Erodible Surface Research Articles

The use of magnesium-enriched brine for stabilization of highly erodible playa surfaces: A comparative study with sodium alginate and sodium silicate

Newly formed playas, such as those resulting from the desiccation of Lake Urmia (LU) in northwest Iran, are significant global dust sources with implications for human health and the environment. Stabilizing these surfaces affordably can be achieved using locally sourced magnesium-enriched brine. To evaluate this approach, for LU playa, we examined the accumulation of ions, minerals deposition, and salt crust (Cr) formation in LU brine under both natural and laboratory conditions. We then assessed the effect of brines with varying Mg2+ concentrations (B0 ≈1.97, B5 ≈2.72, and B15 ≈ 3.62 mol/L) on the stabilization of two highly erodible soils (sand sheets and sandy salt crust), comparing them with commercial stabilizers: sodium alginate (Na-A) and sodium silicate (Na-S). The crusts were evaluated based on thickness, compressive strength, and soil loss in wind tunnel experiments. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) was employed to analyze crust morphology and elemental composition. The results indicated that in the pure crusts, halite was the dominant mineral in salt crusts, while bischofite (MgCl₂∙6H₂O) and epsomite (MgSO₄∙7H₂O) formed during different stages of brine evaporation. Bischofite appeared at the pond margins, indicating deposition from less concentrated brines (B0 and B5), while epsomite dominated the center during the final evaporation stages. Brine treatments significantly reduced soil loss to 1.2%, outperforming Na-A (4.88%), Na-S (30.35%), and the control (34.18%). SEM analysis confirmed aggregate formation due to NaCl and MgCl₂ precipitation. In conclusion, Mg-enriched LU brine demonstrated effectiveness comparable to commercial stabilizers in enhancing the resilience of highly erodible playa surfaces.

Quantifying mine waste rock physical weathering rate and processes for improved geomorphic post-mining landforms

Erodibility of landform surfaces depends on several factors and numerical methods are needed to predict erosion and landform evolution particularly for post-mining landscapes. Surface armouring caused by immobile coarse particles tends to reduce the erosion potential of landform surfaces significantly. However, the breakdown of such material through weathering could destabilise this armour and lead to high erosion rates. Hence, the surface erodibility of newly constructed landforms (here we focus on post-mining landforms) can rapidly change over a few years to decades. At present, it is difficult to predict with certainty the rate, or in some cases the dominant processes and pathways, of soil erodibility and soil production over post-mining landscape design lifetimes (typically 100–1000 years). To improve our understandings of soil evolution and its relationship to soil erosion, data is needed to determine the rate at which fine transportable material is produced from the weathering of larger, non-transportable particles, the resultant fragment size distribution together, and how that distribution evolves over time.Here, laboratory weathering experiments were conducted for four different materials from a single coal mine in the Bowen Basin, Queensland, Australia. Wetting and drying cycles were found to rapidly weather all materials. After 32 wet and dry cycles, all materials had a less coarse particle size distribution than at the start. Heating and cooling had no measurable influence on weathering. Due to the rapid reduction of particle sizes caused by high weathering rates, the materials examined would not provide surface armour capability. A new mathematical methodology was developed to determine the weathering parameters for an existing numerical model based on the weathering mechanism and particle size-dependent weathering rate. Although the materials were collected from the same geographical location, they undergo weathering through different mechanisms and rates. Size dependent weathering rate analysis showed that most samples have high weathering rates for large particles and lower weathering rates for smaller particles. The methods used here are simple and inexpensive and can be easily employed to assess mine rehabilitation materials' weathering and armour potential.

