陆表蒸散发是全球水文循环中的一个重要组分，蒸散发的长期变化对区域水循环和气候变化研究等具有重要意义。在流域尺度，利用水量平衡方法估计蒸散发的方法依赖于陆地水储量变化的估计精度。近年来高精度卫星重力观测的出现，为准确估计陆地水储量变化进而估计蒸散发提供了重要契机。但由于重力卫星的运行时间限制，难以获得更长期的陆地水储量变化估计。为此，本项目拟以长江流域为例，结合卫星重力、气象水文实测资料和陆表模式研究长期的陆地水储量变化和蒸散发估计。重点围绕以下三个方面研究：1）结合卫星重力和实测资料构建陆地水储量长期变化；2）利用重构的陆地水储量变化约束估计流域长期蒸散发量和不确定性评估；3）长期蒸散发和陆地水储量的不同时间尺度变化及影响因素分析。本项目基于合理的重建数据重构陆地水储量变化，提高长期蒸散发估计的精度，研究成果以期为陆地水循环通量的定量估计和水资源管理提供重要的数据和信息支撑。

Land surface evapotranspiration (ET) is an important component in the global hydrological cycle, long-term ET changes are significant for the study of the regional water cycle and climate change. On the basin scale, the estimate of ET based on the water balance method relies heavily on the accuracy of terrestrial water storage changes (TWSC). In recent years, the launch of high-precision satellite gravity data had provided an important opportunity for accurately estimating TWSC and effectively estimating ET. However, due to the orbiting time limitation of gravity satellites, it is difficult to obtain long-term estimates of TWSC. To this end, this project takes the Yangtze River Basin as a case study, combining with satellite gravimetry, hydrometeorological data, and land surface models to study long-term TWSC and ET estimates. The objective is on the following three aspects: 1) constructing long-term TWSC based on satellite gravimetry and hydrometeorological data; 2) estimating ET on the basin using reconstructed TWSC and uncertainty estimation; 3) analyzing the influencing factor of long-term ET and TWSC variations on different time scales. The results of this project will improve the accuracy of long-term ET estimation from the reconstruction of TWSC based on reasonable data. They will provide important data and information support for the quantitative estimation of water cycle flux and water resources management.