TY - JOUR

T1 - Advancing measurements and representations of subsurface heterogeneity and dynamic processes

T2 - towards 4D hydrogeology

AU - Hermans, Thomas

AU - Goderniaux, Pascal

AU - Jougnot, Damien

AU - Fleckenstein, Jan H.

AU - Brunner, Philip

AU - Nguyen, Frédéric

AU - Linde, Niklas

AU - Huisman, Johan Alexander

AU - Bour, Olivier

AU - Lopez Alvis, Jorge

AU - Hoffmann, Richard

AU - Palacios, Andrea

AU - Cooke, Anne-Karin

AU - Pardo-Álvarez, Álvaro

AU - Blazevic, Lara

AU - Pouladi, Behzad

AU - Haruzi, Peleg

AU - Visentini, Alejandro Fernandez

AU - Nogueira, Guilherme E. H.

AU - Tirado-Conde, Joel

AU - Looms, Majken C.

AU - Kenshilikova, Meruyert

AU - Davy, Philippe

AU - Le Borgne, Tanguy

PY - 2023

Y1 - 2023

N2 - 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 generally leads to effective behaviors and emerging phenomena that cannot be predicted from conventional approaches based on homogeneous assumptions and models. However, it is not always clear when, why, how, and at what scale the 4D (3D + time) nature of the subsurface needs to be considered in hydrogeological monitoring, modeling, and applications. In this paper, we discuss the interest and potential for the monitoring and characterization of spatial and temporal variability, including 4D imaging, in a series of hydrogeological processes: (1) groundwater fluxes, (2) solute transport and reaction, (3) vadose zone dynamics, and (4) surface-subsurface water interactions. We first identify the main challenges related to the coupling of spatial and temporal fluctuations for these processes. We then highlight recent innovations that have led to significant breakthroughs in high-resolution space-time imaging and modeling the characterization, monitoring, and modeling of these spatial and temporal fluctuations. We finally propose a classification of processes and applications at different scales according to their need and potential for high-resolution space-time imaging. We thus advocate a more systematic characterization of the dynamic and 3D nature of the subsurface for a series of critical processes and emerging applications. This calls for the validation of 4D imaging techniques at highly instrumented observatories and the harmonization of open databases to share hydrogeological data sets in their 4D components.

AB - 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 generally leads to effective behaviors and emerging phenomena that cannot be predicted from conventional approaches based on homogeneous assumptions and models. However, it is not always clear when, why, how, and at what scale the 4D (3D + time) nature of the subsurface needs to be considered in hydrogeological monitoring, modeling, and applications. In this paper, we discuss the interest and potential for the monitoring and characterization of spatial and temporal variability, including 4D imaging, in a series of hydrogeological processes: (1) groundwater fluxes, (2) solute transport and reaction, (3) vadose zone dynamics, and (4) surface-subsurface water interactions. We first identify the main challenges related to the coupling of spatial and temporal fluctuations for these processes. We then highlight recent innovations that have led to significant breakthroughs in high-resolution space-time imaging and modeling the characterization, monitoring, and modeling of these spatial and temporal fluctuations. We finally propose a classification of processes and applications at different scales according to their need and potential for high-resolution space-time imaging. We thus advocate a more systematic characterization of the dynamic and 3D nature of the subsurface for a series of critical processes and emerging applications. This calls for the validation of 4D imaging techniques at highly instrumented observatories and the harmonization of open databases to share hydrogeological data sets in their 4D components.

KW - GROUND-PENETRATING RADAR

KW - SPECTRAL INDUCED POLARIZATION

KW - 3D AQUIFER CHARACTERIZATION

KW - RESISTIVITY TOMOGRAPHY ERT

KW - SURFACE WATER INTERACTIONS

KW - BIOGEOCHEMICAL HOT-SPOTS

KW - WAVE-FORM INVERSION

KW - FRACTURED-ROCK

KW - REACTIVE TRANSPORT

KW - POROUS-MEDIA

U2 - 10.5194/hess-27-255-2023

DO - 10.5194/hess-27-255-2023

M3 - Journal article

VL - 27

SP - 255

EP - 287

JO - Hydrology and Earth System Sciences

JF - Hydrology and Earth System Sciences

SN - 1027-5606

IS - 1

ER -