Balancing subsurface complexity and model simplicity: How much spatially distributed field data is needed to simulate streamflow in a subalpine critical zone
Abstract
Representing subsurface heterogeneity in hydrological models is particularly challenging, as geological and geophysical data are often sparse and infrequent. Hydrologists face two main challenges in subsurface characterization: determining the necessary depth and detail for accurate flow modeling, and developing cost and time-effective methods to capture subsurface heterogeneity. In this study, we conducted preparatory geological and geophysical surveys to investigate subsurface structures and develop conceptual models for the studied catchment. We began with a simple single-layer subsurface model based on initial field investigations and progressively refined it into a more complex three-layer model that incorporates geological, geophysical, and hydraulic properties measured in the field. These conceptual subsurface models were used to inform a 3D hydrological model applied to a 15.28 ha subalpine catchment at Lautaret Pass. Results show that both the three-layer homogeneous and three-layer heterogeneous models perform best, yielding comparable results for runoff (KGEnp = 89, 91), soil moisture (MAPE = 0.23, 0.22), and evapotranspiration (MAPE = 6.65, 6.60). The three-layer model introduces an active regolith layer at an optimal depth, which is responsible for storing and releasing infiltrated water. We argue that conceptual homogeneous models can meet hydrological objectives, provided they are grounded in reliable geological and geophysical field data. However, we also show that the heterogeneous model performs slightly better in capturing snowmelt amplitude, baseflow, evapotranspiration, and surface heterogeneities. These results highlight how cost and time-effective geophysical methods that capture vertical heterogeneity can be leveraged to upscale critical zone processes.
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BibTeX
@article{gupta2026balancing,
title = {{Balancing subsurface complexity and model simplicity: How much spatially distributed field data is needed to simulate streamflow in a subalpine critical zone}},
author = {Aniket Gupta and Jean-Martial Cohard and Alix Reverdy and Romain Biron and Catherine Coulaud and Hervé Denis and Marc Descloitres and Thierry Dumont and Stéphane Garambois and Basile Hector and Jean-Pierre Vandervaere and Didier Voisin},
journal = {Journal of Hydrology},
year = {2026},
month = sep,
doi = {10.1016/j.jhydrol.2026.136455},
url = {https://hal.science/hal-05761857v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Balancing subsurface complexity and model simplicity: How much spatially distributed field data is needed to simulate streamflow in a subalpine critical zone
AU - Aniket Gupta
AU - Jean-Martial Cohard
AU - Alix Reverdy
AU - Romain Biron
AU - Catherine Coulaud
AU - Hervé Denis
AU - Marc Descloitres
AU - Thierry Dumont
AU - Stéphane Garambois
AU - Basile Hector
AU - Jean-Pierre Vandervaere
AU - Didier Voisin
PY - 2026
DA - 2026/09/24
JO - Journal of Hydrology
DO - 10.1016/j.jhydrol.2026.136455
UR - https://hal.science/hal-05761857v1
AB - Representing subsurface heterogeneity in hydrological models is particularly challenging, as geological and geophysical data are often sparse and infrequent. Hydrologists face two main challenges in subsurface characterization: determining the necessary depth and detail for accurate flow modeling, and developing cost and time-effective methods to capture subsurface heterogeneity. In this study, we conducted preparatory geological and geophysical surveys to investigate subsurface structures and develop conceptual models for the studied catchment. We began with a simple single-layer subsurface model based on initial field investigations and progressively refined it into a more complex three-layer model that incorporates geological, geophysical, and hydraulic properties measured in the field. These conceptual subsurface models were used to inform a 3D hydrological model applied to a 15.28 ha subalpine catchment at Lautaret Pass. Results show that both the three-layer homogeneous and three-layer heterogeneous models perform best, yielding comparable results for runoff (KGEnp = 89, 91), soil moisture (MAPE = 0.23, 0.22), and evapotranspiration (MAPE = 6.65, 6.60). The three-layer model introduces an active regolith layer at an optimal depth, which is responsible for storing and releasing infiltrated water. We argue that conceptual homogeneous models can meet hydrological objectives, provided they are grounded in reliable geological and geophysical field data. However, we also show that the heterogeneous model performs slightly better in capturing snowmelt amplitude, baseflow, evapotranspiration, and surface heterogeneities. These results highlight how cost and time-effective geophysical methods that capture vertical heterogeneity can be leveraged to upscale critical zone processes.
SN - 0022-1694
SN - 1879-2707
ER -