Óscar Ferreira

It is well established that coastal wetlands act as natural buffers, protecting shorelines by dissipating wave energy and reducing flood risk. However, field measurements are still required to determine the effectiveness of different types of vegetation in reducing wave height. This study aims to investigate the role of vegetation and platform geometry in waveheight attenuation in the Ria Formosa wetlands, southern Portugal, by combining field measurements with numerical modelling. Field surveys were conducted to characterize platform morphology and the density of the vegetation, while pressure transducers were deployed to measure wave-height variations induced by boat-generated wakes. The SWAN model was applied to assess the effects of varying boat-generated waves, vegetation densities, platform geometries, and tidal dynamics on wave attenuation. The findings show that a 100 m long gently sloping platform is effective in wave dissipation. Densely vegetated profiles reduce wave height by approximately 46% more than sparse or non-vegetated platforms. Zostera noltei provides greater attenuation than Sporobolus maritimus for higher incoming wave heights (Hs,o ≥ 0.08 m). However, similar attenuation is observed for both species at significant wave height (Hs,o) of around 0.04 m. Wave attenuation increases with decreasing water level and with increasing wave height and vegetation density. However, the effect of density reaches a saturation point at approximately 4800 stems/m2 for Zostera noltei and 1400 stems/m2 for Sporobolus maritimus. This study highlights that wave attenuation in coastal wetlands is determined by platform geometry, vegetation density, and water level, and provides practical guidance for the design and management of sustainable wetland-based coastal defences.

It is well established that coastal wetlands act as natural buffers, protecting shorelines by dissipating wave energy and reducing flood risk. However, field studies are required to determine the effectiveness of different types of vegetation in reducing wave height, being such results still scarce in the existing literature. This study aims to investigate the role of vegetation and profile morphology in wave‑height attenuation in the Ria Formosa wetlands, southern Portugal, by combining field measurements with numerical modelling. Field surveys were conducted to determine the geometry of the platforms and the density of the vegetation, while pressure transducers were used to quantify differences in wakes generated by a boat. The SWAN model was applied to assess the effects of varying boat-generated waves, vegetation densities, platform geometries, and tidal dynamics on wave attenuation. The findings show that platforms with gently sloping platforms about 100 m long are effective at dissipating waves. Densely vegetated profiles reduce wave height by around 46% more than sparse or non-vegetated platforms. Zostera noltei provides greater attenuation than Sporobolus maritimus for higher incoming wave heights (Hs,o ≥ 0.08 m). However, similar attenuation is observed for both species for significant wave heights (Hs,o) close to 0.04 m. Wave attenuation increases as water level decreases, with both wave height and vegetation density, up to a saturation point at around 4800 stems/m2 for Zostera noltei and 1400 stems/m2 for Sporobolus maritimus. Furthermore, attenuation capacity increases with decreasing in water levels. This study highlights that wave attenuation in coastal wetlands is determined by platform geometry, vegetation density, and water level, and provides practical guidance for the design and management of sustainable wetland-based coastal defences.

Early warning systems for coastal erosion and flooding are currently primarily designed for local applications, offering high-resolution, site-specific predictions. Only a few early warning systems (EWS) are used at large regional or national scales. There is also a lack of standardised indicators and thresholds, which vary widely across systems and hinder cross-regional applicability. While current EWS perform well in binary hazard detection (Yes/No hazard; 80–95% accuracy), they struggle to accurately classify intermediate hazard levels. A lack of comprehensive field datasets has impeded rigorous validation for most systems, with many assessments relying on qualitative observations. Improving the reliability of the EWS requires improving their validation against field data obtained during storms and regular updating of the topobathymetric data to include the actual pre-storm morphology. Currently, most EWS rely on outdated or synthetic morphological inputs, which increases prediction uncertainty. The computational constraints of physics-based models may prevent warnings from being issued in time and have led to the adoption of surrogate approaches that depend on robust training datasets. Furthermore, most systems focus solely on hazard detection, paying limited attention to the risk to assets or populations. Future development must prioritise stakeholder engagement and the co-design of systems that incorporate both hazard and risk assessments, in order to improve their usefulness and facilitate decision-making by end users.

