Preprints
https://doi.org/10.5194/tc-2022-17
https://doi.org/10.5194/tc-2022-17
 
01 Jun 2022
01 Jun 2022
Status: this preprint is currently under review for the journal TC.

Estimation of water residence time in a permafrost catchment in the Central Tibetan Plateau using long-term water stable isotopic data

Shaoyong Wang1,2, Xiaobo He1, Shichang Kang1,2, Hui Fu3, and Xiaofeng Hong4 Shaoyong Wang et al.
  • 1State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
  • 2College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
  • 3China Institute of Water Resources and Hydropower Research, Beijing 100049, China
  • 4Water Resources Department, Yangtze River Scientific Research Institute, Wuhan 430010, China

Abstract. Global warming has greatly impacted the hydrological processes and ecological environment in permafrost regions. Mean residence time (MRT) is a fundamental catchment descriptor that reveals hydrological information about storage, flow pathways, and water source within a particular catchment. However, water stable isotopes and MRT have scarcely been investigated due to limited data collection in the high-altitude permafrost regions. This study used the long-term stable isotopic observations to identify runoff components and applied the sine-wave exponential model to estimate water MRT in a high-altitude permafrost catchment (5,300 m a.s.l.) in the central Tibetan Plateau (TP). We found that the isotope composition in precipitation, stream, and supra-permafrost water exhibited obvious seasonal variability. Freeze-thaw cycles of permafrost active layer and direct input of precipitation significantly modified the stable isotope compositions in supra-permafrost and stream water. The hydrograph separation revealed that precipitation and supra-permafrost water accounted for 62 ± 13 % and 38 ± 13 % of the total discharge of stream water, respectively. We estimated that MRT for stream and supra-permafrost water was 100 and 255 days, respectively. Such shorter MRT of supra-permafrost and stream water (compared to the non-permafrost catchments) might reflect the unique characteristics of hydrological process in permafrost catchments. Moreover, the MRT of supra-permafrost water was found to be more sensitive to environmental change than that of stream water. Climate and vegetation factors affected the MRT of stream and supra-permafrost water mainly by changing the thickness of permafrost active layer. We conclude that global warming might retard the rate of water cycle in permafrost regions. Overall, our study deepened the understanding of hydrological processes in high-altitude permafrost catchments and provided a decision-making basis for ecological environmental protection and water resources safety in the source of rivers on the TP.

Shaoyong Wang et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2022-17', Anonymous Referee #1, 15 Jun 2022
  • RC2: 'Comment on tc-2022-17', Anonymous Referee #2, 10 Jul 2022

Shaoyong Wang et al.

Data sets

Long-term water stable isotope data and water residence time in the Central Tibetan Plateau Shaoyong Wang, Xiaobo He, Shichang Kang, and Hui Fu https://figshare.com/articles/dataset/IsoMRTTP/19172765

Shaoyong Wang et al.

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Short summary
This study used the sine-wave exponential model and long-term water stable isotopic data to estimate water MRT and its influencing factors in a high-altitude permafrost catchmen (5,300 m a.s.l.) in the central Tibetan Plateau (TP). We conclude that global warming might retard the rate of water cycle in permafrost regions. Our study will deepen the understanding of hydrological processes in high-altitude permafrost catchments.