14 Mar 2022
14 Mar 2022
Status: a revised version of this preprint is currently under review for the journal HESS.

Advancing measurements and representations of subsurface heterogeneity and dynamic processes: towards 4D hydrogeology

Thomas Hermans1, Pascal Goderniaux2, Damien Jougnot3, Jan Fleckenstein4, Philip Brunner5, Frédéric Nguyen6, Niklas Linde7, Johan Alexander Huisman8, Olivier Bour9, Jorge Lopez Alvis6,a, Richard Hoffmann6,8, Andrea Palacios10,b, Anne-Karin Cooke11,12,c, Álvaro Pardo-Álvarez5, Lara Blazevic3,d, Behzad Pouladi9,e, Peleg Haruzi8,13, Meruyert Kenshilikova9, Philippe Davy9, and Tanguy Le Borgne9 Thomas Hermans et al.
  • 1Department of Geology, Ghent University, 9000 Gent, Belgium
  • 2Department of Geology and Applied Geology, University of Mons, 7000 Mons, Belgium
  • 3UMR 7619 METIS, Sorbonne Université, UPMC Université Paris 06, CCNRS, EPHE, F-75005 Paris, France
  • 4Department of Hydrogeology, Helmoltz Centre for Environmental Research, 04318 Leipzig, Germany
  • 5Laboratory of Hydrogeological Processes, University of Neuchâtel, 2000 Neuchatel, Switzerland
  • 6Urban and Environmental Engineering, Liege University, 4000 Liege, Belgium
  • 7Institute of Earth Sciences, University of Lausanne,1015 Lausanne, Switzerland
  • 8Agrosphere (IBG 3), Institute of Bio- and Geosciences, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
  • 9Geosciences Rennes, UMR 6118, Université de Rennes 1, CNRS, 35000 Rennes, France
  • 10Institute of Environmental Assessment and Water Research (IDAEA), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08034, Spain
  • 11Géosciences Montpellier, University of Montpellier, CNRS, Univ. des Antilles, 34095 Montpellier, France
  • 12Institut d’Optique d’Aquitaine, Muquans, 33400 Talence, France
  • 13Department of Environmental Physics and Irrigation, Agricultural Research Organization – Volcani Institute, 7505101 Rishon LeZion, Israel
  • anow at: Centro de Geociencas , Universidad Nacional Autonoma de Mexico, 76230 Querétaro, Mexico
  • bnow at: Amphos 21 Consulting, 08019 Barcelona, Spain
  • cnow at: Federal Institute for Geosciences and Natural Resources (BGR), 13593 Berlin, Germany
  • dnow at: Ruden SA, 0349 Oslo, Norway
  • enow at: Silixa Ltd, London, UK

Abstract. Essentially all hydrogeological processes are strongly influenced by the subsurface spatial heterogeneity and the temporal variation of environmental conditions, hydraulic properties, and solute concentrations. This spatial and temporal variability needs to be considered when studying hydrogeological processes in order to employ adequate mechanistic models or perform upscaling. The scale at which a hydrogeological system should be characterized in terms of its spatial heterogeneity and temporal dynamics depends on the studied process and it is not always necessary to consider the full complexity. In this paper, we identify a series of hydrogeological processes for which an approach coupling the monitoring of spatial and temporal variability, including 4D imaging, is often necessary: (1) groundwater fluxes that control (2) solute transport, mixing and reaction processes, (3) vadose zone dynamics, and (4) surface-subsurface water interaction occurring at the interface between different subsurface compartments. We first identify the main challenges related to the coupling of spatial and temporal fluctuations for these processes. Then, we highlight some recent innovations that have led to significant breakthroughs in this domain. We finally discuss how spatial and temporal fluctuations affect our ability to accurately model them and predict their behavior. We thus advocate a more systematic characterization of the dynamic nature of subsurface processes, and the harmonization of open databases to store hydrogeological data sets in their four-dimensional components, for answering emerging scientific question and addressing key societal issues.

Thomas Hermans et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2022-95', Ty P. A. Ferre, 01 Apr 2022
    • CC1: 'Reply on RC1', Thomas Hermans, 07 Apr 2022
    • AC1: 'Reply on RC1', Thomas Hermans, 07 Jun 2022
  • RC2: 'Comment on hess-2022-95', Anonymous Referee #2, 27 Apr 2022
    • AC2: 'Reply on RC2', Thomas Hermans, 07 Jun 2022

Thomas Hermans et al.

Thomas Hermans et al.


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Short summary
Although invisible, groundwater plays an essential role for the society as a source of drinking water or for ecosystems by providing baseflow to rivers, but is also facing important challenges in term of contaminations. Characterizing groundwater reservoirs with their spatial heterogeneity and their temporal evolution is therefore crucial for their sustainable management. In this paper, we review some important challenges and recent innovations in imaging and modelling groundwater reservoirs.