Piece 5 - Local and Regional Groundwater Flows
Is the aquifer connected?
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Understand how groundwater circulates across scales, from local preferential pathways to deep and regional flow systems controlled by geological structures and horizontal connectivity.
Identify the connections between recharge areas, deep circulation and discharge zones to better predict groundwater availability, temperature and spring/tunnel inflows.
Key findings
- Groundwater levels control the connectivity of flow systems: rising water tables activate horizontal and deeper pathways, progressively linking local groundwater systems to regional circulation.
- Regional flow systems can connect apparently disconnected hydrological systems — hydrochemical and isotopic approaches revealed groundwater origins and flow paths that cannot be inferred from local hydraulic observations alone.
- In crystalline aquifers, local groundwater flow is organized by a hierarchy of structures — weathered layers provide important storage, while interconnected fractures provide preferential pathways for groundwater circulation.
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HIGH WATER LEVEL
Active zone saturated
→ large horizontal connectivity
→ regional flows
→ large recharge areas
LOW WATER LEVEL
Active zone partly unsaturated
→ disconnected compartments
→ local flow systems
→ smaller recharge areas
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Why does it matter?
Water management
The same aquifer may behave as a relatively connected system during high groundwater levels and as a strongly compartmentalized system during low-water conditions.
Fractured crystalline aquifer connectivity is dynamic: it depends on the saturation state of the shallow permeable zone.
Key publications
Nicolas Guihéneuf, Alexandre Boisson, Olivier Bour, Benoit Dewandel, Jerome Perrin, A.mélie Dausse, Matthieu Viossanges, Shandra Chandra, Shakeel Ahmed, Jean-Christophe Maréchal
Journal of Hydrology, vol. 511, 2014, pp. 320-334
Jean-Christophe Maréchal, Jean Riotte, Christelle Lagane, S. Subramanian, C. Kumar, Laurent Ruiz, Stéphane Audry, M.R.R. Varma, Jean-Jacques Braun
Applied Geochemistry, vol. 26, 2011, pp. S94-S96