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An example of how aeolian processes, in this case more specifically related to dust emission and transport, span many orders of magnitude in spatial and temporal scales. Reproduced from Kohfeld, K.E., Reynolds, R.L., Pelletier, J.D., Nickling, B., 2005. Linking the scales of observation, process, and modeling of dust emissions. Eos, Transactions AGU 86, 11, 113, doi:10.1029/2005EO11000, with permission from AGU.
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Aeolian processes, involving erosion, transportation, and deposition of sediment by the wind, occur in a variety of environments, including the coastal zone, and cold and hot semiarid and arid regions, along the borders of rivers and lakes, as well as over agricultural fields in many climates. The chapters in this volume reflect the diversity of ap...
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Aeolian processes and their role in desertification have been studied extensively at low elevations but have been rarely studied at high elevations in areas such as the Tibetan Plateau, where aeolian processes were active in the geologic past and remain active today. In this review, we summarize research that improves our understanding of aeolian p...
Many planetary surfaces have been shaped by aeolian and fluvial processes, and understanding the resulting landscape is of critical importance to understanding changes in climate. Surface features on Earth and Mars are commonly observed using a variety of remote sensing methods. The observed geomorphology provides evidence of present- and paleo-pro...
Equilibrium concepts are widespread in aeolian geomorphology, especially those incorporating time-averaged parameterizations of fluid flow and sediment transport. The main objective of this chapter is to reflect critically on whether a new paradigm based on coherent flow structures (CFS) is emerging as a viable alternative to the traditional steady...
Aeolian processes have been studied extensively at low elevations, but have been relatively little studied at high elevations. Aeolian sediments are widely distributed in the Yarlung Zangbo River basin, southern Tibetan Plateau, which is characterized by low pressure and low temperature. Here, we comprehensively analyzed the wind regime using data...
Equilibrium concepts are widespread in aeolian geomorphology, especially those incorporating time-averaged parameterizations of fluid flow and sediment transport. The main objective of this chapter is to reflect critically on whether a new paradigm based on coherent flow structures (CFS) is emerging as a viable alternative to the traditional steady...
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... Tais condições derivam obviamente da ação dos ventos não somente com energia, mas constância, disponibilidade de sedimentos com características granulométricas que sejam passíveis de serem transportados, além de áreas relativamente amplas e planas, para que as formas eólicas se projetem desde o contato da praia com o oceano, até as áreas mais interiorizadas (e.g. Tsoar e Pye, 2009;Lancaster, 2013;Hesp, 2013;Walker et al., 2017;Sloss et al., 2018;Hesp e Walker, 2021). Desta forma, diferentes morfologias podem ser verificadas ao longo do litoral, muitas dessas formas relacionadas ao efeito direto à vegetação, como dunas frontais (Arens, 1996;Hesp, 2002) e dunas parabólicas (Tsoar e Blumberg, 2002;Hesp et al., 2010;Hart et al., 2012), além de nebkhas (El-Bana et al., 2002;Marrero-Rodríguez et al., 2020). ...
RESUMO Os processos físicos envolvendo praias e dunas frontais deixam registros morfológicos associados à ação eólica, assim como às ondas. Estas feições apresentam nuances fisiográficas de difícil documentação, pela escassez de dados analíticos. Na última década, houve uma sensível evolução de técnicas de documentação da morfologia de detalhe, utilizando algoritmos associados a Structure for Motion (SfM). Tais análises são possíveis a partir de imagens aéreas obtidas por veículos aéreos remotamente pilotados. Neste sentido, este trabalho teve como objetivo mapear diferentes feições observadas em praias e dunas frontais, na praia do Peró, RJ. Os resultados identificaram cortes eólicos dispostos de maneira recurvada, provavelmente difratados por rugosidade no terreno. Em relação às ondas foi observada uma extensa escarpa erosiva, resultado de ondas de tempestade. Conclui-se que a ferramenta se mostra fundamental para que detalhes e nuances geomorfológicas possam ser descritas e analisadas.
ABSTRACT The physical processes involving beaches and foredunes reveals morphological records associated with wind pattern and waves energy. These features present physiographic characteristics that are difficult to document, due to the scarcity of analytical data. In the last decades, there has been a significant evolution of detailed morphology based in innovative techniques, using algorithms associated with Structure for Motion (SfM). Such analyzes are possible from digital aerial images obtained by remotely piloted aerial vehicles. In this sense, this work aimed to map different features observed on beaches and foredunes, at Praia do Peró, RJ. The results identified recurved blowouts, probably diffracted by roughness present along the surface. In relation to the waves, an extensive erosive escarpment was observed, as a result of storm waves. We concluded that SFM is essential to determine geomorphological details and became an essential tool to analyzed beach and foredunes morphology.
