Dune(s): Fiction, history, and science on the Oregon coast

What connects the sci-fi book Dune with coastal dunes and geoengineering? The answer lies in humans and their world-making activities. This paper proposes an innovative approach to coastal dunes as hybrid environments by analyzing the dunes stabilization programs developed on the US Pacific Coast. It looks into the shifting sands of the Oregon coast and how they influenced Frank Herbert to write his novel, why local communities and federal authorities were interested in fixing the moving dunes and how these works ended up having unexpected consequences. It explores how human features acting as forcing mechanisms on beach-dune systems caused changes that turned into controlling influences in their own right, creating new environments and concerns. The paper ends with a reflection on how fiction and the history of dunes can be used to critically think about the anthropocentric hubris of building futures by geoengineering the planet for environmental repair.

Beach and Dune Erosion: Causes and Interventions, Case Study: Kaulon Archaeological Site

The dune systems are very important from an environmental, landscape, and coastal defense point of view within coastal areas. Currently, dune systems are significantly reduced compared to a few decades ago and, in Europe alone, dune systems have decreased by 70%. During the same period, intense beach erosion processes have often been observed, and, currently, 30% of the world’s coasts are eroding. These processes have various causes, both natural and anthropogenic, and the knowledge of the causes of the erosive processes are very important for an effective planning and management of coastal areas and to correctly plan any interventions on dunes and beaches. The paper, through a case study, analyzes the beach and dune erosive processes, their causes, and the possible interventions. The case study concerns the archaeological site of Kaulon, located on a dune in the Ionian coast of Calabria (Italy). The beach near the site was affected by erosive processes and during the winter of 2013–2014, the site was damaged by two sea storms. To identify the causes of these processes, three erosive factors were analyzed. These factors are anthropogenic pressure, wave climate and sea storms, and river transport. The effects produced by these factors were assessed in terms of shoreline changes and of damage to the beach–dune system, also evaluating the effectiveness of the defense interventions. The main causes of the erosive processes were identified through the cross analysis of erosive factors and their effects. This analysis highlighted that in the second half of the last century the erosive processes are mainly correlated to anthropogenic pressure while, recently, natural factors prevail, especially sea storms. Regarding the interventions, the effects produced by two interventions carried out during the winter of 2013–2014, one built in urgency between the first and second sea storm and the other built a few years after the second sea storm were analyzed. This analysis highlighted that the latter intervention was more effective in defending the site.

Effects of Anthropogenic Pressures on Dune Systems—Case Study: Calabria (Italy)

During the second half of the last century, considerable anthropization processes were observed throughout most of the Italian territory. These processes have altered the equilibrium conditions of several river and coastal ecosystems, causing the destruction of numerous dune systems. This issue is particularly important in territories such as Calabria, a region in southern Italy subject to considerable anthropogenic pressures and characterized by over 700 km of coast. The aim of the paper was to evaluate the effects of anthropogenic pressures on the Calabrian dune systems, especially in regard to the triggering of coastal erosion processes. For this purpose, historical and current cartographic data, such as shapefiles, cartography, and satellite imagery, were analyzed using QGIS. This evaluation was carried out through the comparison between the current extension of the dune systems and their extensions after the Second World War, before the anthropogenic pressures. This evaluation was also carried out through the analysis of shoreline changes in coastal areas, where dune systems are currently present, and in coastal areas where dune systems have been partially or totally destroyed by anthropogenic causes, compared to the 1950s, thus excluding coastal areas without dune systems in the 1950s, and analyzing what was built in place of the destroyed dune systems. Two criteria were defined to identify the levels of destruction of the dune systems and to identify the coastal erosion processes. The analysis showed a strong correlation between the destruction of dune systems by anthropogenic causes and the triggering of coastal erosion processes.

