Pays de la Loire

BRGM has offices in every region of mainland France and in the French Overseas Territories, in order to meet the needs of its regional partners and help them deal with specific local challenges. Presentation of the activities carried out by BRGM's Regional Division for the Pays de la Loire.
Geological map of the Pays de la Loire

Geological map of the Pays de la Loire.

© BRGM

Based in Nantes, BRGM’s Regional Division for the Pays de la Loire has a team of nine staff, including a geologist, a geomatics expert, several hydrogeologists and environmentalists, who are working in partnership with local and regional stakeholders and providing the technical support they need.

A region with strong population growth

The Pays de la Loire is the 8th largest French region in terms of its population, estimated at 3.7 million across five départements: Loire-Atlantique, Maine-et-Loire, Mayenne, Sarthe and Vendée. The region is particularly attractive and increases in population by more than 30,000 every year.

The region consists mostly of highly tectonised, ancient bedrock belonging to the Armorican Massif, with sedimentary overburden along its north-east and south edges, which belong respectively to the Paris and Aquitaine basins.

In economic terms, key influences are the industrial axis along the Loire estuary from Nantes to Saint-Nazaire and the development centre of Le Mans, benefiting from the proximity of the Paris region. The agricultural sector is strong and the Pays de la Loire is the second largest region in France for the value of its agricultural production. Lastly, the coastline is a key feature of the region, attracting many tourists.

The economic and spatial-planning objectives of the Pays de la Loire have been set out in the regional master plan for economic development, innovation and internationalisation (SRDEII) and the regional master plan for spatial planning, sustainable development and territorial equality (SRADDET), to which BRGM contributes expertise in its core areas of specialisation.

Public and private partners

BRGM has extensive experience of both public and private partnerships. We work on projects to help shape public policy, public and private research in response to industrial requirements, and training for every level of spatial planning and decision-making in the region, including decentralised government departments (e.g. DREAL, ARS, DDTM, DDT and prefectures), local and regional authorities (e.g. the Region, cities and intermunicipalities, local public corporations and Departmental Councils), the Loire-Bretagne water agency and the region’s universities.

BRGM also occasionally works with private companies to develop methodologies for research, development and innovation aimed at supporting their various fields of activity.

Practical information

Water sampling for the qualitative and quantitative monitoring of water from the acid mine-drainage, Loire-Atlantique

Natural resources: monitoring groundwater quantity and quality

BRGM carries out studies on water resources and develops tools for managing and protecting them.

The challenges

Because of the variety of groundwater uses (e.g. for the supply of drinking water and the agricultural and industrial sectors) and roles for maintaining the functions of hydrosystems (e.g. wetlands and river systems), the management of groundwater brings major challenges both in terms of quantity (e.g. management of low water periods and conflicting uses) and quality (e.g. diffuse pollution).

A branch of the Loire in low water in the Saumur region

A branch of the Loire in low water in the Saumur region (Maine-et-Loire, 2007).

© BRGM - François Michel

BRGM's involvement and responses

BRGM is working in partnership with local and regional authorities (e.g. Nantes Métropole and Departmental Councils), trade associations (e.g. Syndicat Mixte du SAGE Authion), government agencies and decentralised government departments (e.g. DDTM and ARS), and water agencies (AFB and Loire-Bretagne water agency) to carry out studies on water resources and develop tools for managing and protecting them:

  • Monitoring and early-warning networks
  • Resource characterisation studies
  • Assessment of the vulnerability of aquifers
  • Digital resource models and support for their management
  • In particular, BRGM is managing the network for the monitoring of groundwater resources used for the supply of drinking water in Maine-et-Loire and is carrying out studies on diffuse pollution, including to identify the contamination of the Longué-Jumelles catchment basin by phytosanitary products.
Saprolite from a laterite profile, Vendée

Urban planning for sustainable cities

BRGM provides decision-making support tools for the development of urban and peri-urban areas.

The challenges

Urban developments, particularly in large cities, such as Nantes Métropole and Angers Loire Métropole, are increasingly integrating the optimisation and reuse of land and underground spaces, particularly for making cities more sustainable, resilient and frugal through the reuse of former wasteland, the management of urban water resources, the use of soil and underground materials, and geothermal energy.

