Spatial analysis of surface deformation distribution detected by persistent scatterer interferometry in Lanzhou Region, China

摘要

Persistent scatterer synthetic aperture radar interferometry (PS-InSAR) is a remote sensing method that can be used to detect surface deformation, which is an indicator of potential geohazards. By capturing such deformations over time, it is possible to obtain valuable information regarding geohazards such as landslides. This study focused on the use of PS-InSAR to investigate the distribution and causes of surface deformation in the Lanzhou region of Gansu Province in China. Between 2003 and 2010, 41 advanced synthetic aperture radar images were captured by the Envisat satellite and analyzed using PS-InSAR, and the correlation between the observed surface deformation and topographic, geologic, and anthropogenic factors was derived based on a geographic information system platform. It was found that the largest number and highest density of surface deformations occurred at elevations of 1486-1686 m. It was also established that slope ranges of 25 degrees-30 degrees and 35 degrees-40 degrees are threshold values at which surface deformation changes abruptly, and that slopes with north and northwest aspects are most prone to surface deformation. The lithologies most susceptible to surface deformation are clay, sandy soil, and loess. The normalized difference vegetation index indicated that surface deformation occurred most often in areas with sparse vegetation. Anthropogenic activities, e. g., construction and wastewater discharge, could be inferred as causal mechanisms of surface deformation. Comparison of the distributions of geohazards and surface deformation showed considerable consistency, which proves surface deformation can induce geohazards. These results could help governments improve urban planning and geohazard mitigation.