Parabolic Dunes Research Articles

Dune Pattern interrupted by ephemeral drainages and human activities, on the northern Ordos Plateau in China

Dune patterns are considered a representation of the desert landscape, and their formation and evolution are affected by climatic conditions and regional differences in the sedimentary environment. High-resolution satellite images from 2007 to 2021 were used to quantitatively analyze the spatiotemporal variation of pattern parameters on the northern Ordos Plateau in China by using the dune pattern analysis method. Combined with meteorological factors and land use changes, this analysis provides insight into the dynamic change of dune patterns and the main controlling factors of dunes evolution. The results show that ephemeral drainages and roads developed in the plateau interrupt dune agglomeration downwind without significant changes in the pattern parameters from west to east and without obvious spatial variation trend of parameters in each area separated by linear obstacles. In the past 14 years, the crestlines of the sampled dunes have always been NE-SW and NNE-SSW, with a counterclockwise deflection that gradually occurred with time. The crestline length and dune height showed a decreasing trend, while the dune spacing and defect density showed an increasing trend. After 2012, a significant rise in precipitation and a drop in wind speed contributed to vegetation recovery, promoting the transformation of barchan dunes to parabolic dunes and breaking the original self-organization evolution of dunes. Therefore, the spatiotemporal evolution of dune pattern in the northern Ordos plateau is driven by natural and human factors and differs from that in the hinterland of mobile deserts.

Evolutionary stages of active to vegetated coastal transgressive dunefields in the San Matías Gulf coast, Argentina

The understanding of how active aeolian coastal dunes transform into fully vegetated forms, and the specific dune configurations that emerge, particularly within coastal dune systems, is limited. This study examines the changes in dune morphology associated with vegetation growth within transgressive dunefields in NE Patagonia, Argentina. The dunefields are located along the northern coast of the San Matías Gulf, ranging from relatively small to large, and dominantly active in the past ∼80 years. Satellite and aerial images were analyzed using GIS procedures to calculate vegetation cover changes and dune migration rates and identify different dune types and their evolutionary stages of fixation. Five stages were defined in relation to vegetation cover and dune shapes and patterns, from bare sand to fully vegetated dunes. Transverse or barchanoid ridges (sometimes with aklé [fish scale], or chaotic patterns) convert to partially vegetated sub-parabolic dunes and finish as parabolic dunes. In other cases, the dunes may convert to reticulate, aklé, or chaotic patterns, completely vegetated. Various stages span a continuous range from unvegetated to fully vegetated dunes across a wide array of timeframes. In some cases, it was possible to recognize changes from stage one to five in ∼20 years. Where the initial transverse dune is largely maintained during the stabilization process a distinctive pattern named “gusanos” (worms) was identified. The vegetated surface measured in some areas changed from 11 % to 51 % vegetation cover between 1961 and 2022, with migration rates decreasing from 9.53 m/year to zero between 1991 and 2020. The increase in vegetation growth also coincides with higher temperatures, weaker winds and decreasing grazing livestock within this Patagonia area. The recorded processes are similar to coastal dune and vegetation changes in some semiarid regions from the Southern Hemisphere between 30 and 60° S, especially in South Australia.

The Dunes of Belvedere–San Marco of Aquileia: Integrating High-Resolution Digital Terrain Models and Multispectral Images with Ground-Penetrating Radar Survey to Map the Largest System of Continental Dunes of Northern Italy

The interpretation of high-resolution remote-sensed data (i.e., LiDAR-derived DTMs, aerial photos and satellite images), compared with ground-penetrating radar surveys, historical cartography, geomorphological surveys and stratigraphic data, allowed us to map a large system of dunes near the Grado-Marano Lagoon (NE Italy) and reconstruct its evolution. Remote sensing investigations allowed us to recognize, map and interpret the sandy reliefs as a field of continental aeolian landforms extending for over 15 km2 and consisting of parabolic dunes elongated in the WSW direction. Radar soundings, together with the description of stratigraphic sections and cores, documented the internal clinostratification of the dunes, supporting their aeolian origin. Radiocarbon dating documents that the dunes formed 22 ka ago, at the end of the Last Glacial Maximum, and probably evolved until the first part of the Late Glacial, when vegetation was scarce. The landforms were fed by the sands blown from a paleochannel of Isonzo River flowing eastward of the dune’s field and blown by Bora. This is a very strong katabatic wind, still characterizing the area, but that was likely much stronger during last glaciation, when it was probably sustained by a stronger wind pattern in Central Europe.

