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Coastal sand dunes are highly dynamic aeolian landforms where different spatial patterns can be observed due to the complex interactions and relationships between landforms and land cover. Sediment distribution related to vegetation types is explored here on a single ridge dune system by using an airborne hyperspectral and light detection and ranging (LiDAR) remote sensing dataset. A correlation model is applied to describe the continuum of dune cover typologies, determine the class metrics from landscape ecology and the morphology parameters, and extract the relationship intensity among them. As a main result, the mixture of different vegetation types such as herbaceous, shrubs, and trees classes shows to be a key element for the sediment distribution pattern and a proxy for dune sediment retention capacity, and the anthropic fingerprints can play an even major role influencing both ecological and morphological features. The novelty of the approach is mostly based on the synergistic use of LiDAR with hyperspectral that allowed (i) the benefit from already existing processing methods to simplify the way to obtain thematic maps and coastal metrics and (ii) an improved detection of natural and anthropic landscape.

The availability of high-resolution Digital Surface Models of coastal environments is of increasing interest for scientists involved in the study of the coastal system processes. Among the range of terrestrial and aerial methods available to produce such a dataset, this study tests the utility of the Structure from Motion (SfM) approach to low-altitude aerial imageries collected by Unmanned Aerial Vehicle (UAV). The SfM image-based approach was selected whilst searching for a rapid, inexpensive, and highly automated method, able to produce 3D information from unstructured aerial images. In particular, it was used to generate a dense point cloud and successively a high-resolution Digital Surface Models (DSM) of a beach dune system in Marina di Ravenna (Italy). The quality of the elevation dataset produced by the UAV-SfM was initially evaluated by comparison with point cloud generated by a Terrestrial Laser Scanning (TLS) surveys. Such a comparison served to highlight an average difference in the vertical values of 0.05 m (RMS = 0.19 m). However, although the points cloud comparison is the best approach to investigate the absolute or relative correspondence between UAV and TLS methods, the assessment of geomorphic features is usually based on multi-temporal surfaces analysis, where an interpolation process is required. DSMs were therefore generated from UAV and TLS points clouds and vertical absolute accuracies assessed by comparison with a Global Navigation Satellite System (GNSS) survey. The vertical comparison of UAV and TLS DSMs with respect to GNSS measurements pointed out an average distance at cm-level (RMS = 0.011 m). The successive point by point direct comparison between UAV and TLS elevations show a very small average distance, 0.015 m, with RMS = 0.220 m. Larger values are encountered in areas where sudden changes in topography are present. The UAV-based approach was demonstrated to be a straightforward one and accuracy of the vertical dataset was comparable with results obtained by TLS technology.

ABSTRACT The development of tourism in Mallorca has led to the island's economy being based, almost exclusively, on this sector. Since 1955 mass tourism has affected the economic and social structures of Mallorca. The development was based on a rapid growth of tourist demand and on a chaotic development of tourist facilities. This has had severe consequences for the island: insufficiently controlled urban planning, overcrowded beaches, and erosion of the beach-dune system caused by massive construction on the coastal zone. Many beaches have been transformed into urban beaches and their coastline has retreated. Solutions like sand renourishment have not stopped the erosion process. The increasing number of residents and visitors exerts a strong pressure over water resources producing overextraction and a lowering of the groundwater table in aquifers. A strong seasonal concentration of visitors in coastal summer resorts represents a high peak demand during the dry season. The exhaustion of groundwater resources and the higher water demand are managed with environmentally and economically expensive resources such as seawater desalination. The results show that the dwelling capacity of the island has been exceeded and the present levels of water demand and beach degradation are not sustainable. This indicates that tourism in Mallorca is becoming unsustainable and a water and coastal management policy is urgently required if sustainability is to be achieved.

Cabo Falso is located on the southern coast of the Baja California peninsula. The beach is broad and wide with a steep face and tall foredunes on the backshore. Landwards, an active, predominantly parabolic dune field has developed with average heights of 30 m. Part of the field is used by recreational all-terrain vehicles. The main goal of this study was to identify the principal morphodynamic characteristics of the deposits influenced by these recreational activities and affected by Hurricane Juliette in 2001. The morphology of the study area was monitored using seasonal topographic profiles, examination of aerial photographs from 1972 and 1993, and on-site photographs (November 1999 to April 2002). The topographic profiles indicated that the erosion period for both the beach and the dunes was June to December. Hurricane Juliette was the responsible for most of the observed erosion. The greatest sediment accumulation occurred between December 2001 and February 2002, associated with the onset of the natural recovery process of the beach–dune system. The photographs revealed that the dunes have lost vegetation cover because of the activities of all-terrain vehicles, which erode paths perpendicular to the dune crests. This in turn allows increased sediment movement, resulting in instability of the dune field system.

