Linking Short- to Medium-Term Beach Dune Dynamics to Local Features under Wave and Wind Actions: A Northern Portuguese Case Study

Many coasts suffer from prevailing erosion, with them being particularly vulnerable to predicted climate change impacts, threatening coastal ecosystems, their services, infrastructures and populations. Understanding morpho-sedimentary dynamics is thus essential for management. However, vulnerability may differ locally, depending on exposure/protection local geological morpho-hydrodynamical features, suggesting that a approach erosion risk assessment needed identify understand patterns. Digital elevation models of 14 km long stretch in northern Portugal were extracted aerial surveys obtained between November 2008 February 2019 analysed quantify changes shoreline position sediment budgets, both the whole study area distinct beach segments. The observed subsequently by considering wave wind intensities directions. Overall during decade analysed, beach–dune system studied slightly increased volume (0.6%), although retreated (by 1.6 m average). Temporal variability was at all temporal scales considered—from seasons 5-year periods—with related ocean There trend accretional erosional conditions, first period showing mean increase system’s 0.6% progradation 1.5 m, followed 5-years 0.0% 3.1 retreat. Locally, very variable, ranging 24.0 regression 51.5 progradation, budgets 213.8 m3 loss 417.0 gain, per segment decade. Stretches relatively stable morphologies others or trends found, type, orientation presence defence structures. Rocky beaches least dynamic sandy most dynamic, 0.0 −3.4 respectively, −1.1 −2.9 linear meter coastline, showed how conditions interacted meteo-ocean shaping dynamics, stressing importance monitoring assessment.