Publications scientifiques

Le projet relatif à la reconstruction et au contrôle de la série analogique des hauteurs d’eau observées à Saint-Nazaire, financé par le MEEM, la région Pays de Loire et par le Shom, a débuté le 19 août 2013. Cette étude s’inscrit dans le cadre du programme international GLOSS (Global Sea Level Observing System) de la Commission océanographique intergouvernementale (COI) de l’UNESCO et du SOERE – SO SONEL.

Le Passage du Gois est une chaussée submergée à chaque marée. Il permet de relier le continent à l’île de Noirmoutier à marée basse en traversant la Baie de Bourgneuf. L’érosion constatée le long de la chaussée côté Sud remet en cause sa pérennité. Une analyse des processus hydro-sédimentaires à l’origine de cette érosion a été réalisée pour la DREAL Pays-de-la-Loire dans le cadre d’un projet de classement du site. Le Gois est à l’origine une édification sédimentaire issue d’un hydrodynamisme particulier dans la baie.

The question of the impacts of climate change and sea level rise on small islands is currently much discussed. The many thousands of Pacific islands in their different contexts (geodynamic, climatic, etc.) and the insufficient data available explain why it is difficult to clearly discern the specific role of climate change in the recent evolution of these islands. To address this question, we investigated the recent changes affecting 21 islets in New Caledonia's lagoon.

Filamentous sulfur bacteria of the genus Beggiatoa form large mats covering the sediment in the shallow waters of a Guadeloupean mangrove (French West Indies). The abundance of these bacteria varies over the year and their trophic role may, therefore, also vary. We investigated this variation by conducting a survey examining the stable isotopic compositions of four grazers and four food sources during nine sampling sessions in three different periods of the year.

Severe thunderstorms associated with large hail are among the most important perils in several European regions. Due to the local-scale extent of hail-affected areas and a lack of appropriate observing systems in most regions, hailstorms are not captured accurately and comprehensively, which makes statistical analysis of their frequency or climatology more difficult. Various studies have been conducted so far to describe and analyze the frequency of hailstorms or related impacts.

There are two related measures of sea level, the absolute sea level, which is the increase in the sea level in an absolute reference frame, and relative sea level, which is the increase in sea level recorded by tide gauges. The first measure is a rather abstract computation, far from being reliable, and is preferred by activists and politicians for no scientific reason. For local and global problems it is better to use local tide gauge data. Proper coastal management should be based on proved measurements of sea level.

Storm tide (combination of storm surge and the astronomical tide) flooding is a natural hazard with significant global social and economic consequences. For this reason, government agencies and stakeholders need storm tide flood maps to determine population and infrastructure at risk to present and future levels of inundation. Computer models of varying complexity are able to produce regional-scale storm tide flood maps and current model types are either static or dynamic in their implementation.

This study aims to quantify the vertical motions driving the decadal coastline mobility and their uncertainty at global scale. Multisatellite altimetry is combined with tide gauges and Global Positioning System (GPS) observations to evaluate the marine and crustal components of relative sea level variations. Vertical land motions and sea level variations are estimated simultaneously over the past 20 years for a network of 886 ground stations, with accuracies better than 1.7 mm/yr.