Coastal foredune enlargement – a sign of sea-level change? An example from the Kavatsite beach-dune system

Sea level rise is one of the effects of climate change and the Black Sea is affected, regardless its isolated position from the World Ocean. As a consequent, in various locations worldwide is reported shifting of foredune ridges towards inland and overlapping of newly formed ridges over older secondary features, as parabolic dunes, dune fields, etc. During the field study in 2023, in the Kavatsite foredune ridge was observed such migration of newly formed accumulations on older grey dunes. Comparative analysis of UAV-based photogrammetry and generated orthophoto mosaic overlaid to archive aerial images from the early 20th century showed over 20 m migration of the primary dune ridge inland and also increased beach erosion. Regarding the accelerating sea rise tendency, special attention should be taken to the anthropogenic activities in the coastal zone, including the beach-dune systems – the first natural barrier to the wave action on coasts.

Morphometry of the Samalayuca dunes, northern Chihuahua, Mexico

The Samalayuca Dunes (SMD) (Médanos de Samalayuca), Chihuahua, México, are one of México’s largest and least studied dune fields, now managed as a Protected Area for their ecological characteristics. We present a morphometric characterization of the dune field based on remote sensing and field studies, to advance understanding of its physical environment. SMD’s generally-fine sands originate from shoreline deposits of Paleolake Palomas, transported eastward (downwind) along an aeolian corridor, accumulating primarily as echo dunes upwind of the sierras of Samalayuca and Presidio. A complex wind regime, with northerly and southerly winds complementing regionally-prevailing southwesterlies, modified by topographic effects, shapes the SMD’s morphology. The sand sea covers ~139.7 km2, with ~113.8 km2 in the main eastern body and ~25.9 km2 in a northwestern subfield. We describe six major dune forms: north to south straight-crested dunes, east to west straight-crested dunes, star dunes, vegetated parabolic dunes, relict transverse dunes, and “megastar” (draa) dunes. Mean interdune centroid spacing is 76.5 m. The active dunes, previously described as an “aklé” pattern, are predominantly straight-crested dune sets oriented near-perpendicular to each other with general north-south and east-west crest orientations, 4-5 m high, spaced ~67 m apart for north-south trending crests and ~53 m for east-west trending crests, representing a nearly perpendicular interference pattern in some locations. The active dunes are superimposed in a compound and complex arrangement on relict remnants of much larger north-northwest trending transverse dune ridges fanning out from south to north-northwest, spaced approximately ~1 km apart and ~50 m high. The easternmost dune ridge contains an active set of at least 15 active megastar and reversing dunes up to 120 m tall, increasing in size and complexity from south to north. As a protected area with historical and ecological value, additional geologic investigations should be performed at the SMD, to help conserve this remarkable geologic feature.

Aeolian Landforms in the White Sea Coast: a Review of Classification and Spatial Distribution

This research provides classification and analysis of the spatial distribution of the Holocene aeolian landforms within the White Sea Coast. We identified 5 types of secondary dunes based on the interpretation of detailed satellite images, topographic charts and analysis of literary sources: foredune plains and beach ridges plains, cliff-top dunes, blowouts and parabolic dunes, transgressive dunefields, sand sheets. The dunes were formed mainly from the Middle-Late Holocene. They gravitate towards sandy shores, where post-glacial uplift rates didn’t exceed ~3 mm/year during the Middle-Late Holocene. The coastal dunes were formed in connection with sediments, which entered the coastal zone with solid river flow and from selective erosion of glacial deposits. The rhythms of aeolian processes activation in different parts of the White Sea Coast were non-synchronous.

