Spatial-Temproal Variation Characteristics and Geographic Detection Mechanism of Land Subsidence in Wuhan City from 2007 to 2019

  Objectives  Land subsidence in urban areas brings loss of ground elevation, damages urban infrastructure and buildings, and affects surface runoff and hydrological cycle. Monitoring the status of land subsidence and revealing its formation mechanism is of great significance for sustainable urban development.

  Methods  Using ALOS-PALSAR images from 2007 to 2011 and Radarsat-2 images from 2015 to 2019 as data sources, based on SBAS-InSAR technology to obtain the land subsidence rate and time series, and us‍ing geographic detectors to reveal the dominant driving factors and the interaction mechanism between the driving factors of land subsidence at the scale of planning unit.

  Results  The results show that: (1)The average land subsidence rates from 2007 to 2011 and from 2015 to 2019 were -3.53 mm/a and -1.48 mm/a, respectively. The hot spots for land subsidence from 2007 to 2011 are Hankou, the coast and north of Shahu Lake, the west of Nanhu Lake, and the Baishazhou area. From 2015 to 2019, it is Hankou, the north of Shahu Lake and the Baishazhou area.(2)The temporal and spatial evolution of land subsidence in Wuhan is localized, staged, and related to natural conditions and human activities. Rapid subsidence only occur in certain region, shows the different trends at various stages, and is closely related to the regional natural conditions and human activities.(3)Hydrogeological conditions are necessary conditions to form the spatial-temporal pattern of land subsidence in Wuhan through interaction with various factors such as ground load, underground space development, and engineering construction. The interactive effects between engineering construction and hydrogeological conditions from 2007 to 2011 are found to be significant, so do ground load and hydrogeological conditions from 2015 to 2019.

  Conclusion  The geographic detector can quantitatively identify the driving factors of land subsidence and the interactions between them. The interactive effects between hydrogeological and conditions engineering construction, ground load to a large extent affected spatial variation of land subsidence from 2007 to 2011 and from 2015 to 2019 respectively. In the future, continuous monitoring of land subsidence and multi-scale research on the formation mechanism of land subsidence should be carried out to further enrich the theory and method system of land subsid‍ence research.