Couverture du dossier de presse du 50ème anniversaire du BRGM à La Réunion.
© BRGM
BRGM working for La Réunion from 1974 to the present day
1970-1980: a geological map and hydrogeological directory
In the 1970s, the initial work, carried out via the French Geological Survey in Madagascar, focused on producing a complete 1:50,000-scale geological map of the island, as well as applied geology operations. A major survey of the island's groundwater was also conducted, resulting in the production of the first hydrogeological "directories" of the region and in drilling campaigns to supply drinking water, notably by exploiting the alluvial aquifer of the Rivière des Galets.
1980-1990: a pioneering approach to hazard mapping
The year 1980 was marked by the passage of Cyclone Hyacinthe. This extreme weather event, which caused 12 days of intense rain and resulted in the deaths of 25 people on La Réunion, raised awareness about the dangers of natural hazards and led to a number of studies being conducted in this field. Indeed, the first national maps of natural hazards were produced on the island, at a time when France's risk prevention policy was still in its infancy. The first hazard zones were established in Mafate, Salazie and Cilaos.
1990-2000: development of expertise in risk assessment
Over the course of this decade, BRGM developed its operations in the field of natural hazards. Studies were also conducted into the organisation of construction quarries, with the first quarry guidance plan being drawn up in 1991. Partnerships were established with the Direction Départementale de l'Équipement (Departmental Directorate for Equipment), the Office National des Forêts (French National Forestry Office) and the Departmental Council of La Réunion.
2000-2010: cyclones, coastal erosion and volcanic eruptions
The subject of natural hazards, particularly in relation to emergency situations, remained a key priority for BRGM's teams, who carried out around a hundred expert assessments each year and contributed to the creation of risk prevention plans (PPR). In 2002, Cyclone Dina hit the island, followed by Gamède, another major cyclone, in 2007. The latter broke most of the world's rainfall records and also caused extensive damage to the coastline. A great deal of work was then carried out to map and survey the coastline, resulting in the first digital models of coastal flooding and coastal erosion, etc. In 2007-2008, BRGM produced a morphosedimentological map of the seabed around Réunion's coast.
2010-2020: heliborne geophysics campaign and studies about the access to the island's cirques
To improve geological knowledge of the island, a heliborne geophysics campaign was carried out across the whole of the La Réunion region in 2014. The analysis of the electro-magnetic data provided essential information about the island's subsurface (and this data is still used today) and enabled a 3D map to be produced. Several other projects resulted from the data acquired during this campaign: mapping of material resources, exploration for new groundwater resources, map of salt-water intrusions, imaging of areas prone to landslides, etc.
2020-2024: natural risks at the centre of two major research projects
BRGM has been leading two major research projects on gravity-based and erosion phenomena, two natural risks that are particularly prevalent in La Réunion. The first project, called RenovRisk Erosion, uses geophysical studies to improve knowledge about the main internal structures of landslides. The second project, called RenovRisk Transfert, focuses on coastal risks and aims to analyse the process via which cyclone-related phenomena and risks are transferred between different natural environments, namely the atmosphere, the hydrosphere, the coastal environment and the open ocean.
The coming years: rising to new challenges
BRGM's work will continue to address the major challenges facing today's society, in partnership with local research and public service organisations and in synergy with regional framework programmes. In terms of BRGM's historical field of expertise, i.e. geology and knowledge of the subsurface, the challenge will be to acquire geological knowledge at greater subsurface depths in order to improve our understanding and management of the island's volcanic risks, and to improve our knowledge of the volcanoes' hydrothermal systems. Ultimately, the aim is to develop high-power geothermal energy facilities to produce local electricity that emits less CO2, in line with the region's energy sovereignty objectives.