Experimental study on flow around horizontal multiple pipelines laid on the erodible seabed surface

Experimental study on flow around horizontal multiple pipelines laid on the erodible seabed surface

Assessing Shallow Soft Deposits through Near-Surface Geophysics and UAV-SfM: Application in Pocket Beaches Environments

This study employs a multimethod approach to investigate the sediment distribution in two pocket beaches, Ramla Beach and Mellieha S Beach, in Malta. Both study sites were digitally reconstructed using unmanned aerial vehicle (UAV) photogrammetry. For each case, an ERT and a dense network of ambient seismic noise measurements processed through a horizontal-to-vertical spectral ratio (HVSR) technique were acquired. Electrical resistivity tomography (ERT) analysis enables the estimation of sediment thickness in each beach. HVSR analysis revealed peaks related to beach sediments overlying limestone rocks in both sites and also indicated a deeper stratigraphic contact in Mellieha S Beach. Based on ERT measurements, sediment thickness is calculated for each HVSR measurement. Interpolation of results allows for bedrock surface modelling in each case study, and when combined with digital terrain models (DTMs) derived from photogrammetric models, sediment volumes are estimated for each site. The geometry of this surface is analyzed from a geological perspective, showing structural control of sediment distribution due to a normal fault in Mellieha S Beach and stratigraphic control facilitated by a highly erodible surface in Ramla Beach. The results emphasize the importance of adopting a three-dimensional perspective in coastal studies for precise sediment volume characterization and a deeper understanding of pocket beach dynamics. This practical multimethod approach presented here offers valuable tools for future coastal research and effective coastal management, facilitating informed decision making amidst the growing vulnerability of coastal zones to climate change impacts.

About the role of the Hanratty correction in the linear response of a turbulent flow bounded by a wavy wall

Scallop patterns forming on erodible surfaces were studied historically using a linear analysis of the inner region of a turbulent boundary layer growing on a corrugated wall. Experimental observations show a phase shift between the shear stress at the wall and the wall oscillation that depends on the wavenumber. Anad hoccorrection applied to the turbulent closure and due to Hanrattyet al.(Thorsnesset al.,Chem. Engng Sci., vol. 33, issue 5, 1978, pp. 579–592; Abrams & Hanratty,J. Fluid Mech., vol. 151, issue 1, 1985, p. 443; Frederick & Hanratty,Exp. Fluids, vol. 6, issue 7, 1988, pp. 477–486) was systematically used to recover the reference experimental results. In this study, Reynolds-averaged Navier–Stokes (RANS) and direct numerical simulations (DNS) were performed and revealed the role of the Boussinesq assumption in the results obtained. We show that the Hanratty correction acts as a palliative to the misrepresentation of Reynolds stresses due to the use of the Boussinesq hypothesis. The RANS calculations based on a turbulence model using a second-order moment closure recovered the expected results obtained in the reference DNS calculations, in particular with respect to wall heat transfer. The analysis of these results highlights the critical importance of the anisotropy of the diagonal Reynolds stresses on the prediction of wall transfer under these conditions and their implication in the occurrence of scalloping.

How Bed Composition Affects Erosion by Debris Flows—An Experimental Assessment

AbstractA solid physical understanding of debris‐flow erosion is needed for both hazard prediction and understanding landscape evolution. However, the processes and forces involved in erosion by debris flows and especially how the erodible surface itself influences erosion are poorly understood. Here, we experimentally investigate the effects of bed composition on debris‐flow erosion, by systematically varying the composition of an erodible bed in a small‐scale debris‐flow flume. The experiments show that water and clay content of an unconsolidated bed significantly control erosion magnitude by affecting the transfer of pore pressure, loading conditions, and contraction‐dilation behavior of the bed. As the water content increases and the bed comes close to saturation, erosion increases rapidly, whereas for clay content an optimum for erosion exists around a clay content of 3%–4%. Our results show that small variations in bed composition can have large effects on debris‐flow erosion, and thus volume growth and hazard potential.

Impact of Landes forest fires on air quality in France during the 2022 summer

Abstract. The atypical huge forest fires observed in France during the summer of 2022 are modeled using the CHIMERE model. The impact of these emissions is quantified on ozone, aerosols and aerosol optical depth (AOD). The fires also influence the surface by destroying the vegetation and creating new erodible surfaces. This increases the mineral dust emissions but also reduces the leaf area index (LAI), and then it decreases the biogenic emissions and the dry deposition of gases such as ozone. Results show that the fires induce numerous increases in surface ozone and particulate matter (PM) concentrations close to the sources but also in downwind remote sites such as the Paris area. During the period of the most intense fires in July, the impact of concentrations is mainly due to emissions themselves, and later, in August, ozone and PM concentrations continue to increase but this time due to changes in the burned surfaces.

