Impact of land subsidence on relative sea level rise and coastal inundation in the Yellow River Delta

Yellow River Delta (YRD), China. This study systematically integrated synthetic aperture radar (SAR) data, extensometer deformation data, groundwater level data, satellite altimetry data, and sea level rise (SLR) projections to comprehensively explore the effects of regional subsidence on relative sea level rise (RSLR) and coastal flood inundation in the YRD. Furthermore, this study analyzed the deformation characteristics of soil layers at different depths and identified the main subsiding layers. (1) The excessive exploitation of underground brine and deep groundwater was the key factor driving land subsidence in the YRD. In the inland subsidence zone, land subsidence rates have decreased with rising groundwater levels. The deep strata in this area are the main subsiding layers, and the soil mainly exhibits plastic deformation. (2) The spatial heterogeneity of relative sea level rise (RSLR) in the YRD is caused by land subsidence, with the average coastal land subsidence rate accounting for about 70 % of the RSLR rate. (3) Under different land subsidence scenarios, about 674.9 km 2 to 1053.6 km 2 of land in the YRD is projected to be threatened by flood inundation in 2100. Moreover, the results indicated that under the tested scenarios, the impact of future climate change on flood inundation in the YRD is much smaller than that of land subsidence. • The average subsidence rate in the YRD coastal zone is nearly −16.8 mm/year. • Estimate the RSLR trend at a 500 m spatial resolution along the coastline. • Flood inundation was projected under multiple future land subsidence scenarios. • Reveals the deformation characteristics of soil layers at different depths.