Parabolic dune distribution, morphology and activity during the last 20 000 years: A global overview

AbstractParabolic dunes form and migrate in almost every climate and geographic zones of the world, ranging from the tropical coastlines to the arid continental deserts. Despite their extensive distribution and their importance within the aeolian sediment landscape, the understanding of their morphological development, activity and link with climates remains somewhat limited to local or regional scales. A good understanding of the present climate conditions under which parabolic dunes are formed and/or reactivated would be significantly helpful to constrain past climate models. Similarly, an improved knowledge of parabolic dunes behaviour during past climatic episodes would provide some valuable long‐term data to better predict their future activity. This review first aims at providing a non‐exhaustive global database on parabolic dune morphology and the present wind regimes with which they are associated. To do so, the morphology of 750 dunes distributed worldwide was first analysed using a high‐resolution global digital elevation model, suggesting an intrinsic relationship between the different measured morphoparameters. The analysis of the associated local wind regimes shows that parabolic dunes develop under strong unidirectional winds, which are more conspicuous in coastal than continental environments. Dunes of different ages are globally aligned with present prevailing winds, which suggests a prevalent control of long‐term global atmospheric circulation on dune orientations. Finally, this study explores the link between parabolic dune activity and climates over the past 20 000 years by reviewing ages from the literature and combining them with the ones compiled in the INQUA Dunes Atlas Chronologic Database. Overall, it appears that changes towards drier conditions have triggered dunes migration during both warm and cold periods of the Last Glacial Maximum, Holocene Climate Optimum, Roman Climate Optimum, Medieval Climate Optimum and Little Ice Age. The present day aeolian activity is predominantly linked with deteriorating environmental conditions caused by human disturbances.

Dune slope, not wind speed, best predicts bare sand in vegetated coastal dunes

Globally vegetation cover on coastal sand dunes has increased since at least the 1950s. With the aim of restoring or increasing biodiversity, land managers in several countries have removed vegetation and/or reprofiled dune slopes to reinvigorate geomorphic activity. However, the longevity of these interventions can be relatively short (on the order of 5 to 10 years), and further active management is required. Hypotheses for controls on geomorphic activity on dunes have frequently suggested that wind speedis the most important controlling factor. Here we show dune slope to be the best predictor of bare sand at four predominantly vegetated coastal sand dunes in England and Wales. We suggest that bare sand on steep dune slopes is maintained by three important factors: (1) Wind erosion, due to topographic acceleration (2) Granular avalanches of unconsolidated sediment and (3) Rotational slumping of unstable slopes. Our results indicate that where land managers wish to ‘rejuvenate’ areas of bare sand, efforts should focus on steep windward dune slopes and reprofiling of the dune slope should mimic the concave profiles of active slope faces on active parabolic dunes with an overall slope angle of between 18° and 23° from the dune toe to the crest.

Onset of dune construction based on archaeological evidence, White Sands, New Mexico

AbstractThe White Sands dune field is the largest gypsum dune system in the world, derived from deflation of paleo-Lake Otero deposits. Understanding the timing of initial dune construction, and therefore lake deflation, is critical for understanding regional landscape evolution, including the history of lake desiccation. The onset of dune construction is currently estimated at ~8000 to 6500 cal yr BP, but numerical age control is limited. Archaeological evidence reported here indicates two older phases of gypsum dune construction. An archaeological site draped over a parabolic dune south of the main dune body contains artifacts dating to >12,200 cal yr BP, providing an upper age limit for the landform. Another site buried within a remnant of the main dune field yielded six statistically identical radiocarbon dates averaging ~8770 cal yr BP. The initial phase of terminal Pleistocene deflation and parabolic dune construction was perhaps localized but correlates with a period of regional aridity. Barchans and crescentic ridges comprising the main dune body developed in the Early Holocene in response to elevated salinity in local ground water and extensive exposures of gypsum available for deflation, likely due to aridity.

Quantifying Transgressive Coastal Changes Using UAVs: Dune Migration, Overwash Recovery, and Barrier Flooding Assessment and Interferences with Human and Natural Assets

The advantages derived from the use of Uncrewed Aerial Vehicles (UAVs) are well-established: they are cost-effective and easy to use. There are numerous environmental applications, particularly when monitoring contexts characterized by rapid morphological changes and high rates of sediment transport, such as coastal areas. In this paper, three different case studies of survey and monitoring with high resolution and accuracy obtained through the use of UAVs are presented; these concern transgressive coastal sites. Results allow for the definition and quantification of coastal landforms and processes, including: (i) The anatomy of a parabolic dune and the rate of landward migration that could interfere with a tourist settlement; (ii) The mode and timing of morphological recovery and realignment of a barrier island overwashed by storm surge episodes; and (iii) The potential flood risk of a progradational spit that is a nesting site of a species of migratory breeding birds of conservation concern. The results demonstrate and confirm that, through a good coupling of drone-sensed quality data and accurate topographic control, quantitative estimates that are useful in assessing the impacts of natural processes involving both human and natural assets can be obtained.

