联合地表大地测量及GRACE监测三峡库区的蓄水渗透效应

Construction of the Three Gorges Project (TGP) has changed the geological environment of the Three Gorges region, and thus becomes the attention focus in scientific community. The change of groundwater level is one of the dominate factors to bring on environmental change and potential geological hazards during the impoundment of Three Gorges Reservoir (TGR). This proposal aims to study the relationship between the water loading and its infiltrating effect over the reservoir region according to time-variation gravity and crustal deformation. we can apply the ground gravity survey (continuous and absolute gravity) and spatial time-variation gravity (GRACE) data, GPS time series and hydrological observation data to analyze changes of water infiltration, gravity and crustal deformation caused by changes of the reservoir’s loading. Using high resolution DEM data, the elastic load response equation and Earth model, we can model the ground gravity and displacement and then obtain the distribution of the infiltration effects in the whole reservoir region and local area based on the horizontal infiltration theory and the practical hydraulic conductivity. The modelling results will provide correction to observed data. The purpose of the study is to explore the novel routine of studying the environmental evolution in TGR through the application of spatial and ground data and the combination of modeling and observation. It will be helpful to reveal relationships between the activities of landslips and reservoir induced earthquakes with the variation of reservoir’s loading.

三峡工程的建设改变了三峡地区的地质环境，因而成为科学界关注的焦点，而三峡库区蓄水过程中的地下水变化是环境变化和诱发潜在地质灾害的主要因素之一。本项目拟以库区时变重力与形变响应为切入点，研究库区蓄水负荷变化以及库水渗透效应。联合地表（连续及绝对重力）与空间（GRACE）时变重力、GPS时间序列及水文观测资料，以多种手段分析水库荷载导致的库水渗透变化以及由此引起的重力变化与地壳形变。通过高分辨率DEM数据、弹性负荷响应理论及地球模型，模拟得到库区地表重力场及形变场的理论值，并依据水平渗透理论与实际渗透系数，给出整体库区及局部地区渗透效应及其分布，获得的理论模拟数据将为实际观测资料的对比分析和相关校正提供重要支撑。本研究所利用的空间及地表观测资料、理论模拟结合实际观测的新手段，不仅能够探索研究三峡库区环境变化的新思路，其成果还有助于揭示库区滑坡活动及水库地震等与库水负荷变化及其渗透之间的关系。

作为世界上发电量最大的人工水库，三峡工程为我国经济腾飞带来了巨大的能量资源。但是如此巨大人类工程的建设和建成后的运行将会对环境形成何种程度的扰动，也倍受社会各界的普遍关注。本研究以三峡库区蓄水负荷变化为切入点，研究库区因蓄水导致的地表重力与形变响应。通过高分辨率SRTM-DEM数据与三峡库区主干道及各支流边界的地形对应关系，构建得到不同蓄水水位下的蓄水负荷模型，并且给出了不同水位与库区整体库容量体积及受淹面积之间的数学拟合关系；在此基础上，结合弹性负荷响应理论及macson拟合方法，计算得到整个库区地表重力场及形变场分布，以及时变库区蓄水容量的60阶次球谐模型。本文理论模拟结果能够为实际观测资料的对比分析和相关校正提供重要支撑，有助于挖掘库区滑坡活动及水库地震等与库水负荷变化之间的关系。本研究所利用的空间及地表观测资料、理论模拟结合实际观测的新手段，不仅能够探索研究三峡库区环境变化的新思路，其成果还有助于揭示库区 滑坡活动及水库地震等与库水负荷变化及其渗透之间的关系。