Monitoring lake level changes in China using multi-altimeter data (2016-2019)

摘要

Changes in lake levels are an important indicator of water balance and climate change. However, it is not feasible to perform continuous in situ measurements for a large number of lakes in China. Satellite altimetry has been used successfully to monitor water levels of inland lakes in recent years. In this study, through waveform retracking, lake level estimation, lake level time series construction, multi-altimeter time series fusion and outlier detection, changes in water level of 340 lakes (> 10 km~2) in China between 2016 and 2019 were monitored using multi-altimeter data from Cryosat-2, Jason-2, Jason-3, and Sentinel-3A. Overall, the water levels of these lakes showed a mean increasing trend of 0.343 m/yr. The water levels of 274 lakes have a mean increasing trend of 0.465 m/yr and those of 66 showed a mean decreasing trend of -0.164 m/yr. The annual rate of change of lake water levels increased from south to north and decreased from west to east in terms of spatial distribution. The changes in lake level varied among different basins owing to their high spatial heterogeneity: most lakes in the Songhua and Liao River Basin and Yellow River Basin showed an increasing trend; all lakes in the Huai River Basin were relatively steady; 14 of 19 lakes in the Yangtze River Basin showed a decreasing trend; the great majority of lakes in the Inland River Basin showed an increasing trend; and the lakes located in the southeastern Qiangtang Basin, near the Nyainqen Tanglha Mountain, showed a decreasing trend. In addition, some lakes in the western Qiangtang Basin also showed a decreasing trend. Factor analysis indicated that the factors driving changes in lake level varied among different areas. However, temperature changes in autumn and winter were significantly correlated with changes in lake level.