Dune Formation Research Articles

Fluvial-lacustrine influences on linear dune erosion at Lake Caroline in the Simpson Desert of Australia

Linear dunes are frequently examined with regard to their formation and maintenance; however, erosion or degradation of these landforms is less commonly addressed, due in part to the lack of observable changes in the geologic record. This study investigates the significant erosion of linear dunes along Lake Caroline, a playa in the northern Simpson Desert of central Australia. Field observations, laboratory analyses, and remote sensing imagery document recent fluvial and lacustrine interactions at Lake Caroline. Compositional and geochemical sediment analyses from three ∼2 m deep hand-augured sample sites indicate that the playa is primarily filled with sand from linear dunes, but also contains evaporite minerals and weathered local bedrock. Satellite images show that the playa has flooded at least 58 times since 2001. Our results indicate that present-day aeolian processes are sufficient to mobilize and transport sediment but are dominated by fluvial-lacustrine processes, resulting in the playa-adjacent dunes becoming isolated and starved of local sediment. As a result, the dunes are currently eroding into the playa which supports the conclusion that long-distance sediment transport is not responsible for the formation or maintenance of linear dunes as suggested by the linear due extension hypothesis. Burial dates from optically stimulated luminescence (OSL) indicate the linear dunes have been eroding for as much as 24 ka, and sediment samples from the playa near one linear dune suggest an onset of dune formation in the area before 58 ka. This work documents an instance in geologic time during the late Quaternary when aeolian, fluvial, and lacustrine processes are competing with one another, offering new insights into the dynamics of linear dunes in the arid Simpson Desert.

Novel fracturing fluid made of low molecular weight polymer and surfactant achieves proppant full suspension and filling entire area of hydraulic fractures

In large-scale hydraulic fracturing of unconventional reservoirs, high viscosity friction reducers (HVFR) which employ high concentration polymers of high molecular weight can improve proppant suspension, but still lack long-distance and long-time proppant transport capability. Herein, for the first time, we report a fracturing fluid made of self- assembled low molecular weight polymer and a surfactant (LMPS). When using only 0.1 wt% of the polymer, LMPS has a viscosity of 29.6 mPa·s (170 s−1, 25 ℃) and can achieve full suspension of 40/70 mesh sand at 80 ℃. LMPS can form robust short molecular chain networks through numerous self-assembling association sites, rather than relying on entanglement. Notably, it achieves a minimum loss tangent as low as 0.1 in the viscoelastic response, demonstrating its strong elastic characteristics. According to the creep-recovery test, the strain recovery rate (87.9 %) of LMPS at 0.2 wt% polymer concentration far exceeds that of the HVFR with a concentration as high as 10.1 %. This indicates that LMPS has a stronger deformation-resisting ability, thereby preventing proppant settling. Taking advantage of LMPS’ superior proppant suspension capability, proppant can move with the slurry to the whole fracture for placement, while the HVFR provides only 48 % height support of the fractures in the form of dunes. A field trial shows that at a polymer concentration of 0.2 wt%, LMPS can stably transport 20/40 mesh quartz sand under a slurry rate of 2.8 m3/min and a proppant concentration of 635 kg/m3 during the fracturing process.

Devastation of the cerrado of mato grosso do sul and the advance of arenization in the pardo river watershed