Surface Eroding Methacrylic Anhydride Copolymers and Model Drug Release

AbstractMethacrylic anhydride (MAA)‐based copolymers are synthesized to probe how comonomer composition and type affect the erosion profiles. Anhydrides readily undergo hydrolysis, which when combined with high crosslink density and hydrophobicity tend to exhibit an ideal surface erosion mechanism for drug delivery, tissue adhesives, and biocement applications. The cylindrical (10 mm diameter × 5 mm height) polyanhydrides are degraded under pseudo‐physiological conditions and surface erosion is qualitatively observed via photographs. The non‐anhydride comonomer can be utilized to tune erosion profiles while retaining degradability and product solubility. The comonomer can accelerate or slow the degradation process to a greater extent at low MAA concentrations. Drug release is conducted using purpurin to model hydrophobic drugs. Purpurin concentration is quantified using UV–visible spectral analysis. Purpurin extends the degradation profile due to a combination of local pH changes, hydrophobicity, and molecular diffusion. Linear purpurin release is observed as a function of polymer erosion (0.9897 R2) thus confirming a surface erosion‐mediated drug release mechanism.

On the Scaling and Growth Limit of Fluvial Dunes

AbstractBedforms emerge in a variety of shapes and sizes when a granular erodible surface is subject to a strong enough shear flow, as observed in topographic data from submarine canyons, rivers, deserts, and planetary bodies. The two salient features of bedforms are the ability to collectively transport particles, and to generate form drag thus increasing flow resistance. These two mechanisms are in competition and contribute to force bedforms of increasing size migrating more slowly. In a dedicated large‐scale open channel flow facility, hierarchies of fluvial bedforms were generated and measured in equilibrium conditions. The corresponding scale‐dependent migration velocity and mass flux contributions were quantified in the wave number and frequency domains. Experimental results are paired with a validated set of theoretical models to demonstrate that ripples or dunes reach an equilibrium state when drag partitioning ensures high enough frictional drag to sustain the bedload transport of sediment, and low enough form drag to enable the migration of the largest bedform size. This mechanism is inferred to constrain the growth of bedforms when sediment supply is not the limiting factor.

Documentation of Surface Soil Characteristics as Indicator of Soil Erosion: A Case of East Khasi Hills in and around Shillong, Meghalaya

Soil characteristics are the result of the interaction of pedogenic elements and processes in a specific location. The hilly and mountainous regions are equipped with a diverse set of environmental elements that impact soil spatial variability. This research work is mainly focused on documentation of surface soil characteristics of East Khasi Hills. So many factors are responsible for soil erosion here and dominantly the anthropogenic activities. With the increase of population, changing land use patterns with unscientific manners is one of the ecological phenomena in Meghalayan landscapes. This causes heavy soil erosion especially their agricultural activity such as slash and burn process that makes the land very infertile. Data on surface soil characteristics or surface soil status has been collected from primary field surveys. Base maps were prepared related to this research work with the help of Q-GIS (version 3.6) software and statistical analysis was done using MS Excel 2013 on the basis of both primary and secondary database. Rain induced soil erosion associated with supersaturated soil matrix failure is the major attestation of soil erosion here. Authors mainly have tried to make some inferences towards the correlation of surface soil characteristics and erodibility of the soil.

Influence of different management systems on surface protection and erodibility of a temperate mixed forest

