Long-term deformation monitoring using time series InSAR for Jiaozuo Section in Henan Province of Middle Route of South-to-North Water Diversion Project

The Middle Route of South-to-North Water Diversion Project is an important linear water conveyance project.To ensure its safe operation, it is crucial to comprehensively grasp the spatiotemporal evolution characteristics of deformation in the canal and its surrounding areas, and avoid errors induced by short monitoring intervals.Taking the Jiaozuo Section in Henan Province as the research object, this study collected 151 Sentinel-1A images acquired over nearly six years (from October 2016 to November 2021) and employed long-term InSAR technology to monitor the deformation of the canal foundation and its adjacent areas.GACOS products were adopted to correct atmospheric delays, thereby reducing the impact of atmospheric effects on InSAR monitoring of long-distance linear projects.The results indicate that: ① significant deformation at the levee near the canal bend in Xincheng Subdistrict, Shanyang District of the Jiaozuo Section; four subsidence zones are detected near the main canal in Macun District, with the closest subsidence area less than 200 meters away from the canal.② Surface subsidence in the Jiaozuo Section of the Middle Route shows obvious spatial heterogeneity, with varying degrees of subsidence across the entire region.The maximum annual average subsidence rate reaches 81.49 mm/a, which occurs in the northern part of Yanma Subdistrict, Macun District, while the largest subsidence funnel is located at the junction of Shanyang District and Wuzhi County.③ Comparison and validation with second-order leveling measurements in the same period show a mean error of 1.83 mm and a correlation coefficient (R²) of 0.92 between the two methods.This study demonstrates that the long-term InSAR method can effectively avoid misjudgments caused by seasonal fluctuations in the subsidence field and abnormal rainfall in specific years, enabling comprehensive investigation and detailed monitoring of large-scale water conservancy projects.