Lin et al. (2025) Hydroclimatic controls on lake water oxygen isotope in alpine lake on the northern Tibetan Plateau: Insights from isotope mass balance modeling

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-12-19
• Authors: Yongjie Lin, Mianping Zheng, Chuanyong Ye
• DOI: 10.1016/j.ejrh.2025.103036

Research Groups

• State Key Laboratory of Deep Earth and Mineral Exploration, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, China
• MNR Key Laboratory of Saline Lake Resources and Environments, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, China

Short Summary

This study developed an isotope-based mass balance model for Bangkog Lake on the northern Tibetan Plateau to investigate hydroclimatic controls on lake water oxygen isotope variability, finding evaporation to be the dominant driver, followed by temperature, with precipitation and relative humidity having limited effects.

Objective

• To investigate the seasonal variability of oxygen isotopic composition (𝛿18O) in surface waters of Bangkog Lake, a representative alpine lake on the northern Tibetan Plateau.
• To develop a calibrated isotope mass balance model (MBM) to reconstruct monthly 𝛿18O variations.
• To conduct systematic sensitivity analyses to evaluate the controls of key hydroclimatic parameters (precipitation, evaporation, air temperature, relative humidity) on modeled 𝛿18O outputs.
• To improve the interpretation of 𝛿18O records from Tibetan Plateau alpine lakes for paleoclimate reconstruction.

Study Configuration

• Spatial Scale: Bangkog Lake (31°43′N, 89°29′E), northern Tibetan Plateau, at an elevation of 4525 meters above sea level. The study focused on Lakes II (approximately 55 square kilometers) and III (approximately 70 square kilometers).
• Temporal Scale: Monthly monitoring of stable isotopes and meteorological parameters during 2019. Model simulations were conducted with monthly resolution.

Methodology and Data

• Models used:
  • Isotope-based mass balance model (MBM) for lake water volume and isotopic composition.
  • Craig–Gordon model for calculating the isotopic composition of evaporative flux (𝛿E).
  • Monte Carlo simulation for uncertainty quantification.
• Data sources:
  • Observation: Monthly stable isotopes (𝛿18O and 𝛿D) from 24 lake water samples and 8 river water samples. Monthly meteorological parameters (air temperature, precipitation, evaporation, relative humidity) from a TRM-ZS2 high-precision meteorological station. Hydrological measurements including lake water depth (biweekly) and Grazar River discharge.
  • Satellite: Cloud-free Landsat imagery for lake area delineation.
  • In-situ: Bathymetric data for lake volume calculation.

Main Results

• The calibrated isotope mass balance model successfully reproduced observed monthly 𝛿18O variations in Bangkog Lake, achieving a Nash–Sutcliffe Efficiency of 0.595, an R² of 0.689, a PBIAS of -3.85%, and a Mean Absolute Error (MAE) of 1.63‰.
• Evaporation was identified as the dominant driver of isotopic enrichment in lake water 𝛿18O, with sensitivity tests showing variations exceeding 1.5‰ during peak monsoon months.
• Air temperature exerted a secondary influence on lake water 𝛿18O, with sensitivity amplifying during the summer monsoon period (June–August) and variations exceeding 1.5‰.
• Precipitation amount and relative humidity demonstrated remarkably limited effects on lake water 𝛿18O, with simulated variations generally less than 0.1‰ and 0.06‰, respectively, across wide perturbation ranges.
• The annual evaporation (1820 millimeters) was approximately 5.6 times the annual precipitation (325 millimeters), indicating a persistent net evaporative deficit.
• The pronounced evaporative sensitivity, particularly during summer, establishes lake water 𝛿18O as a robust proxy for past aridity rather than precipitation variability in this alpine system.

Contributions

• Developed and validated a robust isotope mass balance model for a high-elevation alpine lake on the northern Tibetan Plateau, providing a mechanistic framework for understanding its isotopic dynamics.
• Quantitatively established a clear hierarchy of hydroclimatic controls on lake water 𝛿18O, definitively identifying evaporation as the primary driver, temperature as secondary, and precipitation amount and relative humidity as having negligible influence.
• Enhanced the interpretative framework for lacustrine 𝛿18O records from similar high-elevation, arid/semi-arid environments, suggesting their utility as proxies for past aridity and evaporation intensity rather than direct indicators of precipitation variability.
• Provided critical insights for paleoclimate and paleohydrology reconstructions in the Tibetan Plateau, underscoring the importance of process-based modeling for accurate interpretation of isotopic archives.

Funding

• The National Key Research and Development Program of China (Grant No. 2023YFC2906501)
• National Science and Technology Major Project (Grant No. 2025ZD1006607)
• The China Geological Survey (Grant No. DD20230203602)
• The Open Research Project of the Technology Innovation Center for Strategic Mineral Exploration and Development in Plateau-Desert Regions, Ministry of Natural Resources (Grant No. KFKT20230103)
• The State Public-interest Scientific Institution Basic Research Fund (Grant Number: JKYQN2025212)

Citation

@article{Lin2025Hydroclimatic,
  author = {Lin, Yongjie and Zheng, Mianping and Ye, Chuanyong},
  title = {Hydroclimatic controls on lake water oxygen isotope in alpine lake on the northern Tibetan Plateau: Insights from isotope mass balance modeling},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.103036},
  url = {https://doi.org/10.1016/j.ejrh.2025.103036}
}