Despite the significant biodiversity in the Cerrado, the process of occupation, subsequent economic cycles, and intensification of agriculture in a predatory manner have caused profound alterations in this biome. This study analyzed changes in land use and land cover in the Cerrado of Mato Grosso do Sul between 1985 and 2022 by mapping and also investigating the formation and dynamics of sand dunes in the Bauru sedimentary basin, focusing on the Pardo River watershed. MapBiomas Network data, collection 8, were used for land use and land cover analysis. Arenization foci cartography was conducted using brightness index 2 based on Sentinel-2 satellite images in Sentinel Application Platform software. The historical analysis of land use and cover in the Cerrado of Mato Grosso do Sul revealed a rapid transformation of the landscape, with a drastic reduction of native vegetation and an intensification of large-scale monocultures. Between 1985 and 2022, the Cerrado of Mato Grosso Sul lost 4.6 million hectares of native vegetation (forest formations, savannahs, grasslands, and wetlands), representing 24.54% of this territory. Recent changes in land use include pasture-soybean and pasture-eucalyptus. In the Pardo River watershed, arenization foci cover an area of 17,834.34 hectares, with varying dimensions ranging from less than 1 hectare to 376.41 hectares. The arenization process occurs in different slope compartments, such as the base, slope, and interfluves. The physical and chemical characteristics of Quartzipsamments, such as low organic carbon content in soil, are associated with high rates of surface exposure and weakened load-dependent structures, leading to degradation. Arenization occurs where natural vegetation has been suppressed and soil has been depleted by poorly managed production processes.

Estimation of aerodynamic entrainment in developing wind-blown sand flow.

Understanding aerodynamic entrainment, a critical process in wind-blown sand dynamics, remains challenging due to the difficulty of isolating it from other mechanisms, such as impact entrainment. Aerodynamic entrainment initiates the movement of surface particles, influencing large-scale processes like sediment transport and dune formation. Previous studies focused on average aerodynamic shear stress to estimate entrainment, but the role of impulse events, which cause significant shear stress fluctuations, remains under-explored. We used 12 hot-film shear sensors to measure the spatiotemporal distribution of aerodynamic shear stress during wind-blown sand flow development. We identified impulse events exceeding the entrainment threshold and analyzed their intensity, classifying particle movement as rocking, rolling, or saltation. Results indicate that after a 2-m fetch, sediment mass flux stabilizes, with aerodynamic shear stress decreasing to 78% of the entrainment threshold. We identified key trends, including the stabilization of rocking events beyond x = 4.5 m and a significant decrease in saltation frequency, indicating fully developed wind-blown sand flow. Impulse characteristics stabilize at a greater distance (4.5 m) than sediment transport (2 m) because turbulent airflow evolves more slowly. Our findings show that impulse events significantly influence aerodynamic entrainment. These insights enhance understanding of sediment transport dynamics and improve modeling of sand dune movement.

Pengaruh Fasilitas dan Citra Destinasi Wisata Terhadap Peningkatan Kepuasan Wisatawan di Karst Tubing Sedayu

The tourism sector in Bantul Regency has so far only highlighted ecotourism-based tourist destinations in the form of beaches, pine forests, and sand dunes. Sedayu Karst Tubing is part of an ecotourism-based tourist destination, but the number of visitors is not as many as other ecotourism-based tourist destinations in Bantul Regency. Therefore, enhancing tourist satisfaction is essential to boost the number of visitors to Karst Tubing Sedayu. Thus, this research aims to find out how the facilities and image of tourist destinations influence increasing tourist satisfaction. Researchers used quantitative methods with a comparative causal research type, and this research produced the statement that facilities had an effect on increasing tourist satisfaction, as well as that the image of tourist destinations had an effect on increasing tourist satisfaction. Therefore, we can draw the conclusion that both the facilities and the tourist destination's image significantly influence the increase in tourist satisfaction. However, it would be beneficial if the management and the relevant government collaborated to enhance the quality of the Sedayu Karst Tubing tourist destination. This would foster a greater sense of satisfaction among tourists, thereby potentially increasing the number of visits to Sedayu Karst Tubing, Bantul Regency.

