Deformation Mapping for Coal Mining using Time-series InSAR Combining Persistent Scatterers and Distributed Scatterers in Huainan City, China

Underground coal mining often causes persistent land subsidence, which would lead to huge threats to infrastructure and safety in the coal area [1, 2]. Traditional levelling and GPS methods are able to produce reliable measurement of ground subsidence [3]. However, these field surveys are time-consuming and cannot provide deformation map with high spatial sampling density. Synthetic aperture radar (SAR) interferometry (InSAR) is a powerful technology, which can obtain high precise elevation and surface deformation information along line of sight (LOS) using phase information from different SAR images. However, conventional InSAR usually suffers from temporal, geometrical and atmospheric decorrelation. In order to overcome these limitations, several advanced techniques have been proposed, such as Persistent Scatterer Interferometry (PSI) [4, 5] and Small baseline Subset Algorithm (SBAS) [6]. In recent years, Distributed Scatterers Interferometry (DSI) [7, 8] has been proposed to monitor the surface deformation with high spatial density of measurement points. The main drawback of DSI is the computational efficiency [7, 8] in large scale suburb areas. This paper presents an approach to obtain ground deformation using time-series InSAR technique combining PSs and DSs. PSs are selected based on their coherence stability in the stack of interferograms. In order to identify DSs, a selecting strategy combining both classified information and statistical characteristics is used. To control the error propagation and improve the computational efficiency, deformation rate and DEM error on PSs are firstly retrieved using conventional PSI. Then a region grown-based strategy is applied to extract deformation rate on the useful DSs. A series of Radarsat-2 HH polarization images collected in Huainan are processed to verify the effectiveness of the proposed method. A dense ground surface deformation map is obtained. The experimental results show that the potential application of the proposed method. 2. METHOD