Systematics and typology of the relief forms of the Oleshkivski Sands


 
 
 Oleshkivski Sands is one of the most peculiar regions of psammomorphic land- scapes in Europe and in particular the ancient delta region of the Left Bank of the Lower Dnipro. The territory of the sands consists of seven hilly sand massifs and six inter-arenial flat-level geocomplexes. The relief and peculiarities of the formation of this territory are still insufficiently studied, the relief of the intra-arenial landscapes is almost completely unexplored. The objectives of this study were sys- tematics and typology of the relief forms with approaches to elucidating the factors and mechanism of formation of geomorphological formations of Oleshkivski Sands. The methods of research of the relief of the Oleshkivski Sands were based on existing experience in identification, mapping, classification, analysis of sandy landforms, deciphering their portrayal on satellite images, as well as on many years of field research by the author. The generalized and systematized analysis of the relief, illustrated with maps, tables and photo- graphic materials, allowed us to form the systematics of the microforms of the relief and the typology of the mesorelief of the Olesh- kivski Sands. The results of such studies have revealled the morphological and genetic diversity of individual landforms within the arenas and inter-arenial geocomplexes, and a total of seven arenas of the Oleshkivski Sands, and respectively the complicated history of the formation of the region. Of the arenial geocomplexes, the hilly massifs and intra-arenial depressions were considered separately. Among the hilly massifs, the dominant were found to be hilly and undulated chaotically-configured structures, at some places with the distribution of parabolic dunes and dune ridges, and also the subordinate spread of the mound massifs. The morphological and genetic diversity of inter-arenial depressions was determined, which can be considered as diagnostic objects in the formation of the Oleshkivski Sands. The analysis of the relief of the territory of the Oleshkivski Sands revealed that different factors were in operation at different time stages of its formation – fluvial (fluvioglacial), aeolian, suffusion-subsidence, thalassogenic, anthropogenic. Аt the present stage the dominant are aeolian and anthropogenic factors. Special attention was paid to parallel hilly ridges of the Kinburnska and Kelegeiska arenas, considered in the context of the diluvial (catafluvial) paradigm as a manifestation of giant ripples. The discreetly formed parallel ridges and extended hollows of the Kinburn Peninsula are presented in the context of flood-freshet events in the history of the function- ing of the Dnipro and the Southern Bug, in places where water masses flow through watershed geocomplexes.
 
 

Evolution of a coastal transgressive dunefield to a parabolic dunefield, Canunda dunes, South Australia

Various studies have detailed the evolution of barchan dunes to parabolic dunes and a very few studies describe the evolution of coastal transgressive dunefields and continental sand seas to parabolic dunefields. This study examines the evolution and transformation of a 12 km long portion of a formerly large (~50 km along-coast), active, transgressive dunefield (coastal sand sea or erg) dominated by transverse dunes to a coastal barrier dominated by parabolic dunes. A GIS study of vegetation cover change from 1950 to 2017 was conducted, and a stereographic analyses of 1945 to 2020 aerial photography was carried out to determine morphological changes across the dune system. Historical rainfall, aeolian drift potentials, and rabbit numbers are examined as possible drivers of change, and rabbit numbers most strongly correlate with vegetation change. The vegetation cover of the greater dunefield increased in the study area from 26 % cover in 1950 to 54 % by 2020. A largely unvegetated transgressive dunefield dominated by transverse dunes evolved into a parabolic dunefield in <70 years. Vegetation colonisation primarily took place from landward slipfaces, by nebkha formation on dune lobe crests, from interdune swales and flats, and within deflation basins and plains. Vegetation colonisation also occurred above the backshore in the same period. Aeolian landform units such as marginal ridges, nebkha fields, deflation basins and plains, dune ridges, remnant knobs, parabolic dunes, and a foredune-blowout complex were formed as the dune field was colonised and stabilised by vegetation growth. The study provides far greater detail on how vegetational and morphological changes take place as a transgressive dunefield evolves into a parabolic dunefield.