... For the sake of completeness, aeolian landforms and deposits as well as blankets of loess have to be mentioned among the landforms of substage 7c which came into being during the post-glacial and waning last ice age (Habbe, 1997). The aeolian landforms consisting of longitudinal dunes, loess and aeolian sand blankets are categorized and interpreted according to Muhs (2009), Yang et al. (2007, Yan et al. (2011), Lancaster et al. (2013, Borrelli et al. (2017), and Ventra et al. (2017). They were sourced from the depression, categorized as an intermediate trap site which was formerly occupied by the Main fluvial drainage systems but during the Würm ice age laid bare so as to act as a deflation pan (Fig. 1e, 5). ...
The quadripartite/ orthogonal and domal Central European Watershed (CEW) at the NW edge of the Bohemian Massif has been studied by a terrain analysis (fluvial, colluvial, cryogenic, aeolian landforms) combined with geochronological dating (hydraulic correlation) of landforms and the resultant hydrographic correlation of relief generations. It resulted in a morphostratigraphic review (subdivided into a protostage- creating the terrestrial platform, prestages - controlling the physical and chemical regime of the landform series, and stages- fine-tuning of the modern landscape) of the Late Cretaceous to Quaternary relief generations that lead to the creation of the “3 + 1” model of the CEW. The term “3 + 1” refers to a triple junction supplemented with a fourth branch. The characteristic land-form type of the CEW is called the “intermediate sediment trap”, a wetland caused by structural or impact-related damming processes. The evolution of the CEW is discussed by a set of four different drivers:
The endogenous 1st order drivers are activities along lineamentary fault zones which demarcate the watershed systems.
The 2nd order endogenous driver is the alkaline volcanic activity from the Late Cretaceous to the Holocene which contributed to dome-and starlike geomorphological expression.
The 3rd order impact-related driver of the Ries Meteorite impact provoked a deflection and damming of channels thereby leading to one of the intermediate sediment traps.
The 4th exogenous driver is the climate change. It is accountable for the transition from fluvial incision during the Late Cretaceous and Paleogene (humid-tropical climate zone) to a planation during the Neogene (tropical wet and dry paleoclimate zone). The Quaternary humid mid-latitude, dry continental, and (peri)glacial climate zones put the final touch on the CEW's geomorphological outward appearance.
The influence of mining, metallurgy, and mineral processing on the landscape debated in the final stage 8 heralds the onset of the Anthropocene in the CEW.
This review of the evolution of the CEW also lends support to the idea that an advanced terrain analysis can be an efficient tool for mineral exploration.
... On the basis of normalized mass flux, the average thickness of the saltation layer was calculated. It is commonly defined as the height below which 50% of mass flux occurs (e.g., Zingg, 1953;Baas, 2019), and from an exponential decay function, it can be defined as: ...
The vertical distribution of aeolian mass flux is an important issue in aeolian geomorphology. It has been studied mainly on sand surfaces and much less often on gravel surfaces, particularly under natural conditions. We present data of measurements made in 3 beach settings that differed in petrographic composition of the beach sand (quartz, bioclastic, and bioclastic-basaltic sand) and density of pebble coverage (5–70%). We aimed to show the differences/similarities in vertical mass flux profiles induced by surface properties resulting from sediment composition. All measurements were made under conditions of maximum sand transport rate on a dry sand bed by means of passive segmented 0.5-m-high sand traps. The results showed that (i) regardless of the surface type, all vertical mass flux profiles were well fitted by an exponential decay function, but the regression coefficients differed greatly between those for sand surfaces and surfaces with pebble covers of different densities, (ii) changes in these coefficients with wind speed were much more pronounced in the case of sand surfaces than on surfaces with pebbles, (iii) the exponential model underpredicted mass flux in the near-bed region in the case of sandy surfaces, whereas in the case of pebble surfaces, the departures from the model were insignificant, and (iv) a pebble cover with a low density between 5% and 10% strongly affected the concentration of sand in the vertical profile. All mass flux profiles showed that as wind speed increased, the proportion of sand transported in the near-bed region decreased and the proportion of sand transported at higher elevations increased. For each surface type, the height at which the constant proportion of sand was transported may be defined irrespective of wind speed. This height was equal to 3–4 cm in the case of sand surfaces and changed from 6 cm to 11 cm as the density of pebble coverage increased from 5 to 10% to 50–70%. This was also reflected in the average saltation height, which increased slightly with wind speed and significantly with the density of gravel coverage.