Unmanaged artificial forests face severe rates of erosion which could also impose serious threats to their adjacent environment. The Soil and Water Assessment Tool (SWAT) is a widely used physically-based model which estimates sediment yield using the empirical Modified Universal Soil Loss Equation (MUSLE). Although SWAT has been proven to obtain satisfactory results in forested catchments, the lack of representation of surface protection in the MUSLE factors still needs to be addressed. Acknowledging this gap, the present study applied a unique method of evaluating the surface protection and erosion susceptibility of four forest groups (poorly-managed private forest, moderately-managed unfenced Government-managed forest, well-managed fenced Government-managed forest, and natural forest) in the upstream catchment of Ogouchi Reservoir in Japan (262.9 km2) which is dominated by steep slopes (35°–45°). While the individual susceptibility to open and throughfall raindrops can be expressed by stand density, surface protection was found to be additionally influenced by slope and management system. With this, a multiple linear regression equation for surface protection (Pr) was derived from the influencing forest properties. Integrating the combined impacts of open and throughfall raindrops with surface protection, the values of total erodibility coefficient (CTEr) were computed which will then be corresponded to the MUSLE management practice factor (MUSLE P) input in SWAT. Poorly-managed private forests were found to be the most susceptible to raindrop splash erosion due to their exposed surface, while the well-maintained fenced Government-managed forests possess the most ideal condition for erosion control. The results of modeling CTEr at various management scenarios confirmed that the erosion susceptibility of poorly-managed Japanese cypress forest could be about 40% greater than the case of well-managed conifer plantation, a ratio that is close to and within the range of the values earlier reported.

Spatial vegetation structure and its effect on wind erosion of Alxa dryland ecosystem

In wind erosion models, previous parameters related to vegetation morphology and density are limited in describing the spatial distribution of vegetation that influences surface heterogeneity. Thus, it is not fully understood how spatial vegetation patterns affect wind erosion on a field-scale. Based on an investigation of 36 plots of vegetation in Alxa Plateau, northwestern China, we established a multivariate linear model for temporally and spatially averaged aerodynamic roughness length (Z 0) incorporating the height, roughness density, regularity of vegetation patches (curvature) and spacing between patches (connectivity). The curvature positively interacted with the connectivity in affecting the mean Z 0, while it was the most important factor affecting the standard deviation of Z 0. The connectivity modulated the roughness density in affecting the standard deviation of Z 0. The spatial-related terms contributed 37% and 62% to the model variance of the mean and standard deviation of Z 0, respectively. Our results validate the importance of spatial vegetation structure in the vegetation-airflow interactions, with a suggestion of estimating the heterogeneity of surface erodibility by intuitive spatial parameters. Based on that spatial vegetation patterns reflect the ecosystem states, a strengthened linkage between wind erosion and vegetation stability may be useful in erosion regulation in drylands.

Field Evidence for the Initiation of Isolated Aeolian Sand Patches

AbstractSand patches are one of the precursors to early stage protodunes and occur widely in both desert and coastal aeolian environments. Here we show field evidence of a mechanism to explain the initiation of sand patches on non‐erodible surfaces, such as desert gravels and moist beaches. Changes in sand transport dynamics, directly associated with the height of the saltation layer and variable transport law, observed at the boundary between non‐erodible and erodible surfaces lead to sand deposition on the erodible surface. This explains how sand patches can form on surfaces with limited sand availability where linear stability of dune theory does not apply. This new mechanism is supported by field observations that evidence both the change in transport rate over different surfaces and in situ patch formation that leads to modification of transport dynamics at the surface boundary.

DIRECT DETERMINATION OF ERODIBILITYIN DIFFERENT FORMS OF SLOPES IN THE BELMONT STREAM BASIN IN PORTO VELHO - RONDÔNIA – BRAZIL

This study aimed to quantify the surface erodibility (0-10cm) of oxisol in three slope morphologies in the Belmont basin Stream in Porto Velho, Rondônia – Brazil; through direct analysis using the Modified Inderbitzen equipment. The erodibility evaluation method was that of Heidemann, which considers a soil to be erodible when it obtains percentages greater than 5% of its mass disaggregation. The samples were exposed to showering in the Inderbitzen for 90 minutes at flow intensities of 3.00L/min. The erodible potential presented different values for each soil sample. The foothills of the Convex Slope - CX showed to be the most erodible of this, with a value of 14.51% of breakdown. The RectilinearSlope - RT presented the top and bottom as more erodible (12.43% and 7.8% respectively). The Concave slope - CV proved to be the most erodible slope of all analyzed, with the percentage of its surface above 20% of disaggregation. It was observed in the sample thirds that the different formats and slopes spatially influence the intensity of soil erosion in each slope third, influencing the variability of the erodible potential along the slopes.

