ORIGINAL RESEARCH article
Front. Water
Sec. Water and Hydrocomplexity
This article is part of the Research TopicWater Resources in South Asia: River and Glacial dynamics, climate change and societal-water interactionsView all articles
On the Effects of Climate Downscaling for Projecting Hydrologic Response of Catchments in High Mountain Asia
Provisionally accepted
Anju Vijayan Nair1
Diogo S. A. Araujo1
Ethan D Gutmann2Sungwook Wi3
Jamyang Phuntshok4Karma Toeb4
Mujtaba Hassan5
Rijan Bhakta Kayastha6Efthymios I Nikolopoulos1*- 1Rutgers, The State University of New Jersey, New Brunswick, United States
- 2National Center for Atmospheric Research (UCAR), Boulder, Colorado, United States
- 3Cornell University, Ithaca, New York, United States
- 4National Center for Hydrology and Meteorology, Thimphu, Bhutan
- 5Institute of Space Technology, Islamabad, Islamabad, Pakistan
- 6Kathmandu University, Dhulikhel, Nepal
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The coarse spatial resolution of Global Climate Models (GCMs) makes the assessment of future hydrological dynamics particularly challenging over complex terrain regions like High Mountain Asia (HMA). Climate downscaling is therefore essential to better understand the impacts of climate change on water resources in HMA. Owing to this need, we investigate the effect of downscaling climate models on the hydrological projections of glacierized catchments in HMA with a specific focus on streamflow projections, relative contribution of streamflow components, and peak flows over five study basins in HMA. For this, four CMIP6 GCMs under SSP5-8.5 scenario were downscaled using two statistical techniques – parametric Cumulative Distribution Function (CDF) matching and Generalized Analog Regression Downscaling (GARD) – and used for streamflow simulations using the Hydrological Model for Distributed Systems. The original GCMs exhibited a wet bias across all basins in the dominant precipitation season and a cold bias (-4.3oC to -13.6oC) over the glacier-dominated basin. CDF matching and GARD performed well in reducing the bias from original GCMs over high precipitation seasons. Future precipitation increases over winter and spring seasons for basins in Pakistan and over summer and fall seasons for basins in Nepal and Bhutan. An increase in rainfall-runoff component is anticipated in the future across all basins, while the contribution to streamflow from snowmelt decreases over central and eastern basins. The overall water availability across the basins is projected to increase, along with extreme flows. The results revealed the impact of choice of downscaling techniques and GCMs on the catchment climatology, affecting the hydrological projections.
Keywords: Climate downscaling, High Mountain Asia, streamflow projections, WaterResources, Glacio-hydrological model
Received: 13 Apr 2025; Accepted: 13 Nov 2025.
Copyright: © 2025 Vijayan Nair, Araujo, Gutmann, Wi, Phuntshok, Toeb, Hassan, Kayastha and Nikolopoulos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Efthymios I Nikolopoulos, efthymios.nikolopoulos@rutgers.edu
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