Erosion Distributions Research Articles

Environmental transport and sorting of glass retroreflective microbeads and their potential as proxies for road marking paints

Road marking paints are a potentially important contributor to the global microplastic pool but very little reliable information is available on their erosion or environmental distributions. As potential carriers of or proxies for road paints, we determine the concentrations and sorting of retroreflective glass microbeads in marking materials and in fractionated (< 5 mm) local dusts, soils and sediments. As an aid to our investigation, we also determine the concentrations of metals of geochemical significance or components of road paint pigments in markings and geosolids. Concentrations of beads up to 92,800 kg−1 were observed in street dusts, with a median diameter (350 μm) greater than that in road marking samples (270 μm). Few beads were found in adjacent (< 5 m) or more remote soils (six beads in ten 50-g samples) and none were detected in replicates of a sample of roof dust, suggesting that aeolian transport is limited. Concentrations up to 3700 kg−1 were found in estuarine sediments close to bridges or stormwater runoff effluents, and with increasing sediment depth concentrations and median diameter decreased; beads were not, however, detected in sediments 400 m away from any significant roads or runoff effluents. These observations suggest that bead accumulation is constrained locally but that the precise distance travelled and extent of burial in sediments are inversely related to size. Road marking paints sampled from urban streets readily fragmented into pieces smaller than glass microbeads, suggesting that while beads might carry small quantities of paint, transport and dispersion of the two particle types may not be directly coupled. Environmental ratios of V to Bi and Cr to Pb, as markers for BiVO4- and PbCrO4-pigmented yellow paints, respectively, did not correlate with bead distribution, presumably because these metals have a multitude of additional anthropogenic sources. However, an inverse relationship between bead concentrations and K:Ca suggests that this ratio might be a useful proxy of road marking paint in regions that are geologically similar.

Geomorphological processes following the construction of an offshore artificial island in the radial sand ridges of the South Yellow Sea

Offshore artificial islands represent a novel way to develop and utilize marine space resources. Previous research has focused on predicting erosion and deposition distributions following the islands construction, utilizing laboratory experiments and numerical simulations. However, the absence of long-term continuous monitoring has hindered systematic studies on the geomorphological processes of these islands. A 20-years of underwater terrain monitoring scheme was conducted before and after construction of the Rudong Artificial Island in Jiangsu Province, China. The results were combined with on-site observations of tidal currents, suspended sediment concentrations, and surficial sediment to investigate the evolution of the water channel–sand ridge system and the development process of local scour around the artificial island. The results indicated that after the construction of the artificial island, its surrounding water channels showed an overall evolution trend of the north channel shifting towards the north, the middle channel widening and moving south, and the south channel extending westward and southward. Scour has been observed at the four corners of the artificial island, with the peak depths of 7.3 m, 5.6 m, 13.7 m, and 12.2 m at the southwest, northwest, northeast, and southeast corners respectively. The scour in the southwest and northwest corners reached an equilibrium within five years. However, in the southeast corner, continuous erosion of the shoal on the southeast side of the artificial island enhanced the local hydrodynamic force, leading to further scour development. The large-scale scour in the northeast corner was mainly caused by changes in the local flow field following the construction of water intake pipelines and their protection projects. These geomorphological changes are the joint results of the natural evolution of the radial sand ridges and local erosion and deposition from engineering construction. Currently, the sandbanks surrounding the island are still undergoing dynamic evolution following engineering construction, and local scour around the island has not yet reached equilibrium.

Numerical study on sediment erosion characteristics of Francis turbine runner

Sediment erosion is a prevalent and significant challenge to hydro turbines in mountainous rivers. In order to gain an insight into the erosion characteristics of Francis turbines, this study considers the influence of actual sediment gradation and emphasizes the erosion mechanism from the perspective of flow structure. Numerical results reveal a significant correlation between erosion distributions and the location of inter-blade vortices, which is dependent on operating conditions. Specifically, at small or optimal openings, inter-blade vortices predominantly form on the suction side of blades, which coincidentally experiences the most severe sediment erosion. Conversely, at a large guide vane opening, sediment erosion and vortices are primarily distributed at outlet of pressure side, aligning closely with actual site observations at a hydropower station. With increase of operating heads, the average erosion rate of suction side decreases at all guide vane openings, while that of pressure side elevates significantly. In addition, the effect of particle size on sediment erosion was discussed and the maximum erosion rate is demonstrated to be proportional to sediment diameter. These findings would provide important engineering insights for operation optimization to reduce sediment erosion.