An automatic method for extracting sand dunes based on slope cost distance from digital elevation models

Sand dunes significantly impact climate, water resources, and human infrastructure, reflecting sand sources and wind conditions. However, their complex and heterogeneous terrain leads to fragmented and poorly continuous dune extraction results. Focusing on the Badain Jaran Desert, this study developed a sand dune extraction method using slope cost distance analysis with FABDEM data. First, positive and negative terrains were segmented using 30 m resolution digital elevation data. Next, slope patches were classified based on specific criteria: slope less than 1.5°, patch area greater than 0.01 km2, and patches entirely within negative terrains. The filtered patches served as source data, and slope raster data were used to calculate slope cost distance. Sand dunes and interdune areas were delineated based on a predefined slope cost threshold. Post-processing, such as smoothing and vector conversion, yielded the final extraction results. The method effectively extracted compound transverse megadunes and pyramid megadunes, addressing misclassification issues and accurately defining interdune areas. It demonstrated faster processing speeds compared to traditional methods, with high precision (89.38 % & 90.37 %), accuracy (96.5 % & 92.89 %), and recall (94.77 % & 98.63 %). The results are more complete and less fragmented, aiding in the extraction of micro-scale dune features and revealing macro-scale spatial patterns, which are beneficial for studying dune formation, development, and wind dynamics.

Modeling flow resistance and geometry of dunes bed form in alluvial channels using hybrid RANN–AHA and GEP models

Dunes formation in sandy rivers significantly impacts flow resistance, subsequently affecting water levels, flow velocity, river navigation, and hydraulic structures performance. Accurate prediction of flow resistance and dune geometry (length and height) is essential for environmental engineering and river management. The current paper introduces two models to evaluate the flow resistance and geometry of dunes formed in sand-bed channels. The first model, RANN–AHA is a hybrid artificial intelligence model using the recurrent artificial neural network (RANN) linked with the artificial hummingbird optimization algorithm (AHA) to optimize the biases and weights of the neural network model. The second model uses gene expression programming (GEP) as a nonlinear approach based on a genetic algorithm (GA) and genetic programming (GP) to explicitly determine dune characteristics. For both models, the input parameters include flow and sediment characteristics, while Manning's roughness coefficient (nM), and relative dune height, h/H or h/L, were used as output parameters where h is the dune height, H is the flow depth above the dune crest, and L is the dune length. Five different published flume data sets were compiled for the analysis. Sensitivity analysis was done using different combinations of input parameters. It was found that the combination of hydraulic radius divided by median diameter (RH/d50), Reynolds number (Re), Particle densimetric Froude number (F∗), and grain Froude number (FG) yielded the best prediction accuracy for estimating Manning nM and relative height, h/H or h/L, with a root mean square error (RMSE) = 0.00027, 0.0504, and 0.0078 and a correlation coefficient (R) = 0.9989, 0.942, and 0.9272, respectively. Model verification proved that the RANN–AHA model outperformed the GEP model and most of the previous studies available in the literature when predicting the roughness coefficient and dune geometry in sand bed channels.

Chronology of Sedimentation and Landscape Evolution in the Okavango Rift Zone, a Developing Young Rift in Southern Africa

AbstractThe Kalahari Basin in southern Africa, shaped by subsidence and epeirogeny, features the Okavango Rift Zone (ORZ) as a significant structural element characterized by diffused extensional deformation forming a prominent depocenter. This study elucidates the Pleistocene landscape evolution of the ORZ by examining the chronology of sediment formation and filling this incipient rift and its surroundings. Modeling of cosmogenic nuclide concentrations in surficial eolian sand from distinct structural blocks around the ORZ provides insights into sand's residence time on the surface. Sand formation occurred from ∼2.2 to 1.1 Ma, coinciding with regional tectonic events. Notably, provenance analyses of sand within ORZ's lowermost block where large alluvial fans are found indicate different source rocks and depositional environments than those of the eolian sands found at a higher elevation. This suggests that the major phase of rift subsidence and the following incision of alluvial systems into the rift occurred after eolian dune formation. Luminescence dating reveals that deposition in alluvial fan settings in the incised landscape began not later than ∼250 ka, and that a lacustrine environment existed since at least ∼140 ka. The established chronological framework constrains the geomorphological effects of the different tectono‐climatic forces that shaped this nascent rifting area. It highlights two pronounced stages of landscape development, with the most recent major deformation event in the evolving rift probably occurring during the middle Pleistocene transition (1.2–0.75 Ma). This event is reflected as a striking change in the depositional environments due to the configurational changes accompanying rift progression.

