Monitoring coastal storms’ effects on the Trabucador barrier beach (Ebro Delta) through Sentinel-2 derived shorelines

The vulnerable Trabucador barrier beach has recently suffered significant storm-induced geomorphological changes. This study presents the monitoring of its shoreline during storm events for assessing their effects on beach dynamics. After fine-tuning the CoastSat tool (i.e. optimal NDWI threshold) for shoreline extraction from Sentinel-2 imagery (S2), results were validated with GNSS-RTK reference shorelines (RMSE = 6.8 m). Shorelines were extracted from Dec-2019 to Feb-2021, encompassing 11 storms (Hs > 2m; duration = 24h), including Gloria (Jan-2020). Results showed that S2 imagery provides enough temporal and spatial resolution to capture the storm effects on the site. The shoreline timeseries gave relevant information about the geomorphological processes occurring during storm events (barrier breaching, erosion, washover), allowing the assessment of their cumulative effects. These results might be important for coastal management, in a site suffering from chronic flooding.
Peer Reviewed
Postprint (author's final draft)