InSAR-derived surface deformation of Chaoshan Plain, China: Exploring the role of human activities in the evolution of coastal landscapes

Abstract

Understanding the characteristics of different human-induced coastal surface deformation will improve our understanding of recent temporal-spatial evolution trends of the coastal terrain, and help better predict the risks of coastal disasters. However, few surface deformation studies have focused on the distinction between different types of anthropogenic ground deformation. Based on Sentinel-1 Synthetic Aperture Radar (SAR) data, this study employs the hybrid multi-temporal Interferometric Synthetic Aperture Radar (InSAR) method to extract the surface deformation of Chaoshan Plain from 2015 to 2020, with a spatial resolution of 30 m × 30 m. A series of historical optical satellite images and groundwater extraction data are used to help distinguish different types of human activities that have induced surface deformation. The characteristics of ground deformation induced by different types of anthropogenic activities are explored in the space and time dimensions. Results show that InSAR ground deformation in the study area is mainly caused by three types of human activities: groundwater extraction, land reclamation, and construction. Groundwater extraction has impacted >50% of the regional surface deformation by area. The interannual variability of the surface deformation rate corresponds well to that of groundwater extraction, and the subsidence effect can last for more than five years with seasonal variability. The maximum surface subsidence rate in land reclamation areas reaches ~100 mm/year, with a linear decreasing trend against time. Without extra compaction, the reclamation area can continue to deform almost at the same rate for several years. The rapid increase of overlying loads caused by construction in the reclamation area has led to a sharp decrease in the deformation rate within 2–3 years after the completion of the construction. In areas absent of other human-induced deformation, construction activities are shown to cause surface subsidence of 10–20 mm/year in a relatively short period. In areas experiencing a combination of construction and groundwater extraction, land subsidence rates of >50 mm/year are observed. This study shows that the spatial and temporal analysis of the correlations between human activities and InSAR surface deformation is an effective way to attribute the driven factors of coastal plain deformation.