Identification of Marine Landforms as a Form of Coastal Area Management in Pangandaran District

Changes in marine landforms in coastal areas are relatively rapid and need to be analyzed to determine environmental management policies. Complex marine landforms are found in the coastal areas of Pangandaran Regency and have strong pressure to fulfill community activities, not only for local communities but also for outside communities. Basically, community activities are adapted to regional environmental conditions. The aim is to optimize the potential of natural resources and minimize environmental degradation, but in reality, this has not been fully implemented. The method used in this research is a descriptive method using a field survey approach. Marine landforms resulting from the accretion process in the Pangandaran coastal area are spit landforms, aeolian-marine sedimentation in the form of coastal dunes, fluvio-marine sedimentation in the form of estuaries and alates, organic-marine landforms and white sand beaches associated with reefs. The landforms resulting from erosion are Cliffs, notches, wave-cut platforms, stacks, and stumps. The impact of landforms resulting from sedimentation in the Pangandaran coastal area is mainly spit landforms that cover river mouths and the occurrence of flooding, puddles, and even accumulation of organic waste, landforms resulting from erosion, the impact of which is the decline of the coastline accompanied by avalanches of material towards the sea, especially on beaches that have non-resistant rocks such as sedimentary rocks and alluvial deposits. Management of the Pangandaran coastal environmental area must be carried out in an integrated manner, land buritan (hinterland), which has steep slopes and resistant rock, is designated as limited production land, and the development of the spit at the river mouth is made into a jetty, and the beach has beach cups waves with rip currents and water bathymetry. -10 meters above sea level, a wave-protecting wall must be built, and the coastal border area must be used as vegetative-based conservation land.Keywords: Marine landforms, Coastal Management, Pangandaran

Role of aggregates in the forming process of tephric loess dunes distributed along the Pacific coast of eastern Japan

The Pacific coast of eastern Japan contains specific aeolian landforms of geomorphological interest in terms of their formation processes in humid climates and Holocene paleoenvironments. Wind erosion landforms, characterised by blowouts, were observed at the heads of coastal cliffs which consisted of marine gravel sediments, weathered volcanic ash layers (WVALs) and black soil layers (BSLs). The blowouts were accompanied by downwind tephric loess dunes. We analysed the physicochemical properties of the WVAL, BSL and dune sediment samples. The results revealed that clay and silt contents in dune sediments were 5–48% and 20–35%, respectively. The fine particles were in the form of aggregates in the WVALs, BSLs and dune sediments, with contributions from andic properties. WVAL and BSL aggregates were prone to movement in saltation, depositing into the dunes in a formation process similar to that of clay dunes in semiarid zones. The tephric loess dunes were characterised as clay dunes based on their high clay and silt contents. In addition, the dunes were characterised by durable aggregates derived from short-range-order minerals, such as allophane. The prevailing northeasterly winds caused by intense low pressures were responsible for dune formation in the study areas. Radiocarbon dating revealed two active wind periods. The first was approximately 1005–895 cal. BC to 358–281 cal. BC, and the second was 771–886 cal. AD to 1021–1155 cal. AD.

