Jinghui Fan

CRInSAR for landslide deformation monitoring: A case in threegorge area

Landslide in threegorge area is a severe geohazard threatening many people. Conventional differential SAR interferometry (DInSAR) and Persistent Scatterers for SAR interferometry (PSInSAR) technique are unsuitable for landslide deformation monitoring in this area due to temporal and lack of natural phase stable point targets. The method of DInSAR using corner reflectors (CRInSAR) is a powerful tool in the vegetation area. The procedure of DInSAR using corner reflectors (CRInSAR) used by this paper is briefly introduced. Using ENVISAT ASAR time series data, the deformation of 12 corner reflectors (CR) in Shuping landslide are analyzed. As to the CR with slow creep deformation, the CRInSAR results are reliable. But as to the CR with nonlinear accelerated deformation, our CRInSAR method still needs to be enhanced.

Detection of land subsidence in Beijing, China, using Interferometric Point Target Analysis technique

Land subsidence in Beijing is supposed to be caused by over-exploitation of ground water, which is leading to a rapid decline of water levels, drying out clay layers that finally result in land subsidence.

Monitoring Urban Subsidence in the City of Tianjin (China) by Differential SAR Interferometry

Using ASAR images covering the period from April 2003 to August 2004, we show that ENVISAT SAR Interferometry can provide us valuable information to map the subsidence phenomena of Tianjin area. The approach of interferogram stacking has been used in order to reduce the influence of the atmospheric fluctuations on the deformation estimation. In the process of removing topographic component from the inerferometric images, SRTM DEM are used. The geoid height in the area has been compensated. In the stage of unwrapping, the coherence values of pixels in the interferograms are taken into consideration and the method based on the minimum cost flow algorithm and the triangulation of sparse points are used. KeywordsDInSAR; subsidence; urban area

Monitoring of landslide deformation based on the coherent targets of high resolution InSAR data

Landslides are a kind of typical natural disaster in China, which pose serious threats to civil lives, property and living environment. Therefore, the identification, monitoring and prevention of landslides have been considered as a long-term geological work for the public welfare. In this article, 8 TerraSAR-X high resolution strip-map mode images, acquired in the period from January to March 2012 and covering Fanjinping landslide in Zigui county, Hubei province, were used to test the usability in monitoring the deformation of single landslide. The results of two-pass DInSAR sketched the region and the shape of the deformation field of Fanjiaping landslide. Corner reflectors’ linear deformation rate using CRInSAR method could be approximately validated by the in-situ GPS measurements. From the coherent pixels’ linear deformation rate map, it was inferred that the deformation could be more obvious in the tail of the Muyubao landslide while the lowest frontier of this landslide might prevent the slide. Due to its shorter revisiting period and high bandwidth,,the high resolution TerraSAR-X images can keep better coherence than previous satellite SAR data in the test area and provide basic guarantee to monitor the deformation of single landslides.

Mapping the Deformation of Shuping Landslide Using DInSAR and Offset Tracking Methods

Shuping landslide, belonging to Zigui county, Hubei province, is located on a north-inclined slope at the south bank of Yangtze River and about 50 km away from the Three Gorges Dam. The landslide occupies less than 1 km2 and is covered by densely vegetations. Since the first impoundment of the Three Gorges Reservoir ended on June 15, 2003, the landslide has suffered obvious deformation. The maximum value of Shuping landslide in special month is up to several decimetres.

Monitoring the deformation of a landslide with differential SAR interferometry using corner reflectors

In order to monitor the surface deformation of Shuping landslide in the Yangtze River Three Gorges area, the method of differential SAR interferometry (DInSAR) using corner reflectors (CR) was applied. 12 CR, including 10 pyramidal corner reflectors (PCR) and 2 asymmetrical cubic corner reflectors (ACCR), were designed, made, and deployed on Shuping landslide. Based on the numerical test and the preliminary analyses of 5 ENVISAT ASAR images, we concluded that: 1) ACCR can provide strong response signal even without the best SAR look angle and is especially fit for the multi-angle applications of DInSAR; 2) given a simple phase model, the least square (LS) method can be used to analyze the CRs differential phase and get the accumulative deformation value.

A study on different PS-like methods for subsidence in Tianjin, China

In this paper, the methods, primary PS-like method and Stanford Method for PS (StaMPS) are both studied and used to monitor the subsidence in Tianjin area.

A method for InSAR baseline refinement and its application

Interferometric baseline plays a very important role in InSAR data processing, and it will directly affect the accuracy of interferometric result. In this article, three classical baseline estimation methods were described. By comparing and combining three methods, a new baseline estimation method and its flow were listed. RADARSAT-2 satellite image data and grid digital elevation model ASTER GDEM (30m resolution) in Kailuan area are used as sample data. By analyzing the differential interferometric results generated with different baseline estimation methods, it can be concluded that the new method used by this article is correct and feasible.

DInSAR for land subsidence monitoring using high resolution COSMO-SKYMED SAR Data: Preliminary results compared with ASAR

DInSAR can map ground deformation phenomena over tens-of-kilometers-wide area with centimeter-scale accuracy level, and has been considered as a powerful tool. Because of the data availability, previous DInSAR applications were mainly base on ERS, JERS, ENVISAT ASAR, and RADARSAT-1 data with resolution coarser than 10m. Nowadays, several kinds of high resolution SAR data are available for DInSAR and there are high expectations for the application of these data. In this paper, COSMO-SkyMed SAR data and grid digital elevation model ASTER GDEM (30m resolution) are used as research data. COSMO-SkyMed SAR data are preliminary processed by DInSAR technique for land subsidence mapping of Tianjin and Beijing area. Meanwhile, the DInSAR results from COSMO-SkyMed and ASAR data are preliminary compared. COSMO images are more suitable to extract high-precision ground deformation information than ASAR images in civil application given precise orbit data. While COSMO data are suitable for deformation monitoring in a relatively small and important area, ASAR data are fit for regional survey.

Linear Deformation Rate Derivation from Multi-baseline Differential Interferogram Stacks

Decorrelation caused by temporal changes influences phase unwrapping of differential interferogram in repeat-pass D-InSAR phase delay due to atmosphere disturbance degrades the accuracy of D-InSAR for small deformation monitoring. In this paper, we present a stacking D-InSAR approach using multi-baseline differential interferograms to estimate the linear deformation based on Rank Defect Free Network Adjustment Model (RDFNA) and to increase the deformation temporal sampling rate and estimate the linear deformation accurately. The Minimum Cost Flow (MCF) algorithm based on Delaunay triangulation network generated with sparse grids is adapted for phase unwrapping of individual interferogram. Scatterers with high coherence values over a given threshold in the interferogram stack are selected for the network generation. Therefore, with the multi-baseline differential interferogram stack, the linear deformation rate can be calculated with the unwrapped phase of each point accurately.