Castelle, B.; Marieu, V., and Bujan S., 2019. Alongshore-variable beach and dune changes on the timescales from days (storms) to decades along the rip-dominated beaches of the Gironde Coast, SW France. In: Castelle, B. and Chaumillon, E. (eds.), Coastal Evolution under Climate Change along the Tropical Overseas and Temperate Metropolitan France. Journal of Coastal Research, Special Issue No. 88, pp. 157–171. Coconut Creek (Florida), ISSN 0749-0208. The high-energy meso-macrotidal 110-km long Gironde coast, SW France, is primary composed of quasi-straight sandy beaches bordered by high and wide coastal dunes. Beaches are intermediate double-barred and are essentially morphologically variable alongshore with ubiquitous rip channels incising both bars. These rip channels enforce a strong alongshore variability in the morphology of the dry beach and/or of the dune, morphological patterns referred to as megacusp embayments. In this study, we use 70-year diachronic shoreline data, 3.5-year semi-annual in situ shoreline surveys since 2014, combined with 12.5-year monthly to semi-monthly topographic surveys collected since 2005 at Truc Vert beach. Results show that 2 types of megacusp can be identified: (1) accretive megacusps on the upper beach, forming through a sequence of accretionary beach states following a storm event, are enforced by inner-bar rip channels with a spacing of O(100 m) and a typical lifetime of a few months and (2) erosive megacusps cutting the dune, forming during severe-storm driven erosive events, which are primarily enforced by the outer-bar morphology with a spacing of O(1000 m). These erosive megacusps do not migrate alongshore and can persist for years to decades. The outstanding winter of 2013/2014 drove the formation of erosive megacusps all along the coast, dramatically altered the coastal landscape and also impacted the behaviour and mean spacing of the accretive megacusps during the subsequent years. Overall, the study demonstrates the complex interplay between the nearshore morphology and the alongshore-variable changes of the foreshore/backshore from the timescales of days to decades, with accessional outstanding winters having the potential to deeply affect beach morphology and rhythmicity on the time scale of a few years, at least.

We propose an optimized Structure-from-Motion (SfM) Multi-View Stereopsis (MVS) workflow, based on minimizing different errors and inaccuracies of historical aerial photograph series (1945, 1979, 1984, and 2008 surveys), prior to generation of elevation-calibrated historical Digital Surface Models (hDSM) at 1 m resolution. We applied LiDAR techniques on Airborne Laser Scanning (ALS) point clouds (Spanish PNOA LiDAR flights of 2014 and 2019) for comparison and validation purposes. Implementation of these products in multi-temporal analysis requires quality control due to the diversity of sources and technologies involved. To accomplish this, (i) we used the Mean Absolute Error (MAE) between GNSS-Validation Points and the elevations observed by DSM-ALS to evaluate the elevation accuracy of DSM-ALS generated with the LAScatalog processing engine; (ii) optimization of the SfM sparse clouds in the georeferencing step was evaluated by calculating the Root Mean Square Error (RMSE) between the Check Points extracted from DSM-ALS and the predicted elevations per sparse cloud; (iii) the MVS clouds were evaluated by calculating the MAE between ALS-Validation Points and the predicted elevations per MVS cloud; iv) the accuracy of the resulting historical SfM-MVS DSMs were assessed using the MAE between ALS-Validation Points and the observed elevations per historical DSM; and (v) we implemented a calibration method based on a linear correction to reduce the elevation discrepancies between historical DSMs and the DSM-ALS 2019 reference elevations. This optimized workflow can generate high-resolution (1 m pixel size) hDSMs with reasonable accuracy: MAE in z ranges from 0.41 m (2008 DSM) to 5.21 m (1945 DSM). Overall, hDSMs generated using historical images have great potential for geo-environmental processes monitoring in different ecosystems and, in some cases (i.e., sufficient image overlapping and quality), being an acceptable replacement for LiDAR data when it is not available.

