Spatial analysis of England and Wales coastline change using remote sensing

Abstract

Understanding coastal change at national scales requires spatially consistent datasets capable of capturing both the diversity and dynamism of shoreline behaviour. This study applies the CoastSat shoreline-extraction framework to satellite imagery spanning 1999–2020 to quantify sandy-coastline change across England and Wales at 10 m alongshore resolution. More than one million transects were analysed using spatial autocorrelation and principal component analysis (PCA) to identify dominant modes of variability and assess the coherence of shoreline change. Results reveal pronounced spatial heterogeneity. Autocorrelation decays within the kilometre scale, suggesting that decadal-scale shoreline behaviour is governed by small-scale, localised morphodynamic processes. PCA further shows that the dominant long-term mode of change (PC1) is stable, whereas higher-order components capture wider regional and temporal variability. Transitions between erosional and accretional states are rare, demonstrating path-dependence and persistence in shoreline trajectories. The findings highlight the value of high-resolution, reproducible Earth-observation datasets for national coastal assessment, while also underscoring ongoing uncertainties associated with satellite-derived shoreline extraction. From a management perspective, the strong localisation of morphological change and the persistence of shoreline states reinforce the need for adaptive, site-specific strategies within broader national planning frameworks. Continued integration of satellite monitoring with local observations, models and climate projections will be essential for supporting resilient coastal management across the UK.