PhD – futurisks

Mirna BADILLO

An integrated framework to assess compound climate risks to small islands habitability (2023-2026 ; WP1/WP3/WP4)

Supervisor(s): Virginie Duvat, Professor of coastal geography, La Rochelle Université, LIENSs ; Gonéri Le Cozannet, Researcher, BRGM ; Jérémy Rohmer, Researcher, BRGM

Funding: 100% FUTURISKS

Atoll islands will be increasingly affected by climate-related changes, such as sea level rise, rising temperatures, and ocean acidification. These changes will simultaneously affect multiple dimensions of atoll island systems (environmental, social and economic), challenging their resilience. This research aims to better understand the complex interactions between climatic and non-climatic factors that influence the habitability of these islands. It proposes the development of an integrated model, based on Bayesian networks, to assess the future impacts of climate change on key dimensions of habitability (Duvat et al., 2021), such as food security, access to freshwater, the availability of habitable land, and economic activities.

Lila BAHROUN

Supervisor(s): Héloïse Michaud, Researcher, SHOM, Frédéric Bouchette, Professor, Université de Montpellier, Géosciences Montpellier, and Yann Krien, Professor assistant, LEGOS)

Financement: 50% FUTURISKS + 40% SHOM + 10% Géosciences Montpellier

Overseas coastlines are environments particularly exposed to coastal flooding hazards. They are exposed to extreme weather and ocean phenomena, such as cyclones, and are facing increasing vulnerability in a climate change context. Rising sea level, coral reef deterioration, and intensification of extreme events are among the factors exacerbating vulnerability. These territories also present significant human, economic, and environmental stakes, which therefore implies amplified risks.

However, there is in those specific environments a lack of knowledge on physical processes leading to those flooding events. These areas contain a very wide range of geomorphological environments (sandy beaches, rocky beaches, reefs, lagoons and coastal developments). This project focuses on the least documented environments: lagoons and reefs. The aim is to understand and predict wave transformation and the impact on water levels at the coast, by pursuing numerical developments on phase-resolved models, as well as the analysis of in-situ and satellite data. Data and models will complement each other to improve our understanding of processes and ultimately the realism of an operational model for all types of environment.

Hermitage-les-Bains beach (photo from Mai-Linh Doan)

Johanna BARROS

The relocation of assets and activities in response to coastal erosion and marine submersion risks in Martinique and Guadeloupe: from policy implementation to social reception (2024-2027 ; WP4)

Supervisor(s): Catherine MEUR-FEREC, Professor of geography, Université de Bretagne Occidentale, LETG, Carola KLOECK, Professor of political sciences, Sciences Po Paris, CERI

Funding:

In the face of worsening coastal erosion and marine submersion risks in the French Caribbean, relocation is increasingly discussed as a climate change adaptation strategy. This retreat strategy—still marginal in practice—raises significant legal, social, political and territorial challenges, especially in island contexts. In Martinique and Guadeloupe, land constraints linked to coastal concentration, and the specific case of the “bande des 50 pas géométriques”—a colonial legacy where many residents live without legal property rights—make implementation particularly complex.

This thesis examines how relocation is being implemented in Guadeloupe and Martinique through various mechanisms (slum clearance programs, pilot projects, local initiatives) and at different stages of progress. It focuses on how affected residents receive, contest or appropriate these policies, through the lens of their personal experiences, risk perceptions, residential trajectories, and relationships with public institutions.

By combining the analysis of institutional frameworks with a study of social reception, this research seeks to understand under what conditions relocation can—or cannot—become a legitimate and sustainable response to the growing challenges of coastal adaptation in French overseas territories.

Bel-Air district exposed to cliff erosion, Petit-Bourg, Guadeloupe (Petit-Bourg town hall)

Axelle GAFFET

Contributions of exceptional distant-source swells to past sea submersions in French Overseas Territories (2022-2025 ; WP1)

Supervisor(s): Xavier Bertin, Senior researcher CNRS, La Rochelle Université, LIENSs ; Damien Sous, Professor assistant, Université de Pau et des pays de l’Adour, SIAME ; Gaëtan Dufour, Project manager at Créocéan

Funding: 100% CIFRE CREOCEAN

Due to the concentration of populations and associated activities in coastal areas, the increase in coastal hazards and the degradation of coral reefs linked to global change, tropical islands will face an alarming increase in coastal risks in the coming decades. Major submersion events can occur in the wake of a tropical cyclone, but also as a result of exceptional distant swells, a phenomenon little known until now. Over the past decade, understanding of the contribution of waves to extreme sea levels has progressed enormously, thanks to studies combining field observations and high-resolution numerical simulations. The representation of tropical sea states must be improved and the the major events of the past decades need to be revisited, to better understand and quantify the importance of setup and infragravity waves in the associated marine submersions.

Mila GEINDRE

Wave transformation processes in coral reef environments (2023-2026 ; WP2)

Supervisor(s): France FLOC’H, Associate Professor, Université de Bretagne Occidentale, Geo-Ocean (UMR 6538) ; Damien SOUS, Associate Professor à l’école d’ingénieurs SeaTech and research, Institut Méditerranéen d’Océanologie (MIO) de l’Université de Toulon

Funding: 50% FUTURISKS + 50% UBO

This phd thesis aims to improve the spectral parameterization of key processes involved in wave transformation over coral reefs, based on observational data. It specifically focuses on friction, depth-induced breaking, and nonlinear energy transfers. These processes are closely linked to the incident wave hydrodynamics (wave height, period, water depth, etc.) and to the multi-scale geomorphological features of reef systems (reef type, slope, roughness, benthic cover, etc.).