... In reviewing this progress, note the importance that incremental advances in sensor data/technology have had on driving increased understanding of dunes and dune systems. Remote sensing is especially valuable for allowing enquiry at the largest scale for desert dunes, the dunefield and sand sea, and Lancaster et al. (2013) provides a useful appraisal of both remote sensing efforts and challenges at this synoptic level of dune study. Together, these authors highlighted some significant research considerations that are still pertinent, including application of remote sensing imagery to: (i) estimate the effects of vegetation cover on aeolian transport, (ii) provide observational evidence of dune form evolution, (iii) facilitate spatial analysis of dunefield pattern and improved methods for dune movement detection, (iv) quantify three-dimensional topographic change in dune systems, and (v) expand availability (e.g., low or zero cost and accessibility) of high-quality geospatial data, and the development of spatial and chronological databases. ...
This review focuses on recent advances that have taken place in the use of remote sensing to observe aeolian processes, and to highlight recent approaches that have enabled and been employed to observe and quantify aeolian processes at a range of scales. As remote technologies continue to develop, the review emphasizes the significance that, in their different forms, these data are applicable across all scales at which aeolian processes operate. To address this, the review examines a range of space-borne, airborne and near-surface technologies.
... Nebkhas are unique biogeomorphological features that are formed by aeolian sand accumulating around clumps of vegetation or single shrubs in arid and semi-arid environments (Cooke et al., 1993;Tengberg and Chen, 1998;Lancaster et al., 2013;Wang et al., 2017). They usually have the form of a mound and are also called coppice dunes or hummock dunes in arid and semi-arid environments (Fig. 1). ...
... It has been suggested that the nebkhas are formed by sand accumulating around clumps of vegetation, thus their formation is strongly related to the wind environment that affects sand transport and accumulation, as well as factors that influence sand availability and vegetation growth (Pye and Tsoar, 2009;Lancaster et al., 2013). Moreover, the growth rate of nebkhas would be expected to strongly depend on their current height. ...
Nebkhas, also known as nebkha dunes or coppice dunes, are a unique biogeomorphological aeolian landform that is common in arid and semi-arid regions. They are often regarded as a signal of regional desertification and could be potential dust sources due to their relatively large content of fine sediments, but they also serve as “fertile islands” that enhance biodiversity at a micro-habitat. How the interactions between plant growth and aeolian sand deposition affect the formation and development of nebkhas has not been well documented, though. In this study, the chronology and morphological features of nebkhas in the Mu Us dune field, north-central China were studied using radionuclide (¹³⁷Cs) dating and unmanned aerial vehicle (UAV) photogrammetric survey. The results show that the nebkhas are mainly distributed around lake basins and dry river valleys with relatively flat topography. Most nebkhas have heights around 0.5-1.5 m, and according to a new integrated age-height model, they mostly formed in the last fifty years. Widespread nebkha growth over that time is interpreted as a response to both desiccation of lake beds and river valleys and a pronounced decline in strong wind frequency. The regular rounded shape of the nebkhas in the study area may reflect the growth form of prostrate, extensively branched Nitraria tangutorum, the dominant formative shrub, and response to the low-energy wind environment. A nebkha’s height and horizontal length increase synchronously in the early stage of the development, while the increase in horizontal length and projected area accelerates when the dunes become larger. Feedbacks involving both aeolian sand transport and shrub growth can explain a decline in growth rate with increasing height and an apparent height limit of about 4 m. This study also implies that nebkhas are important biogeomorphological features demonstrating how biotic and abiotic interactions can shape landforms and influence ecological functioning in arid and semi-arid environments.
... Due to the existence of a very large number of case studies on SDS problems, including analyses both on-site and using remote sensing detection methods (Furman 2003;Miller 2003;Goudie and Middleton 2006;Walker et al. 2009;Engelbrecht and Derbyshire 2010;Akhlaq et al. 2012;Ginoux et al. 2012;Groll et al. 2013;Lancaster et al. 2013;Rashki et al. 2013;Sissakian et al. 2013;Nabavi et al. 2016;Opp et al. 2016;Middleton 2017;Abbasi et al. 2018;Groll et al. 2018;Groll et al. 2019;Foroushani et al. 2020), the objective of this study is not to repeat these published results. The majority of SDS publications do not focus on a comprehensive approach integrating the causes, the wide range of effects on different natural, economic, and social spheres, and the side-effects associated with SDS consequences. ...