Defining literacy is essential because it establishes a baseline for education, enables robust assessment and measurement of progress, supports policy and accountability, makes domain-specific differences explicit, and can improve equity by enabling better-designed interventions to promote learning. UNESCO notes that, beyond its conventional concept as a set of reading, writing and counting skills, literacy is now understood as a means of identification, understanding, interpretation, creation, and communication in an increasingly digital, text-mediated, information-rich and fast-changing world. Consequently, multiple domain literacies have emerged, including science, health, media, digital and financial literacy, and more recently AI literacy. While ocean literacy has gained significant traction in the last decade, for the coast an early coastal literacy framework was proposed in 2010 by CoastNet (UK charity that has since closed), but it was primarily oriented towards integrated coastal zone management. The objective of this work is thus to define coastal literacy and what it comprises.To develop a definition tailored to coastal contexts, related literacy constructs were reviewed, particularly ocean literacy, climate literacy and risk literacy. Across frameworks, literacy is commonly articulated through dimensions (for example, knowledge, awareness and attitudes) and, in some cases, through explicit principles. The Ocean Literacy Framework is a prominent example, currently comprising seven principles and 45 concepts, and defines ocean literacy as understanding the ocean’s influence on humanity and humanity’s influence on the ocean. Although coasts form part of the broader ocean system, coastal environments have distinct characteristics: they concentrate human activities, involve frequent and direct human–environment interactions, and are often exposed to hazards. Coasts also exist at the interface of multiple Earth system spheres, linking the ocean, land and atmosphere. The framework of coastal literacy was developed building on the literature review and on a two-day focus group using structured brainstorming methodologies. The proposed framework comprises seven principles: (P1) Each coast is unique and has value on its own; (P2) Coasts consist of many different and connected parts; (P3) Coasts are dynamic, changing from seconds to millennia; (P4) Human activities impact the coast, and coasts continually affect humans; (P5) Coasts are inherently hazardous environments that can place people and infrastructure at risk; (P6) Climate change is affecting coastal ecosystems and challenging future coastal use; and (P7) We share responsibility for looking after the coasts for present and future generations. A key contribution of these principles is how they frame human–coast relationships. They recognise the intrinsic coastal value independent of human use or resource exploitation (P1), position humans as part of coastal systems (P2, P4), explicitly foreground coastal risk (P5), and treat shared responsibility as a component of literacy (P7). They also embed sustainability by emphasising the need to safeguard future generations, including in the context of climate change (P6). Further work is needed to elaborate the concepts underpinning each principle and to refine the framework through additional validation; however, the principles presented here provide a structured foundation for defining and operationalising coastal literacy.

Coastal areas are highly vulnerable to extreme events, particularly in rocky coastal environments where cliff collapse poses a significant risk to human occupation. This study presents a simplified method for assessing coastal risk at the top of rocky cliffs, integrating hazard and exposure into a single risk index. The methodology is based on the Coastal Risk Assessment Framework and incorporates hazard (inland extent of cliff mass movements) and exposure (land use) indices to calculate a Coastal Index (Ci). This approach was applied to the coastline of the municipality of Lagoa (Algarve, southern Portugal), which is characterised by indented rocky cliffs, pocket beaches, and subject to high touristic pressure. Risk maps were developed to determine the spatial variability, revealing a predominantly low to moderate risk along the coastline. However, 22% of the study area was identified as having high to very high coastal risk, particularly in areas with urban or touristic development close to the cliff edge. The method provides a straightforward tool for coastal management, enabling the identification of risk hotspots and the optimization of resource allocation for risk reduction.

Coastal storms can promote damaging impacts on barrier islands, induced by coastal flooding and beach erosion (Leaman et al., 2021). Process-based morphodynamic models, implemented with high- resolution topo-bathymetric and oceanographic data, enable the assessment of these coastal hazards at regional and local scales and the development of early warning systems. The advent of global models to characterise wave forcing (global wave reanalyses) and topo-bathymetry (global digital elevation models, DEM) allows the quantification of storm impacts to be extended to larger scales and data-poor areas. However, the uncertainties and limitations associated with the use of input conditions from low-resolution global models must be comprehensively addressed, as they can lead to errors in the subsequent model outputs. This work explores the uncertainties in global models and in the resulting quantification of storm impacts.

Quantifying and understanding coastal geomorphological change are of paramount importance for coastal management and policy making (Boak and Turner, 2005). For wave-dominated coastal barriers, contemporary morphological change is mainly determined by hydrodynamic forcing conditions and antecedent beach morphology (e.g., Burvingt and Castelle, 2023). However, in geologically controlled barriers, beach morphodynamic processes and responses are additionally influenced by the pre-existing geological framework (Robinet et al., 2020). These geological controls are rarely considered in shoreline change assessments, despite being essential for predicting future coastal change at the management scales (Cooper et al., 2018). This work examines the influence of foreshore configuration with varying degrees of geological control on shoreline evolution using seven years of satellite derived shoreline data from three beaches in the Outer Hebrides barriers (NW Scotland).

Contemporary shoreline change is driven by a complex combination of factors, and as such is often highly variable along the coast. While differences in beach morphology can explain some of the variability in shoreline change, the geological constraints imposed by coastal geology are often overlooked. This work examines the influence of foreshore configurations with varying degrees of non‐dynamic geological control, which are analysed in combination with hydrodynamic forcing to investigate seasonal to multiannual shoreline evolution along five coastal barriers in the Outer Hebrides, Western Scotland. These barriers are characterised by strongly geologically constrained evolution and are exposed to a storm‐dominated wave climate. Due to the variable temporal interval between available cloud‐free Planet Scope images, monthly averaged vegetation lines from 2016 to 2023 were derived from satellite imagery as a shoreline position indicator using an automated approach validated by visual inspection. The satellite‐derived vegetation lines have a sub‐pixel accuracy with a root mean square error of 3 m. Changes in monthly averaged shoreline position are statistically correlated with monthly extreme storm conditions, characterised by both extreme water levels and wave conditions. However, the control exerted by the variable geological configuration along the barriers results in distinct inter‐ and intra‐site shoreline change behaviour, with lower shoreline variability observed in barrier sectors fronted by rocky foreshores, compared to sediment‐rich foreshores. The observed multiannual shoreline change from 2016 to 2023 is characterised by a small but statistically significant accreting trend (mean 0.4 m/yr), likely representing the recovery of the barriers from extreme winter storms that impacted northern European coasts from 2013 to 2015. The results demonstrate that considering variable geological controls in shoreline change assessments improves the understanding of shoreline variability along coastal barriers, allowing to identify distinct storm‐driven shoreline behaviour according to the degree of geological control.