. All this presupposes a global relocation plan. It is today and now that we must prepare for these changes,” warns expert Virginie Duvat.



Virginie Duvat, professor of geography at the University of La Rochelle, main author of the chapter devoted to the impacts of global warming on small islands in the second part of the sixth report of the IPCC, the Intergovernmental Panel on Climate Change. Virginie Duvat is with her team on a mission to the West Indies as part of the Adaptom project. For three years, she will assess the potential of nature-based solutions to reduce coastal risks and promote adaptation to climate change in French overseas territories. The first year of this program is devoted to the West Indies.

Overseas Planet: What do you think explains the floods of April 30, 2022 in Guadeloupe?

Virginia Duvat: These phenomena of sudden flooding are explained by extremely intense rains in developed low-lying areas and in which water accumulates all the more easily as it has been sealed.

These phenomena bear witness to the planning errors that have been made in the past. It would have been necessary to envisage drainage systems to the height of the quantities of water which can accumulate in these sectors.

Virginie Duvat, geography teacher

Are these intense rains part of the phenomena that could intensify with climate change?

Virginia Duvat: Yes, we expect an increase in intense rain events, much more intense.

What are the other impacts of climate change in the West Indies?

Virginia Duvat: In addition to intense rainfall events, we can expect a rise in sea level. In Guadeloupe as in Martinique, the sea level will rise by 82 cm by 2100 if we base ourselves on the IPCC pessimistic scenario (RCP8.5). To this will be added an intensification of cyclones. These three factors together will increase the risk of flooding. In sectors like Jarry and certain districts of Pointe à Pitre which are built on very low land, there will be chronic flooding. By 2060, these areas will be subject to half-year flooding. And exposed coasts will be subject to storm surge phenomena.

In Saint Martin, Nettle Bay, after Hurricane Irma in 2017



©Virginie Duvat

Will climate change change our use of coastlines?

Virginia Duvat: Yes, due to ever more rapid coastal erosion, climate change will modify our use of the coasts. The impacts on human societies will be all the more important since the coasts of Guadeloupe and Martinique concentrate a large part of the populations, inhabitants and tourists, activities and infrastructures such as port and airport.

Erosion of the Raisins Clairs beach in Saint François in Guadeloupe

Erosion of the Raisins Clairs beach in Saint François in Guadeloupe



©Caroline MARY

Erosion of the Caravelle beach in Sainte Anne in Guadeloupe

Erosion of the Caravelle beach in Sainte Anne in Guadeloupe



©Virginie Duvat


How can we adapt today?

Virginia Duvat: To avoid flooding, drainage systems must be revised to improve the evacuation of these waters wherever there is a risk of overflow. And of course, beyond these technical solutions, wherever we are concerned by phenomena of both flooding and marine submersion, we will have to think about the relocation of human constructions inland, because some low-lying areas will no longer be habitable if we evolve on a climate scenario of relatively rapid warming.

Around a map of Guadeloupe, the geographer specializing in coastlines, Virginie Duvat and Alain Brondeau

Around a map of Guadeloupe, Virginie Duvat, the geographer specializing in coastlines and Alain Brondeau, the Overseas delegate of the Conservatoire du Littoral



©Caroline MARY

Everywhere overseas and particularly in the West Indies, there are many projects to restore mangroves and corals to limit the erosion of territories. Until now, we mainly saw engineering works. Can these nature-based solutions work?

Virginia Duvat: The coasts of Martinique and Guadeloupe are bordered in the urban areas by riprap cords which have been put in place to fix the coastline and protect the developed areas. These heavy protections are not enough to stop the erosion, sometimes they even aggravate the phenomenon. Over the past ten years, we have seen an increasing use of nature-based solutions. They consist of better protecting, restoring and even recreating coastal and marine ecosystems with regard to the protection service they provide to local populations. They are our best breakwaters against storm waves and our best protection against erosion.

