Chengsheng Yang

Monitoring mine collapse by D-InSAR

Abstract 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.

Mining collapse monitoring with SAR imagery data: a case study of Datong mine, China

Abstract A mining-induced collapse is often characterized by large deformation gradient, spatial discontinuity, and temporal nonlinearity, resulting in the loss of interferometric SAR (InSAR) coherence and consequently subsidence information in areas of steep deformation gradients. In this study, we present different SAR deformation monitoring schemes to map the mining-induced subsidence and collapse. First, SAR data with different wavelengths, including C-band ERS-1, C-band Envisat ASAR, and X-band TerraSAR-X data, are used to highlight three mining subsidence stages and their temporal evolutions over Datong mine (China) in the past 20 years. Mining-induced subsidence over a region can be delimited from InSAR deformation maps, where InSAR coherence is lost over the area of peak subsidence. Second, in order to monitor the large-gradient surface deformation caused by underground mining activities, three SAR deformation monitoring schemes are proposed, including a full-resolution interferogram method, a “remove-restore” phase unwrapping method, and a fusion of phase and offset measurements. Then, taking the Datong coalfield as an example, we demonstrate the capabilities of these methods on mapping large-gradient deformation. Finally, we have found that over 80% of coalfields have deformed during the past 20 years. We conclude that the fusion of the InSAR phase and offset measurements can provide a reliable estimate of large-gradient mining-induced deformation.

Two-dimensional deformation monitoring over Qingxu (China) by integrating C-, L- and X-bands SAR images

Multi-band synthetic aperture radar (SAR) data sets with different imaging parameters enrich the ground deformation monitoring by interferometric synthetic aperture tadar (InSAR) technique. It is desirable to integrate of these images to produce the high-precision three-dimensional (3-D) or two-dimensional (2-D) deformation. In this study, high-precision east–west horizontal and vertical deformation rate over Qingxu region (Shanxi province, China), where serious deformation associated with the excessive pumping of ground water is documented, is produced through integrating of 22 C-band ENVISAT/ASAR, 16 L-band ALOS/PALSAR and 11 X-band TerraSAR images. The results show that the vertical and east–west deformation rate reach to −16.68 and −4.6 cm year−1, respectively, indicating the severe surface deformation in our study area. The comparison between our observed 2-D deformation and global position system (GPS) observations displays that the standard deviations of east–west deformation and vertical deformation are about 4.7 and 3.8 mm year−1, respectively, demonstrating the reliability of our result. This study should help us to better understand the formation and development of the deformation over the research area and provide scientific evidence on a sound management of ground water pumping to mitigate potential damages on infrastructures and environments.

Small-scale loess landslide monitoring with small baseline subsets interferometric synthetic aperture radar technique—case study of Xingyuan landslide, Shaanxi, China

Abstract. Small baseline subsets interferometric synthetic aperture radar technique is analyzed to detect and monitor the loess landslide in the southern bank of the Jinghe River, Shaanxi province, China. Aiming to achieve the accurate preslide time-series deformation results over small spatial scale and abrupt temporal deformation loess landslide, digital elevation model error, coherence threshold for phase unwrapping, and quality of unwrapping interferograms must be carefully checked in advance. In this experience, land subsidence accompanying a landslide with the distance <1  km is obtained, which gives a sound precursor for small-scale loess landslide detection. Moreover, the longer and continuous land subsidence has been monitored while deformation starting point for the landslide is successfully inverted, which is key to monitoring the similar loess landslide. In addition, the accelerated landslide deformation from one to two months before the landslide can provide a critical clue to early warning of this kind of landslide.

Complex Deformation Monitoring over the Linfen–Yuncheng Basin (China) with Time Series InSAR Technology

The Linfen–Yuncheng basin is an area prone to geological disasters, such as surface subsidence, ground fissuring, fault activity, and earthquakes. For the purpose of disaster prevention and mitigation, Interferometric Synthetic Aperture Radar (InSAR) was used to map ground deformation in this area. After the ground deformation characteristics over the Linfen–Yuncheng basin were obtained, the cross-correlations among regional ground subsidence, fault activity, and underground water level were analyzed in detail. Additionally, an area of abnormal deformation was found and examined. Through time series deformation monitoring and mechanism inversion, we found that the abnormal deformation was related mainly to excessive groundwater exploitation.

