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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2018-34
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
09 Feb 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
Quantification of different flow components in a high-altitude glacierized catchment (Dudh Koshi, Nepalese Himalaya)
Louise Mimeau1, Michel Esteves1, Isabella Zin1, Hans-Werner Jacobi1, Fanny Brun1, Patrick Wagnon1, Devesh Koirala2, and Yves Arnaud1 1Université Grenoble Alpes, IRD, Grenoble INP, CNRS, IGE, Grenoble, France
2Nepal Academy of Science and Technology, NAST, Kathmandu, Nepal
Abstract. In a context of climate change and water demand growth, understanding the origin of water flows in the Himalayas is a key issue for assessing the current and future water resources availability and planning the future uses of water in downstream regions. This study estimates the relative contributions of rainfall, glacier and snow melt to the Khumbu River streamflow (Upper Dudh Koshi, Nepal, 146 km2, 43 % glacierized, elevation range from 4260 to 8848 m a.s.l.), as well as their seasonal variability during the period 2012–2015, by using the physically based glacio-hydrological model DHSVM-GDM (Distributed Hydrological Soil Vegetation Model – Glaciers Dynamics Model). One of the main issues in high elevated and glacierized catchments hydrology is the limited representation of cryospheric processes, which control the evolution of ice and snow, in distributed hydrological models. Here, the impact of different snow and glacier parametrizations was tested by modifying the original DHSVM-GDM snow albedo parametrization, by adding an avalanche module, and by adding a reduction factor for the melt of debris covered glaciers. Results show that this new version of DHSVM improves the simulation of the snow covered area and the glacier mass balances, thus improving the reliability of the overall hydrological simulation. In the presented case study, ice and snow melt contribute each more than 40 % to the annual outflow. 69 % of the outflow originates from glacierized areas. Our simulations also highlight that winter flows are mainly controlled by the release from the englacial water storage. In general, it is shown that the choice of a given parametrization for the snow and glacier processes has a significant impact on the simulated water balance. The sensitivity of the model to the glaciers inventory was tested, demonstrating that the uncertainty related to the glacierized surface leads to an uncertainty of 20 % on the simulated ice melt component.
Citation: Mimeau, L., Esteves, M., Zin, I., Jacobi, H.-W., Brun, F., Wagnon, P., Koirala, D., and Arnaud, Y.: Quantification of different flow components in a high-altitude glacierized catchment (Dudh Koshi, Nepalese Himalaya), Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-34, in review, 2018.
Louise Mimeau et al.
Louise Mimeau et al.
Louise Mimeau et al.

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Short summary
In a context of glacier shrinkage caused by climate change, this study quantifies the contributions of glacier melt, snow melt, and rain to the river streamflow in a Himalayan catchment (Everest region). This study discusses the representation of the snow and glacier processes in hydrological models and its impact of on the estimated flow components, and also addresses the issue of defining the glacier contribution to the river streamflow.
In a context of glacier shrinkage caused by climate change, this study quantifies the...
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