Coupling a global glacier model to a global hydrological model prevents underestimation of glacier runoff
- 1Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, the Netherlands
- 2Institute of Earth Surface Dynamics, Faculty of Geosciences and Environment, University of Lausanne, Lausanne, Switzerland
- 3Department of Geoscience and Remote Sensing, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, the Netherlands
- 4Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium
- 5Netherlands eScience Center, Amsterdam, the Netherlands
- 6Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zürich, Zürich, Switzerland
- 7Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
- 8Department of Geosciences, University of Fribourg, Fribourg, Switzerland
- 9Department of Physical Geography, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
- 1Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, the Netherlands
- 2Institute of Earth Surface Dynamics, Faculty of Geosciences and Environment, University of Lausanne, Lausanne, Switzerland
- 3Department of Geoscience and Remote Sensing, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, the Netherlands
- 4Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium
- 5Netherlands eScience Center, Amsterdam, the Netherlands
- 6Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zürich, Zürich, Switzerland
- 7Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
- 8Department of Geosciences, University of Fribourg, Fribourg, Switzerland
- 9Department of Physical Geography, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
Abstract. Global hydrological models have become a valuable tool for a range of global impact studies related to water resources. However, glacier parameterization is often simplistic or non-existent in global hydrological models. By contrast, global glacier models do represent complex glacier dynamics and glacier evolution, and as such hold the promise of better resolving glacier runoff estimates. In this study, we test the hypothesis that coupling a global glacier model with a global hydrological model leads to a more realistic glacier representation and consequently an improved runoff prediction in the global hydrological model. To this end, the Global Glacier Evolution Model (GloGEM) is coupled with the global hydrological model PCR-GLOBWB 2 using the eWaterCycle platform. For the period 2001–2012, the coupled model is evaluated against the uncoupled PCR-GLOBWB 2 in 25 large-scale (>50.000 km2) glacierized basins. The coupled model produces higher runoff estimates across all basins and throughout the melt season. In summer, the runoff differences range from 0.07 % for weakly glacier-influenced basins to 252 % for strongly glacier-influenced basins. The difference can primarily be explained by PCR- GLOBWB 2 not accounting for glacier flow and glacier mass loss, thereby causing an underestimation of glacier runoff. The coupled model performs better in reproducing basin runoff observations mostly in strongly glacier-influenced basins, which is where the coupling has the most impact. This study underlines the importance of glacier representation in global hydrological models and demonstrates the potential of coupling a global hydrological model with a global glacier model for better glacier representation and runoff predictions in glacierized basins.
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Pau Wiersma et al.
Status: open (until 12 Jul 2022)
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RC1: 'Comment on egusphere-2022-106', Anonymous Referee #1, 20 Jun 2022
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The manuscript tests the hypothesis that coupling a global glacier model (i.e., GloGEM) with a global hydrological model (i.e., PCR-GLOBWB 2) leads to a more realistic glacier representation and improved runoff prediction in the global hydrological model. both the uncoupled benchmark and the coupled model were run for 25 large-scale glacierized basin during the hydrological years 2001-2012. Overall, the manuscript is clearly written, and the results are well discussed.
I have only two main concerns and one specific point for this study:
- The authors test a widely accepted hypothesis that the physical representation and simulation of hydrological model will be improved if its corresponding parameterization is optimized on a global scale. I am not quite sure that a test of a widely accepted hypothesis is a true innovation (I leave this question to the editor). If the test is done by coupling the global hydrological model and global glacier model physically instead of simply replacing the PCR-GLOBWB 2 runoff by the GloGEM runoff for glacierized areas, the novelty of this study make sense at least from a practical point of view.
- In both Abstract and Introduction sections, the authors mentioned that global runoff prediction can be improved through the coupling of GHMs and GGMs. However, only runoff “simulation” was tested in this study rather than “prediction”. The authors are suggested showing the results of runoff prediction (not for the calibration/validation periods but for the prediction period) as well.
A specific point: Paragraph 165 in P7, extra periods.
Pau Wiersma et al.
Data sets
GHMGGM data Pau Wiersma https://doi.org/10.5281/zenodo.6386298
Model code and software
GHMGGM code Pau Wiersma https://github.com/pauwiersma/GHMGGM.git
Pau Wiersma et al.
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