Monitoring mine collapse by D-InSAR

For harmful ground collapse and its special deformation characteristics,which causes SAR images to lose coherence,InSAR technology cannot be applied in monitoring surface collapse in mining areas.We took the Shenmu mining area in northern Shaanxi province as an example to study subsidence in mining areas and proposed an interpolated multi-view processing method.The results show that this method can improve the detectable deformation gradient to a certain extent and can become a good reference value for monitoring large scale gradient deformation.We also analyzed the rules for temporal decorrelation in mining.

Land subsidence monitoring by D-InSAR technique

Nowadays, the researches of using Differential Interferometric Synthetic Aperture Radar (D-InSAR) tech- nique to monitor the land subsidence are mainly on how to qualitatively analyze the subsidence areas and values, but the analysis of subsidence process and mechanism are insufficient. In order to resolve these problems, 6 scenes of ERS1/2 images captured during 1995 and 2000 in a certain place of Jiangsu province were selected to obtain the subsidence and velocities in three time segments by ''two-pass'' D- InSAR method. Then the relationships among distributions of pumping wells, exploitation quantity of groundwater, and confined water levels were studied and the subsidence mechanism was systematically analyzed. The results show that using D-InSAR technique to monitor the deformation of large area can obtain high accuracies, the disadvantages of classical observation methods can be remedied and there is a linear relationship among the velocities of land subsidence, the water level and the exploitation quantity.

Monitoring of reclamation-induced ground subsidence in Macao (China) using PSInSAR technique

The long-term reclamation-induced ground subsidence in Macao, a coastal city of southern China was investigated. Persistent scatterer interferometry (PSI) technique was applied to retrieve the deformation rate in Macao during the period from April 2003 to August 2010 with a total of 41 scenes of descending ASAR data sets. The PSI-retrieved results show a relatively stable pattern in Macao Peninsula, Taipa Island and Coloane Island, with an average subsidence velocity of -3 mm/a. In contrast, relatively large subsidence rates are highlighted in Cotai area, a new reclamation land in 1990s, in which an average subsidence velocity is about -10 mm/a. A consistent relationship between the PSI results and the leveling measurements indicate that this PSI technique is an effective tool to monitor the reclamation-induced ground subsidence with a high accuracy and adequate spatial details. Accordingly, the valuable ground subsidence results generated by PSI can be used not only for early detection and remedial activities of potential settlement of building, but also for helping the local government to formulate regional sustainable development planning and decision-making in disaster prevention and mitigation.

On the application of DInSAR to deformation monitoring in desert areas

The DInSAR technique is used for monitoring the desert height changes to study sandstorms. Hunshandake Sandy Land, as the test area, is one of the main sources of sandstorms in Beijing. In order to study the sandstorm source and its impact, a pair of EnviSat ASAR images of Oct. 11, 2005, and Oct. 26, 2004, is processed on the basis of analysis of six ERS-2 and EnviSat radar images. After the image configuration, flat earth effect correction, data filtering, phase unwrapping, and geo-coding, a deformation model over Hunshandake desert is built. According to the results, the height decreased in most areas and increased in a few areas, which basically coincides with the strong sandstorm appearing in Beijing in the Spring of 2005. The results show DInSAR has an important role in monitoring of desert surface deformation.

川西鲜水河呷拉宗古滑坡发育特征与形成演化过程

青藏高原东缘是中国乃至全球地形陡度最大、内外动力作用最强烈、天气变化极端频繁的区域,复杂的地质演化过程导致该区成为古滑坡分布最集中和复活危害最大的地区。本文以川西鲜水河断裂带呷拉宗古滑坡为研究对象,在野外调查、钻探和物探、InSAR监测、室内试验及数值模拟分析的基础上,对呷拉宗古滑坡的发育特征、形成演化过程及复活因素进行了分析研究。结果表明,①呷拉宗古滑坡形成于距今约42~30ka的晚更新世晚期,体积达3150×10^4m^3,属巨型古滑坡;②鲜水河断裂活动是呷拉宗古滑坡形成的主控因素,历史强震的震裂效应形成古滑坡的雏形,后续的断裂蠕滑作用进一步造成坡体开裂,加剧大气降水渗入,并对裂缝有扩展作用;③SBAS-InSAR监测及数值模拟结果显示,目前该滑坡整体稳定性较好,但在多个部位存在不同程度的裂缝、陡坎及坍塌,局部变形强烈,在强震和极端降雨条件下可能发生较大规模复活滑动。建议加强采取排水和抗滑等防护措施。

Use of SAR interferometry for monitoring illegal mining activities: A case study at Xishimen Iron Ore Mine

The development and application of the ''digital mine'' concept in China depends heavily upon the use of remote sensing data as well as domestic expertise and awareness. Illegal mining of mineral resources has been a serious long term problem frustrating the Xishimen Iron Ore Mine management. This mine is located in Wu'an county in Hebei province, China. Illegal activities have led to enormous economic losses by interfering with the normal operation of the Xishimen mine and have ruined the surrounding environ- ment and the stability of the Mahe riverbed the crosses the mined area. This paper is based on field recon- naissance taken over many years around the mine area. The ground survey data are integrated with Differential Synthetic Aperture Radar Interferometry (D-InSAR) results from ALOS/PALSAR data to pin- point mining locations. By investigating the relationship between the resulting interferometric deforma- tion pattern and the mining schedule, which is known a priori, areas affected by illegal mining activities are identified. To some extent these areas indicate the location of the illegal site. The results clearly dem- onstrate D-InSAR's ability to cost-effectively monitor illegal mining activities.

Advances in space-borne SAR interferometry and its application to ground deformation monitoring

The development of Differential Synthetic Aperture Radar Interferometry （D-InSAR）, in terms of its evolution from classic to advanced forms, such as Least-Squares approach, Permanent Scatterer Interferometry, Small Baseline Subset, and Coherent Pixel Technique, is reviewed, describing concisely the main principles of each method and highlighting the difference and relationship between them. Applications of InSAR technology in China were then introduced, together with the obstacles to overcome and feasible strategies, such as integrating MERIS/MODIS data to compensate for the atmospheric effect and GPS, and multi-platform SAR data to make InSAR technique practical and operational under various conditions. The latest devel- opments were then analyzed along with high-quality SAR data, available thanks to the newly launched high-tech satellites, TerraSAR-X, and Cosmo Sky-med, and conclusions were drawn about the main limitations of the technique.