1.College of Remote Sensing and Geomatics Engineering,Nanjing University of Information Science and Technology;2.Shanghai Astronomical Observator,Chinese Academy of Sciences
鄱阳湖水位变化复杂，传统的技术难以对鄱阳湖水位变化进行大范围高精度地动态监测。2018年9月，搭载了全球先进光子计数激光测高仪的冰、云和陆地高程2号卫星（ICESat-2）的成功发射，对内陆中大型湖泊水位动态变化监测成为可能。本研究利用ICESat-2卫星2018-2020年逐月的ATL13全球内陆水体数据估计和分析了鄱阳湖水位变化特征，利用鄱阳湖湖口、星子和康山水文站实测数据进行验证和误差修正，并结合各测站水位数据、降雨量数据分析鄱阳湖水位动态变化及其原因。结果表明：①鄱阳湖年内水位变化剧烈，具有明显的季节变化规律，总体水位呈上升趋势，6-10月为高水位期，其他月份为低水位期，水位高峰期出现在 7-9 月。②ICESat-2测高水位与实测水位具有较高的线性相关性，决定系数(R2)在0.846以上，经过误差修正以后决定系数高达0.974。均方根误差（RMSE）表现为湖口站1.660m，星子站1.073m，康山站0.836m，经过误差修正重新计算后，其测量精度提升近1m，均方根误差提高为湖口站0.663m，星子站0.659m，康山站为 0.440 m。③鄱阳湖水位变化与降雨量变化高度相关，主要受降雨量影响，表现为1-2 月和 10-12 月降雨量较少，为枯水期，水位下降；3-10 月降雨量增多，为丰水期，水位上涨；降雨主要集中出现在7-9月，对应水位高峰期。
The water level change in Poyang Lake is very complex, while traditional techniques are difficult to monitor such dynamic changes with large scale and high precision. In September 2018, the Ice, Cloud and Land Elevation 2 (ICESat-2) satellite, equipped with the world's advanced photon counting laser altimeter, was successfully launched, which provides a good opportunity to monitor the dynamic changes of water levels in medium and large inland lakes. In this study, the monthly ATL13 global inland water data product of ICESat-2 satellite from 2018 to 2020 are used to estimate and analyze the water level variation of Poyang Lake. The measured data of Hukou, Xingzi and Kangshan hydrology stations were used for verification and error correction, and the water level and rainfall data of each station were combined to analyze the dynamic variation of Poyang Lake water level and its causes. The results showed that: (1) The annual water level of Poyang Lake varied sharply with obvious seasonal variation, and the overall water level showed an increasing trend. The high-water level period was from June to October, and the low water level period was in other months, and the peak of water level appeared from July to September. (2) ICESat-2 has a high linear correlation with the measured water level with the coefficient of above 0.846, and the coefficient is as high as 0.974 after error correction. The root mean square error (RMSE) is 1.660m at Hukou station, 1.073m at Xingzi station, and 0.836m at Kangshan station. After error correction and recalcitration, the measurement accuracy is improved by nearly 1m, and the RMSE is 0.663m at Hukou station, 0.659m at Xingzi station, and 0.440 m at Kangshan station. (3) The variation of water level in Poyang Lake is highly correlated with the variation of rainfall. The precipitation is low in January-February and October-December, and the water level decreases in the dry season. From March to October, the rainfall increases, and the water level rises. Rainfall mainly occurs from July to September, when is the peak of water level.
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