Monitoring Lake Water Level Changes in the Middle and Lower Yangtze River Basin Based on ICESat-GLAS Altimetry Data
ICESat-GLAS测高数据在长江中下游湖泊水位变化监测中的应用

Changes in lakes because of global climate change has become a national and international issue. We selected six typical lakes in China and analysed ICESat-GLAS data (ice, cloud, and land elevation satellite-geoscience laser altimeter system) to extract lake water elevations for 2003-2009. ICESat-GLAS altimeter waveform data were denoised by a Gaussian filter and used to distinguish between water and land. Lake boundaries were extracted from pre-processed Landsat TM imageries using a Fusion algorithm. Water level values within lake boundaries were used to construct inter-annual and annual water level time-variation curves. We found that the spatial accuracy of lake boundary data extracted from Landsat TM imageries is 10 m. The mean accuracy of measured ICESat altimeter data in the vicinity of Jiangba station at Hongze Lake, Chenglingji station at Dongting Lake, Xingzi and Changdu stations at Poyang Lake, Xishan station at Tai Lake, Zha station at Chao Lake and Gaoyou station at Gaoyou Lake are validated and assessed by observation data, and mean accuracy was -3.9 cm, -8.3 cm, -9.0 cm, -2.5 cm, -3.1 cm and -4.1 cm, respectively. Lake water levels in the middle and lower reaches of the Yangtze River basin show periodic fluctuation, and compared with historical observation data, the mean water level has decreased slightly. Lake water levels have been affected by regulation of the Three Gorges Project since October 2006. The relationship between lake water levels in the middle and lower Yangtze River basin and annual precipitation was correlated. Average water level changes for Hongze and Tai Lakes in 2006 fluctuated significantly. The average water level of Dongting, Poyang, Chaohu and Gaoyou Lakes peaked from June to October 2006.