Significant role of permafrost in regional hydrology of the Upper Indus Basin, India

G Jeelani; Wasim Hassan; Virendra Padhya; R D Deshpande; A P Dimri; Suhail A Lone

doi:10.1016/j.scitotenv.2024.170863

Significant role of permafrost in regional hydrology of the Upper Indus Basin, India

Sci Total Environ. 2024 Apr 1:919:170863. doi: 10.1016/j.scitotenv.2024.170863. Epub 2024 Feb 8.

Authors

G Jeelani¹, Wasim Hassan², Virendra Padhya³, R D Deshpande³, A P Dimri⁴, Suhail A Lone²

Affiliations

¹ Department of Earth Sciences, University of Kashmir, 190006, India. Electronic address: geojeelani@kashmiruniversity.ac.in.
² Department of Earth Sciences, University of Kashmir, 190006, India.
³ Geoscience Division, Physical Research Laboratory, Ahmedabad 380009, India.
⁴ School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.

PMID: 38340842
DOI: 10.1016/j.scitotenv.2024.170863

Abstract

Upper Indus Basin (UIB), being climatologically sensitive and socio-economically important, has emerged as a hotspot for eco-hydrological studies. Permafrost, one of the essential components of the regional hydrological cycle with a critical role in microclimate, is also an important water resource in the UIB. Despite being an important component of the cryospheric system, permafrost is least studied in the UIB. In present study, we used stable oxygen and hydrogen isotopic composition in supra-permafrost water (SPFW) and aufeis along with precipitation, snowpack, glacier and other groundwaters to assess their variability and estimate their contribution to regional hydrology. The sources are evolving isotopically, depending on physiographic and hydrometeorological factors, with each source attaining different (if not distinct) isotopic signatures. The isotopic signatures (with different ranges) of sources help in estimating the contribution from these sources. A significant altitude gradient of δ¹⁸O is observed in stream water, SPFW and other groundwaters. Isotopic composition in SPFW is differentially modulated by fractionation, resulting in isotopic variability from the source waters. The results suggest snowmelt and/or glacier melt as the source of SPFW. To stream flow, SPFW is the dominant contributor (43 ± 18 %) at higher elevations (> 4300 m a.m.s.l.) in July, followed by snowmelt (26 ± 10 %). In September, SPFW contribution decreases (14 ± 8 %), but the contribution from other groundwaters becomes dominant (39 ± 11 %) to stream flow. The results indicate the significant role of seasonal thawing and freezing of active layer on the contribution from SPFW. This study highlights the significant role of permafrost in the hydrological system of the basin. The study also emphasizes the need to understand the dynamics of permafrost, taliks of various types (e.g., supra-permafrost subaerial talik) and active layer under changing climate to define the subsequent implications to regional hydrology, eco-hydrological systems and micro-climate of permafrost regions.

Keywords: Glacier melt; Hydrogen; Oxygen; Permafrost; Snowmelt; Upper Indus Basin.