Resolving surface displacements in Shenzhen of China from time series InSAR

Abstract

Over the past few decades, the coastal city of Shenzhen has been transformed from a small fishing village to a mega city as China's first Special Economic Zone. The rapid economic development was matched by a sharp increase in the demand for usable land and coastal reclamation has been undertaken to create new land from the sea. However, it has been reported that subsidence occurred in land reclamation area and around subway tunnel area. Subsidence and the additional threat of coastal inundation from sea-level rise highlight the necessity of displacement monitoring in Shenzhen. The time Series InSAR technique is capable of detecting sub-centimeter displacement of the Earth's surface over large areas. This study uses Envisat, COSMO-SkyMed, and Sentinel-1 datasets to determine the surface movements in Shenzhen from 2004 to 2010 and from 2013 to 2017. Subsidence observed can be attributable to both land reclamation and subway construction. Seasonal displacements are likely to be associated with precipitation. The influence of ocean tidal level changes on seasonal displacement is not strongly evident from the results and requires further investigations. In general, InSAR has proven its ability to provide accurate measurements of ground stability for the city of Shenzhen.