Qi et al. (2026) Quantifying evaporation losses in the river-lake continuum in arid regions basins using isotope data

Identification

• Journal: Ecological Indicators
• Year: 2026
• Date: 2026-01-01
• Authors: Xiaoyu Qi, Zhigang Sun, Guofeng Zhu, Rui Li, Yinying Jiao, Zhijie Zheng, Wenmin Li, Yani Gun, Jiangwei Yang, Ziwen Liu
• DOI: 10.1016/j.ecolind.2026.114610

Research Groups

• College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, Gansu, China
• Shiyang River Ecological Environment Observation Station, Northwest Normal University, Lanzhou 730070, Gansu, China
• Key Laboratory of Resource Environment and Sustainable Development of Oasis, Gansu Province, Lanzhou 730070, Gansu, China

Short Summary

This study quantified surface water evaporation losses along the river-lake continuum in the arid Shiyang River Basin (China) from 2019 to 2021 using stable isotopes and the Craig-Gordon model, revealing that cumulative evaporation accounts for 13.76 % of total surface water, with terminal lakes and reservoirs experiencing the highest losses amplified by human water management.

Objective

• To estimate evaporation losses of surface water across different sections of rivers, reservoirs, and terminal lakes.
• To analyze the factors that cause differences in evapotranspiration loss across the different river and lake sections.

Study Configuration

• Spatial Scale: Shiyang River Basin, Northwest China, extending 260 km from the Qilian Mountains (2000–5000 m elevation) through oasis plains (1300–2000 m) to the Tengger Desert. The study covered seven hydrological sections: two mountain rivers, two mountain reservoirs, two oasis rivers, and one terminal lake.
• Temporal Scale: April to October, 2019 to 2021 (3 years). Monthly sampling campaigns for surface water and event-based precipitation. Meteorological data recorded every 30 minutes.

Methodology and Data

• Models used: Craig-Gordon model (C-G model), implemented in the Hydrocalculator software.
• Data sources:
  • Observation Network: Systematic monitoring of surface water, precipitation, and meteorological parameters (temperature, relative humidity, wind speed) from 2019 to 2021.
  • Stable Isotopes: Stable hydrogen (δ2H) and oxygen (δ18O) isotope values of surface water and precipitation, analyzed using a Liquid Water Isotope Analyzer (DLT-100, Los Gatos Research, USA).
  • Meteorological Data: Collected from eight automatic weather stations co-located with precipitation observation stations.
  • Runoff Data: Obtained from the Water Resources Utilization Center of Shiyang River Basin, Water Resources Department of Gansu Province.

Main Results

• Stable isotopes (δ18O and δ2H) in surface water showed a gradual enrichment trend from the source to the terminal section of the river, with pronounced enrichment in the desert area (Qingtu Lake).
• Evaporation loss rates varied significantly along the continuum: 1.77 % for mountain rivers, 2.95 % for mountain reservoirs (Xiying Reservoir), 5.64 % for oasis rivers, 7.49 % for oasis reservoirs (Hongyashan Reservoir), and 33.17 % for the terminal lake (Qingtu Lake).
• Reservoirs exhibited substantially higher evaporation losses than rivers in both mountainous and oasis regions, while the terminal lake experienced the greatest overall loss.
• Cumulative evaporation losses for the entire river-lake continuum in the Shiyang River Basin were estimated at approximately 13.76 % of total surface water.
• Human water management, particularly artificial reservoirs (10.44 % of total surface water loss) and ecological water transfers (33.17 % loss in terminal lake), significantly amplified evaporation losses.
• Uncertainty analysis indicated that relative humidity had the greatest influence on evaporation loss estimates, followed by the isotopic composition of precipitation and temperature.

Contributions

• Provides the first systematic, basin-scale quantification of evaporation losses along the full river-lake continuum in an arid inland basin (Shiyang River Basin) under intensive human water management.
• Demonstrates the significant role of anthropogenic interventions, such as reservoir construction and ecological water transfers, in enhancing evaporation losses in arid regions.
• Offers a feasible observation and calculation scheme for basin-scale evaporation loss estimation using stable isotopes.
• Strengthens the quantitative understanding of surface water evaporation dynamics under intensive human regulation, providing a scientific foundation for improved water balance assessments and sustainable water resource management in arid inland basins.

Funding

• National Natural Science Foundation of China (42371040)
• Key Natural Science Foundation of Gansu Province (23JRRA698)
• Key Research and Development Program of Gansu Province (22YF7NA122)
• Cultivation Program of Major key projects of Northwest Normal University (NWNU-LKZD-202302)
• Oasis Scientific Research achievements Breakthrough Action Plan Project of Northwest normal University (NWNU-LZKX-202303)

Citation

@article{Qi2026Quantifying,
  author = {Qi, Xiaoyu and Sun, Zhigang and Zhu, Guofeng and Li, Rui and Jiao, Yinying and Zheng, Zhijie and Li, Wenmin and Gun, Yani and Yang, Jiangwei and Liu, Ziwen},
  title = {Quantifying evaporation losses in the river-lake continuum in arid regions basins using isotope data},
  journal = {Ecological Indicators},
  year = {2026},
  doi = {10.1016/j.ecolind.2026.114610},
  url = {https://doi.org/10.1016/j.ecolind.2026.114610}
}