The North China Plain in China is one of the areas with the scarcest water resources, and it is an area with more groundwater extraction. The form of groundwater in this area is severe, and it is necessary to monitor the changes in groundwater reserves in this area. Traditional use of groundwater wells to monitor changes in groundwater levels makes it difficult to obtain accurate changes in groundwater reserves. GRACE/GRACE-FO satellite gravity has made great achievements in the changes of land water reserves and groundwater reserves, but due to the low spatial resolution, it is not possible to obtain the changes of groundwater reserves in the North China Plain. This paper integrates GNSS and GRACE/GRACE-FO satellite gravity data, based on the load deformation theory, effectively integrates GNSS and satellite gravity data, separates groundwater balance effect and groundwater load impact, obtains the change of groundwater reserves in the North China Plain from 2018 to the end of 2021, and conducts comparative analysis on the observation data of groundwater wells and precipitation data, finding that the downward trend of groundwater level has slowed down, The groundwater reserves in the North China Plain declined as a whole, and the groundwater in some areas of Beijing rose slightly.

采用三峡地区全球导航卫星系统(global navigation satellite system,GNSS)和重力连续观测数据,结合水文气象和地形资料,计算大地高、地面重力等变化,通过与地质灾害事件的空间对比分析确定评价所用的观测要素和权重,对地质环境稳定性进行了定量评价.研究发现,整个三峡地区的地质环境总体上较为稳定,三峡大坝下游地区稳定性普遍较好.但是,库区腹地秭归—云阳段的长江沿岸有5～6处形状及面积不同的局部地段,稳定性较弱;三峡库区外围的房县、镇坪县也存在一些稳定性较弱的地区.所提出的地质环境稳定性定量评价方法和研究结果对于区域地质环境评估和地质灾害防治等具有重要参考价值.

The Longmenshan fault zone is located in the transition zone between the eastern margin of Qinghai-Xizang Plateau and Sichuan Basin. It is an important part of the north-south seismic belt in China, and the tectonic activity is frequent, and the 2008 Wenchuan earthquake and the 2013 Ya’an earthquake are all on the tectonic fault. In this paper, the coordinates’ time series and velocity fields in the region with high precision are obtained based on GAMIT/GLOBK. The strain parameters in the region are calculated by using the strain model and the high-precision dynamic model of the fault zone and the surrounding crust are constructed, and the time-space distribution of the abnormal information of the fault zone is extracted and analyzed with the reference of the earthquake such as Wenchuan and Ya’an. The study in this paper can be used as a reference for the analysis of crustal movement characteristics and the assessment of geological hazards in Sichuan-Yunnan region.

Geological hazard monitoring is essential to the prevention and control of geological hazards, yet conventional monitoring is often conducted for local geological hazards, and the relation between monitored results and geological hazards remains poorly understood. In this study, a regional load deformation field model was constructed using data from 26 Continuously Operating Reference Stations (CORS) and 8 gravity stations in the Three Gorges area. The relation between load-induced changes and geological hazards, as the regular characteristics (RCS) in this paper, is obtained by comparing the geological hazards with the impact of the total load change in the whole region of the Three Gorges area and the entire process from 2011 to the beginning of 2015. Geological hazards are more prone to occurring when there are one or more RCS, especially abnormal dynamic environment appears at the same time, such as solid high tide and heavy rainfall. The RCS included the ground geodesy height change rate increasing, the ground gravity change rate decreasing, the ground vertical deviation diverging, the ground geodesy height gradient growing larger and the ground gravity gradient growing larger. Using all of the 18 geological hazards from May to July 2013 to verify the RCS, it was found that the comprehensive observations of CORS and gravity stations can effectively monitor the RCS of the load-induced changes. The results of this study provide more insights associated with the geological hazards monitoring and analysis methods as well as effective support for geological hazard forecasting.

