Urbanization and land subsidence: multi-decadal investigation combined SBAS-InSAR and multi-factors in Shanghai, China

Abstract

Situated in the Yangtze River Delta’s alluvial plain, Shanghai has faced intensified land subsidence problems since the economic reforms of the 1990s. However, previous studies have lacked long time-series land subsidence monitoring and an analysis of multifactorial interactions in Shanghai over the past years. This study analyzed Shanghai’s land subsidence from 1992 to 2020 using SAR data from ERS-1/2, ENVISAT ASAR, and Sentinel-1A, applying the SBAS-InSAR technique. The geo-detector method was used to identify key factors affecting land subsidence, including groundwater, urban structure, metro development, and population dynamics. The results showed that (1) the utilization of multi-sensor SAR data enables the comprehensive analysis of urban land subsidence over an extended temporal series, facilitating the acquisition of its spatiotemporal distribution; (2) the extent of subsidence in Shanghai was gradually spreading from the core to the outskirts, and the rate of subsidence was gradually decreasing during 1992-2020 period; (3) groundwater was the most influential factor on land subsidence, and the interaction between groundwater and metro had a stronger influence on land subsidence.

Keywords

• SBAS-InSAR
• land subsidence
• Geo-detector
• long-term monitoring
• Shanghai