Satellite Altimetry Reveals Significant Changes in Water Levels of Chinese Lakes Over Two Decades
Jan 08, 2024
In a recent study published in the Big Earth Data on Jan.3, scientists from the Aerospace Information Research Institute (AIR) under the Chinese Academy of Sciences (CAS) harnessed satellite altimetry to monitor water level changes in 988 lakes, each exceeding 10 square kilometers, across China. The research, spanning from 2002 to 2023, utilized data from ICESat/-2, Cryosat-2, Jason-1/2/3, and Sentinel-3A/3B altimeters, employing techniques such as waveform retracking, lake level extraction, time series construction, multi-altimeter data fusion, and outlier removal.
The findings highlight the significant role of satellite altimetry in addressing the scarcity and inconsistency of traditional lake level measurements. Due to limitations in time and space coverage, satellite altimetry emerges as a vital alternative for assessing water balance, understanding water cycles, and evaluating water resources in the face of climate and environmental changes.
This comprehensive dataset, monitoring 55% of lakes for over a decade and providing more than 12 annual measurements for 34%, offers a valuable resource for studying long-term lake dynamics. To validate the accuracy of the satellite-derived lake levels, in situ data from 21 lakes were utilized, revealing average root mean square errors ranging from 0.163 m to 0.596 m for individual altimeter datasets and 0.332 m for the fused lake levels.
Over the monitoring period, the study observes a general increase in water levels across Chinese lakes, with an overall annual average rate of change of 0.123 m/a and 0.151 m/a at 20 and 10-year scales, respectively. Notably, larger lakes exhibit a significant upward trend in water levels, while smaller lakes experience a faster rate of decline. The Tibetan Plateau region stands out with the most substantial increase in water storage, boasting an average annual water level change rate surpassing 0.15 m/a over the past two decades.
This high-precision spatiotemporal dataset opens new avenues for estimating changes in lake water storage, analyzing trends in lake levels, understanding plateau flooding dynamics, and exploring the intricate relationship between lake ecosystems and water resources. The study is expected to advance our understanding of the complex interactions shaping China's diverse lake systems.
Contact: luyq@aircas.ac.cn
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