湖泊既是陆地水资源的重要储蓄场所，也是区域和全球水文循环系统的重要组成部分，其水量波动对气候变化较为敏感。为了掌握湖泊面积、水位和水量的变化规律，借助1988-2018年Landsat TM/ETM/OLI影像和归一化差异水体指数NDWI（normalized difference water index）提取青海湖湖泊水域面积；利用ICESat-GLAS（ice, cloud, and land elevation satellite-geoscience laser altimeter system）测高数据提取青海湖湖泊水位变化，并结合观测资料检验陆地GLAS光斑脚点高程和湖泊水位的估测精度。根据湖泊面积与水位、水量与水位的关系，构建1988-2018年青海湖湖泊面积-水位-水量波动时变序列，并探讨湖泊水位、面积、水量的年内和年际变化特征。结果表明：GLAS光斑脚点高程与高程实测值的标准误差为0.14 m，与SRTM3高程标准误差为0.26 m；1988-2018年青海湖年均水位和水量总体上呈增加趋势，其中年均水位最低值出现于2004年，平均水位为(3 193.0±0.16) m，湖泊面积为(4 190±13) km2；与1988年年均水位相比，2018年青海湖年均水位上升了(1.93±0.22) m，湖泊年均面积扩张了(197.75±6.3) km2，湖泊水量增加了(8.93±0.12) km3。
英文摘要:
Lakes are not only important storage places for terrestrial water resources, but also play a vital role in the regional and global hydrological cycles, the water storage of which fluctuates with the climate change. In order to grasp the fluctuation law of lake area, water level and water storage, the lake area of Qinghai Lake was extracted by means of Landsat TM/ETM/OLI imageries during the period of 1988-2018, based on normalized difference water index (NDWI), and the water level change of Qinghai Lake was estimated using ice, cloud, and land elevation satellite-geoscience laser altimeter system (ICESat-GLAS) altimetry data. And then the GLAS footprint elevation of land surface as well as lake water surface was validated with the measured data. Based on the relationship between the lake area and water level, water storage and water level, the time-varying series of lake area-water level-water storage of Qinghai Lake during 1988 to 2018 were constructed, and the characteristics of inter-annual and intra-annual variations of the lake water level, lake area and water storage was discussed. The results show that the root mean square error (RMSE) between the GLAS footprint elevation and the measured elevation was 0.14 m, and the RMSE between GLAS footprint elevation and that of SRTM3 product was 0.26 m. In the period of 1988 to 2018, both the water storage and water level of Qinghai Lake increased. The lowest annual mean water level appeared in 2004, when the mean annual water level of Qinghai Lake was (3 193.0±0.16) m, and the lake area was (4 190±13) km2. Compared to 1988, the mean lake water level of 2018 rose by (1.93±0.22) m, the mean lake area expanded by (197.75±6.3) km2 and the water volume increased by (8.93±0.12) km3.