Evolution of the Shoreline Between the Ports of Valencia and Sagunto, Spain (1957–2024)

Coastal areas are increasingly affected by erosion due to climate change and human interventions, threatening the stability of many shorelines. Understanding coastal dynamics is therefore crucial for developing effective conservation and management strategies. This study analyzes the evolution of the coastline between the Port of Valencia and the Port of Sagunto from 1957 to the present, one of the most anthropized littoral cells in the Eastern Mediterranean, where urban development, groyne fields, and major harbor structures strongly modify longshore transport. Using Geographic Information Systems (GIS), including QGIS and the DSAS extension, five shoreline change indicators (EPR, LRR, NSM, SCE, and WLR) were calculated based on coastlines extracted from orthophotos and satellite images. The analysis was conducted across five distinct zones and three temporal scales (long, medium, and short term) to capture spatial and temporal variations. The results reveal significant heterogeneity: the Arenas–Malvarrosa–Patacona area shows long-term accretion but recent erosion (LRR = +0.88 m/year; NSM = +58 m), Port Saplaya shows moderate erosion (LRR ≈ 0.27 m/year), Pobla de Farnals is undergoing strong erosion (LRR = −0.57 m/year; NSM = −44 m), Puzol appears recently stabilized (2015–2024; LRR ≈ +0.06 m/year) and Marjal dels Moros, historically stable, now exhibits a short-term retreat of −0.53 m/year. Overall, coastal evolution in the study area exhibits a clear pattern, being influenced by both natural processes and human actions: long-term accretion occurs exclusively in sectors located updrift of major infrastructures, while most remaining areas show persistent or recently accelerated erosion, reflecting the cumulative impact of sediment scarcity, coastal armoring and increasing storm intensity. The data provide valuable insights for medium- and long-term coastal planning and sustainable territorial management.