Abstract
In this study, we monitor pavement and land subsidence in Tabriz city in NW Iran using X-band synthetic aperture radar (SAR) sensor of Cosmo-SkyMed (CSK) satellites (2017–2018). Fifteen CSK images with a revisit interval of ~30 days have been used. Because of traffic jams, usually cars on streets do not allow pure backscattering measurements of pavements. Thus, the major paved areas (e.g., streets, etc.) of the city are extracted from a minimum-based stacking model of high resolution (HR) SAR images. The technique can be used profitably to reduce the negative impacts of the presence of traffic jams and estimate the possible quality of pavement in the HR SAR images in which the results can be compared by in-situ road roughness measurements. In addition, a time series small baseline subset (SBAS) interferometric SAR (InSAR) analysis is applied for the acquired HR CSK images. The SBAS InSAR results show land subsidence in some parts of the city. The mean rate of line-of-sight (LOS) subsidence is 20 mm/year in district two of the city, which was confirmed by field surveying and mean vertical velocity of Sentinel-1 dataset. The SBAS InSAR results also show that 1.4 km2 of buildings and 65 km of pavement are at an immediate risk of land subsidence.
Highlights
Land subsidence is a gradual downward movement of the ground due, e.g., to the withdrawal of a large amount of water from underground layers [1,2,3] or mining activities [4]
The main objective of this study is to examine the potential of high resolution (HR) synthetic aperture radar (SAR) data in urban areas, for deformation monitoring, and for gathering auxiliary information on the buildings and pavement by HR SAR data
The main aims of the study were to assess pavement quality and the pavement area affected by land subsidence in urban areas using SAR images
Summary
Land subsidence is a gradual downward movement of the ground due, e.g., to the withdrawal of a large amount of water from underground layers [1,2,3] or mining activities [4]. The trend for ground subsidence is not usually sudden; it takes several years to be visible. The land subsidence starts slowly and spreads to adjacent areas, where it could affect agricultural, industrial, and urban activities. Sinkholes appear in agricultural land when the underground space becomes too large and causes a sudden collapse. Reviving such land for agricultural activities would be difficult after the failure point. Land subsidence takes place in agricultural land and in urban areas. The land subsidence phenomenon is as complex as in nonurban areas—a mixture of geotechnical, hydrogeological, and engineering aspects [8]
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