Monitoring and analyzing surface subsidence based on PS-InSAR in Nanning region, China

Surface subsidence is an environmental geological phenomenon in which the elevation of the crust surface is reduced due to the compression of underground loose soil layers under the influence of natural geological factors or human activities. It has the characteristics of high monitoring difficulty and long duration. Differential Interferometric Synthetic Aperture Radar (D-InSAR) was susceptible to signal decorrelation and atmospheric delay. It is difficult to obtain high-precision, high-temporal resolution urban land subsidence information. Therefore, this paper introduced Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) with high spatial-temporal resolution and high precision for urban surface subsidence monitoring and analysis research, taking Nanning region as an example. Based on the twenty Sentinel-1A TOPS SAR images, this paper completed the acquisition of surface subsidence information from July 2015 to February 2017 in Nanning region, and conducted subsidence spatial-temporal analysis in this region. The experimental results show that the uneven surface subsidence in Nanning region was obvious. The subsidence rate of most areas during the study period ranged from -31.5 to +17.5 mm/a. The ground in the central part of Xi Xiangtang district showed a trend of recovery, while the surface subsidence in Jinling town in the northwest of Xi Xiangtang district was as high as -30 mm/a, and most of the Jiangnan district is in a stable state. The surface subsidence was relatively large in Qingxiu district, Yongning district and northern Liangqing district, among which the largest cumulative subsidence in Qingxiu District is 61.5 mm. In addition, the surface subsidence in the study area was more affected by urban traffic track construction and real estate development significantly.