The Bulgarian Black Sea Coast is a well-formed mosaic of pockets, small, gravelly-sandy beaches, and erosion-prone or erosion-resistant cliffs. A significant portion of the depositional cost along the Strandzha sector includes sand beaches with frontal and stabilized dunes, whose high-resolution mapping is a major task in this work. Currently, unmanned aerial systems (UAS) are the main method for topographic reconstruction. The world's experience in UAS surveys and the rapid capture of hard-to-reach large shore areas are the reasons why we emphasize using drones to map coastal landforms. Based on high-resolution UAS-derived data, a map of depositional landforms was created for the Harmani-Sozopol beach-dune system for the first time. Raster RGB orthophoto mosaics have been used to digitalize and classify different types of dunes. Elevation data from DSM with 15 cm resolution were used to identify beach and dune morphological features: shoreline position, dune foot line, dune crest line, and stable vegetation line. The spatial analysis in the Digital Shoreline Analysis System (DSAS) of the obtained elements allows an accurate assessment of the shoreline changes (erosion/accretion) and dynamics of the dune field. For the time period of 1918-2022, using the Linear Regression Rate (LRR) indicator, an average accretion rate of +0.02 m/yr was reported for Harmani beach-dune system. For the last 100 years, the area has registered a decrease in area by over 55% from 14.5 ha to 6.5 ha. The paper aims to present a multidisciplinary approach to the study of highly dynamic coastal landforms, the results of which would benefit local authorities in drawing up management plans for the Bulgarian Black Sea coast.

Anthropogenic development has historically concentrated in coastal areas to exploit resources from fishing and commercial navigation. In recent centuries, intensive tourism has added pressure on sandy shorelines, leading to their modification. This development model has led to the disappearance of most coastal sand dunes and their rich biodiversity, which includes specialized plant and animal species adapted to sandy substrates, harsh arid conditions, and variable levels of salinity. The European Community’s conservation policies, particularly the Habitats Directive (Council Directive 92/43/EEC), have facilitated the preservation and restoration of the few remaining dune systems. However, these policies have unfortunately overlooked the protection of the adjacent beaches, which are integral to the coastal ecosystem. The loss of biodiversity typical of the beach–dune ecosystems is examined in relation to the anthropogenic disturbance factors, with particular attention to mechanical beach cleaning. Indeed, the metabolizable energy generated by this decomposer biomass is crucial for supporting a diverse trophic network of predators, ranging from insects to birds. The rapid disappearance of the specialized beetle fauna is examined, and some essential criteria for defining standard biotic indices suitable for monitoring these ecosystems are suggested. This approach aims to support more effective conservation programs for these fragile environments. We recommend revising the regulatory framework for safeguarding beach–dune ecosystems, while also proposing some key management principles to be incorporated into the protection guidelines.

Claudino-Sales, V.; Wang, P., and Carvalho, A.M., 2018. Interactions between various headlands, beaches, and dunes along the coast of Ceará State, Northeast Brazil. The equatorial coast of NE Brazil consists of long and wide sandy beaches, segmented by rhythmic headlands, sometimes with seacliffs. Large and extensive mobile transgressive dunefields distribute up to 6 km landward of the coastline. The coastal area of Ceará state, as examined in this study by the means of measurements, field work, and remote sensing, illustrates a characteristic morphology composed of interactive headland, beach, and dune systems. Under persistent unidirectional wind and wave forcing, the morphodynamics of the studied coast is strongly controlled by the headlands because they produce an interruption of the longshore sand transport at their contact, resulting in accretion updrift of the headland and in erosion downdrift of the headland. The headland bypass dunefield activates one major mechanism and dynamics of the system headland-beach-dune because they refeed the beaches in the process of erosion downdrift. Littoral bypass is also an important process, supplying the cell with new sand, together with the erosion that takes place in the zetaform beach. Such a unique system can be strongly affected by anthropogenic activities, which can influence nearly all the factors at all temporal and spatial scales.

Hydrotechnical structures reshape sandy coasts by altering hydrodynamics and sediment transport, yet their long-term effects on sediment texture remain underexplored, particularly in the Baltic Sea. This study investigates the spatial and temporal variations in sediment grain size near two ports (Šventoji and Klaipėda) on the sandy Baltic Sea coast, considering the influence of jetties, nourishment, and geological framework. A total of 246 surface sand samples were collected from beach and foredune zones between 1993 and 2018. These samples were analyzed in relation to shoreline changes, hydrodynamic data, and geological context. The results show that sediment texture is most affected within 1–2 km downdrift and up to 4–5 km updrift of port structures. Downdrift areas tend to contain coarser, poorly sorted sediments because of erosion and the exposure of deeper strata, while updrift zones accumulate finer, well-sorted sands via longshore transport. In the long term, the geological framework controls sediment characteristics. In the medium term, introduced material that differs in grain size from natural beach sediments may alter the texture of the sediment, either coarsening or refining it. The latter slowly returns to its natural texture. Short-term changes are driven by storm events. These findings highlight the importance of integrating structural interventions, nourishment practices, and geological understanding for sustainable coastal management.