Holocene evolution of parabolic dunes, White River Badlands, South Dakota, USA, revealed by high-resolution mapping

AbstractThe White River Badlands (WRB) of South Dakota record eolian activity spanning the late Pleistocene through the latest Holocene (21 ka to modern), reflecting the effects of the last glacial period and Holocene climate fluctuations (Holocene Thermal Maximum, Medieval Climate Anomaly, and Little Ice Age). The WRB dune fields are important paleoclimate indicators in an area of the Great Plains with few climate proxies. The goal of this study is to use 1 m/pixel-resolution digital elevation models from drone imagery to distinguish Early to Middle Holocene parabolic dunes from Late Holocene parabolic dunes. Results indicate that relative ages of dunes are distinguished by slope and roughness (terrain ruggedness index). Morphological differences are attributed to postdepositional wind erosion, soil formation, and mass wasting. Early to Middle Holocene and Late Holocene paleowind directions, 324°± 13.1° (N = 7) and 323° ± 3.0° (N = 19), respectively, are similar to the modern wind regime. Results suggest significant landscape resilience to wind erosion, which resulted in preservation of a mosaic of Early and Late Holocene parabolic dunes. Quantification of dune characteristics will help refine the chronology of eolian activity in the WRB, provide insight into drought-driven landscape evolution, and integrate WRB eolian activity in a regional paleoenvironmental context.

Rapid Magnetic Susceptibility Characterization of Coastal Morphosedimentary Units at Two Insular Strandplains in Estonia

Coastal archives of changing hydrometeorological conditions include mineralogical anomalies, such as heavy-mineral concentrations (HMCs) of variable thickness and intensity, which contain varying ferrimagnetic (e.g., magnetite) fractions. As an effective alternative to laborious mineralogical and granulometric analysis, we present the first set of bulk-volume low-field magnetic susceptibility (MS) databases from beach and dune lithosomes in the Western Estonian archipelago: Harilaid cuspate foreland (westernmost Saaremaa Island) and Tahkuna strandplain (northernmost Hiiumaa Island). Readings were conducted both in situ from trench walls and on core subsamples. At the Tahkuna site, late Holocene beach ridges reveal substantially lower values: quartz-dominated dune sequences grade from 5–20 μSI downward to diamagnetically dominated (−1–7 μSI) beach facies. Values are higher (20–140 μSI) in historically reactivated parabolic dunes that are encroaching southward over the strandplain. At the Harilaid site, four beach dune ridges (height: 2–3 m) that span the past 250–300 years show a general increase in mean MS from 320–850 μSI with decreasing age, with peaks of 1000–2000 μSI below the dune crests (depth: ~0.3–0.6 m) likely related to contemporary wind acceleration during ridge aggradation. The highest mineralogical anomalies range from 2000–5500 μSI in the historic dune sections and exceed 8000 μSI along the actively eroding upper-berm segments, typical of HMCs generated by moderate storms. MS anomalies are likely correlated with high-amplitude electromagnetic signal responses in georadar records and provide useful information for optical luminescence sampling strategies. Our study demonstrates that magnetic susceptibility trends provide a useful means of rapidly assessing relative temporal changes in overall wave/wind climates, help identify and correlate discrete anomalies related to extreme events, serve as local beach/dune boundary indicators, and represent potentially quantifiable paleo-energy indices.

The Role and Frequency of Wildfires in the Shaping of the Late Glacial Inland Dunes – A Case Study from the Korzeniew Site (Central Poland)

Abstract The study examines sedimentology, stratigraphy, and the impact of wildfires on aeolian and soil processes during the Late Glacial Termination in the Korzeniew site, central Poland. The site, within a parabolic dune's central and lee-slope area, presents stacked aeolian sand units intermixed with six charcoal-enriched palaeosols. Thirteen optically stimulated luminescence (OSL) dates on quartz and six radiocarbon dates establish the chronological framework, dating deposition processes. Initial aeolian sand deposition occurred towards the Late Pleniglacial's end. Climate amelioration during the Bølling interstadial led to permafrost thaw and gleyic soil formation, later overlain by migrating parabolic dunes from the older Allerød interstadial. Wildfires, influenced by vegetation cover, deposited charcoals on the dune's lee slope. These charcoals underwent pedogenic reworking amid episodes of aeolian sand deposition during the Allerød interstadial and Younger Dryas, stabilizing in the earliest Holocene. Wildfires significantly impacted local vegetation development and aeolian activity. Despite the warmth of the Allerød interstadial, increased fires correlated with expanding pine forests and their heightened fire susceptibility. Short-term climate shifts likely destabilized vegetation, fostering fire occurrences during the Allerød interstadial.

