Geological map of Ile-de-France.
BRGM’s Division for the Paris Region is based in Paris. It has several staff in Paris and Orléans, who specialise in groundwater, geothermal resources, soil and groundwater pollution, material resources, natural risks and waste management.
France’s leading region
With 12 million people and covering an area of 12,000 km2, the Paris Region accounts for 19% of the French population.
It has eight départements: Essonne (91), Hauts-de-Seine (92), Paris (75), Seine-et-Marne (77), Seine-Saint-Denis (93), Val-de-Marne (94), Val-d'Oise (95) and Yvelines (78).
Although the region is highly urbanised – 21% of it is built up – agricultural land accounts for 50% of the regional land area, with an additional 28% being covered in woodland and forest.
As a cultural and intellectual metropolis and scientific and urban hub, the Paris Region accounts for 28% of France’s gross domestic product, with seven competitiveness clusters and many leading companies in the automotive, aeronautics, printing, electronics, pharmaceutical and food-processing sectors. Forty percent of French researchers work in the region, making the region unique in Europe for its creative and innovative capacity.
The spatial-planning and economic objectives of the region have been set out in the regional master plan for economic development, innovation and internationalisation (SRDEII) and in the regional master plan for the Paris Region (SDRIF), to which BRGM is contributing expertise in its core areas of specialisation.
Public and private partners
BRGM has extensive experience of partnerships working on projects to help shape public policy, carry out public and private research in response to industrial requirements and conduct training aimed at every level of spatial planning and decision-making in the region: DRIEE, Seine-Normandie water agency (AESN), Eau de Paris, Regional Council, ADEME, Departmental Councils, ARS, DDTs, Ville de Paris, Établissements Publics d’Aménagement, Société du Grand Paris, Institut d’Aménagement et d’Urbanisme, inter-municipalities and trade associations.
BRGM also works with private companies of all sizes to develop methodologies and undertake research, development and innovative projects to support their fields of activity.
What's new in the Paris region?
Natural resources: groundwater protection and sustainable management
Because of the Paris basin’s sedimentary context, several aquifers are superimposed, representing a key resource requiring protection from overexploitation and pollution, even though groundwater accounts for just 35% of the drinking water supply versus 65% for surface water.
The objectives of the 11th programme of the Seine-Normandie water agency (AESN) and of the master plan for water development and management (SDAGE) are still mainly to improve the quality of water bodies through the protection of catchments against diffuse and industrial pollution.
Climate change adaptation is another major challenge as a variety of water uses need to be met (e.g. agricultural, industrial and drinking water supply).
Conflicting claims for the use of underground space, energy extraction, water resources for the supply of drinking water, irrigation, industrial uses and what to do about contaminated sites and soils are set to be major issues in the coming years.
Extract from the 3D geological model of the Paris Basin, with the geological map overlaid onto the digital terrain model (Paris, 2000).
BRGM's involvement and responses
Following an agreement between the regional and interdepartmental authority for the environment and energy (DRIEE), BRGM and AESN, BRGM is conducting multiple operations in connection with the qualitative and quantitative management of groundwater in the Seine-Normandie basin.
This work aims to improve the assessment of the status of water and the pressures it is under and refine the scope of the actions undertaken under the water agency’s programme of measures.
A project to establish a zoning of groundwater bodies was undertaken in the basin using the BDLISA Level 3 repository. This pilot operation, which opens up various possibilities, e.g. for optimising monitoring networks and identifying pressures/impacts, could be extended to other basins.
At the same time, the implementation of QUALINET – a statistical and multi-criteria computing tool coupled with an R-BD-GIS mapping tool for assessing groundwater body status and quality changes – is enabling BRGM to investigate the variables and pressures explaining the status of groundwater bodies with regard to the objectives of the European Framework Directive. This tool assists managers by providing support in identifying and extracting outliers in piezometric and chemical data, using increasingly complex methods, from comparing data with bound values which should not be exceeded to reviewing neighbouring values around a measured point.
The Seine-Normandie SIGES website (Information System for Groundwater Management) is dedicated to groundwater management in the Seine-Normandie basin and promotes the dissemination of hydrogeological knowledge to different audiences. It contains:
- groundwater data for the basin;
- georeferenced databases and associated map-based documents;
- videos and animations.
To prevent low water levels in regional rivers, BRGM has conducted several studies that have highlighted the importance of groundwater contribution to river flows in the upstream basin of the Seine, and the value of implementing forecasting models.
These have led to the development of tools to aid minimum stream flow prediction/management.
With regard to the protection of water resources, BRGM is considering providing support with the permanent closure of two former deep boreholes in the Albian aquifer, identified in the SDAGE as a key resource that should be preserved.
As part of the third regional plan for health and the environment, BRGM is providing support with the assessment of the potential impact on groundwater of the region's considerable industrial past.
- Monitoring using the legacy groundwater level monitoring network, including measurement, remote transmission and databanking of water level data for the Seine-Normandie basin aquifers – AFB
- Hydrological Situation Bulletin for the Seine-Normandie basin
- Support to water policing services (DRIEE)
Energy: development of geothermal energy
The improvement of energy efficiency as set out in the climate-air-energy plans at local and regional level (PCAET) should lead to a significant increase in the use of alternative energies such as geothermal energy. Groundwater resources are particularly crucial and extensive in the region. They include:
- shallow aquifers at depths of up to 200 m, mainly in Quaternary and Tertiary sands, sandstones, chalks and limestones. Their yield can vary, reaching or even exceeding 100 m3/h, making it possible to carry out major operations with heat pumps for service-sector activities and collective accommodation.