... The essential prerequisites for sand and dust transport are sandy and dusty particles under dry and loose conditions on land surfaces (Chesworth 1992;Mahmoodi et al. 2016), as well as a wind strong enough to mobilize these particles by abrasion and/or deflation from the surface and to transport them (Lancaster et al. 2013). ...
... Splash effects of the grains. • Saltation (Lancaster et al. 2013;Mahmoodi et al. 2016). The more loose the particles, the higher their erodibility for wind erosion and the higher the SDS potential. ...
Barren ground and sites with low coverage by vegetation (e.g., dunes, soil surfaces, dry
lakes, and riverbeds) are the main source areas of sand and dust storms (SDS). The understanding of causes, processes (abrasion, deflation, transport, deposition), and influencing factors of sandy and dusty particles moving by wind both in the boundary layer and in the atmosphere are basic prerequisites to distinguish between SDS. Dust transport in the atmosphere modulates radiation, ocean surface temperature, climate, as well as snow and ice cover. The effects of airborne particles on land are varied and can cause advantages and disadvantages, both in source areas and in sink or deposition areas, with disturbances of natural environments and anthropogenic infrastructure. Particulate matter in general and SDS specifically can cause severe health problems in human respiratory and other organs, especially in children. Economic impacts can be equally devastating, but the costs related to SDS are not thoroughly studied. The available data show huge economic damages caused by SDS and by the mitigation of their effects. Management of SDS-related hazards utilizes remote sensing techniques, on-site observations, and protective measures. Integrated strategies are necessary during both the planning and monitoring of these measures. Such integrated strategies can be successful when they are developed and implemented in close cooperation with the local and regional population and stakeholders.
... La velocitat mínima que necessita el vent per moure un gra de sorra depèn de les característiques físiques i químiques del sediment i de les característiques ambientals i topogràfiques. Les superfícies compactades per humitat o crostes de sal són menys movibles que les sorres seques i no compactades, mentre que les altes temperatures ambientals afavoreixen el transport en aire (Lancaster, Baas, & Sherman, 2013;Nickling, 1986). Bagnold (1941) El vent, a més, fa arribar partícules de sal en suspensió (salt spray) de mar cap a terra, tot augmentant la salinitat en superfície de la zona litoral activa i condicionant la mobilitat de les partícules i la morfologia dunar. ...
Coastal dune systems are located in the inner section of beaches and are essential parts of beach-dune systems. They become exclusive habitats for some animals and floristic species and work as a natural protection barrier for goods located near the shoreline. According to Habitats Directive from the European Union, dunes are habitats of Community interest and some dune environments are even considered of Priority interest. In Catalonia, 11 beach-dune restricted habitats have been identified which host 37 plants whose exclusive habitat are beach-dune systems. Apart from natural and protective functions, beaches also accomplish cultural and leisure role.
Dune morphologies are dynamic environments of great ecological, biological, geological and landscape values, under constant natural and human disturbance. The accelerated intensification of economic activities along the coast during the last decades has led to an accelerated occupation of the coastal areas, particularly along the low-lying coastal stretches. Usually, urbanization processes causes the disappearance of the coastal dune systems. The artificialization and rigiditzation of the coast complicates beach-dune systems recovery after non-storm periods. Storms erosion produces dune scarp that recovers naturally during calm seasons. The disappearance of the dune landscape hinders the exchange of sediments between beach and dunes and endangers the littoral active zone. Sediment budget is also modified by the decrease in sediments provided by rivers and alongshore transport disruption.
In this context of rapid change in beach-dune systems, the historical transformation in Catalan dune systems has been described and assessed. This research quantifies the change and points out its main causes. Likewise, the current dune morphologies are studied and classified according to morphological and ecological criteria. Finally, a set of check list indexes are developed with the objective of assessing the different parts that interact in the beach-dune system and establish the dune restoration potential of each system. Depending on this potential, beach-dune systems have been classified according to the most appropriate management measures.
The results validated that human developed coasts in Catalonia show a high-degraded dune landscape. Along the last decades, dunes have disappeared from 60% of the beaches studied, whereas 30% of dunes have been reduced in extension, and only 10% have suffered fewer changes. Costa Brava is one of the most affected regions by dune degradation, closely followed by Barcelona province and Costa Daurada. The land cover changes analysis confirmed that reduction of dune habitat occurred due to urbanization processes and the prioritization of recreational functions against natural and protection ones.