In order to obtain deformation parameters in each block of Sichuan-Yunnan Region (SYG) in China by stages and establish a dynamic model about the variation of the strain rate fields and the surface expansion in this area, we taken the Global Positioning System (GPS) sites velocity in the region as constrained condition and taken advantage of the block strain calculation model based on spherical surface. We also analyzed the deformation of the active blocks in the whole SYG before and after the Wenchuan earthquake, and analyzed the deformation of active blocks near the epicenter of the Wenchuan earthquake in detail. The results show that, (1) Under the effects of the carving from India plate and the crimping from the potential energy of Tibetan Plateau for a long time, there is a certain periodicity in crustal deformation in SYG. And the period change and the earthquake occurrence have a good agreement. (2) The differences in GPS velocity fields relative Eurasian reference frame shows that the Wenchuan earthquake and the Ya'an earthquake mainly affect the crustal movement in the central and southern part of SYG, and the average velocity difference is about 4-8 mm/a for the Wenchuan earthquake and 2-4 mm/a for the Ya'an earthquake. (3) For the Wenchuan earthquake, the average strain changed from 10 to 20 nanostrian/a before earthquake to 40-50 nanostrian/a after the earthquake, but before and after the Ya'an earthquake, the strain value increased from about 15 nanostrian/a to about 30 nanostrian/a. (4) The Wenchuan earthquake has changed the strain parameter of each active block more or less. Especially, the Longman block and Chengdu block near the epicenter. The research provides fundamental material for the study of the dynamic mechanism of the push extrusion from the north-east of the India plate and the crimp from Qinghai Tibet Plateau, and it also provides support for the study of crustal stress variation and earthquake prediction in Sichuan Yunnan region. (C) 2018 COSPAR. Published by Elsevier Ltd. All rights reserved.

Guanzhong is one of the important industrial and agricultural developed areas in 'One Road and One Belt'. It is necessary to monitor and analyze groundwater storage (GWS) variations in this area to reveal the characteristics of GWS, which is of great importance for economic and social development. Firstly, based on the gravity field model from the Gravity Recovery and Climate Experiment (GRACE) satellite data from 2003 to 2014, the combined filter and method of single-scale factor are applied to invert the terrestrial water storage (TWS) variations in the Guanzhong area. Then by subtracting the results of GLDAS average surface water from TWS, GWS variations in this area are determined. Finally, the correlation between TWS and GLDAS is analyzed, and the GWS variations are compared with that from the WGHM groundwater model and well observations. The results show that (1) the TWS variations in the Guanzhong area have a strong correlation with the GLDAS model (VIC, NOAH, CLM, and MOSIC). The most correlation coefficients between them are greater than 0.7, whereas the correlation coefficient between the model average and TWS is up to 0. 8. (2) During 2003 to 2008, GWS in the Guanzhong area showed a positive growth trend, and the increase rate was 0. 25 cm . a(-1), which is consistent with the trend of well observations in the same period. However, there was a long-term depletion of GWS from 2003 to 2013, and the depletion rate is -0. 37 cm . a(-1), which agrees well with the WGHM estimation result of -0. 35 cm . a(-1) for the same period. (3) There are obvious annual variation characteristics of GWS in the Guanzhong area. The rate of GWS depletion during 2003 to 2014 was -0. 44 cm . a(-1), which was in good agreement with the rainfall in this area, while during the drought years, i. e., 2008, 2012 and 2013, GWS also decreased significantly.

在高精度大地测量观测数据处理和相关地球物理解释中,大气负荷由于影响较大,需要考虑.利用全球大气模型和区域气象站气压数据,采用移去恢复方法和球谐分析方法,计算了三峡地区大气负荷对地壳形变和重力变化的影响.提供了一种利用局部气压数据改善该区域大气负荷影响变化计算效果的合理算法,提高局部气压数据和全球模型数据利用的合理性和准确性.研究发现,大气负荷对垂直形变的影响在空间分布上中长波占优,在三峡地区的年变化幅度大于20 mm,对地面重力变化影响的年变化幅度一般不超过10μGal,对水平形变影响较小.

The changes of the Earth rotation, the plates' movement and the environment of observation can cause the point shift in the GPS network, even if the observation period is a month, the displacement of the two times cannot be ignored. In this paper, take the terrestrial network station and CORS station network in Sichuan province as an example, using the method of limit error ellipse, the horizontal direction of the station is compared and analyzed. And using the stability of the station to indicate the degree of displacement, so as to identify the stability of the fixed point and unstable fixed point; at the same time, the stability of the elevation direction of the station is analyzed by the method of mathematical statistics. It provides a theoretical basis for the analysis of the stability of the network and a reference basis for the selection of the stability of the station to do a permanent reference station.