OLIG: coastal observatory of the islands of Guadeloupe

The need

This Observatory is part of France’s national strategy for integrated coastline management, adopted in 2012. Its aim is to fill the gap in knowledge about coastal dynamics in order to better anticipate coastal risks and provide reliable information for the implementation of coastline management policies. 

The results

As the Observatory's technical partner, BRGM organises campaigns for collecting topo-bathymetric data at sites that are representative of the Guadeloupe coastline. The Observatory also provides a framework for carrying out expert assessments at the request of government departments.

Ten sites in Guadeloupe, all remarkable for their historical dynamics, are currently being monitored. These include open sandy beaches (La Perle), reef beaches (Raisins Clairs, Autre Bord), pebble beaches (Simaho, Anse Caraïbe) and cliffs (Carangaise). The degree of anthropisation of the sites monitored also varies, with some sites heavily constrained by human developments (beach in the market town of Sainte-Anne) and others that are in a more natural state (Sainte-Claire beach). Measurement campaigns are carried out twice a year, with a monitoring protocol adapted to the nature of each site. These measurements include:

• Differential GPS monitoring of reference topo-bathymetric profiles;
• Differential GPS monitoring of the coastline and the limit of vegetation;
• Photogrammetric monitoring by drones;
• Regular video monitoring of the coastline.

Generally speaking, the observations made show a wide range of trends between the different sectors. While long-term changes in the coastline show chronic retreat on sandy beaches, in the short term, annual and seasonal changes may vary depending on the nature and geography of the site being studied.