As a result of historical transformation, among 823 beaches that currently compose the Catalan shoreline, only 127 host some type of dune morphology comprising incipient dunes, dune ridges, dune ridges with semifixed dunes, ramp type dune, climbing dunes, fixed dunes and dune fields. The most extensive and developed dunes are located in the Ebre Delta, Costa Daurada, Pals Bay, Llobregat Delta and in the Gulf of Roses. Other dune systems are small-sized and associated to urban structures that impede their full development. Regardless of their volume and extension, the Catalan coastal dunes reflect, in general, an advanced status of degradation related to the lack of management focused on maintaining and restoring dune morphologies.
Given this dune degradation, the application of the indexes proposed in this Thesis allowed to classify beaches of Catalonia in three groups according to the most suitable management measures: dune conservation, dune restoration, dune recovery and renaturalization of the dry beach. The results verify that the most part of studied beaches presents higher values in dune restoration potential index, which corresponds to urban and urbanized touristic beaches. Secondly, a group of beaches is defined for conservation measures and composed by natural beaches. A third group is proposed for dune recovery where dunes have been disappeared during the last decades and beaches present environmental characteristics good enough for dune development. Finally, it has been recommended the renaturalization of beaches in those systems whose environmental characteristics do not allow dune ridge development. These beaches are the ones made up of coarse sands with light winds.
... Research trends reported here focus on the morphologic changes to the nearshore, beach and dune profile associated with atmospheric, hydrologic and oceanic processes. We refer readers to the volumes in coastal geomorphology (Sherman, 2013) and aeolian geomorphology (Lancaster et al., 2013) in the Treatise in Geomorphology (Shroder, 2013) as well as Holman et al. (2015) for a treatment of these forces. We add to these reviews by examining research trends in coastal geomorphology that have developed in tandem with process studies. ...
Trends in research on morphologic changes on beaches and foredunes on sandy shores are identified from the 1960s to the present. Research during this period evolved from early descriptive explanation and classification of profile change, to instrumented field investigations, to modelling of landform change at larger scales. Research efforts have become increasingly more collaborative, with increasing use of field instrumentation, data acquisition systems and remote sensing. Rich datasets are resulting in more comprehensive computational models. Human-altered systems are of increasing interest, but knowledge of these systems lags far behind knowledge of natural systems. Research is becoming more relevant to societal needs as the vulnerability of coastal populations increases. The need for investigation of understudied or unexplored environments, including human altered ones, is ongoing. Many basic research issues remain, but future studies would profit from the development of new models rather than validating or reconfiguring old models. Collaboration between geomorphologists and engineers may open up research opportunities, particularly in modifying beaches and dunes built for shore protection to provide natural values in restricted space. Application of models to enhance knowledge of effects of sea level rise and coastal storms would be useful to managers developing resiliency plans.
... Las acumulaciones de arena eólica asociadas a la presencia de plantas son un rasgo común de la mayor parte de las regiones áridas y semiáridas (BaGNOLD, 1984; GUTIérrEz-ELOrza, 2001; LaNCaSTEr, 1995; LaITy, 2008; LIVINGSTONE & WarrEN, 1996; PyE & TSOar, 1990; WarrEN, 1988). Las denominaciones que recibe son varias: nebkhas –la más admitida en la literatura científica–, vegetated dunes, coppice dunes. ...
The main aim of this paper is the study of aeolian landforms in the National Park
of Teide. The most important landforms are related with Quaternary volcanic activity, fluvial
and periglacial processes but we can found also landforms produced by aeolian erosion
(stone pavement) and sedimentation (topographic dunes and vegetated dunes). Indeed, we
explain the potential of dunes as proxy data to study the paleoclimates along the Holocene.
Key words: topographic dunes, vegetated dunes, stone pavements, proxy data, Holocene,
National Park of Teide.
The wind’s ability to carry silt and deposit it is referred to as the aeolian process. The Earth’s surface is significantly shaped by this process, particularly in dry and semi-arid areas where there is minimal water erosion. Sand dunes, ripples, and other distinctive landforms can be created by the movement of windblown particles. Additionally, the aeolian process has an impact on a number of biological and environmental processes, such as plant cover, air quality, and soil stability. For several fields, including geology, geography, environmental science, and engineering, it is crucial to comprehend the mechanics and impacts of aeolian processes.
