Thompson et al. (2026) Simulation of the Hydro-ecological Impacts of Climate Change on an Upland Peatland in the Massif Central

Identification

• Journal: Wetlands
• Year: 2026
• Date: 2026-03-23
• Authors: Julian R. Thompson, Arnaud Duranel, Emma Keisser, Philippe Durepaire, Hervé Cubizolle
• DOI: 10.1007/s13157-026-02046-7

Research Groups

• Department of Geography, University College London (UCL), London, UK
• Jean Monnet University, UMR 5600 CNRS EVS, Saint-Etienne, France
• Réserve Naturelle Nationale de la Tourbière des Dauges, Conservatoire d’Espaces Naturels de Nouvelle Aquitaine, Sauvagnac, France

Short Summary

This study assesses the hydro-ecological impacts of 60 climate change scenarios on peat ecosystems in the Dauges National Nature Reserve using high-resolution hydrological modeling. Results project increased hydrological seasonality, with wetter winters and drier summers, leading to declining summer peat groundwater levels and a reduction in the area suitable for mire vegetation, particularly at peatland margins.

Objective

• To assess the hydro-ecological impacts of climate change on peat ecosystems within the Dauges National Nature Reserve, focusing on stream discharge and peat groundwater levels.
• To evaluate the future extent of peat-forming wetlands by translating simulated hydrological conditions into changes in mire vegetation distribution.

Study Configuration

• Spatial Scale: A 2.31 km² catchment encompassing the Dauges National Nature Reserve, modeled with a 10 m × 10 m grid (23,111 cells).
• Temporal Scale: Climate change impacts projected for two 30-year time slices: 2041–2070 (2050s) and 2071–2100 (2080s), compared to a baseline period of 2001–2013. Climate projections reference period: 1976–2005.

Methodology and Data

• Models used:
  • MIKE SHE (fully distributed, physically-based hydrological model for land phase processes: evapotranspiration, unsaturated zone, saturated zone, overland flow).
  • MIKE 11 (1-dimensional hydraulic model for channel flow, dynamically coupled with MIKE SHE).
  • HYLUC model (for calculating evaporation from interception in tall vegetation).
• Data sources:
  • DRIAS-2020 dataset: High-resolution (8 km) regional climate simulations from the Euro-Cordex ensemble, statistically corrected, providing monthly delta factors for precipitation, temperature, and wind speed for three Representative Concentration Pathways (RCP2.6, RCP4.5, RCP8.5) and 12 Global Climate Model (GCM)/Regional Climate Model (RCM) pairs.
  • Digital Elevation Model (DEM): Aggregation of 5 m spatial resolution dGPS survey (mire), IGN BD Alti 25 m DEM (southern catchment), and digitized points/contours from 1:1000 topographic maps.
  • Meteorological data: Saint-Léger-la-Montagne meteorological station (4 km from site) and a station within the mire (for precipitation and Penman-Monteith reference evapotranspiration).
  • Field investigations: Geological drilling, electrical resistivity tomography for saturated zone layer definition.
  • Vegetation data: CORINE biotope vegetation map, reclassified into nine categories.
  • Hydrological observations: Daily mean groundwater table depth (16 shallow dip wells) and stream discharge (gauging stations at Pont de Pierre and three upper stream reaches) for model calibration and validation.

Main Results

• Climate Forcing:
  • Annual precipitation: Increases projected for 45 of 60 scenarios. Ensemble mean increases: 5–8% for RCP2.6, 1–5% for RCP8.5. Winters become wetter, and summers become drier.
  • Annual potential evapotranspiration: Increases projected in all cases. Ensemble mean increases: 2–3% for RCP2.6, 6–12% for RCP8.5.
  • Annual net precipitation: Declines projected for nearly half of RCP4.5 scenarios and a majority of RCP8.5 scenarios.
• Stream Discharge:
  • Mean stream discharge: Increases in most cases (78% upstream, 77% downstream). Ensemble mean increases: 8–9% for RCP2.6, 2–4% (2050s) and -1–2% (2080s) for RCP8.5 (at catchment outlet).
  • Seasonality: Flows become more seasonal with increasing high flows (Q5) and declining low flows (Q95). Q5 increases for >85% of scenarios. Q95 declines for >65% of scenarios, with larger declines for higher radiative forcing (e.g., 53% decline for RCP8.5 in 2080s at Rocher for EM6).
• Peat Groundwater Levels:
  • Winter high groundwater levels (GWD-5): Changes are very small (range -0.2 cm to 0.4 cm).
  • Summer low groundwater levels (GWD-95): Declines dominate (>80% of cases). Ensemble mean increases <1 cm for RCP2.6, with declines of 5–7 cm (2050s) and 12–14 cm (2080s) for RCP8.5.
  • Mean groundwater levels: Lower mean levels projected in >70% of cases.
  • Spatial patterns: Largest declines in groundwater levels are concentrated around peatland margins.
• Mire Vegetation Distribution:
  • Area suitable for mire vegetation (September seepage > 0.005 mm/day): Declines in 41 of 60 scenarios (68.3%).
  • Ensemble mean area changes: Small (<1%) increases for RCP2.6, with declines of 12–13% for RCP8.5 in the 2080s.
  • Mean September seepage in suitable areas: Declines in 43 of 60 scenarios (71.7%). Ensemble mean declines: 10–15% (RCP4.5, 2050s) to 29–32% (RCP8.5, 2080s).
  • Foci of change: Areas simulated as no longer able to support mire vegetation, and those retaining suitability but with largest seepage declines, are concentrated around the mire margin.

Contributions

• First study to utilize the complete set of DRIAS-2020 climate change scenarios for a wetland impact assessment, providing high-resolution projections for France.
• Novel evaluation of future peat-forming wetland extent based on a robust, spatially distributed hydro-ecological threshold (mean September groundwater seepage).
• Demonstrates the potential buffering capacity of peatlands and groundwater discharge in mitigating climate change impacts on streamflow, particularly for low flows.
• Identifies peatland margins as particularly vulnerable areas to climate change-induced hydrological shifts, highlighting their importance for conservation.

Funding

• UK Natural Environmental Research Council (NERC) doctoral studentship (Grant no. NE/H525203/1)
• University of Saint-Etienne (Project: Eco-hydrologie et fonctions des zones humides dans un contexte de changement climatique – L’exemple des têtes de bassin versant tourbeuses du Massif Central cristallin (Limousin et Monts du Forez))
• Conservatoire d’Espaces Naturels de Nouvelle-Aquitaine (Project: Hydrological modelling for climate change impact assessment: Dauges National Nature Reserve, Limousin, France)

Citation

@article{Thompson2026Simulation,
  author = {Thompson, Julian R. and Duranel, Arnaud and Keisser, Emma and Durepaire, Philippe and Cubizolle, Hervé},
  title = {Simulation of the Hydro-ecological Impacts of Climate Change on an Upland Peatland in the Massif Central},
  journal = {Wetlands},
  year = {2026},
  doi = {10.1007/s13157-026-02046-7},
  url = {https://doi.org/10.1007/s13157-026-02046-7}
}