Land subsidence monitoring in Xiongxian area of China by time series SAR interferometry combining permanent and distributed scatterers

Due to the mass exploitation of geothermal and groundwater resources, serious land subsidence occurred in Xiongxian in recent years. However, most previous researches on the surface subsidence of Xiongxian has been carried out on the basis of deformation monitoring technology of permanent scatterers (PS) with sparse measurement. In this study, time-series SAR interferometry combining PS and distributed scatterers (DS) was used to detect land subsidence in Xiongxian during 2018. The coherence-weighted PT algorithm was utilized to extract optimal phase from the coherence matrix. DS pixels were selected by the temporal coherence, which was calculated from the interferometric phase with low noise and clear fringes. The results show that the method of the identified DS jointly with the PS can significantly improve the spatial density of measurement points with measurement accuracy ensured. The northern part of Xiongxian suffers land subsidence more severely than the east. It provides the basis of the valid prevention and cure measure.