Investigation of erosion behavior of particle-fluid flow in offshore platform T-pipes

The process of viscous oil exploitation is often accompanied by small sand particles, which harms safety production and causing consequences such as erosion. T-shaped pipes are widely used in offshore platform, and its flow protection is very important for the safe operation. This work aims to investigate the particle trajectory and erosion ratio rule in viscous oil transportation by simulation, experiment and support vector machine (SVM) model. The sensitivity analysis and the orthogonal method results demonstrate that the erosion ratio (ER) of T-pipes is proportional to the water content, gas content and sand content. And the erosion ratio (ER) of T-pipes is inversely proportional to the viscosity. The water content has the greatest effect on the pressure drop (Δp). The viscosity value around 326.79 mPa s can significantly reduce the erosion ratio while maintaining a low-pressure drop. Meanwhile, SVM model is used to calculate the erosion ratio (ER) with the mean squared error (MSE) being 4.25 × 10−6 in the training set and 0.0002 in the test set. The most severe erosion area is located in the downstream branch symmetrically. The erosion mechanisms are impact deformation and sliding, that dominate the erosion distributions.

Effects of axial misalignment welding defects on the erosive wear of natural gas piping

When considering solid particles in the pipe and axial misalignment weld defects in natural gas transmission systems, changes in the flow field due to structural differences can lead to various erosion characteristics in the bends. To investigate the erosion process within the bend, the computational fluid dynamics (CFD) - discrete phase model (DPM) method to develop a bend model with axial misalignment weld seam defects was employed. The erosion distributions of a bend with an axial misalignment weld were investigated under various transport parameters, bend orientation, axial misalignment height, and particle incidence angle. The results indicated that the erosion rate of the outermost elbow increases with the increase of the height of the axial misalignment weld on the outside of the bend pipe. When the axial misalignment height ranges from 1 mm to more than 5 mm, the difference in the maximum erosion rate escalates from 7 % to approximately 30 %. When the length of the inlet straight pipe is shorter, an increased incident angle intensifies the erosion effect and vice versa. This research can provide a reference for field construction work involving defective natural gas pipe bends.

Soil Organic Carbon Lateral Movement Processes Integrated Into a Terrestrial Ecosystem Model

AbstractLateral movement of soil organic carbon (SOC) induced by soil erosion and runoff changes spatial distributions of SOC, and further changes the land‐atmosphere CO2 exchange and terrestrial carbon budget. However, current ecosystem models do not or only poorly integrate the process of SOC lateral movement and cannot simulate the impacts of soil erosion on the carbon cycle. This study integrated SOC erosion and deposition processes into a process‐based ecosystem model (i.e., Integrated BIosphere Simulator (IBIS)), and separately simulated the lateral movements of dissolved organic carbon (DOC) and particulate organic carbon (POC). The model was evaluated in three river basins in Northeast China that are dominated by cropland, forest, and grassland. The results showed that the model reproduced well the production, erosion, and deposition of DOC and POC. The annual SOC lateral movement (1.34–7.22 g C m−2 yr−1) induced by erosion in the three tested basins was 0.27%–1.45% of the annual net primary production. The model developed in this study has great implications for simulating the lateral movements of SOC in terrestrial ecosystems, which can improve model performance in projecting the terrestrial carbon budget.

Advancing soil erosion prediction in Wadi Sahel-Soummam watershed Algeria: A comparative analysis of deep neural networks (DNN) and convolutional neural networks (CNN) models integrated with GIS

This study employs adaptive deep learning (utilizing DNN and CNN approaches) to accurately predict soil erosion, a crucial aspect of sustainable soil resource management. The goal is to develop fuzzy logic models for erosion forecasting in a large watershed with limited in-puts, comparing them to predictions from the Revised Universal Soil Loss Equation (RUSLE). Integration of GIS enables analysis of satellite data, providing crucial details like land use, slope, rainfall distribution, and flow direction. This synergistic approach enhances erosion prediction capabilities and yields spatial erosion distributions. Producing precise erosion risk maps within GIS is crucial for prioritizing high-risk areas and implementing effective conservation methods in the Wadi Sahel watershed, Algeria. The assessment in the Oued Sahel-Soummam watershed involved overlaying five RUSLE factor maps using Arc GIS spatial analysis, resulting in an aver-age annual soil loss of 4.22 tons per hectare. The DNN and CNN models were integrated with GIS for detailed calculation of annual average soil loss (tons per hectare per year) and mapping erosion risk areas in Wadi Sahel-Soummam watershed. Using the CNN model, estimated annual soil loss in Sahel-Soummam wadi was about 4.00 tons per hectare per year, while the DNN model estimated around 4.13 tons per hectare per year. This study employed two deep learning models for erosion prediction, with the DNN model featuring six hidden layers performing no-tably better than the compared CNN model.