The largest Quaternary inland eolian system in Brazil: Eolian landforms and activation/stabilization phases of the Xique-Xique dune field

Eolian systems are sensitive to vegetation and climate changes, but also to the sediment supplied by neighbor depositional systems. This sensitivity is manifested in the alternation between periods of sand dune mobility and stability. In the Xique-Xique eolian system, the largest Quaternary interior dune field in Brazil (∼8000 km2), the neighboring depositional system responsible for the sand supply is the São Francisco River. We interpreted periods of dune activity and stabilization by mapping eolian landforms of this system, describing depositional facies under them and dating by optically stimulated luminescence (OSL-SAR). The stabilized parabolic landforms characterized and mapped (all formed by SE to E winds) were simple megadunes (25.5 ± 4.4 to 5.8 ± 2.0 ka), compound dunes (15.8 ± 1.2 to 5.2 ± 1.4 ka) and perched dunes (14.0 ± 1.0 and 1.2 ± 0.1 ka). We also recognized eolian plains (14.0 ± 2.1 to 6.5 ± 0.7 ka) and active parabolic dunes. Eolian deposits of undifferentiated landforms have also been described and dated (253.8 ± 19.0 to 8.2 ± 1.3 ka). The ages obtained allowed identification of two main phases of dune activity (∼60 to 18 ka and ∼16 to 5 ka) separated by a short period of stabilization marked by a paleosol (∼18 ka). The main periods of eolian activity are associated with phases of fluvial aggradation and high sediment supply, whereas dune stabilization since 5 ka is correlated with low sediment supply during the Late Holocene fluvial incision phase. The periods of eolian activity and stabilization respond not only to climate changes in the area occupied by the eolian system but mainly to local fluvial sediment supply by the river, which in turn can respond to more regional climatic controls. The Xique-Xique eolian system results from the coupling of abundant sediment supply from the fluvial system, high eastern wind speeds, and a significant wind deceleration caused by mountains on the western border of the dune field.

Factors controlling the development of cold-climate dune fields within the central part of the European Sand Belt – Insights from morphometry

The central part of the European Sand Belt is an area where intense aeolian processes led to the development of large dune fields in the Lateglacial. They have been studied principally in terms of their stratigraphy, with less attention given to their evolution and geomorphology. It is also uncertain whether large dune fields in cold areas arise analogously to those formed in other climatic zones. To fill this gap, we performed a morphometric analysis of 31 stabilized dune fields in Poland using high-resolution LiDAR data. We related the outcomes to the morphological zones associated with the extent of the ice sheet during the LGM, the position and basement shape of the dune fields. The results indicate that dune fields in cold areas evolve in the same way as in other climatic zones, as expressed in the preserved relation between crest length, spacing, and defect density. The study found that the investigated dune fields have simple patterns composed of single populations of transverse to parabolic dunes facing E-ESE, suggesting their simultaneous formation in the Younger Dryas. At the same time, the varying degree of dune fields pattern development indicates the different duration of aeolian processes that shaped individual dune fields. The dominance of transverse dunes transformed partially or completely into parabolic dunes reflects the increasing role of vegetation over time and the decreasing supply of sand. The development of the dune field patterns was not found to be correlated with the extent of the ice sheet during the LGM, the morphological position, and the basement shape of the dune fields.

Geographic object‐based image analysis (GEOBIA) of the distribution and characteristics of aeolian sand dunes in Arctic Sweden

