Research On Urban Ground Subsidence Based On Sentinel-1A Images Using MT-InSAR

Urban land subsidence is one of the major engineering geological problems in the world.Land subsidence will cause damage to buildings,roads,bridges,etc.,which seriously affect human life and production activities.Therefore,the identification and monitoring of surface deformation in urban areas is of great significance in determining vulnerable urban areas where geological disasters are likely to occur.Spaceborne Synthetic Aperture Radar(InSAR),a ground-based observation technique developed rapidly in recent years,has become an important measure for urban land subsidence monitoring.The multi-temporal InSAR(MT-InSAR)method developed on the basis of the InSAR technique uses multiple SAR images in the same study area to analyze the point targets with stable backscattering intensity in the time series,reducing the error in the traditional InSAR technology,it can obtain the millimeter or even centimeter-level monitoring accuracy,and meet the requirements of a large-scale,long-term and high-precision continuous monitoring of the urban surface.At the same time,the launch of the Sentinel-1 satellite provides a shorter access period and greater coverage and open access to its data,which can provide more opportunities for us to study surface deformation.the main contents of this paper include:(1)The basic theories of InSAR technology and MT-InSAR technology are elaborated in detail.Two representative algorithms of multi-temporal InSAR technology are described in detail:PS-InSAR and Stanford method for persistent scatterers algorithm(StaMPS).At the same time,the key issues in the application of MT-InSAR technology in urban surface monitoring are summarized and analyzed.In addition,the problems of the deburst and registration of the SAR image of the Sentinle-1A satellite TOP mode in the interference processing are also analyzed.(2)Taking Wuhan as an example,MT-InSAR technology was used to monitor the subsidence of Wuhan's surface during the period from March 2017 to January 2018.The data provided by the European Space Agency Sentinel-1A satellite was used.The experimental results show that the whole city of Wuhan is relatively stable,and there is a large amount of settlement in some areas.In terms of distribution,the settlements in most of the central and surrounding areas are relatively stable,and there are multiple settlement funnels in the main city.The annual average sedimentation rate in Wuhan is around 20mm/year,and the maximum cumulative settlement is 40mm.The larger settlement funnels are located in Hanjiang District,Hanyang District and Hongshan District.Through the internal and external accuracy evaluation of the experimental results,we found that the MT-InSAR technology and Sentinel-1A data can meet the accuracy requirements of urban ground monitoring and can be used for urban surface settlement monitoring.