Surface Displacement Monitoring Utilizing Sentinel-1 Time Series Images and Levelling Survey Data in Hanoi’s Inner City

Surface displacement in major cities occurs for various reasons, including groundwater extraction and urbanization. The changes in groundwater levels and load construction on the land have affected geological structures, causing surface displacement. Many studies have been studying and utilizing the InSAR technique to monitor and measure the velocity of surface displacement on the Earth’s surface across a wide range. In this article, the authors used Sentinel-1A image time series and the PSInSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) approach to monitor surface displacement in Hanoi’s inner city from 2018 to 2019. The results indicate that the study area experiences surface displacement velocities ranging from −15.3 mm to +18.5 mm per year. The accuracy of the method is assessed by utilizing 55 levelling measurement points across two distinct areas: 43 of these points are located at buildings, and the 12 remaining are situated at groundwater stations. The correlation coefficient (R2) between persistent scatterer (PS) points and levelling points is greater than 0.8, with a value of 0.847 in the building area and 0.859 in groundwater stations. Simultaneously, the study results indicate that there is the minimal surface displacement at building locations in the central districts. Surface displacement is particularly high in Hanoi’s western and southern districts, including Thanh Xuan and Hoang Mai.