Urban hazards caused by ground deformation and building subsidence over fossil lake beds: a study from Taipei City

Widespread land subsidence has become an increasing problem in urban areas worldwide and is caused by a combination of effects, of which in particular climate change, growing urbanization trends, and unbalanced groundwater extraction are considered to be the primary ones. While groundwater extraction can be a dominant reason for inland subsidence, other factors comprise excessive surface load of buildings or unsuitable substrate for foundations. In this study, a closer look is taken at Taipei City, which has been facing challenges of ground subsidence, and whose ground movement has been investigated using time series of Sentinel-1 remote sensing data. The results indicate that a specific region of the city experiences significant surface subsidence in local areas of former (dormant) river and lake beds with rates of up to 60 mm between 2017 and 2020. Furthermore, a precise spatio-temporal heterogeneity of deformation was identified upon combination of precipitation and groundwater level data. It can be shown that widespread monitoring using remote-sensing data is a feasible tool to identify and track locations exposed to subsidence hazards for urban planning and urban development phases in the future.