Abstract: Urban land subsidence not only threatens the life safety of local residents, but also causes great losses to the local social
economy. Changzhou is located in the land subsidence zone of the Yangtze river delta, which is also one of the most economically
developed areas in China. It is of great significance to carry out land subsidence monitoring in Changzhou city to map and detect
ground subsidence, so as to provide help to decision making for disaster prevention and reduction. This manuscript used twenty-three
TerraSAR-X high-resolution radar images and adopted SBAS InSAR method to obtain the average subsidence rate and cumulative time
series of surface deformation during the observation period. The temporal and spatial evolution characteristics of surface deformation in
Changzhou from 2012 to 2013 had been analyzed. The results show that during the entire observation period, the overall land
subsidence characteristics of Changzhou city can be summarized to as “the whole area is basically stable and the local settlement in
Wujin district is serious”. Besides that, the PSInSAR method was used to reveal the specific spatial-temporal characteristic of land
subsidence around the important transportation lines in Wujin district, Inhomogeneous land subsidence were detected around these
background to reveal the temporal and spatial characteristics of land subsidence in Changzhou during the last fifty years.
Comprehensive analysis showed that the ground subsidence in the study area after the groundwater was completely forbidden had been
effectively controlled, the subsidence rate had been slowed down, and surface rebound had occurred. Although the land subsidence in
the Wujin area was also slowing down, obvious subsidence was still witnessed in that area. The subsidence around some important
traffic lines had exceeded the safety threshold. Enhanced monitoring of these areas was necessary as well as the routine monitoring in
the whole study area. Besides that, early warning systems and forecasting mechanism for hazards, site selection and planning for new
urban constructions should be conducted in order to provide valuable information for decision making.

Key words: ground subsidence, SBAS InSAR, PSInSAR, TerraSAR-X, High-resolution traffic line monitoring, Changzhou