Rehabilitation of the Île Beaulieu district, Nantes, France.

Rehabilitation of the Île Beaulieu district, Nantes, France.

© BRGM

BRGM's involvement and responses

BRGM operates through agreements with local and regional authorities (e.g. CARENE and Nantes Métropole) and their public local planning corporations (e.g. SAMOA and Nantes Aménagement). Its work covers all issues relating to the soil and subsurface and is focused on providing decision-making support tools for the development of urban and peri-urban areas:

  • Inventory and characterisation of potential historical and current sources of contamination
  • Identifying natural and anthropogenic sources of contaminants in urban soils
  • Management of wasteland
  • The circular economy, and especially the reuse of excavated materials
  • Expert audits and consulting concerning the characterisation of different types of pollution
  • Support for water management in urban contexts
  • Assessment of the geothermal potential
  • BRGM’s work in this area focuses on:
  • Identifying potential sources of pollution and characterising the quality of urban soils so that these can be reused by Nantes Métropole districts.
  • Integrating groundwater in urban development: assessing the rainwater infiltration potential and considering aquifers when planning underground developments.
Autumn storm, Atlantic

Coastal risks: addressing coastal erosion to support communities

BRGM assists government departments and local and regional authorities by providing multi-faceted support for sustainable coastal management.

The challenges

The Pays de la Loire coastline stretches over 450 km, including 215 km of beaches. It is densely populated, particularly in the summer, when its population increases dramatically. The prevention of coastal risks and most notably, the management of land areas to address coastal erosion are key challenges.

Houses damaged by dune erosion at Tranche-sur-Mer, in the wake of the Xynthia storm in Vendée, W France

Houses damaged by dune erosion at Tranche-sur-Mer, in the wake of the Xynthia storm (Vendée, W France, 2010).

© BRGM - Rodrigo Pedreros

BRGM's involvement and responses

BRGM assists government departments and local and regional authorities by providing multi-faceted support for sustainable coastal management:

  • Coastline monitoring
  • Characterising coastal hazards and drawing up hazard maps for risk prevention plans
  • Assessing the impact of coastal structures
  • Adapting to climate change

BRGM is involved in a variety of ways, for example by:

  • Contributing to the coastal observatory of the Océan-Marais-de-Monts intermunicipality
  • Identifying and mapping hazards caused by rocky cliffs and banks in Loire-Atlantique and Vendée
  • Characterising the structure of sandy shorelines (SIBLES project)
Entrance to La grotte à Madame, Loire Atlantique

Geology: support for stakeholders

BRGM identifies and maps subterranean cavities. It carries out stability diagnoses of cavities and cliffs and assesses associated hazards.

The challenges

The history and structure of geological formations have determined the existence and exploitability of mineral raw materials: mining may well be a thing of the past, but in the Loire basin, geological deposits provide many exploitable materials, such as crushed hard rock aggregates for the construction industry and clays for making bricks and tiles.

The soil and subsurface can also generate risks for people’s lives and their possessions, such as caused by rockfalls from cliffs along the Loir and Loire valleys. Furthermore, in some areas, the ground may have been weakened by subterranean cavities, such as quarries, cave dwellings and cellars (e.g. the hillsides around Saumur).

Lastly, loose earth containing certain types of clays can damage homes if the clay shrinks and swells due to successive droughts (the so-called drought hazard).

Rockfall at La Chartre-sur-le-Loir, Sarthe, France

Rockfall at La Chartre-sur-le-Loir, Sarthe, France.

© BRGM

BRGM's involvement and responses

BRGM identifies and maps subterranean cavities. It carries out stability diagnoses of cavities and cliffs and assesses associated hazards.

Recent work includes:

  • Mapping subterranean cavities and assessing associated hazards (e.g. caused by slate quarries near Angers)
  • Mapping clay shrinkage and swelling hazards for each of the region's départements
  • Supporting DREAL with the regional quarries master plan
A tributary of the Loire at low water, Maine-et-Loire

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