Efficient Two-Way Coupled Analysis of Steady-State Particle-Laden Hypersonic Flows

A direct solution approach for surface erosion in particle-laden hypersonic flows is extended for use in low-cost two-way coupled solutions of dilute gas-particle flows. The trajectory control volume method, which uses a sparse set of probe particles to predict surface erosion distributions on general vehicles, is reformulated for the solution of source terms by mean trajectory subdivision and computing a flux differencing. The approach is verified successfully against a boundary-layer solution and shown to agree well with experimental measurements. A representative Mars entry case, with conditions and geometry based on the ExoMars Schiaparelli capsule, is solved with the approach to study the impact of two-way coupling on surface heating and erosion. Results indicate that, for realistic loading conditions, heating is largely unmodified compared to one-way coupled results at peak heating trajectory conditions, and no measureable difference is observed in the surface erosion rate. At exaggerated loading conditions high enough to observe coupling effects, the worst-case collisional heating can increase heating by up to 60%.

Experimental analysis of shock smoothing design strategy for reducing cavitation erosion aggressiveness

This article presents the experimental analysis of cavitation erosion for two cascade hydrofoil profiles. The aim is to evaluate the change in erosive intensity between a conventional smooth blade surface and one generated by the means of inverse design specifically to reduce cavitation aggressiveness. The applied design strategy consists in imposing a reduced amplitude and gradient at the cavity closure pressure jump in order to bring down the potential energy contained in the vapor sheet. The result is a unique geometry that presents a surface kink located at cavity closure, which successfully smoothes the pressure jump according to computational fluid dynamics (CFD) verification analysis. Here, an experimental rig is constructed and equipped with a pressure sensing system and high-speed imaging to capture the flow field. The measurements for both geometries are first compared against a set of steady-state CFD solutions, which demonstrate the reliability of the inverse design solver for generating targeted flow characteristics in non-cavitating and cavitating conditions. Visual recordings also reveal significant changes in the aspect of the vapor sheet between the two blades indicating a shift in its dynamic behavior. Erosion intensity levels are then measured by paint method at identical conditions. The outcome of the experiment is highly conclusive as a marked reduction in paint erosion is observed for the design geometry. The measured data also serve as a benchmark test for predictive cavitation erosion models by comparing the measured erosion distributions for each blade to those obtained numerically from unsteady CFD.

A study of sediment erosion of runner seal of a Francis turbine

Abstract Suspended sediment particles included in working fluid of hydro turbines often cause erosion and reduce reliability and lifetime of the hydro turbine. It is important for understanding and suppressing erosion problems to understand characteristics of two-phase-flows of liquid and solid particles. In the present study, experimental and numerical studies were carried out to understand mechanisms of erosion in runner seal of a Francis turbine. The experiments were carried out using small-scale seal models. Flow patterns were visualized using coated mica flakes to understand entire flow patterns and a particle image velocimetry were also carried out to measure velocity field in a meridional cross-section. Accelerated erosion tests were also carried out and it was observed similar erosion distributions to that was observed in the actual hydro-turbine. Numerical flow simulations were also carried out to examine mechanisms of the erosion, contributions of each forces acting on the particles and appropriate parameters to capture characteristics of liquid-solid flows and erosion distribution, which were observed in experiments.

Investigation of influencing factors of wear in a sandblasting machine by CFD-DEM coupling

In order to study the effect of particle characteristics and operating conditions (particle diameter, density, shear modulus, initial stacking height and inlet pressure) on the wear of the sandblasting machine, the gas-solid two-phase flow inside a sandblasting machine under different operating conditions was simulated by coupling the CFD and DEM methods in this work. Combining with the Archard wear model, the erosion was calculated and the erosion distributions were obtained in different sandblasting machine parts, including the top cover, inlet pipe, cylindrical part, conical part and lower pipe. The simulation results demonstrate that severe erosion in the sandblasting machine occurs at the lower pipe near the outlet, the conical part and the joints between different parts. The erosion volume order for different parts from high to low is: the lower pipe, conical part, cylindrical part, inlet pipe and top cover. The erosion volume of the sandblasting machine increases with the increase of particle diameter, density, shear modulus, stacking height and inlet pressure. Comparatively, the initial stacking height and inlet pressure have more influence on the erosion, while the particle density and shear modulus have less influence.

