Dune Research Articles

Effect of dune sand on concrete mechanical strength and ballistic resistance

Effect of dune sand on concrete mechanical strength and ballistic resistance

OSL-based chronology of the cold-climate aeolian sand dunes, Moravian Sahara, lower Morava Basin, Czechia

The Moravian Sahara dune field located in southeastern Czechia represents a unique aeolian system preserving the Late Glacial environment. Until now, the main focus has been concentrated on defining its multigenerational development and examining the environmental factors controlling its formation. However, current studies have failed to bring robust chronologies, so environmental and temporal comparisons with the main aeolian phases in Europe could not be made. Here, we present a study combining chronological and environmental interpretations. To do so, four boreholes were drilled to obtain the samples for optically stimulated luminescence, quartz grain morphoscopy and sediment maturity estimation. The results show that the Moravian Sahara dune field developed episodically between the Last Glacial Maximum (LGM) and Younger Dryas, with the peak occurring during the Oldest Dryas. Quartz grain analysis revealed that the phases of wind-blown sand deposition were short and that the dune sediments had three different sources. Furthermore, it appears that the katabatic winds propagated to the study area during the LGM and Late Pleniglacial and were replaced by westerlies since the Oldest Dryas. Finally, the chronology of aeolian activity in the study area shows that Moravian Sahara dune field development was antecedent to the European Sand Belt and shares more similarities with the landforms in the Carpathian Basin located further south.

Arbuscular Mycorrhizal Fungi and Soil Fungi Associated with Uniola paniculata L. (Sea Oats) on Restored and Natural Sand Dunes on the Georgia Coast, U.S.A.

Arbuscular Mycorrhizal Fungi and Soil Fungi Associated with Uniola paniculata L. (Sea Oats) on Restored and Natural Sand Dunes on the Georgia Coast, U.S.A.

Indica rice "Takanari" outcompetes japonica rice "Koshihikari" under low fertility conditions in soil developed on a sand dune

Significantly, soil fertility and rice variety influence rice growth. Under different conditions, Indica rice "Takanari (Tak)" outperformed Japonica rice "Koshihikari (Kos)" in terms of N-uptake and biomass production. However, it is still unclear how Tak and Kos respond to rice growth and N-uptake in low-fertility (sandy) and normal (alluvial) soils. Therefore, we conducted a pot experiment at Tsuruoka in the 2022 rice-growing season. Tak and Kos were transplanted individually and interplanted (Tak+Kos) with the main treatments of alluvial soil, sandy, and sand with chemical fertilizers (sand+CF). Rice growth parameters (shoot height, tiller numbers, and leaf color) were weekly investigated, while rice biomass and N-uptake were measured after harvest. Shoot height, rice tillers, leaf color, plant biomass, and N-uptake were significantly different among all treatments. Tak had significantly higher rice biomass and N-uptake than Kos in all treatments for both planting modes. The ratios of aboveground biomass and N-uptake between Tak and Kos in interplanting were higher than their respective ratios in individual planting. The ratios of aboveground biomass in interplanting were higher than in individual planting at 41.7 %, 26.4 %, and 18.4 % in sandy, alluvial, and sand+CF, respectively. Whereas, the ratios of N-uptake in interplanting were higher than in individual planting at 41.9 %, 36.6 %, and 26.6 % in sandy, alluvial, and sand+CF, respectively. Regardless of low growth for both varieties in the sandy, Tak increased the competitive ability of N-uptake and biomass production. Therefore, rice cultivar selection and management of fertilizing practices are required for rice growing in low-soil fertility fields.

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.

Windblown sand around obstacles - simulation and validation of deposition patterns

Sand dunes are iconic landmarks of deserts, but can also put human infrastructures at risk, for instance by forming near buildings or roads. We present a simulator of sand erosion and deposition to predict how dunes form around and behind obstacles under wind. Inspired by both computer graphics and geo-sciences, our algorithm couples a fast wind flow simulation with physical laws of sand saltation and avalanching, which suffices to reproduce characteristic patterns of sand deposition. In particular, we validate our approach via a qualitative comparison of the erosion and deposition patterns produced by our simulator against real-world patterns measured by prior work under controlled conditions.

