Research Highlight - Natural and anthropogenic drivers of the water table dynamics in a riparian fen peatland
Renaud, A., Mügler, C., Durand, V., & Pessel, M. (2025). Natural and anthropogenic drivers of the water table dynamics in a riparian fen peatland. Journal of Hydrology, 652, 132655. https://doi.org/10.1016/j.jhydrol.2024.132655
“The HydroGeoSphere (HGS) code succeeded in modelling the effect of strong temporal variations of the atmospheric forcings on water table levels in the Jarcy peatland over several years.”
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This publication, co-authored by Adrien Renaud, Claude Mügler, Véronique Durand, and Marc Pessel, examines the natural and anthropogenic drivers of water table dynamics in a riparian fen peatland along the Essonne River in France. This study leverages HydroGeoSphere (HGS) to couple surface and subsurface hydrology, providing new insights into how precipitation seasonality, vegetation activity, and river regulation influence peatland water levels.
Traditional approaches to wetland hydrology often focus on annual precipitation or groundwater levels, but these overlook the combined effects of vegetation cycles and human interventions such as dam operations. By integrating long-term field monitoring with HGS simulations, this research captures the critical role of seasonal rainfall distribution and river–peatland exchanges in sustaining water tables.
The study found that vegetation transpiration was a primary driver of seasonal drawdowns, while lateral inflows from the river buffered extreme declines during dry summers. Model results showed that precipitation timing mattered more than annual totals, with summer rainfall playing a decisive role in recovery. Simulations also revealed that the removal of a downstream dam reduced summer water tables by up to 38 cm, highlighting how hydrological restoration projects can significantly alter wetland resilience.
HydroGeoSphere proved essential in this work by reproducing both seasonal and event-driven dynamics, validating the importance of peatland structure— particularly a highly conductive surface layer overlying a deeper, less permeable horizon— in mediating hydrological responses. This research highlights the need to account for both natural variability and anthropogenic change when managing riparian peatlands, offering valuable guidance for conservation and water resource planning under a changing climate.
Abstract:
Riparian fens are peatlands that are fed by precipitation, groundwater, and surrounding surface water bodies. They can therefore be influenced by meteorological conditions, emphasised by global warming, and anthropogenic constraints such as flow regulation of the nearby rivers. In this paper, field monitoring and numerical modelling were used to identify the main drivers of water table dynamics at the site scale in a riparian fen peatland located along a regulated river. To this end, water table levels were recorded during three years in a riparian fen located in the alluvial plain of the Essonne River in France. A 2D transect hydrological model was built using the physically-based code HydroGeoSphere. It was composed of two superimposed soil layers identified in undisturbed soil cores taken from two distinct locations. Laboratory and field experiments revealed contrasting properties between these two layers, with a more decomposed peat layer at the surface (one metre deep) showing higher hydraulic conductivity compared to the deeper, more organic layer. Both measured and simulated results showed that the strong fluctuations of the water table in the peatland were mainly due to the seasonal life cycle of the vegetation. The water supply to the riparian peatland from the nearby river was essential when the vegetation was active by limiting the water table drawdown during very dry periods. Modelling results highlighted the importance of the river stage on the amplitude of the water table since a 26 cm drop led to a decrease of up to 38 cm of the piezometric levels. Both data and simulations also proved that the precipitation seasonal distribution plays a more critical role than the total annual precipitation on the water table depth, particularly in summer. This paper demonstrates the importance of precipitation seasonality and river hydraulic regime on the sustainability of a riparian peatland.