Esch et al. (2025) Modelling runoff in a glacierized catchment: the role of forcing product and spatial model resolution

Identification

• Journal: Hydrology and earth system sciences
• Year: 2025
• Date: 2025-11-28
• Authors: Alexandra von der Esch, Matthias Huss, Marit Van Tiel, Justine Berg, Daniel Farinotti
• DOI: 10.5194/hess-29-6761-2025

Research Groups

• Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, Zurich, Switzerland
• Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Sion, Switzerland
• Institute of Geography and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
• Department of Geosciences, University of Fribourg, Fribourg, Switzerland

Short Summary

This study assesses the reliability of glacio-hydrological simulations in a 39.4 km² glacierized catchment in Switzerland, investigating the impact of varying meteorological forcing products and spatial model resolutions. It finds that precipitation forcing has the largest effect on model results, and resolutions coarser than 1000 meters fail to capture essential glaciological and topographic details, affecting the accuracy of small and medium-sized glaciers.

Objective

• To investigate how the choice of meteorological forcing product influences the reliability of simulated runoff and glacier mass balance.
• To assess how the performance of the glacio-hydrological model changes when coarsening its spatial distribution.
• To determine the model's reliability in simulating glacier mass balance and runoff when measured runoff data is unavailable for calibration.

Study Configuration

• Spatial Scale: Gletsch catchment (39.4 km², 44% glacierized); model resolutions from 25 meters to 3000 meters.
• Temporal Scale: Simulation period 2000–2022 (22 years) at daily resolution; calibration period 2013–2021; evaluation period 2001–2022.

Methodology and Data

• Models used: Glacier Evolution Runoff Model (GERM).
• Data sources:
  • Meteorological forcing:
    • Grimsel-Hospiz Automatic Weather Station (point data).
    • MeteoSwiss TabsD (temperature) and RhiresD (precipitation) (1 km grid).
    • ERA5-Reanalysis (approximately 30 km grid).
    • ERA5-Land (9 km grid).
  • Topography: SwissALTI3D Digital Elevation Model (DEM) (native 2 m resolution, downsampled to various resolutions).
  • Glacier mass balance (calibration): Geodetic glacier ice volume change for Rhonegletscher (2013–2021), converted to mass change using a density of 850 kg m⁻³.
  • Glacier mass balance (evaluation): Annual and seasonal glacier-wide mass balance measurements for Rhonegletscher (2007–2022) from GLAMOS.
  • Catchment runoff (calibration/evaluation): Continuous daily observations from the Rhone-Gletsch gauging station (2000–2022) from the Federal Office for the Environment, Switzerland (BAFU/FOEN).

Main Results

• Impact of Meteorological Forcing:
  • Single-data calibration (geodetic mass balance only) showed good agreement for annual glacier mass balance across all forcing products but consistently underestimated winter snow accumulation and summer runoff, particularly with gridded products.
  • Multi-data calibration (geodetic mass balance and runoff) significantly improved seasonal glacier mass balance and reduced runoff underestimation (with precipitation corrections of +20% to +30%), but relied on constant adjustments that may not reflect physical reality.
  • Precipitation biases in forcing products were identified as a primary driver of inaccuracies in seasonal snow accumulation and melt processes.
• Impact of Spatial Model Resolution:
  • Annual glacier mass balance was not significantly affected by resolutions up to 1000 meters, but seasonal shifts in melt onset and runoff timing occurred at resolutions of 200 meters and coarser.
  • Coarser resolutions (e.g., >1000 meters) oversimplified glaciological and topographic details, excluding smaller glaciers and leading to biases in melt dynamics and runoff contributions.
  • The 3000-meter resolution consistently overestimated total runoff and melt components, suggesting an earlier melt onset due to amplified ablation parameter adjustments.
  • Coarser resolutions (e.g., 1000 meters, 3000 meters) showed abrupt glacier area retreat and diverged initial glacier areas (approximately ±2 km²).

Contributions

• Systematically quantifies the impact of meteorological forcing products (from point data to coarse grids) and spatial model resolution (25 meters to 3000 meters) on glacio-hydrological simulations.
• Assesses the trade-offs between computational efficiency and model reliability under varying data availability scenarios (single-data vs. multi-data calibration).
• Highlights the critical need for high-resolution and accurate precipitation forcing data and careful calibration strategies to reliably capture seasonal glacio-hydrological processes, especially in data-scarce regions.

Funding

• Swiss National Science Foundation grant IZINZ2_209531

Citation

@article{Esch2025Modelling,
  author = {Esch, Alexandra von der and Huss, Matthias and Tiel, Marit Van and Berg, Justine and Farinotti, Daniel},
  title = {Modelling runoff in a glacierized catchment: the role of forcing product and spatial model resolution},
  journal = {Hydrology and earth system sciences},
  year = {2025},
  doi = {10.5194/hess-29-6761-2025},
  url = {https://doi.org/10.5194/hess-29-6761-2025}
}