Life histories in Fiji as reconstructed from first millennium CE Sigatoka Sand Dune burials using isotopes

This paper aims to re-examine the dietary practices of individuals buried at Sigatoka Sand Dunes site (Fiji) in Burial Ground 1 excavated by Simon Best in 1987 and 1988 using two approaches and a reassessment of their archaeological, bioarchaeological and chronological frame. First, stable carbon and nitrogen isotope analysis was applied to document dietary changes between childhood and adulthood using an intra–individual approach on paired bone–tooth. Second, the potential adaptation of the individuals to their environment was evaluated through regional and temporal comparisons using inter–individual bone analysis. Ten AMS radiocarbon dates were measured directly on human bone collagen samples, placing the series in a range of approximately 600 years covering the middle of the first millennium CE (1,888 to 1,272 cal BP). δ13C and δ15N ratios were measured on bone and tooth collagen samples from 38 adult individuals. The results show that δ15N values from tooth are higher than those s from bone while bone and tooth δ13C values are similar, except for females. Fifteen individuals were included in an intra–individual analysis based on paired bone and tooth samples, which revealed six dietary patterns distinguished by a differential dietary intake of marine resources and resources at different trophic levels. These highlight sex–specific differences not related to mortuary practices but to daily life activities, supporting the hypothesis of a sexual division of labour. Compared to other Southwest Pacific series, Sigatoka diets show a specific trend towards marine food consumption that supports the hypothesis of a relative food self–sufficiency requiring no interactions with other groups.

Dune behavior in the Source Area of the Yellow River under climate changes observed from various remote sensing datasets

Sand dunes are a landscape feature with a quick response time to climate change and human influences (e.g. grazing, greening projects, and fixation structures). Their migration rates and their development can help to gather information about changing environmental conditions over time. The Source Area of the Yellow River (SAYR), located upon the Tibetan Plateau, is highly complex with topographical, hydrological, and climatological influences on active dunes, making it a good study area for these interactions. Based on remote sensing datasets, spanning the last 54 years, 415 dunes were mapped for migration rate calculations. Further, climate data from ERA-5 reanalysis and a local climate station was used to assess their changes within a changing climate. Generally, dune migration rates are rather slow with an average of 3.62 m y-1. In accordance, the averaged resultant drift potential (RDP) values are lower than 10 m3/s−3(−|-). Further, we assessed the density development of the main active barchan dune field in direct premise of the Yellow River. Throughout the past 54 years, we observed the emergence of more than 5 new barchans per square kilometer. This increase is likely attributed to higher sand flux from the Yellow River, which has resulted from increased discharge due to declining snowfall and rising precipitation levels.

Landcover-based detection of rapid impacts of extreme storm on coastal landscape

On September 24, 2022, Post-Tropical Hurricane Fiona made landfall in Atlantic Canada and caused unprecedented damages to the coastal communities and ecosystems therein. The aftermath triggered local government and communities in Prince Edward Island (PEI), Canada to rethink current policies and practices for coastal protection in the context of climate change. This historic hazard represents the escalating frequency and intensity of extreme weather events that globally threaten coastal regions, accelerating coastal erosion and endangering communities. This study employs landcover-based detection to assess rapid storm impact of Fiona on coastline of PEI using Sentinel-2 satellite images, to gauge the efficacy of landcover-based detection and quantify storm-induced coastal environmental changes. Our results indicate that, following Fiona, over 51 km2 coastal land loss due to the erosion at beach foreshore and inundation at tidal flat, and over 11 km2 sand dune loss mainly on the PEI north shore. This constitutes a 3.5 % loss of coastal land resources within the 1798 km2 PEI coastal zone. Fiona also caused over 194 km2 area in coastal buffer zone showed temporal fluid-mud from the eroded sediments of sand dunes, cliffs, and tidal flats, suggesting the significant sediment loss from vertical structures in addition to the direct retreat. The landcover-based method can be regarded as a valuable tool for the storm impacts on coastal environments. Based on the coastal change pattern, more sustainable coastal protection and adaptation measures should be developed, focusing on reducing hydrodynamic intensity and improving erosion capacity, with consideration of the increasing likelihood of more intense and frequent storm events in a warming climate.