Regional differences in the grain size characteristics of surface sediments from typical barchan dunes in arid zones

The grain size characteristics of aeolian sediments are the combined result of sand sources, regional airflow regimes, dune morphology, etc., and are essential for understanding the formation and evolution of barchan dunes. Based on field investigations and laboratory experimental data, in this paper, we explored differences in the grain size characteristics of the surface sediments of barchan dunes at the southeastern edge of the Taklimakan Desert (TKLM-SE), the western (QB-W) and southern parts of the Qaidam Basin Desert (QB-S), the sand belt connecting the Badain Jaran Desert and the Tengger Desert (BT-B), and their responses to sand sources, dune morphology, and wind regimes. The main results were as follows: (i) The mean grian size distribution patterns of the windward slope toe to the leeward slope toe through the dune crest/ridge varied with different transects of the barchan dunes and different deserts, showing four types including gradually fining (GF), gradually coarsening (GC), coarsening followed by fining (CF), and fining followed by coarsening (FC). The patterns were GF and CF in the TKLM-SE; GF, GC, and FC in the BT-B; GF, GC, and CF in the QB-W; and GF in the QB-S. (ii) The interdune sediments provided the source material for the formation and development of barchan dunes and their grain size varied in different deserts. The interdune sediments were composed of gravel and very fine sand in the TKLM-SE, while they were composed of medium and fine sand in the QB-W, QB-S, and BT-B. (iii) The windward side of the barchans varied with different wind directions, and dune height affected dune surface airflow velocity and direction, changing the pattern of grain size distribution on the dune surface. The wind regime over a ten-day or half-month scale could explain the variance in the grain size distribution patterns better than that on an annual scale. (iv) Grain size characteristics of dune surface sands changed with dune shape due to changes in the surface airflow velocity and direction and the sediment-carrying capacity of the airflow. With an increasing ratio of dune height to dune width, the grain size of the dune crest sands became coarser. These results help advance our understanding of the grain size characteristics of barchan dunes and regional variabilities in their patterns.

Experimental investigation of pressure drop of spherical and non-spherical coarse particles in pneumatic conveying in horizontal pipes

In this work, the conveying flow pattern and pressure drop of spherical and non-spherical coarse particles in a horizontal pipe were measured experimentally. The experimental results show that when coarse particles are conveyed in stratified flow and sedimentation and dune formation, the rate of increase of pressure drop with superficial velocity is related only to the particles and not to the conveying conditions. The rate of increase of pressure drop with velocity is larger for spherical particles than for non-spherical particles in stratified flow, and the rate is smaller for spherical particles than for non-spherical particles in sedimentation and dune formation. The pressure drop varies linearly with the solid-gas ratio, and the slope of the linear relationship characterises the friction of the conveying pipe and the interaction parameters between the particles. The reduction in pressure drop for spherical particles is greater than that for non-spherical particles when the solid-gas ratio is increased by the same magnitude. In addition, to verify the experimental results of this work the data cited in the published literature were compared and the results were in good agreement. On the one hand, the variation rule of pressure drop with superficial velocity obtained in this investigation is an enrichment of the classical phase diagram. On the other hand, the experimental results are of guiding significance for the design and engineering application of coarse particle pneumatic conveying systems.

Enhancing pier local scour prediction in the presence of floating debris

AbstractLocal scour poses a grave threat to bridge foundations, potentially causing catastrophic collapses. This study uses FLOW-3D with the Reynolds-Averaged Navier-Stokes model to analyze pier scour and dune formation under bridges. It focuses on submerged debris shapes near the water's surface. Results closely match experiments when specific conditions are met. The study introduces an innovative approach to debris impact assessment. Instead of traditional methods, it proposes a novel equation accounting for debris's effective area and elevation. This enhances reliability by over 20%, improving scour depth assessment in debris-laden scenarios. This advances the understanding of debris's role in local scour, benefiting bridge design and management practices.

