Zou et al. (2026) Seasonal variation of groundwater flow path induced by freeze‒thaw process drives the changes of DOC export and DOM composition in streams in an alpine catchment, Qinghai‒Tibet Plateau

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-01-11
• Authors: Changjian Zou, Rui Ma, Jing Xiong, Zhao Pan, Ziyong Sun
• DOI: 10.1016/j.jhydrol.2026.134943

Research Groups

• Hubei Key Laboratory of Yangtze River Basin Environmental Aquatic Science, School of Environmental Studies, China University of Geosciences, Wuhan, China
• Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, Nanjing, China

Short Summary

This study investigates how freeze-thaw induced changes in groundwater flow paths in an alpine catchment on the Qinghai-Tibet Plateau influence dissolved organic carbon (DOC) export and dissolved organic matter (DOM) composition in streams. It reveals significant seasonal variations in groundwater flow, DOC concentrations, and DOM characteristics, demonstrating that groundwater contributes substantially to stream DOC flux, especially during specific periods.

Objective

• To understand the control of freeze-thaw-induced changes in the groundwater flow path on dissolved organic matter (DOM) composition and lateral dissolved organic carbon (DOC) export to rivers at the catchment scale in alpine regions.

Study Configuration

• Spatial Scale: A sub-catchment with seasonally frozen ground (SFG) on the northeastern Qinghai‒Tibet Plateau (QTP).
• Temporal Scale: Seasonal variations, specifically examining periods like April to June 15, June 15 to October 26, and October 26 to November 6.

Methodology and Data

• Models used: A numerical groundwater flow model considering the freeze‒thaw process.
• Data sources: Seasonal variations in DOC concentrations and DOM components of groundwater at different aquifer depths and stream water.

Main Results

• Groundwater flow velocity and flow path exhibited seasonal changes influenced by the freeze-thaw process.
• DOC concentrations and DOM characteristics in groundwater (at various aquifer depths) and stream water varied significantly seasonally.
• The maximum DOC concentration in stream water was observed from October 26 to November 6.
• The DOC flux in streams peaked from April to June 15.
• The contribution of groundwater DOC flux to the total DOC flux in the main stream varied seasonally:
  • 70% during April to June 15.
  • Approaching nearly 100% from June 15 to October 26.
  • 86% from October 26 to November 6.
• The annual DOC export flux per unit area in the study area was greater than that in medium- and large-sized SFG or permafrost catchments on the QTP with similar hydrological conditions.

Contributions

• Provides a better understanding of DOC migration and transformation affected by flow path variation on the Qinghai‒Tibet Plateau.
• Addresses the importance of groundwater contribution in seasonally frozen ground (SFG) to cold regions' carbon cycles.
• Offers significant insights into biogeochemical processes and regional carbon cycling in alpine areas under climate change.

Funding

• Not specified in the provided text.

Citation

@article{Zou2026Seasonal,
  author = {Zou, Changjian and Ma, Rui and Xiong, Jing and Pan, Zhao and Sun, Ziyong},
  title = {Seasonal variation of groundwater flow path induced by freeze‒thaw process drives the changes of DOC export and DOM composition in streams in an alpine catchment, Qinghai‒Tibet Plateau},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.134943},
  url = {https://doi.org/10.1016/j.jhydrol.2026.134943}
}