Tensile properties of six desert shrub species in Hobq Desert, China

Abstract Desert shrubs are often planted to control wind erosion, land desertification, and desert expansion. Their motions of bending and vibration can absorb and disperse kinetic energy of wind, so as to protect the erodible surfaces close-by. According to continuum mechanics, the quantification of mechanical properties of shrubs is critical to understand their dynamic behaviors. In this study, the conventional tensile tests of six dominant desert shrub species’ stems mainly sampled in the Hobq Desert of China are performed. It is found that the tensile strength of Tamarix ramosissima and Hedysarum scoparium are larger than others, whereas Caragana korshinskii and Hippophae rhamnoides are more flexible. And then, it is theoretically and experimentally proved that the tensile strength and Young’s modulus of these desert shrubs both decrease with the increase of diameter.

Experimental Comparison of Inclined Flows with and without Intense Sediment Transport: Flow Resistance and Surface Elevation

The effect of the intense transport of lightweight sediment without turbulent suspension (Shields numbers of mixture flow from 0.34 to 1.80) on resistance and surface elevation of water flow in an open channel is experimentally examined. Flows over fixed and mobile plane beds, at the same water flowrate and bed slope, are compared. Detailed measurements—including distributions of solids and velocity—permit to identify flow interfaces and determine the role of sediment transport on flow resistance. Two friction factors for mobile bed flows are introduced: one for water only and another one for the mixture. The first seems to be insensitive to the water submergence, while the latter follows the classic formula for the hydraulically rough regime: both increase with respect to the equivalent clear water flow. The water surface elevation seems unaltered by the presence of sediment transport, thus reducing the need for the modelling of the evolution of an erodible bed surface in, at least, some routine applications in fluvial hydraulics.

Measurement report: The Urmia playa as a source of airborne dust and ice-nucleating particles – Part 1: Correlation between soils and airborne samples

Abstract. The emergence of desiccated lake bed sediments and their exposure to wind erosion as a consequence of climate change and drought in arid and semiarid regions of the world poses a growing hazard. Airborne dust originating from such soils can create health and environmental issues due to their high salt content and the presence of toxic elements. The aim of the present study is twofold, namely to investigate the newly emerged playa surfaces of western Lake Urmia (LU) in Iran and their contribution to aerosol in the region by means of physicochemical, mineralogical, and elemental analyses and to study the ice nucleation (IN) activity of both surface-collected soil and airborne dust samples. The playa surfaces created by desiccation of LU on the western shores were mapped and sampled at 130 locations. Soil samples were subjected to physicochemical analyses, and their erodible fraction was determined. Based on these analyses, four highly erodible playa surfaces from the northwest to the south of LU were selected as sites for collection of dust by impaction and soil samples from the uppermost surface. Their particle physicochemical properties (size distribution, elemental and mineralogical composition) were compared with their IN activity determined by emulsion freezing experiments in a differential scanning calorimeter (DSC) in two suspension concentrations of 2 wt % and 5 wt %. The physicochemical soil properties differed significantly between the different playa surfaces, which affects their susceptibility to wind erosion. Sand sheets and sandy salt crusts were the most erodible playa surfaces due to their high sand fraction and low organic matter and clay content, favouring the presence of small aggregates. Mineralogical analyses document the prevalence of quartz, carbonates, and clay minerals, such as kaolinite, palygorskite, and chlorite in all of the samples. The predominant elements in the samples are Ca, Fe, Al, Si, and Na (and in some cases Ba, Sr, and Zn). The correlation between soil and dust samples based on mineralogical composition, elemental enrichment factors, and physicochemical properties confirm that the playa surfaces are the major contributors to dust in the region. IN activity with onset temperatures ranging from 245 to 250 K demonstrates the high potential of dust blown from Urmia playa surfaces to affect cloud properties and precipitation. Freezing onset temperatures and the fraction of heterogeneously frozen droplets in the emulsions reveal variations in IN activity depending on the mineralogical composition of the samples but which are also influenced by organic matter, salinity, and pH. Specifically, IN activity correlates positively with organic matter and clay minerals and negatively with pH, salinity, and (surprisingly) K-feldspar and quartz content. The high wind erodibility and dust production of the LU playa surfaces together with their high IN activity can play an important role in the climate of the region and thus needs careful monitoring and specific attention.