Sand Trapping Fences as a Nature-Based Solution for Coastal Protection: An International Review with a Focus on Installations in Germany

Sand trapping fences are a widely used nature-based solution to initiate dune toe growth along sandy shorelines for coastal protection. At present, the construction of sand trapping fences is based on empirical knowledge, since only a few scientific studies investigating their efficiency exist. However, the restoration and maintenance of beach-dune systems along the coast requires knowledge of the interaction between the beach-dune system and the sand trapping fences to provide guidance for coastal managers on how and where to install the fences. First, this review gives an overview of the typical aerodynamic and morphodynamic conditions around a single porous fence and the influence of various fence height and porosity values to understand the physical processes during dune establishment. Second, different approaches for evaluating the efficiency of sand trapping fences to trap sediment are described. This review then highlights significant differences between sand trapping fence configurations, nationally as well as internationally, regarding the arrangement, the materials used, and the height and porosity. In summary, it is crucial to enable an intensive exchange among the respective coastal authorities in order to create uniform or transferable guidelines taking local conditions into account, and thus work collaboratively on the idea of sand trapping fences as a nature-based solution in coastal areas worldwide.

A New Application of the Disturbance Index for Fire Severity in Coastal Dunes

Fires are a disturbance that can lead to short term dune destabilisation and have been suggested to be an initiation mechanism of a transgressive dune phase when paired with changing climatic conditions. Fire severity is one potential factor that could explain subsequent coastal dune destabilisations, but contemporary evidence of destabilisation following fire is lacking. In addition, the suitability of conventional satellite Earth Observation methods to detect the impacts of fire and the relative fire severity in coastal dune environments is in question. Widely applied satellite-derived burn indices (Normalised Burn Index and Normalised Difference Vegetation Index) have been suggested to underestimate the effects of fire in heterogenous landscapes or areas with sparse vegetation cover. This work assesses burn severity from high resolution aerial and Sentinel 2 satellite imagery following the 2019/2020 Black Summer fires on Kangaroo Island in South Australia, to assess the efficacy of commonly used satellite indices, and validate a new method for assessing fire severity in coastal dune systems. The results presented here show that the widely applied burn indices derived from NBR differentially assess vegetation loss and fire severity when compared in discrete soil groups across a landscape that experienced a very high severity fire. A new application of the Tasselled Cap Transformation (TCT) and Disturbance Index (DI) is presented. The differenced Disturbance Index (dDI) improves the estimation of burn severity, relative vegetation loss, and minimises the effects of differing soil conditions in the highly heterogenous landscape of Kangaroo Island. Results suggest that this new application of TCT is better suited to diverse environments like Mediterranean and semi-arid coastal regions than existing indices and can be used to better assess the effects of fire and potential remobilisation of coastal dune systems.

Monitoring the Dynamics of Formby Sand Dunes Using Airborne LiDAR DTMs

Coastal dunes play an important role in coastal erosion risk management, where they act as a dynamic natural sea defence line. Formby coast is part of the Sefton coast in the Northwest of England and is one of the largest and most rapidly evolving sand dune systems in the UK. Such dune systems require continuous comprehensive monitoring activity to understand their dynamics. In this research, we investigate the use of airborne LiDAR digital terrain model DTMs for monitoring the dynamics of the sand dunes at Formby between 1999 and 2020. We found that the rate of elevation change for the beach and the dune areas ranges from −0.78 to 0.02 m/year and −0.92 to 0.73 m/year, respectively. The beach and the frontal dunes have had significant sand erosion, while the inner dunes gained sand during the measurement period. Vegetated areas remained unchanged due to the impact of vegetation in stabilizing the movement of the dunes. Formby beach had a volume loss of about 907,000 m3 in the last 21 years, while the dunes had a volume increase of about 1,049,000 m3 over the same period. The total volume of the entire dune system, consisting of both the beach and dune areas, remained unchanged, which indicates that the growth of the inland dunes is fed by sand from the beach. All the volumetric changes occurred due to sand redistribution within the system, with erosion along the beach, and deposition and erosion in the dune areas.