Revegetation enclosures installed by the ONF in Guadeloupe

Plant species that grow naturally on the beach fix the sand and thus limit erosion. To limit trampling, the ONF has placed a re-vegetation enclosure at the Pointe des Châteaux with a sign that reads “Let’s stop erosion by helping the forest to regenerate”.



©Caroline MARY

You may have seen some of these nature-based solutions projects, what did you think of them?

Virginia Duvat: Here in Guadeloupe, there are many experimental projects of nature-based solutions. We can cite the project to maintain sargassum on the Saline beach in Le Gosier to limit its decline, carried out by the Conservatoire du Littoral and the town hall. In Jarry, the Conservatoire du littoral renatures areas of the swampy forest illegally occupied by companies which are thus better protected from flooding. The Carib Coast project consists, among other things, of revegetating the upper beaches. The ONF has placed revegetation enclosures at Pointe des Châteaux and on other beaches on the island to limit trampling so that the vegetation re-grows and can fix the sand. There are also projects to restore marine ecosystems such as the one carried out by the Grand Port Maritime which is installing eco-moorings to prevent boats from pulling out seagrass beds with their anchors. Today, we do not know how to assess the effectiveness of these nature-based solutions in the face of climate change.

The rate of warming will largely determine the chances of success of these nature-based solutions and how long they can potentially be used where they will work.

Virginie Duvat, geography teacher

A pond in Jarry

In Jarry in Guadeloupe, a pond where there was a service station illegally installed on this space before it was recovered by the Conservatoire du littoral as part of its JA-RIV program. “This service station was equipped with a pump which collected water 24 hours a day to expel it. Today, nature has taken back its rights” Alain Brondeau, Overseas delegate of the Conservatoire du Littoral



©Caroline MARY

Jarry in Guadeloupe was built on a swampy forest

Jarry in Guadeloupe was built on a swampy forest. The Jarry area, which concentrates a large part of the island’s economic activity, is particularly vulnerable to flooding and marine flooding.



©Caroline MARY


Have the public authorities and the State taken the measure of the stakes?

Virginia Duvat: The public authorities have taken the measure of the stakes in these territories. As proof, the various relocation projects that are implemented. In Martinique, the municipality of Le Prêcheur, in Guadeloupe, the municipality of Capesterre and Petit Bourg where relocation projects for families who occupy housing that goes to the sea. In these critical situations, the public authorities are aware, but in general , the adaptation efforts that are deployed are extremely insufficient and are not up to the climate challenges, so there is an imperative to move up a gear and put in place much more ambitious, proactive and cross-cutting policies to larger spatial scales. Significant investments must be made in this reorganization and this territorial revolution. Overseas territories are on the front line of impacts.

How to speed up the process?

Virginia Duvat: Today, funding for the adaptation of territories to the impacts of climate change comes mainly from public funds. They are insufficient. It is therefore now necessary to bring on stage the private actors who must take up these issues. This is all the more important since it is not just a financial imperative. The work carried out by the Conservatoire du littoral in Jarry with companies clearly shows how a public establishment must collaborate with private actors in order to be able to successfully implement its adaptation actions.

There are already many plans to move overseas populations. At Le Prêcheur in Martinique, Guadeloupe, Capesterre and Petit Bourg but also in Guyana where a district of Awala Yalimapo must be relocated and finally the village of Miquelon in Saint-Pierre and Miquelon. Do you think that population movements will increase overseas?

Virginia Duvat: “Reshoring will develop overseas, that’s for sure. I really see the current projects as small pilot projects that allow you to learn by doing, but you will have to relocate on a much larger scale than what we are doing today because it will be, for example, entire districts of Pointe à Pitre which will find themselves threatened. It is estimated that 6% of the Guadeloupe coastline occupied today by man could become uninhabitable. We will therefore have to prepare to abandon areas in which the populations will not be able to maintain themselves. All this presupposes a global relocation plan. We really need a global reflection on the scale of the territory to find the possibilities and how to articulate the relocation imperatives of the different municipalities who are going to be affected. It is today and now that we must prepare.


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