Develop of a machine learning model to evaluate the hazards of sand dunes

Develop of a machine learning model to evaluate the hazards of sand dunes

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.

Introduction to the special issue of The Natural History of Two Peoples Bay Nature Reserve, Western Australia

Context This paper introduces the special issue of Pacific Conservation Biology devoted to the natural history of Two Peoples Bay Nature Reserve on the south coast of Western Australia. Methods This paper provides the background to the special issue. Key results Two Peoples Bay Nature Reserve was gazetted in 1967 for the conservation of the native biota, including two species; the Djimaalap/noisy scrub-bird (Atrichornis clamosus) and Ngilgaitch/Gilbert’s potoroo (Potorous gilbertii), both believed extinct for over 100 years before being rediscovered on the Reserve. The Reserve is 4774.7 ha in area, with wetlands, heathlands, granite outcrops, sand dunes, beaches, cliffs, and islands. Since it was established, mean annual rainfall has decreased by 16.8%, mean annual maximum temperature has increased by 0.2°C, and mean annual minimum temperature has increased by 0.7°C. Conclusions The paper poses the question: what do the changes of drier winters, hotter summers, and more extreme weather events mean for managers of conservation areas such as Two Peoples Bay? Implications Changing climate will pose problems for the managers of Two Peoples Bay Nature Reserve in ensuring the conservation of the Djimaalap/noisy scrub-bird and Ngilgaitch/Gilbert’s potoroo.

Observations of wave run-up affected by dune scarp during storm conditions: a two dimensional large-scaled movable bed experiment

Artificial dunes serve as essential nature-based defenses against the increasing threats posed by climate change and rising sea levels along coastal regions. However, these man-made dunes are particularly susceptible to erosion during severe storm events, necessitating careful consideration of their design for effective coastal protection. Among the myriad factors influencing artificial dune design, wave run-up stands out as a paramount concern. Not only is wave run-up crucial in assessing the extent of coastal flooding, but it also plays a significant role in shaping shoreline dynamics. During intense storm events, wave run-up amplification leads to substantial erosion of sand dunes, forming dune scarps that resemble cliffs. To address these challenges, we conducted a series of innovative two-dimensional large-scale laboratory experiments using movable beds. These experiments aimed to provide a quantitative understanding of wave run-up characteristics on dune scarps. Additionally, our study explored the feasibility of using existing empirical formulas to predict the 2% exceedance of wave run-up (referred to as R2%) in such scenarios. Our results revealed a consistent trend in R2% values, irrespective of variations in the surf similarity parameter when wave run-up was influenced by a dune scarp. Notably, our findings recommend the adoption of the Stockdon empirical formula, incorporating beach slope from the still water level to the dune scarp toe, as an effective method for predicting R2% during highly erosive conditions. This approach can significantly enhance the design and functionality of artificial dunes, bolstering their capacity to safeguard coastal areas from the impacts of severe storms and erosion, thus contributing to resilient coastal ecosystems and sustainable coastal management.

Aeolian dynamics at the northern edge of Deliblato (Banat) Sand Sea, Vojvodina, Serbia, at the time of the last deglaciation

Abstract The Deliblato (Banat) Sand Sea, which is one of the largest areas of аeolian sand in Europe, is located near the Iron Gate, which marks the crossing of the Danube River through the biggest gorge of this river. Here, Danubian alluvium has served as the sand source for the Banat Sand Sea, which was formed primarily through southeasterly (Košava) winds. Utilizing a multi-proxy approach, the objective of this study is to gain a better understanding of the environmental dynamics of the Banat Sand Sea. To achieve this goal, we conducted an analysis of an archive representing an approximately 20-m-thick dune formation on the northern edge of this dune field. Using optically stimulated luminescence (OSL) dating, we calculated aeolian sedimentation rates and dune ages. Sand was deposited here approximately between 17 ka and 13 ka. Magnetic susceptibility, grain size, and colorimetric analyses were interpreted in terms of local paleoenvironmental conditions. Calculated sedimentation rates (SR) indicate intensive aeolian deposition during the study period that range from 483 cm/ka to 502 cm/ka. We compared our data with regional and other European archives, as well as with climatic variations recorded in the Greenland ice core North Greenland Ice Core Project (NGRIP).