- deep aquifers at depths of up to 2,000 m (Dogger, Triassic and Lusitanian). Such aquifers, especially the Dogger reservoir – highly mineralised but with an excellent yield – have been tapped for the development of geothermal district heating systems. The Dogger aquifer is being exploited using the ‘doublet’ technology, which uses a closed loop, with one production well and one injection well; a single doublet system can supply 3,000 to 6,000 housing units.
However, the geothermal potential of the Albian, Lusitanian and Triassic formations remains to be clarified as possible alternatives to the Dogger.
Furthermore, geological and regulatory contexts are conducive to the development of heat pumps on vertical exchangers.
A geothermal well in the Paris basin (Coulommiers, 2011).
© CFG Services - C. Lecoutre
BRGM's involvement and responses
A study to evaluate the development potential of geothermal energy was carried out under the regional climate-air-energy plan (SRCAE). The study was co-funded by ADEME, the Regional Council for the Paris Region and BRGM, and may be updated. Work in partnership with the École Normale Supérieure Paris Orsay to improve knowledge of the Albian is being considered.
The issue of re-injection in sands (including Ypresian and Albian) for geothermal energy is also a concern for industry players.
Because of the exceptional aquifer formed by the Dogger strata with temperatures of 70°C, the Paris Region is in an ideal position to develop geothermal energy; BRGM has been supporting this since the 1980s.
Despite temperatures ranging from 45°C to 60°C, the Lusitanian aquifer has not yet been exploited. It could become an alternative to the Dogger aquifer in eastern Paris.
The potential of the aquifer formed by Triassic strata also remains to be identified.
Concerning minor geothermal areas, a map showing regulatory zoning was released at the end of 2017/beginning of 2018. This identifies the geological risks associated with open- or closed-loop geothermal systems.
- Decision-making tool for geothermal heat pumps (ADEME, ARENE, BRGM)
Geology: spatial planning and support for stakeholders
The Greater Paris project and its implications in the context of the Paris Region master plan (SDRIF) are major challenges until 2030. The development of transport networks and the building of many new homes while minimising urban sprawl will lead to the use of more underground space and this should be better understood.
The sustainable city project will need to ensure the city consumes less, but more efficiently, to protect green areas and improve the living environment, while tackling climate change. The ‘Greater Paris’ metropolis was created in 2016. It includes Paris and the départements of the inner suburbs.
Understanding different areas and the daily realities and needs of communities who inhabit them is necessary for this project to be carried out successfully and for progress to be made towards a circular economy.
BRGM's involvement and responses
To address the challenges of the sustainable city, BRGM will draw on several areas of expertise in transport, housing, the management of excavated earth and natural risks.
The building of housing on a large scale will increase the demand for materials, especially aggregates for concrete manufacturing. As well as reducing consumption by increasing the efficiency of building techniques and recycling materials from demolition sites, the Paris Region will need to find similar resources within the region.
High-quality alluvial materials, especially in the Seine valley, have been intensively exploited and are now in short supply.
Gypsum is still mined today in Seine-et-Marne and Val d'Oise. Sparnacian plastic clays are used for the ceramics and refractory materials industries, in the south of Seine-et-Marne in particular.
Discussions with DRIEE are underway under the regional quarry master plan to update the regional resource map in line with future housing and infrastructure needs in the Paris Region (for the Paris 2024 Olympics).
Under the PREDEC (regional plan for the prevention and management of waste from building and civil engineering sites), BRGM could support the current approach by assessing the volume of subsurface earth that could be generated to build 70,000 housing units and improve the management of building site waste through multi-criteria approaches.
The management of excavated materials remains a topical issue. Today soils are characterised by taking samples to advise what should be done with them (e.g. recovery or landfill) and the associated costs. This is a huge challenge because of the volumes involved – 41 million m3 – and their economic implications. Several important issues remain unresolved. The chemical and mineralogical characterisation of excavated material and its connection with urban geochemical baselines is an area to which BRGM could contribute. This information is critical for the Paris Region when determining what to do with excavated material.
In the environmental field, a regional historical inventory (IHR) of former industrial and service-sector sites conducted by BRGM across the eight départements has revealed several environmental black spots, for example where there is high exposure to health hazards. BRGM’s multi-criteria and interdisciplinary approaches could be used to support the sustainable reclamation of wastelands.
The information acquired by public and private operators essentially concerns land sections. Taking a more comprehensive, three-dimensional perspective would provide useful geological information to planners, especially with regard to depths from just below the surface (0–50 m) to 100 m. A 3D subsurface map covering the footprint of the Greater Paris project would be valuable to improve knowledge and help planners take subsurface risks into account.
- Reflecting on the urban piezometric network concept;
- Developing databases for analytical data from classified and contaminated sites (AESN, MTES, BRGM);
- Third-party expert assessment of site remediation projects;
- Mapping of the clay soil shrinking and swelling hazard for seven départements (DDT, MTES);
- Geological model of regional subsurface strata (especially gypsum-bearing layers);
- Geological model of Tertiary aquifers in the Paris basin.