区域陆地水储量变化的重力效应研究

In the framework of monitoring network of crustal movement on Chinese continent and the monitoring network of tectonic environment on Chinese continent, the hydrological gravity effect will be investigated by using continuous gravity observations and diffusion equation of underground water and surface loading theory and taking the current hydrological model into account in order to provide references for refining hydrological model and the monitoring, application and development of water resource of our country. Selecting one or two gravity observatories where the background noises are low to be the regional reference, the accurate tidal gravity and loading correction models will be developed to remove the corresponding effects from the absolute and relative gravity time series. Applying well records and meterologic data in solving 1D or 3D diffusion equation of ground water to obtain the regional soil moisture changes of different depths, by which the variation of regional land water storage will be derived. Accordingly, how the land water affects the gravity measurements can be evaluated in terms of the Green’s function method as well as the assimilated hydroligical model. By analyzing the theoretical and simulated gravity changes, the hydrological effect signal will be retrieved according to iteration and the diffusion factor of ground water in typical area will be obtained to esimate the land water storage change with respect to time in Chinese continent.

依托“中国地壳运动观测网络”和“中国大陆构造环境监测网络”，采用中国大陆连续重力观测资料，基于地下水扩散方程和表面负荷理论，顾及已有的陆地水模型，研究水文重力效应，为水文模型的精化、我国水资源的监测、应用和开发提供重要参考。选取1~2个背景噪音水平较低的连续重力观测台站作为局部参考，建立局部高精度重力潮汐和环境负荷改正模型，并对绝对重力和流动重力观测作精密的重力潮汐和环境负荷改正。利用水井和气象数据，通过求解1D或3D地下水扩散方程，获得不同深度的局部土壤湿度的变化，进而得到局部陆地水储量的变化，结合陆地水同化数字模型，采用积分Green函数的数值计算方法，研究陆地水（包括地表水和地下水）变化对地表重力场观测的影响特征。分析比较理论模拟结果和重力仪观测结果，提取水文效应信号，经过反复迭代，获得典型区域的地下水扩散系数，估计中国大陆陆地水储量随时间变化。

地下水位变化对地面重力场的影响十分显著，可达到数十微伽的量级，在利用地面高精度重力场观测研究地壳运动、地下物质运移以及监测地震等灾害过程中，如何有效消除地下水对重力观测的影响是的一个十分重要的科学问题。本项目按照计划任务书，在收集和整理包括陆态网络连续重力（包括拉萨，丽江和武汉在内的高精度超导重力仪观测资料）和全球陆地水同化模型、局部水文和气象观测数据基础上，采用国际标准资料处理方法对不同台站连续重力观测资料进行统一的分析处理，系统研究了台站背景噪音水平与陆地水储量变化的重力效应。采用经典地表负荷理论和积分Green函数方法，较系统地实施了重力观测的精密大气、海洋与地下水负荷潮汐改正，确定区域重力潮汐和环境负荷改正模型。在此基础上，将高精度超导重力仪观测结果应用于检测地球液态核动力学效应等科学问题研究，取得了重要进展。