EFFECT OF DUNE SAND AND FLY ASH ON THE MICROSTRUCTURE OF FIBER REINFORCED CONCRETE

The current study investigates the effect of dune sand (DS) and fly ash (FA) on the microstructure of fiber-reinforced concrete (FRC). Concrete is a widely used construction material, and understanding its behavior under different conditions is important for optimizing its performance. The use of alternative materials, like FA and DS, in concrete production has gained attention due to their abundance and potential environmental benefits. The research methodology involved the preparation of FRC mixes with different combinations of FA and DS, along with varying fiber content. The microstructural analysis of the samples was conducted through scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The findings revealed that the addition of FA and DS influenced the microstructure of the FRC. Furthermore, the inclusion of FA contributed to improved pore structure and enhanced the pozzolanic reaction, resulting in a denser microstructure. The incorporation of steel and basalt fibers demonstrated significant effects on the microstructure of the concrete. The results provide valuable insights for optimizing the design and performance of concrete structures in arid regions while considering sustainable materials.

EXAMINING THE APPLICABILITY OF ALKALI ACTIVATED BINDERS (AABS) AS A LANDFILL LINER AND COVER

Landfill liner is a containment system used between landfill waste and the ground soil to prevent the migration of leachate into the soil and groundwater. Clay is typically used as a liner in the landfill barrier system due to efficiency and low permeability. Over the last decade, different types of binders such as cement, fly ash, and slag have been used with clay to improve the mechanical characteristics and reduce hydraulic conductivity of natural clay liners. This study introduced a new sustainable technique where treated dune sand mixed with alkali activated binder (AAB) made with fly ash (FA), ground-granulated blast-furnace slag (GGBFS), and alkali activated solutions are used as a landfill liner system, due to the unavailability of natural clay in most countries. Therefore, lab-scale compacted specimens with different mixing ratios of AABs treated desert sand were prepared and cured for 7 days to conduct a series of compressive strength. The results showed that the 20% binder mixed with 30% FA, 70% slag, and alkali solution of 0.5 have a high compressive strength with 12 MPa compared with other mixing ratios. However, a 10% binder with same precursors ratio of FA and slag has shown a less strength regardless of alkali solution with around 3 MPa. Finally, all mixing ratios have shown that the strength met the requirements of landfill liner system which were greater than 200 kPa.

DEVELOPMENT OF A SELF-LEVELING FLY ASH-SLAG GEOPOLYMER MORTAR

Exponential growth in the world population and increase in demand for concrete are pressing researchers and scientists to find sustainable alternative materials for Portland cement and natural aggregates. Self-leveling mortar is extensively used in construction applications, such as floor leveling, repair, resurfacing, or adhesion. Yet, limited research has been carried out on enhancing this material’s sustainability. This paper aims to produce a geopolymer mortar produced with fly-ash (FA), ground granulated blast furnace slag (BFS), and desert dune sand. Geopolymer mortar samples were produced with different binder-to-sand (B:S), FA-to-slag (FA:BFS), and alkali-activator solution-to-binder (AAS/B) ratios. Alkaline solution was blended with sodium silicate and sodium hydroxide with a molarity of 8 M (ratio of 1.5). Fresh and hardened properties of the developed self-leveling mortars were assessed. Experimental results showed that the flow, initial and final setting time, and 7-and 14-day compressive strength were in respective ranges of 17.3-40.3 cm, 21-155 minutes, 42-221 minutes, 6.0-70.3 MPa, and 5.2-78.7 MPa. Furthermore, an increase in FA:BFS, B:S, and AAS/B ratios enhanced flowability and prolonged setting time but reduced compressive strength at both ages. These research findings advocate the use of a self-leveling, cement-free geopolymer mortar to be utilized in various buildings and repair applications.

