1.
Characterisation of groundwater bodies in the Scheldt pilot river basin district
Ph. Meus*
ICS-SCALDIT, P08 « Groundwater »
* Ministère de la Région wallonne, Direction générale des Ressources naturelles et de l’Environnement, Division de l’Eau, Direction des Eaux souterraines
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2. Pilot river basins
Scheldt PRB
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3. Scheldt river basin and district
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4. Initial characterisation of GWB
delineation of groundwater bodies
inventory of pressures (-> impress group)
general character of the overlying strata in the catchment area from which the groundwater body receives its recharge
those groundwater bodies for which there are directly dependent surface water or terrestrial ecosystems
GWBs at risk...
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5. French approach Criteria main aquifers, eventually aggregated
hydrological/hydrogeological basins
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6. 1st step delineation of systems
Flemish approach
1st step delineation of systems
main aquitards
geographical
Criteria
Central flemish system
Basement system
Ypresian aquitard
Basement + central systems
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7. 2nd step: delineation of groundwater bodies
Flemish approach
2nd step: delineation of groundwater bodies
aquifers (high resolution)
piezometric depressions
Criteria
GWBs
Central system
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8. Wallonian approach Criteria
main aquifers eventually aggregated, and productivity based!
hydrological/hydrogeological basins
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9. Groundwater body delineation for whole district
Scheldt district
France
Wallonia
Flanders
Carboniferous limestones GWBs
Cretaceous chalk GWBs
Eocene sands GWBs
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10. Delineation of groundwater bodies:
an example of capture ?
Jeker
Fontijbeek
Mombeek
Demer
Scheldt basin
Meuse basin
Wallonia
Flanders
-200
-100
100
200
5000
10000
15000
20000
25000
30000
35000
40000
afstand (m)
hoogte mTAW
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11. Groundwater bodies characterisation: typology
Country/Region
Geological unit
GWB name
Identity
Aquifer setting
Aggregation?
Aquifer type
Lithologies
Flow type
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12. Step by step, the impact assessment within the WFD
Vulnerability
mapping (2nd type map)
Ex. higher concentration of NO3 -, reduced spring discharge
Ex. charges of NO3-,
high pumping rate
Pressures
Diffuse sources pollution
Point sources pollution
Abstraction
Artificial recharge
Source
Target 1
Target 2
Groundwater body surface
Groundwater body s.s.
Pressures transfer through the unsaturated zone
Recharge areas (1st type map)
Pressures transfer through the saturated zone
Changing state of GWB - trends
By reference to thresholds, maybe an impact
Pathway 1
Pathway 2
Ex. NO3- > 25 mg/l,
insufficient discharge
in surface water
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13. GWB vulnerability assessment
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14. Conclusion
delineation of GWDs now fully achieved at the district scale
this work has allowed criteria for
characterisation of recharge zones
evaluation of GWBs at risk
characterisation of GW-SW interactions, as well as dependent ecosystems
further characterisation will follow the new groundwater directive and appropriate guidelines
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