在青藏高原及周边地区，地下水储量变化是重要但被了解最少的水资源信息，即使从卫星重力测量质量反演结果中分离，也面临极大困难。当利用卫星重力球谐模型，不同后处理会导致十分不同的结果；当利用球谐模型和质量模型也会导致不同结果；土壤湿度、冰川（包括积雪）、湖泊和冻土的信号干扰，会大大增加地下水储量变化估计的不确定性。本项目拟利用最新GRACE模型，根据冰川物质平衡、湖水等独立观测和模拟的时变信号，确定卫星重力模型和滤波方法，提取研究区可靠的水文重力信号；用最新的水文模型、InSAR/遥感/测高观测结果和冻土ALT变化模型，较精确模拟土壤湿度、雪水、冰川、湖水和冻土信号；水文重力信号去除这些信号分离出地下水信号，对地下水信号进行质量反演，有效减少信号泄漏影响，根据误差来源，严格进行结果不确定性评估。本研究将给出研究区可靠地下水储量变化估计结果，对水资源合理利用、区域发展和全球变化研究具有重要意义。

In the Tibetan Plateau and surrounding areas, groundwater storage changes are important but the least understood water resource information. It faces great difficulties to get groundwater storage changes in the region, even if separated from the inversion results of terrestrial water storage changes using satellite gravity measurement. Very different inversion results come from different de-striping procedures, when using GRACE spherical harmonic models; and so do they when using GRACE spherical harmonic models and MASCON models. Signal interference from soil moisture, glaciers (including snow), lakes and permafrost greatly increases the uncertainty of estimation results of groundwater storage changes. In the project, three steps are proposed to address the challenges. Firstly, reliable hydrological gravity signals of terrestrial water storage changes in the study area will be extracted by selecting the GRACE models and de-striping procedures, based on independent observation and simulation results of glacier mass balance, lake water and other hydrological components. Then, accurate hydrological gravity signals of soil moisture, snow, glaciers, lakes and permafrost will be simulated using the latest hydrological models and observation results of InSAR, remote sensing and satellite altimetry, as well as active layer thickness (ALT) changes of permafrost. Finally, the project will separate and invert the groundwater storage changes, and determine uncertainties of the inversion results considering the sources of errors. This study will provide reliable estimation results of groundwater storage changes in the study area, which is of great significance for the rational use of water resources, regional sustainable development and global change research.