Pan et al. (2026) A refined reservoir evaporation loss estimation approach through improved wind function expression accuracy

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-07-24
• Authors: Cuihong Pan, Zengliang Luo, Lunche Wang, Zigeng Niu, Zushuai Wei, R Y Wang
• DOI: 10.1016/j.jhydrol.2026.136090

Research Groups

• Hubei Key Laboratory of Regional Ecology and Environmental Change, School of Geography and Information Engineering, China University of Geosciences, Wuhan.
• State Key Laboratory of Geomicrobiology and Environmental Changes, China University of Geosciences, Wuhan.
• School of Artificial Intelligence, Jianghan University, Wuhan.

Short Summary

The study proposes a weighted wind direction method to refine reservoir evaporation estimates by accounting for reservoir geometry and wind field heterogeneity, applying this approach to 6,853 large reservoirs globally from 1985 to 2021.

Objective

• To reduce the uncertainty in Penman-based reservoir evaporation estimates by improving the representation of wind direction, moving beyond simple spatial averages to incorporate reservoir shape and spatial distribution features.

Study Configuration

• Spatial Scale: Global (6,853 large reservoirs).
• Temporal Scale: 1985–2021 (monthly intervals).

Methodology and Data

• Models used: Penman equation, Weighted wind direction method.
• Data sources: Ground-based meteorological observations, TerraClimate, ERA5-Land, and FLUXCOM evaporation products.

Main Results

• Accuracy Improvement: The weighted wind direction method showed better agreement with ground-based observations than the mean wind direction method, reducing the mean relative root mean square error (rRMSE) by 0.29 and the mean absolute percentage error (MAPE) by 25.43%.
• Product Consistency: Evaporation estimates using the weighted method were more consistent with ERA5-Land, TerraClimate, and FLUXCOM products.
• Fetch Length Correlation: A strong negative correlation (CC $\le -0.7$) was identified between differences in fetch length and differences in evaporation between the two methods.
• Global Trends: Between 1985 and 2021, 53.92% of reservoirs showed an increasing trend in evaporation, while 12.31% showed a decreasing trend.
• Seasonality: Monthly evaporation seasonality exhibited a spatial pattern that weakened from high latitudes in the Northern Hemisphere toward the Southern Hemisphere.

Contributions

• The research provides a refined reservoir-scale weighted wind direction method that accounts for reservoir geometry, significantly reducing the bias and uncertainty inherent in traditional Penman-based estimates that rely on spatial wind averages.

Funding

• Not specified in the provided text.

Citation

@article{Pan2026refined,
  author = {Pan, Cuihong and Luo, Zengliang and Wang, Lunche and Niu, Zigeng and Wei, Zushuai and Wang, R Y},
  title = {A refined reservoir evaporation loss estimation approach through improved wind function expression accuracy},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.136090},
  url = {https://doi.org/10.1016/j.jhydrol.2026.136090}
}