Although invisible, groundwater plays an essential role for society as a source of drinking water or for ecosystems by providing a base flow to rivers, but it also faces significant contaminant challenges. Characterizing groundwater reservoirs with their spatial heterogeneity and temporal evolution is therefore crucial for their sustainable management.
For 4 years, the European network ITN ENIGMA (2017-2021) trained 15 PhD students on new techniques for monitoring and imaging hydrogeological systems, allowing a dynamic and spatially resolved vision of underground environments. This project coordinated by the CNRS-INSU (see box) was based on the highly instrumented sites of the SNO H+ (OZCAR infrastructure) and the main hydrogeological observatories in Europe.
In this article, a research team identifies the hydrogeological processes for which an approach combining monitoring of spatial and temporal variability, including 4D imaging, is needed: (1) groundwater flows that control (2) the transport, mixing and reaction processes of the solutes, (3) the dynamics of the non-saturated zone and (4) the interaction between surface and groundwater at the interface between different compartments of the critical zone. The study highlights recent innovations in this area and recommends a more systematic characterization of the dynamic nature of subsurface processes. This includes harmonizing open databases to store hydrogeological datasets in their four-dimensional components, in order to address emerging scientific questions and key societal issues.
Référence :
Hermans, T., Goderniaux, P., Jougnot, D., Fleckenstein, J., Brunner, P., Nguyen, F., Linde, N., Huisman, J. A., Bour, O., Lopez Alvis, J., Hoffmann, R., Palacios, A., Cooke, A.-K., Pardo-Álvarez, Á., Blazevic, L., Pouladi, B., Haruzi, P., Kenshilikova, M., Davy, P., and Le Borgne, T. (2022) Advancing measurements and representations of subsurface heterogeneity and dynamic processes: towards 4D hydrogeology, Hydrol. Earth Syst. Sci. doi :10.5194/hess-2022-95
