MONITORING AND ANALYZING THE SURFACE SUBSIDENCE IN LANGFANG BY TIME-SERIES INTERFEROMETRIC RADAR TECHNIQUE

Abstract. In this paper, the subsidence change maps in Langfang were obtained using ASAR images covering Langfang area acquired from August 2007 to September 2010 with the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) technique. Surface subsidence spatial-temporal characteristics in Langfang was investigated. The analysis of experimental results show that 1) prominent uneven subsidence patterns were identified in Langfang. Specifically, surface subsidence rates ranged from −77 mm/year to 4 mm/year, and maximum subsidence rate was detected in Nanjianta Town; 2) the standard deviation of the target point subsidence rates in the study area ranges from 0.8 mm/year to 9.3 mm/year, 70.4% of the monitoring point standard deviations in study area are less than 3 mm/year; 3) surface subsidence time series presented nonlinear variation trend. The surface subsidence has a tendency to gradually expand around the center of Nanjianta Town, and the scope and trend of expansion to the north and west of Langfang are more serious.