Dem'Eaux: improving our knowledge of the water volumes that can be sustainably abstracted from the Roussillon coastal aquifer
The Roussillon plain is bordered by the Pyrenees to the west, the Corbières massif to the north and the Mediterranean to the east.
© Laura Baillet
Located between the sea and the mountains in an area where increasing needs for water are affecting the available resource, this aquifer will be studied until 2019 in order to better understand its properties and constraints in the context of climate change.
The ultimate aim of this project, entitled Dem'Eaux Roussillon, is to gain knowledge of the volumes of water that can be sustainably abstracted from the different layers of the aquifer. This knowledge will be based on the use of a 3-dimensional real-time resource management tool to be developed as part of the project.
Groundwater provides 90% of the drinking water supply in the former Languedoc-Roussillon region. This is a major issue, particularly with regard to climate change.
The karst and multiple-layer sedimentary systems from which this resource is pumped are representative of the main aquifers exploited around the Mediterranean and in other regions of the world. The development of tools for optimum use of these reservoirs therefore has the potential to generate international activities for laboratories and companies in the region.
The aim of the Dem'Eaux Roussillon project is to demonstrate water resource characterisation and concerted management solutions in the multiple-layer sedimentary system of the Roussillon Pliocene-Quaternary aquifer.
Tools and methods for characterising and managing the Roussillon reservoir, developed with the skills and know-how of the region's public research establishments and companies, will contribute to the latter's mutual technological and scientific development and enhance their international visibility.
Background and objectives
Located on the coastal edge of the Pyrénées-Orientales department, the Roussillon plain is one of the driest regions in France with average annual rainfall of 570 mm over the 1980-2010 period. Nevertheless, this region has extensive urban development (Perpignan agglomeration and coastal resorts) and agricultural development (about 15,000 ha of fruit and vegetable crops). Much of this development has been made possible by the groundwater contained in the Pliocene-Quaternary formations of the Roussillon plain.
Situation of sedimentary aquifers and interactions with their environment. The question marks illustrate the main issues and interactions involved in the Pliocene-Quaternary aquifer.
© Duvail & Aunay, 2005
The volume of water abstracted from the Pliocene-Quaternary aquifers has now reached 80 million m3/year (SAGE Roussillon, 2012). This abstraction has led to a regular drop in the fill level of the aquifer over the entire plain. To address this, in 2008 local water management stakeholders created a Water Development and Management Scheme ("Pliocene-Quaternary aquifers of the Roussillon plain”, SAGE) to keep the aquifers in good condition (an objective for 2015 set by the Water Framework Directive - WFD) and ensure rational water resource management.
Despite the technical and scientific work carried out to date (including a research project funded by ANR (VULCAIN) and a recent study to determine the abstractable volumes), the complexity of this reservoir (geometry of the deposits, organisation of flows, interface relationships) and the numerous issues at stake (uncontrolled number of abstraction points, intensity of abstraction in summer, localised and diffuse pollution problems) are such that the conditions for protecting and ensuring optimum and sensible use of this aquifer are currently unknown.
Although the deep waters of this reservoir (mostly located under an impermeable cover) are not considered particularly vulnerable to human and agricultural activities, several catchments are affected by nitrate and pesticide pollution. In many cases this contamination is mainly attributed to defective boreholes connecting superficial aquifers with deep Pliocene aquifers, but this has not been documented with certainty.
This anthropogenic pollution is compounded by the risk of seawater intrusion in coastal horizons. Coupled with a chronic drop in piezometric levels on the plain, the scale of abstraction in summer creates a risk of saline intrusion that could affect the entire water resource. Finally, existing climate projections (reduced recharge and sea level rise) and the increasing demand for water due to sustained demographic growth will probably exacerbate the existing pressure on this resource in the future.
The Dem'Eaux Roussillon project combines regional knowledge of geology, geophysics, geochemistry, hydraulics, economics, electronics, spatial imaging and computer science to remove the barriers to understanding the behaviour of the Roussillon Pliocene-Quaternary aquifer by integrating all of the natural and anthropogenic issues related to it and their future trends.
The Dem'Eaux Roussillon project adopts a multidisciplinary approach involving a broad range of the scientific skills required for studying the selected reservoirs available in the Languedoc-Roussillon region. The conclusions of the R&D activities will provide an understanding of how reservoirs work, enabling their optimum protection and use.
The work is subdivided into several approaches:
Establishing a 3D geological model, using existing data acquired in particular by oil companies and academic teams (maps, seismic profiles, drilling databases, etc.) and acquiring additional data (two core drillings, field surveys, geophysics, exploratory boreholes, etc.). Land-sea geological correlations will be one of the strengths of this approach. This will follow on from the PhD work of C. Labaune, J. Lofi, E. Husson, C. Duvail, M. Rabineau and G. Jouet.