AbstractCurrent climate change in the Arctic is unprecedented in the instrumental record, with profound consequences for the environment and landscape. In Arctic Sweden, aeolian sand dunes have been impacted by climatic changes since their initial formation after the retreat of the last glacial ice sheet. Dune type, location and orientation can therefore be used to explore past wind patterns and landscape destabilisation in this sensitive area. However, knowledge of the full spatial extent and characteristics of these dunes is limited by their inaccessibility and dense vegetation cover. Geographic object‐based image analysis (GEOBIA) permits the semi‐automatic creation of reproducible parameter‐based objects and can be an appropriate means to systematically and spatially map these dunes remotely. Here, a digital elevation model (DEM) and its derivatives, such as slope and curvature, were segmented in a GEOBIA context, enabling the identification and mapping of aeolian sand dunes in Arctic Sweden. Analysis of the GEOBIA‐derived and expert‐accepted polygons affirms the prevalence of parabolic dune type and reveals the coexistence of simple dunes with large coalesced systems. Furthermore, mapped dune orientations and relationships to other geomorphological features were used to explore past wind directions and to identify sediment sources as well as the reasons for sand availability. The results indicate that most dune systems in Arctic Sweden were initially supplied by glaciofluvial and fluvial disturbances of sandy esker systems. Topographic control of wind direction is the dominant influence on dune orientation. Further, our approach shows that analysing the GEOBIA‐derived dune objects in their geomorphological context paves the way for successfully investigating aeolian sand dune location, type and orientation in Arctic Sweden, thereby facilitating the understanding of post‐glacial landscape (in)stability and evolution in the area.

Foredune blowout formation and subsequent evolution along a chronically eroding high-energy coast

Coastal dune systems provide important ecosystem services, while being vulnerable to marine erosion. In these environments, blowouts can develop and promote sand transport from the beach to the back of the dune, but are generally fought by coastal dune managers. There are only few quantitative studies on the 3D evolution of blowouts and how they can develop into parabolic dune. We investigate the morphological evolution of a 2-km long freely evolving dune system in southwest France from 1947 to 2021 using historical aerial photos and digital surface models from Lidar and UAV photogrammetry. The combination of these remote sensing methods shows an alongshore non-uniform erosion with a mean of 1.26 m/year, and with erosion rates in the north of the study area four times larger than in the south. Over the study period, three large blowouts developed in the northern, (more rapidly eroding) sector and subsequently evolved into parabolic dunes, with a depositional lobe migrating landward into the forest. Two parabolic dunes naturally stabilized by vegetation colonization, without any reactivation phase, with the third one still migrating landward with an average migration of 7.2 m/year. A high-frequency and high-resolution analysis of the active blowout was performed between 2014 and 2021. Compared to the adjacent areas, this blowout promoted dune landward migration. Since 2014, the high erosion scarp in the adjacent southern sector prevented the transport of sand resulting in a loss of dune volume due to marine erosion. In contrast, in the adjacent northern sector and in front of the blowout, the presence of vegetation and paleosols at the dune toe favored sand deposition and limited marine erosion. In chronically eroding sectors, promoting blowouts and thus landward dune migration may be considered as an efficient management approach to maintain the dune system.

Surface-area development of foredune trough blowouts and associated parabolic dunes quantified from time series of satellite imagery

• Blowout surface area quantified from medium-scale satellite imagery. • Blowouts grow, stabilize and decay with a life time exceeding multiple decades. • Seasonal variation in blowout area increases with latitude. • Foredune erosion results in episodic, yet temporary increase in blowout surface area. Foredune trough blowouts are elongated wind-eroded depressions in the most seaward dune and their adjoining depositional lobes. Despite their importance to the sand budget and floral diversity of coastal dunes, the spatiotemporal evolution of trough blowouts is not well understood. We designed an automated workflow in the Google Earth Engine platform to produce time series of blowout surface area from medium-resolution satellite imagery available since the mid-1980s and applied it to a blowout system in the Netherlands, Denmark and the USA. Blowout surface areas were found to vary on multi-annual, seasonal and episodic time scales. Multi-annual change reflects successive development through stages of growth, stabilization and decay. The transition from growth to stabilization appears to be related to a change in blowout shape (width-to-length ratio). The decay phase starts with vegetation obstructing the blowout connection to the beach; the lobe can still migrate inland and develop into a parabolic dune before also becoming fully vegetated. The seasonal variations in blowout area increase with latitude; the observed larger areas in winter at the Dutch and Danish site presumably reflect seasonal plant development and the effect of stronger winds in winter. Episodic increases in blowout area, observed during winter at the Danish site only, are associated with pronounced foredune erosion. None of the episodic events changed blowouts into a different stage or persistently affected seasonal dynamics. Future work should focus on the combined analysis of changes in blowout area and sand volume to improve our understanding of sand-vegetation interactions driving blowout dynamics.