Coastal vulnerability to extreme weather events: An integrated analysis of erosion, sediment movement, and land subsidence based on multi-temporal optical and SAR satellite data.

Coastal areas undergo continuous transformations, altering their geometry under the influence of external forces like tides, waves, and extreme events. Thus, monitoring the impact of extreme weather events on coastal regions is crucial to prevent potential cascading hazards. Here, we utilized time-series optical and SAR satellite data and tide records, coupled with sophisticated analytical techniques, to analyze erosion processes, sediment transport, and vertical land movement (VLM) at an embayed sandy beach (i.e., Haeundae Beach, South Korea). We found a significant erosion rate of -4.12 m/year during typhoon periods, compared to non-typhoon periods (-3.61 m/year). Between 2017 and 2023, 5.63 ha of beach area and 14,428.9 m of sediment were lost due to typhoon-induced sand movement, leading to coastline retreat and foreshore erosion. The PS-InSAR-derived localized VLM trends of fast-subsiding areas (-3.57 mm/year), combined with a current sea-level rise (2.34 mm/year), underscores the heightened vulnerability to future extreme weather events. The findings of this study provide insights into the erosional processes, land subsidence, and sediment transport due to extreme weather events, which can contribute to the development of erosion control technologies and engineering applications to prevent cascading hazards. The proposed integrated framework can be implemented in similar coastal environments to mitigate climate-change-induced coastal vulnerabilities.