The O-ZNS project begins to produce original scientific knowledge on the transfer of mass and heat through the ZNS of the Beauce aquifer carbonate. During the EGU 2020 conference held from the 4th to the 8th may 2020 virtually this year, the team presented research work covering several topics including geophysics, the coupling of geophysics and geomechanics, hydrogeology and environmental monitoring tools through 5 contributions.
The main O-ZNS well (4m in diameter and 20m deep) provides access to the entire vadose zone of the aquifer thanks to the installation of monitoring and imaging tools for long-term measurements and the coupling between processes (geophysics, geochemistry, hydrogeology, microbiology, etc.) within real-time in situ monitoring of mass and heat transfers from the soil surface to groundwater across the continuum “soil – rhizosphere – vadose zone –capillary fringe – aquifer”.
Geophysical imagery has provided valuable information on the distribution and transfer of water in the vadose area. The multi-method technique with different observation scales highlights the complexity of the vadose zone and the relevance of the approach. The results of the different methods (geophysics, geology and laboratory measurements) are generally consistent with each other. Calibrations thanks to the geophysical measurements at laboratory are however necessary for the quantification of the hydrodynamic parameters and allowing coupling between geophysical imaging and hydrogeological modeling.
Other laboratory hydrogeological characterizations made it possible to obtain q(h) and K(h) curves of loose sediments with a strong link with respect to the physical properties of the material of the portion considered and to the nature of the associated clay minerals. Unaltered carbonate matrix has microfractures where water circulates and create confined zones. In addition, the altered matrix with more expressed fractures and cavities where the calcite has been replaced by phyllosilicates has a high capacity of water retention.
Finally, the results of tracing with non-reactive chemical (bromide) on laboratory cores have shown that the time for water transfer along the column of the vadose zone (around 18 m) is approximately 30 days.
Find the summaries and presentations (oral, poster) in PDF:
To know more
Mohamed AZAROUAL – Plateform manager O-ZNS
firstname.lastname@example.org / +33 2 38 64 32 54