Deformation monitoring and risk assessment of ultra-high voltage transmission channel based on Sentinel-1 and RADARSAT-2 multi-source InSAR data

Ultra-high voltage (UHV) transmission lines are key infrastructure ensuring the safe cross-regional transmission of national energy. However, these lines are often located in regions facing multiple disturbances, such as complex terrain, frequent geological disasters, and intense human activities, all of which pose significant threats to the stability of tower foundations. To achieve high-precision deformation monitoring and risk identification for typical mountainous transmission corridors. This study selects the ±800 kV Qishao Line transmission corridor in Badong County, located in the southwestern part of Hubei Province, as the research area. The study integrates two types of C-band SAR data from Sentinel-1A and RADARSAT-2, employing SBAS-InSAR technology to perform time-series deformation analysis from July 2019 to August 2020. Additionally, the Getis-Ord Gi* statistical method is introduced to assess subsidence hot spots. The results show that the annual average deformation in the region, as obtained from Sentinel-1A data, mainly ranges from −10 mm/a to +10 mm/a, indicating a generally stable deformation trend. In contrast, RADARSAT-2, with its high resolution, identifies several local strong subsidence areas, with the maximum annual subsidence rate reaching −95.6 mm/a. These areas are mainly located in geomorphological transition zones such as the northern bank of the Yangtze River and valley intersections. A typical slope area on the northern bank of the Yangtze River shows persistent subsidence bands with an annual average deformation exceeding −76 mm/a, which closely coincides with tower foundation construction areas, steep slopes, and traffic disturbance zones. In the valley-crossing section, significant subsidence hot spots (greater than −20 mm/a) are identified in the mid- and lower slope foot regions, while cold spots are observed in the high-slope areas, with deformations lower than −5 mm/a. Both data types exhibit highly consistent time-series trends at characteristic points, and scatter density map analysis demonstrates a strong linear correlation between them, validating the complementarity and fusion potential of multi-source InSAR data for deformation monitoring in complex mountainous environments. The multi-source InSAR monitoring and spatial aggregation analysis framework developed in this study enables rapid identification of high-risk sections in UHV transmission corridors. It provides high-resolution, quantitative support for slope deformation early warning, tower foundation stability assessment, and operation and maintenance scheduling, offering excellent engineering adaptability and broad applicability.