Evolution Pattern of Land Subsidence Using InSAR Time-Series Analysis in Bangkapi, Bangkok, Thailand

Subsidence in Bangkok has occurred continuously for a long time. This research applied radar satellite imagery (Sentinel-1 101 images, 2017–2022) to track land subsidence using the time series INSAR technique. The study area was in the Bang Kapi area in Bangkok, which has a high level of cumulative subsidence. The pattern of cumulative subsidence change was analyzed using the standard deviation ellipse (SDE) technique. The results showed that the Bang Kapi area had the highest cumulative subsidence in 2019 (-125.31 mm). The movement of the subsidence center changed every year in different directions with three patterns identifiable. The first pattern showed the evolution of subsidence in a northeast-southwest direction, the second pattern showed subsidence evolution in a northwest-southeast direction, and the third pattern presented evolution that did not appear to be in any specific direction. The size of the subsidence area in 2017 and 2022 increased, whereas between 2018 and 2021, the subsidence area decreased compared to other years during the research period.