Maëlys GIRAULT

The reconstruction of trajectories of exposure and vulnerability to support coastal adaptation to climate change: application to the French Pacific islands (New Caledonia; French Polynesia) (2023-2024 ; WP3)

Supervisor(s): Virginie Duvat Professor of coastal geography, La Rochelle Université, LIENSs ; Alexandre Magnan, Researcher, Cawthron Institute

Funding: 100% FUTURISKS

The study proposes to demonstrate the importance of long-term history for the analysis of adaptation to climate change through two aspects: the reconstruction of Trajectories of exposure and vulnerability and the investigation of structural and long-term barriers to the governance of adaptation. This deep contextualisation effort should ensure fair and adapted adaptation practices. The analysis focuses on the management of current and future coastal risks of erosion, marine submersion, flooding and the combination of these pressures in two French Pacific territories: New Caledonia and French Polynesia.

Alice JACOBEE

Socio-cultural Habitability for Climate Change Adaptation on the Coastal Areas of New Caledonia

Supervisor(s): Virginie Duvat Professor of coastal geography, La Rochelle Université, LIENSs ; Alexandre Magnan, Researcher, Cawthron Institute

Funding: 100% ADEME

Living in coastal areas depends on many conditions that are highly sensitive to climatic hazards: cyclones, rainfall, marine heatwaves, droughts, and sea-level rise. These phenomena lead to flooding, shoreline retreat, and coral bleaching, all of which coastal populations must adapt to. Yet, research on habitability has largely focused on physical, technical, or economic criteria, without sufficiently integrating socio-cultural dimensions, which are essential to the way people inhabit a place. Moreover, the concept has long been framed from the perspective of temperate Europe, which set the standards by which the habitability of tropical territories was assessed.

This thesis proposes to reframe habitability from the perspective of the inhabitants of tropical environments in New Caledonia. It seeks to promote dialogue between inhabitants, scientists, and institutions around three key areas: (i) identifying the socio-cultural factors of habitability, (ii) analyzing their role in exposure and vulnerability to climate change, and (iii) exploring contrasting visions of the future of these territories. The objective is to produce a methodological tool capable of capturing the socio-cultural contextuality of the territories, in order to support actors in developing climate adaptation strategies that are culturally grounded and scientifically robust.

Lola ORMIERES

Analysis of Storm Surges and Coastal Flooding Caused by Cyclones in the French Tropical Islands Over the Past Four Decades (2023-2026 ; WP2)

Supervisor(s): Xavier Bertin, Senior researcher CNRS, La Rochelle Université, LIENSs ; Franck Dollique, Professor, Université des Antilles, IRD, BOREA MNHN ; Yann Krien, Assistant professor, LEGOS

Funding: 100% FUTURISKS

As tropical islands face increasing hazards from extreme sea levels and marine submersion due to climate change, sea level rise, possible intensifying cyclones, and the degradation of coral reefs, this research aims to better understand the key processes driving coastal risks such as marine submersion. The study will combine the analysis of both observational data and numerical simulations. While atmospheric storm surge is relatively well understood, the contribution of wave energy dissipation at the coast to water level along with its interactions with complex features such as rough seabeds (e.g., reefs), currents, and tides remains less studied and poorly understood. Using data from recent field surveys (e.g., Mayotte 2023, Guadeloupe 2017), the project will investigate the physical mechanisms influencing coastal mean water levels during past extreme events, supported by coupled wave–hydrodynamic modeling.

Anni SCHLÜTER

Evolutions des risques de submersion marine dans les iles tropicales françaises au cours du 21ème siècle

Supervisor(s): Xavier Bertin, Senior researcher CNRS, La Rochelle Université, LIENSs ; Kevin Martin, researcher, CNRS, LIENSs ; Virginie Duvat, Professor of coastal geography, La Rochelle Université, LIENSs

Funding: 50% FUTURISKS + 50% La Rochelle Université

Aline ZRIBI

Representativeness and uncertainties of the cyclone hazard in the French Overseas Territories (2023-2026 ; WP1)

Aline Zribi

Supervisor(s): Xavier Bertin, Senior researcher CNRS, La Rochelle Université, LIENSs ; Swen Jullien, Researcher, IFREMER, LOPS ; Guillaume Dodet, Researcher, IFREMER, LOPS

Funding: 50% FUTURISKS + 50% IFREMER

The French Overseas Territories located in tropical zones are particularly exposed to tropical cyclones, which are responsible for violent winds, heavy rainfall, extreme waves and marine submersion. These are complex phenomena (stochastic aspect, highly coupled dynamics, multi-scale interactions, etc.) that remain difficult to characterise, even a posteriori. The aim of this thesis is to reconstruct several major cyclonic events that have occurred since the 1980s, in order to analyse their characteristics and assess the uncertainties associated with the cyclonic hazard in these territories.