Investigation of land subsidence in the northern estuary region of the Yellow River Delta

Known as one of the world’s most dynamic deltas in terms of land-sea changes, the Yellow River Delta is rich in natural resources such as brine groundwater and oil. It is affected by tectonic movements, natural consolidation and compaction of loose sediments, and especially frequent anthropogenic activities. Consequently, various degrees of land subsidence occur, and the northern estuary region of the Yellow River Delta is one of the areas experiencing more intense land subsidence, presenting possible threats to the safety of local inhabitants and economic activities. Therefore, accurate monitoring and understanding the spatiotemporal distribution characteristics of land subsidence in the northern estuary region of the Yellow River Delta are of great significance to mitigate geological impacts and economic losses in the region. In this work, land subsidence information in the northern estuary region of the Yellow River Delta was obtained using InSAR time series technology, based on Sentinel-1A/B data collected from January 2020 to December 2021. Additionally, multi-source data, including soft soil thickness, precipitation, oil field and brine mining areas, were incorporated to identify the influencing factors and asses their relative importance in land subsidence through random forest analysis and post-interpretation techniques. The results show that land subsidence in the northern estuary region of the Yellow River Delta presents uneven distribution characteristics, exhibiting maximum annual average subsidence rate exceeding -100 mm/year. The results of the random forest model indicate that the primary factors influencing land subsidence in the northern estuary region of the Yellow River Delta are brine groundwater extraction and the thickness of the soft soil layer. Meanwhile, the post-interpretation analysis demonstrates changes in the relationships between the different influencing factors and land subsidence.