1. V G
222nd Working Group C Plenary Meeting March 2012 Groundwater bodies delineation in France
Susanne Schomburgk, BRGM, Water Division
Sarah Bonneville , Ministry of Ecology, Sustainable Development, Transports and Housing
Groundwater and water resource Unit

2. National Guidance document National Harmonisation
Introduction
Who’s doing what ?
Coordinator : MEDDTL (French Ministry of Ecology, Sustainable Development, Transports and Housing )
Fulfilment : the 6 Water Agencies for the 9 mainland RBD
Technical support : BRGM
(French Geological Survey)
National Guidance document
“Circulaire”
Delineation
National Harmonisation
Ministry/BRGM/
national expert group
Water agencies
BRGM

3. Groundwater body delineation
Before the WFD:
A national aquifer delineation/hydrogeology data base named “BDRHFv1” (“Base de Données du Référentiel Hydrogéologique Français”
Based only on hydrogeological properties
For the WFD:
Construction of a new frame of reference
Based on geological and hydrogeological criteria
Very occasionally on pressures in order to have a stable map
Exchanges between GWB are possible
Deep groundwater bodies without any link with surface waters, in which no drinking water is (and will be) removed (salinity, temperature…) is not included in a GWB
A GWB can present a spatial heterogeneity (qualitative and quantitative)

4. Groundwater body delineation
6 main types of lithology
Mainly sedimentary (excluding alluvial)
Alluvial
Crystalline basement rocks
Volcanic rocks
“Intensively folded” (mountains areas)
impervious “locally aquifer”
+ further criteria (e.g. karstic, coastal, confined/not confined …)
The whole territory is covered by a GWB
Limited number of GWB : ~ 500
Aquifers aggregation in order to avoid having “too many” entities
“Reporting” unit and not “knowledge” unit
Reasonable for the WFD reporting

5. Groundwater body delineation
574 GWB
533 in mainland France (15 trans-districts, 23 transboundaries)
38 in overseas territories
Distribution of GWB types
a very heterogeneous geology

6. Ranges of superposition for a GWB – French approach

7. Are we happy with this GWB delineation ?
10 years after the WFD, the GWB are well known and recognised by water managers, by the public, etc...
But….
10 ranges in France but at the EU level only 5 ranges seem to be wished
Some limits don’t perfectly fit with the hydrogeological limits : better knowledge now than in 2004!
new numerical géological mapping-system (scale :1/ )
national database of boreholes with geological passes (under coverage),
new local and regional hydrogeological studies
Many GWB are too large and heterogeneous: difficulties to represent sub- parts « in poor status »
Confined aquifers
Transbondary aquifers

8. Delineation of confined aquifers
49 of 534 GWB in mainland France
1) At surface: according to coverage boundary, (much bigger surface if no boundary)
2) delineation under coverage of deep confines aquifer
Remaining questions
Depth?
Lowest wells know in the aquifer? Knowledge of aquifer behaviour?
Exemple : Chalkstone, very low permeability in > 50 m depth

9. Transboundary aquifers

10. Conclusion – next steps
An updated GWB delineation will be available in for the river districts Loire- Brittany, Adour-Garonne and Rhône- Mediterranean /Corsica
« Relatively » small changes to facilitate the next WFD reporting:
Mainly adjustment of GWB boundaries following new knowledge (new hydrogeological reference system)
Exemples of open questions in discussion between ministry, water agencies and BRGM(expert group):
Management of depth for confined aquifers
Complete coverage of the territory?
Subdivision or creation of new GWB
Consequences to manage
Changes in the status assessment
The GWB code of a borehole may change: need to link codes to the reporting period