Küçükoğlu et al. (2025) Global evolution of inland water levels: drying-speed analysis using ICESat-2 ATL13

Identification

• Journal: Journal of Hydrology
• Year: 2025
• Date: 2025-10-31
• Authors: Merve Küçükoğlu, Yunus Kaya
• DOI: 10.1016/j.jhydrol.2025.134486

Research Groups

• Harran University, Graduate School of Natural and Applied Sciences, Department of Geomatics Engineering, S¸anlıurfa, Turkey
• Harran University, Faculty of Engineering, Department of Geomatics Engineering, S¸anlıurfa, Turkey

Short Summary

This study analyzed global inland water level dynamics for over one million lakes and reservoirs from 2018-2025 using ICESat-2 ATL13 data, revealing that more than half of monitored bodies experienced decreasing water levels and demonstrating the capability of satellite altimetry for near-term global-scale monitoring.

Objective

• To investigate global inland water level dynamics and drying trends for over one million lakes and reservoirs using ICESat-2 ATL13 data.
• To demonstrate the capability of satellite altimetry for tracking near-term global-scale lake-level evolution and providing a reproducible baseline for ongoing monitoring.

Study Configuration

• Spatial Scale: Global, covering more than one million lakes and reservoirs.
• Temporal Scale: 2018 to 2025 for observed data, with monthly time series constructed and short-term future predictions up to 12 months.

Methodology and Data

• Models used: Statistical methods, machine learning (LSTM), rolling-origin validation, and a newly introduced drying-speed index (DSI) defined as the mean of negative year-over-year changes.
• Data sources: ICESat-2 ATL13 satellite altimetry data; in-situ gauge measurements from 195 lakes (7,553 collocations) for validation.

Main Results

• Validation against in-situ gauges yielded a Root Mean Square Error (RMSE) of approximately 0.35 meters and a Mean Absolute Error (MAE) of approximately 0.26 meters.
• More than half of the monitored lakes and reservoirs exhibited decreasing water levels, with observed patterns varying by size and geographic region.
• Short-term projections demonstrated skill within horizons of up to 12 months, providing data-driven extrapolations with quantified uncertainty.
• The study established satellite altimetry as a capable tool for tracking near-term global-scale lake-level evolution and providing a reproducible baseline for ongoing monitoring.

Contributions

• Provides the first global, comprehensive analysis of inland water level dynamics for over one million lakes and reservoirs using high-precision ICESat-2 ATL13 data, extending the temporal scope beyond previous regional or short-term studies.
• Introduces a novel drying-speed index (DSI) to quantify persistent water level declines.
• Overcomes limitations of previous radar altimeter missions (coarse footprints, limited coverage, retracking uncertainties) and earlier laser altimeters (sparse sampling, single-beam coverage) by leveraging ICESat-2's centimeter-level accuracy and broader coverage.
• Delivers validated short-term (up to 12 months) future predictions of water levels, offering a reproducible baseline for ongoing global monitoring efforts.

Funding

Not specified in the provided text.

Citation

@article{Küçükoğlu2025Global,
  author = {Küçükoğlu, Merve and Kaya, Yunus},
  title = {Global evolution of inland water levels: drying-speed analysis using ICESat-2 ATL13},
  journal = {Journal of Hydrology},
  year = {2025},
  doi = {10.1016/j.jhydrol.2025.134486},
  url = {https://doi.org/10.1016/j.jhydrol.2025.134486}
}