Deformation at longyao ground fissure and its surroundings, north China plain, revealed by ALOS PALSAR PS-InSAR

Abstract The Longyao ground fissure (LGF) is the longest and most active among more than 1000 ground fissures on the North China Plain. There have been many studies on the formation mechanism of the LGF, due to its scientific importance and its potential for damage to the environment. These studies have been based on both regional tectonic analysis and numerical simulations. In order to provide a better understanding of the formation mechanism, the deformation of the crack and its surrounding environment should be taken into consideration. In this paper, PS-InSAR technology was employed to assess the ground deformation of LGF and its surrounding area, using L-band ALOS-1 PALSAR images from 2007 to 2011. The characteristics of ground deformation, relationships between fissure activity and surrounding faults and groundwater exploitation were analyzed. This study shows that the north side of Longyao fault (LF) is uplifting while the south side is subsiding. This provides the tectonic conditions responsible for the activity of the ground fissure. Local groundwater exploitation also plays an important role in the development of ground fissures. InSAR observations were modeled to infer the loading depth (-2.8 km) and the slip rate (31.1 mm/yr) of LF.

Surface subsidence and ground fissures activity monitoring based on D-InSAR: A case of Datong city

The Synthetic Aperture Radar Interferometry technique has become one of geological disaster monitoring tools, for its economical, efficient, high-precision and large-scale surface deformation monitoring capacities. Datong is a wellknown historical and cultural city, which is also a major energy bases and known as “town of coal sea” reputation in China. Since 1980s, with the development of industry and agriculture the amplitude of groundwater withdrawal has increased year by year, which lead to serious surface subsidence and ground fissures hazards in this city, even active up-to-date. Presently, 10 ground fissures with a total length of 34.5 km can be found in Datong region. However, the city-level spirit leveling only carried out during years of 1988–1993 to monitor the surface subsidence, and ceased later on. So in this paper, we collect 8 scenes of Envisat SAR data covering Datong city to minitor the subsidence evolution during Jan. 2005 to Feb. 2008. The interferometric pairs are set according to the principles that temporal and geometric baseline limits. Finally, we obtain the annual and accumulated subsidence amounts. The study shows that the land subsidences in Datong are greatly correlated with the groundwater withdrawal and seasonal variation. And some new sobsidence cones are located at new economic and technological development zones of Datong city. Thirdly, ground fissures deformation in Datong is controlled by the regional tectonic activity and also affects the land subsidence in its surroundings.

Research on CR-based offset technique for mining deformation monitoring

Underground mining induced displacements in most areas of China amount to meter-level while with small spatial coverage, spatially discontinuous and temporally nonlinear features. Traditional phase-based InSAR methods can hardly obtain large deformation in the center of land subsidence area due to the phase noise, maximum monitoring ability. This paper systematically studies the offset tracking technique based on SAR image intensity maps with and without pre-installed Corner Reflectors (CRs).The results of this experiment indicate that the high resolution SAR data with the aid of pre-installed CR points can better solve the large gradient deformation monitoring problem. In addition, offset tracking method has the potential to achieve two-dimensional deformation field along the line-of-sight and along the azimuth directions, which can provide more detailed information regarding mining induced deformation, which is complimentary to the traditional phase-based and intensity-based techniques.

Large coverage surface deformation monitoring with multiple insar techniques and multiple sensor SAR datasets: a case study in Linfen-Yuncheng basin, China

The Linfen-Yuncheng Basin (LYB) is one of the most serious geo-hazards regions in China, which have been experiencing severe geo-tectonic movement, seismic, land subsidence and ground fissures. To monitor the complex surface deformation at LYB, Interferometric Synthetic Aperture Radar (InSAR) is employed. Forty-nine scenes acquired from three SAR tracks from 2007 to 2011 are used to obtain the ground deformation over LYB based on four multi-temporal InSAR analysis methods (i.e. PI-RATE, Stacking, SBAS and TCP). The maximum displacement is observed in Jishan County with the subsidence rate up to 120 mm/yr in the vertical direction. Two visually triangular areas are recognized at Jishan and Taocun-Xiaxian, which are controlled by local normal faults. In addition, cross-validation of the results in overlapping areas between adjacent tracks, ascending and descending tracks are conducted, which show good consistency among four methods.

Mapping overall taiyuan graben basin deformation with SBAS-InSAR technique

Taiyuan graben basin has been suffering serious ground deformation due to the combined effects of groundwater pumping, ground fissures and faults. However, most ground deformation monitoring mainly focus on the single city, thus it is difficult to reveal the regional extent of the deformation. Fifty-five ALOS/PALSAR images acquired from three adjacent tracks from 2007 to 2011 are used to obtain annual deformation rate based on Small Baseline Subsets (SBAS-InSAR) technique. The standard deviations of deformation differences between two adjacent tracks are 3.7mm/a and 4.2mm/a, respectively. Large subsidence funnels mainly occur in the regions, where the groundwater pumping is intensive. The maximum subsidence is observed in Qingxu with the land subsidence rate up to 240mm/a, while regions with subsidence rates ranging from 50 to 90mm/a are detected in other locations. Meanwhile, significant deformation differences are retrieved in both sides of the faults, which could be explained as the faults-controlled deformation.