Continuity and discontinuity at the burial site of Roonka, Murray Gorge, South Australia

Identifying continuity and discontinuity in Holocene hunter-gatherer burial sites is often challenging. Roonka, is the largest excavated burial area in Australia. Despite preliminary analysis in the 1970–1980s chronology was challenging given the complex record of dune formation, intrusive burials, erosion and exposure. As part of collaboration with the River Murray and Mallee Aboriginal Corporation, we have re-analysed the legacy data. We have combined three tools: 3D reconstruction and spatial analysis of the site; Bayesian analysis of the radiocarbon sequence, and archaeothanatology to gain a deeper understanding of the relationships between burials and dune formation and hence the connection between changes in burial practices and environmental change. Analysis confirms that the site was used as a burial place over the last 8000 years, but the burial record has been significantly impacted by erosion. The most likely cause of erosion is ENSO-driven climatic change. Other changes that are not coincident with climatic change but alter the intensity of site use were identified by tracing the number of burials over time. Analysis indicates a shift from occasional and specialised use to increasing use in the mid to Late-Holocene. We argue that burial practices became more diverse and demographically inclusive over time. In summary, our analysis clearly demonstrates that it was not a place for everybody all the time. The selection of ‘who’ and ‘when’ demonstrates access to and maintenance of a broader set of persistent burial places in the Murray Valley region during the Holocene.

AeoLiS: Numerical modelling of coastal dunes and aeolian landform development for real-world applications

The formation and evolution of coastal dunes result from a complex interplay of eco-morphodynamic processes. State-of-the-art models can simulate aeolian transports and morphological dune evolution under certain conditions. However, a model combining these processes for coastal engineering applications was not yet available. This study aims to develop a predictive tool for dune development to inform coastal management decisions and interventions. The aeolian sediment transport model AeoLiS is extended with functionalities that allow for simulations of coastal landforms. The added functionalities include the effect of topographic steering on wind shear, avalanching of steep slopes and vegetation processes in the form of growth and wind shear reduction. The model is validated by simulating four distinct coastal landforms; barchan-, parabolic-, embryo dunes and blowouts. Simulations, based on real-world conditions, replicate the landform formation, migration rates and seasonal variability.

Foredune initiation and early development through biophysical interactions

Coastal dunes result from complex interactions between sand transport, topography and vegetation. However, uncertainty still persists due to limited quantitative analyses, integrating plant distribution and morphologic changes. This study aims to assess the initiation and maintenance of feedback processes by analysing the early development stages of incipient foredunes, combining data on the evolution of the plant cover and communities and dune morphology. Over three years, the monitoring of a newly formed dune (1 ha plot) reveals the progressive plant colonisation and the episodic accumulation of sand around vegetated areas controlled by sediment availability. Distinct colonisation rates were observed, influenced by inherited marine conditions, namely topography and presence of beach wrack. Berm-ridges provided elevations above the critical threshold for plant colonisation and surface roughness, aiding sediment accumulation. Beach wrack above this threshold led to rapid expansion and higher plant concentration. In the initial stages, vegetation cover significantly influenced sediment accumulation patterns, with higher accumulation around areas with high plant cover and low slopes or around areas with sparse vegetation but milder slopes. As the dune system matured and complexity grew, the link between vegetation cover and accumulation became nonlinear. Mid to low coverages (5–30 %) retained most of the observed accumulation, especially when coupled with steep slopes, resulting from positive feedbacks between vegetation, topography and sand transport. As foredune developed, vegetation cover and diversity increased while inherited morphologies grew vertically, explaining the emergence of dune ridge morphological types. Flat surfaces lacking wrack materials experienced a three-year delay in colonisation and sand accumulation, leading to the formation of terrace-type incipient foredunes. These observations underline feedback processes during the early stages of dune formation, with physical feedbacks primarily driving initiation and biophysical feedbacks prevailing in subsequent colonisation stages.

Drivers of dune formation control ecosystem function and response to disturbance in a barrier island system.

