Résumé
Most of the world's coastal environments are experiencing the negative effects ofclimate change combined with anthropogenic activities. In order to limit those effects,policy makers and managers need to understand the process that is taking place onthe coast. Where the safety of goods and persons, but also the tourism economylinked to the preservation of beaches and the natural heritage of these interfaceenvironments, rich in biodiversity (mangroves, coral reefs, seagrass beds) are theprimary concerns. CARIB-COAST is an international project led by the BRGM(https://www.carib-coast.com/en/). Its ambition is to pool, co-construct anddisseminate approaches to monitoring, coastal risk prevention and adaptation toclimate change in the Caribbean. An analysis of existing monitoring practicesallowed to better constrain the needs for coastal monitoring in the Caribbeanterritories and propose a strategy based on the experiences carried out in thedifferent participating countries. In this respect, pilot sites have been identified inGuadeloupe, Martinique, Saint-Martin, Jamaïca, Puerto Rico and Trinidad andTobago to strengthen or initiate coastal monitoring approaches and assess the roleof coastal ecosystems like mangroves, seagrass and coral reefs in the protectionagainst coastal erosion. Many studies focus on Coastal vulnerability Index (CVI), oneof the predictive approaches to coastal classification by incorporating various coastalvariables. This index-based method simplifies a number of complex and interactingparameters, and is widely used to measure vulnerability of the coastlines. Given theextent of the area of interest, the diversity of pilot sites and variables to be integratedin the CVI calculation, and the intent to develop a common approach for all areas,this study has taken advantage of current available remote sensing data to constructa vulnerability index.In this study, the proposed Ecosystem-based CoastalVulnerability Index (EBCVI) involves a wide range of variables, mainly focused onecosystem characteristics, represented by diverse data types, and their contributionto coastal protection against erosion. In particular, we used remotely-sensed data tocontribute to (i) current mangrove restoration actions, (ii) the evaluation of coral reefsevolution and their role on erosion and (iii) the promotion of seagrass protection.The calculation of the EBCVI relies on:● the production of mangroves distribution maps, using high resolutionSentinel 2 data in a supervised classification approach.● the use of seagrass and coral reefs distribution and types mapsprovided by the Allen Coral Atlas● the calculation of surface metrics (texture, density, fragmentation…), fromvery high resolution Pleiades and Planetscope images, describingecosystems at a fine scale.● the application of a multi-criteria analysis to these metrics combined withother variables (geomorphology, socio-economics...) in order to mapcoastal vulnerability by assessing EBCVI values for each pilot site. Theknowledge of local partners will allow a weighting of the importance ofeach criteria in the index.This index has the potential to be used as a management tool in order to assessimpacts of climate change on Caribbean coasts through the development of existingobservatories and good practices around a common protocol, and triggering (iv) newinitiatives in the Caribbean region, enabling an appropriate implementation of shortand long term policies dedicated to coastline protection.