Sediment erodibility in the Changjiang (Yangtze) subaqueous delta: spatial–temporal distribution and sedimentary significance

Delta evolution in the context of no sediment discharge has become a global concern, and an accretion-to-erosion conversion is occurring in the Yangtze estuary. This conversion could threaten Changjiang subaqueous delta development. Sediment erodibility is an important indicator of subaqueous delta vulnerability. However, the present and future erodibility of the Changjiang subaqueous delta remains unclear. In this study, 37 short cores were collected from the Changjiang subaqueous delta, and the critical shear stress of the sediment was measured using a cohesive strength meter (CSM) and compared with estimates based on an empirical Shields diagram. The sediment erodibility was analyzed by comparing the sediment critical shear stress with the bed shear stress simulated using a numerical model (i.e., FVCOM), and sediment activity was introduced to discuss the geomorphological change in the subaqueous delta. The CSM-derived critical shear stress is significantly higher than that derived from the empirical Shields formula, but it better shows the erodibility of the sediment. The annual surface sediment activity ranges from 5% to 30% based on the CSM, indicating low surface erodibility. Moreover, the critical shear stress in this region increases as water depth increases, but the bed shear stress shows the opposite trend. Therefore, the erodibility of the Changjiang subaqueous delta is lower than that of the shallow area, indicating no accretion-erosion conversion or continued vertical erosion under sediment starvation in the coming decades. These findings can provide suggestions for erosion assessment and management in large river deltas under decreasing sediment discharge.

A granular energy-controlled boundary condition for discrete element simulations of granular flows on erodible surfaces

Entrainment of the substrate, which can cause the volume of geophysical flows to increase by many times and greatly affects its mobility, occurs frequently. Even though many large-scale studies have been conducted to investigate entrainment during flows, particle-scale studies are urgently needed to understand this complex process. We propose a novel configuration with an energy-controlled boundary to model inclined granular flows on erodible surfaces with the aim of investigating the rheological features of granular flows with entrainment. The erosion degree is controlled by adjusting the energy of the bottom granular bed. The bulk velocity, stress, microstructure, and constitutive behavior are systematically analyzed. Our simulations capture the exponentially decaying velocity in the creeping region, confirming that this configuration can be applied to study geophysical flows with entrainment. The velocity at the free surface increases with erosion depth, which means entrainment can greatly enhance the mobility of granular flow. However, the flow in the shear band still belongs to the inertial regime. The novel energy-controlled configuration provides effective and efficient way to investigate granular flows on erodible surfaces, serving as an initial step to understand geophysical flows involving entrainment, which is essential to develop new geo-disaster mitigation strategy.

A predictive mechanistic model of drug release from surface eroding polymeric nanoparticles.

Effective drug delivery requires ample dosing at the target tissue while minimizing negative side effects. Drug delivery vehicles such as polymeric nanoparticles (NPs) are often employed to accomplish this challenge. In this work, drug release of numerous drugs from surface eroding polymeric NPs was evaluated in vitro in physiologically relevant pH5 and neutral buffers. NPs were loaded with paclitaxel, rapamycin, resiquimod, or doxorubicin and made from an FDA approved polyanhydride or from acetalated dextran (Ace-DEX), which has tunable degradation rates based on cyclic acetal coverage (CAC). By varying encapsulate, pH condition, and polymer, a range of distinct drug release profiles were achieved. To model the obtained drug release curves, a mechanistic mathematical model was constructed based on drug diffusion and polymer degradation. The resulting diffusion-erosion model accurately described drug release from the variety of surface eroding NPs. For drug release from varied CAC Ace-DEX NPs, the goodness of fit of the developed diffusion-erosion model was compared to several conventional drug release models. The diffusion-erosion model maintained optimal fit compared to conventional models across a range of conditions. Machine learning was then employed to estimate effective diffusion coefficients for the diffusion-erosion model, resulting in accurate prediction of in vitro release of dexamethasone and 3'3'-cyclic guanosine monophosphate-adenosine monophosphate from Ace-DEX NPs. This predictive modeling has potential to aid in the design of future Ace-DEX formulations where optimized drug release kinetics can lead to a desired therapeutic effect.