Barrier islands are landscape features that protect coastlines by reducing wave energy and erosion. Quantifying vegetation-topographic interactions between adjacent habitats are essential for predicting long-term island response and resilience to sea-level rise and disturbance. To understand the effects of dune dynamics on adjacent interior island ecosystem processes, we quantified how sediment availability and previous disturbance regime interact with vegetation to influence dune building and ease of seawater and sediment movement into the island interior on two US mid-Atlantic coast barrier islands. We conducted field surveys of sediment accretion, vegetative cover, and soil characteristics in dune and swale habitats. Digital elevation models provided assessment of water flow resistance from the mean high water mark into the island interior. We found that geographic location impacted sediment accretion rates and Panicum amarum (a species increasing in abundance over time in the Virginia barrier islands) accreted sediment at a significantly lower rate compared to other dune grasses. Dune elevation impacted the ease of seawater flow into the island interior, altering soil chlorides, annual net primary productivity, and soil carbon and nitrogen. Our work demonstrates the importance of incorporating biological processes and cross-island connectivity into future scenario modeling and predictions of rising sea-levels and increased disturbance.

Shifting Trends of Estate Sand Dunes and Effects on Population Activities in The Cua Dai Area, Quang Nam Province Vietnam

The movement of estuarine dunes is a complex process, attracting a lot of attention from scientists. Since its second visible appearance in 2018, many scientists with specialized methods have sought to understand the causes and mechanisms of dune formation in front of Cua Dai. Some studies have shown that the dunes in front of Cua Dai tend to move north and are associated with the dunes on the north bank of Cua Dai. However, these studies only evaluate based on natural laws and ignore the impact of people's development activities. Using general research methods of geographical science, the article has shown the current and future movement trends of dunes in front of Cua Dai: expanding to the west, moving inside Cua Dai, down south, and tending to connect with the sand bar on the southern shore of Cua Dai.

Exploring The Influence Of Artificial Root Systems Modeled After Marram Grass (Ammophila Arenaria) On Dune Erosion

Vegetated dune systems represent a remarkable landform along numerous coastal areas worldwide. They provide a valuable contribution to local ecosystems and coastal protection. The influence of vegetation on the stability of soils potentially counteracts erosion and, on sandy coasts under suitable conditions, leads to the accumulation of sediments driven by aeolian transport, resulting in dune formation (Feagin et al. 2015). The assessment of the coastal protection potential of dunes is far from being a streamlined, mature procedure, and it will demand more parameters than merely the dunes’ height, dimensions or volume, but tentatively also their vegetation coverage. Artificial dunes or dunes regenerated through sand nourishment often lack additional substrate stabilization since no vegetation bound root systems are present (Nordstrom and Jackson 2022). The role of stabilizing root components in the overall dune body matrix is currently not well understood, in particular, when highly dynamic processes such as wave attack is involved. The hypothesis of this novel work hence is that root systems of dune grass (i.e., A. arenaria) can be quantified for the modelling in experimental campaigns and for more reliable erosion results. To investigate this hypothesis novel physical experiments are currently conducted in the wave flume at the Leichtweiß-Institute for Hydraulic Engineering and Water Resources in Braunschweig (Germany), testing different root surrogate materials and quantities for the first time.

Wind Tunnel Test of Sand Particle Size Distribution along Height in Blown Sand

In aeolian sand movement, the vertical distribution of sand particle size is intricately linked to sand flux, wind–sand flow field and dune development. In the present study, the distribution characteristics of sand grains in four particle size ranges at nine heights were investigated through sand blowing tests at five different reference wind speeds. The correlation between sand particle size and wind speed indicates that when the particle size was ≥0.35 mm, there was a linear variation of mass percentage with wind speed. When the particle size was <0.35 mm, when Z ≤ 0.15 m, a linear variation of mass percentage with wind speed was found; when Z > 0.15 m, an exponential modification in mass percentage with wind velocity was observed for sand grains falling within this specific range of particle sizes. The correlation between sand particle size and height indicates that when the reference wind speed was ≥15 m/s, the mass percentage of sand particles varied linearly with height. When the reference wind speed was ≤13.5 m/s, the mass percentage of sand grains with particle size in the 0.25–0.35 mm range increases first and then decreases with increasing height. The present results can provide a reference for subsequent research on the aerodynamic characteristics of wind–sand flow fields and on the mechanism of dune formation.