Stepwise estimation of height change time series and two-dimensional surface deformation over mountain excavation and City construction region with TS-InSAR technique

Abstract

In recent decades, the Mountain Excavation and City Construction (MECC) activities have become the main way of acquiring land for construction in densely populated cities. In China, for example, Lanzhou City is one of the typical cities for MECC, which has significantly changed the landscape and resulted in the surface deformation. To monitor accurately surface deformation, the height changes cannot be ignored, as it changes from meters to more than 70 m due to the MECC. In this study, a new time-series Interferometric Synthetic Aperture Radar (InSAR) algorithm is proposed to stepwise estimate the ground height changes and deformation, where the onset of height changes is firstly detected automatically for each pixel. Then height changes and deformation are estimated with different SAR datasets for different pixels. Experimental test on Lanzhou city shows that the ground height changes vary between 70 m and −80 m from October 2014 to May 2022, and the correlation between the multi-track results is over 0.89. Meanwhile, the correlation with the ICESat-2 height changes results reaches 0.94. In addition, two-dimensional (2D) deformation is recovered by fusing ascending and descending deformation, where subsidence with slight rebound phenomena is revealed at the center of the landfill area. Finally, finite difference model (FDM) is employed to simulate the land filling process, which can well explain the 2D surface deformation.

Keywords

• Mountain excavation and city construction
• Height changes
• Surface deformation
• InSAR
• Lanzhou