Prospective socio-economic approach
Using high-resolution spatial and temporal characterisation of water use and its future trends and through socio-economic forecasting scenarios based on the existing situation (ANR VULCAIN, ANR EAU&3E and ERA-NET AQUIMED projects).
Interactions of water resources and use with the sea, including coastal erosion and sea level rise. The coastal sedimentary compartment cannot be properly understood without an overview of the water sources (river inflows) and offshore losses. This approach will follow on from the PhD work of P. Durand, C. Brunel, P. Ferrer and M. Gervais and from the Life Response, ANR Miseeva and Med Coastance projects.
Geochemical and hydrogeological approach
Combined with a study to understand the fluid circulation, in response to the issues of deep karst contributions and saline intrusions for Roussillon. The knowledge acquired will then be used to test and/or improve the conceptual model by interpreting the data acquired over many years and by carrying out new acquisitions (pumping tests, multi-sensor acquisition, conductivity, thermal and flow profiles, etc.). The project will focus on issues of quantifying the resource and its vulnerability to saline intrusions. High-resolution spatial and temporal characterisation of the quantitative and qualitative state (with respect to saline intrusions, but also diffuse pollution) of the groundwater resource in the aquifer and hydrodynamic modelling of its future development will be carried out. In particular, two hydro-geophysical observatories will be set up for acquiring water pressure, conductivity and temperature data with high spatial and temporal resolution over a complete profile of the aquifer. These observatories will observe the vertical and lateral flow dynamics (recharge processes and saline intrusions respectively). This work follows on from the PhD work by B. Aunay and the ANR VULCAIN and GRAIND'SEL projects.
Calculation and modelling approach
To establish a conceptual model for the functioning of the hydrosystem by integrating it with the 3D geological model. All the results will then be made available on an interactive online platform for managers and the public.
A collaborative R&D project
The aim of the Dem'Eaux Roussillon project is to develop tools and methods for reservoir characterisation and management by pooling the skills and know-how of public research institutions and companies in the Occitanie region. The data acquired and produced will be made public and available on request.
The results of the various tasks carried out by the project partners are summarised in the form of reports or publications.
The list below will be updated with links to the pdf documents as they are produced.
- P1 - Final Project Summary Report
- P2 - Geology field booklet
- P3 - Geological outcrop observation assignment report
- P4 - Core drilling monitoring report and interpretation
- P5 - Geological Land-Sea Correlation Report
- P6 - 3D geological modelling
- P8/16 - Integration of scientific and technical knowledge in territorial water management planning processes
- P9 - Detailed analysis of irrigation use
- P10 - Assessment of services related to the use of gravity-fed irrigation
- P11 - Analysis of the behaviour of flows between canals, surface water and groundwater in the upstream catchment area of the Têt
- P12 - Computer consumption analysis tool
- P13 - Prototype drinking water demand forecasting tool incorporating uncertainties
- P15 - Abstraction optimisation tool
- P18/19 - Interactions of fluvio-marine forcings at the land-sea interface
- P20 - Current/future marine flood modelling
- P22 - Report on the construction and installation of hydro-geophysical observatories on the Dem'Ter and Dem'Mer wells
- P23 - Conceptual model of the pliocene-quaternary aquifer
- P24 - Hydrodynamic model of the pliocene-quaternary aquifer
- P26 - Digital platform architecture
- P27 - DEM'EAUX Roussillon observation and management tools - Follow Roussillon
With a budget of 5.8 million euros, 20% of the project is financed by the State and the Occitanie/Pyrénées-Méditerranée Region (under the 2015-2020 State-Regional Plan Contract), 15% by the European ERDF fund and the Rhône-Méditerranée-Corse Water Agency, 5% by Perpignan Méditerranée Métropole and 3% by the Pyrénées Orientales Departmental Council. The remaining 57% of the project funding is provided through the financial participation of most of the partners.
Funders of the Dem'Eaux Roussillon project. Project co-financed under the ERDF-ESF 2014-2020 Languedoc Roussillon Operational Programme.
© Dem'Eaux Roussillon
4 research institutions
- BRGM (coordinator)
- University of Perpignan Via Domitia (UMR CEFREM)
- INRAE (UMR GEAU)
- University of Montpellier (Montpellier Geosciences combined research unit)
- BRL Ingénierie
- Fugro GEOTER
- Yellow Scan
- Synapse Informatique
2 management bodies
- Syndicat Mixte des Nappes de la Plaine du Roussillon (SMNPR)
- Syndicat Mixte de la Têt Bassin Versant (SMTBV)
Partners of the Dem'Eaux Roussillon project.
© Dem'Eaux Roussillon