DEVELOPMENT OF A SELF-LEVELING FLY ASH-SLAG GEOPOLYMER MORTAR

Exponential growth in the world population and increase in demand for concrete are pressing researchers and scientists to find sustainable alternative materials for Portland cement and natural aggregates. Self-leveling mortar is extensively used in construction applications, such as floor leveling, repair, resurfacing, or adhesion. Yet, limited research has been carried out on enhancing this material’s sustainability. This paper aims to produce a geopolymer mortar produced with fly-ash (FA), ground granulated blast furnace slag (BFS), and desert dune sand. Geopolymer mortar samples were produced with different binder-to-sand (B:S), FA-to-slag (FA:BFS), and alkali-activator solution-to-binder (AAS/B) ratios. Alkaline solution was blended with sodium silicate and sodium hydroxide with a molarity of 8 M (ratio of 1.5). Fresh and hardened properties of the developed self-leveling mortars were assessed. Experimental results showed that the flow, initial and final setting time, and 7-and 14-day compressive strength were in respective ranges of 17.3-40.3 cm, 21-155 minutes, 42-221 minutes, 6.0-70.3 MPa, and 5.2-78.7 MPa. Furthermore, an increase in FA:BFS, B:S, and AAS/B ratios enhanced flowability and prolonged setting time but reduced compressive strength at both ages. These research findings advocate the use of a self-leveling, cement-free geopolymer mortar to be utilized in various buildings and repair applications.

EXAMINING THE APPLICABILITY OF ALKALI ACTIVATED BINDERS (AABS) AS A LANDFILL LINER AND COVER

Landfill liner is a containment system used between landfill waste and the ground soil to prevent the migration of leachate into the soil and groundwater. Clay is typically used as a liner in the landfill barrier system due to efficiency and low permeability. Over the last decade, different types of binders such as cement, fly ash, and slag have been used with clay to improve the mechanical characteristics and reduce hydraulic conductivity of natural clay liners. This study introduced a new sustainable technique where treated dune sand mixed with alkali activated binder (AAB) made with fly ash (FA), ground-granulated blast-furnace slag (GGBFS), and alkali activated solutions are used as a landfill liner system, due to the unavailability of natural clay in most countries. Therefore, lab-scale compacted specimens with different mixing ratios of AABs treated desert sand were prepared and cured for 7 days to conduct a series of compressive strength. The results showed that the 20% binder mixed with 30% FA, 70% slag, and alkali solution of 0.5 have a high compressive strength with 12 MPa compared with other mixing ratios. However, a 10% binder with same precursors ratio of FA and slag has shown a less strength regardless of alkali solution with around 3 MPa. Finally, all mixing ratios have shown that the strength met the requirements of landfill liner system which were greater than 200 kPa.

Data-Driven Assessment of the Impact of Hurricanes Ian and Nicole: Natural and Armored Dunes in the Aftermath of Hurricanes on Florida’s Central East Coast

Hurricanes Ian and Nicole caused devastating destruction across Florida in September and November 2022, leaving widespread damage in their wakes. This study focuses on the assessment of barrier islands’ shorelines, encompassing natural sand dunes and dune vegetation as well as armored dunes with man-made infrastructure such as seawalls. High-resolution satellite imagery from Planet was used to assess the impacts of these hurricanes on the beach shorelines of Volusia, Flagler, and St. Johns Counties on the Florida Central East Coast. Shorefront vegetation was classified into two classes. Normalized Difference Vegetation Index (NDVI) values were calculated before the hurricanes, one month after Hurricane Ian, one month after Hurricane Nicole, and one-year post landfall. LiDAR (Light Detection and Ranging) was incorporated to calculate vertical changes in the shorelines before and after the hurricanes. The results suggest that natural sand dunes were more resilient as they experienced less impact to vegetation and elevation and more substantial recovery than armored dunes. Moreover, the close timeframe of the storm events suggests a compound effect on the weakened dune systems. This study highlights the importance of understanding natural dune resilience to facilitate future adaptive management efforts because armored dunes may have long-term detrimental effects on hurricane-prone barrier islands.