Monitoring Coastal Erosion and Subsidence on the western coast of Portugal using PSInSAR and InSAR

Portugal's coastal regions face significant challenges due to climate change, with potential GDP reductions of 2% to 5% by 2100, primarily driven by erosion and sea-level rise. The dense occupation of coastal areas increases vulnerability, underscoring the need for detailed studies to model future scenarios and implement mitigation strategies. The Atlantic oceanographic forcing impinges the soft sediment coastline and causes further stress on the erosion-prone coastal stretches.

This project aims to assess coastal erosion along Portugal's western edge, focusing on areas such as Quiaios, Cova Gala, São Pedro de Moel, and the Pedrogão dunes. Coastal retreats are analyzed using the InSAR (Interferometric Synthetic Aperture Radar) technique, complemented by traditional Earth observation methods and topo-bathymetric data to refine this methodology.

The research also employs the PSInSAR (Persistent Scattering Interferometry Synthetic Aperture Radar) technique to study subsidence in rocky coastal areas and evaluate risks. It is also applied to monitor spurs and coastal vegetation, analyzing its relationship with erosion processes.

The PSI technique was chosen for its ability to provide precise measurements of ground displacements, making it effective for beach monitoring and reducing atmospheric noise. By processing InSAR data, it enables millimeter-scale measurements of ground displacement along the satellite’s line of sight, using a point cloud of persistent scattering (PS) elements.

Besides long-term trends, detailed focus will be on determining impacts of coastal storms on the sediment dynamics and resilience capacity of the studies coastal systems. Results will also contribute to the establishment of high-resolution erosion rates which will allow better coastal planning.

This work is supported by the Portuguese Fundação para a Ciência e Tecnologia, FCT, I.P./MCTES, through national funds (PIDDAC): UID/50019/2025 and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020).