Modelling alpine glacier geometry and subglacial erosion patterns in response to contrasting climatic forcing

AbstractClimate exerts a primary control on glacier mass balance, driving changes in ice flux, which affects basal sliding and subglacial erosion. Although past glacier reconstructions have been widely used as paleo‐climate proxies, extracting quantitative temperature/precipitation data from paleo‐glaciers is still challenging. The iSOSIA ice model was used over a synthetic landscape to quantitatively investigate the non‐linear dependence of glacier geometry and ice dynamics on climate forcing, as well as to analyse how spatial patterns of subglacial erosion and erosion rates vary between the accumulation and ablation zones for different climatic settings. We performed 10 calibrated climatic scenarios with different combinations of temperature and precipitation rate in two separate sets of simulations [maintaining either same equilibrium line altitude (ELA) or same ice extent; SA and ST, respectively]. Our results reinforce the role of climate and the importance of ice flux in conditioning glacier geometry. In SA simulations, contrasting climatic scenarios showed a major influence on glacier length and thickness. In ST simulations, calibrated ELAs presented a variability of over 300 m in order to maintain similar ice extent, but showed reduced changes in glacier thickness. These results highlight the importance of ice flux to predict glacier geometry, when compared to the overall mass balance from an ELA estimate. Subglacial abrasion and quarrying showed notable differences between the accumulation and ablation zones for varying climatic forcing, with multimodal erosion distributions for increased precipitation/temperature, shifting erosion towards higher‐elevation tributaries and connecting erosion patches in the ablation zone. Such trends highlight the role of subglacial hydrology and ice‐bed contact (cavitation) in dictating patterns of subglacial erosion, while the depth of erosion relates closely to ice flux and climate inputs. Our results have potential implications for paleo‐climate reconstructions based on glacier geometry and provide insights on how subglacial erosion can help estimate paleo‐climatic conditions from paleo‐glacial records.

Impacts of Corn Straw Coverage and Slope Gradient on Soil Erosion and Sediment Size Distributions in the Mollisol Region, NE China

Impacts of Corn Straw Coverage and Slope Gradient on Soil Erosion and Sediment Size Distributions in the Mollisol Region, NE China

SPATIAL EVALUATION OF LAND AND SOIL PROPERTIES IN THE EXAMPLE OF NEVŞEHİR PROVINCE, TURKEY

In this study, some land and soil properties were spatially evaluated with the help of 1/25.000 scaled digital soil maps belonging to Center of province in the Central Anatolia Region, Turkey. Land use capability, large soil groups, soil depths, erosion, slope and spatial distributions of current land uses were carried out in the research. Arc GIS 10.3.1 software, which is one of the Geographic Information Systems (GIS) software, was used for spatial analysis. With a maximum of 262518 in the study area, VI. class lands. Class I cover an area of ​​247 . In terms of large soil groups, and soils are dominant and the area covered by these soils is 450187 . The least area was found to be reddish brown soils with 124 . It has been determined that the least area in the depth classes is A class (greater than 150 cm) soils. In the study area, it is the soil with the maximum C class (50-90 cm) depth. When the land was examined in terms of slope, it was determined that the land with the highest 3rd degree slope (12-20%) was formed. The research area consists of soil structure that can be exposed to the 2nd degree erosion class at most. When the current land uses are examined, it is the garden area with the least usage area in the region and the area it covers is 3400 . It has been observed that the most dry farming areas are located in the study area. It is thought that the results obtained as a result of the study will be the basis for the agricultural studies to be carried out in Center of province.

A novel approach for solid particle erosion prediction based on Gaussian Process Regression

Based on Gaussian Process Regression (GPR) method, a novel non-linear approach is adopted to predict solid particle erosion in standard elbows. Several data sets extracted from Computational Fluid Dynamics (CFD) results and experimental tests are used to evaluate the effectiveness of the approach for gas-solid as well as gas-liquid-solid flows. Elbow diameter, particle size and density, fluid density and viscosity, and flow velocity are considered as input parameters. By combining input parameters into dimensionless groups, dimensionality reduction is performed. This is conducted to understand the dimensionless numbers governing the erosion phenomenon and effect of dimensionality reduction on erosion prediction. Results and error analysis show that for gas-solid flow, over 80% of the predictions have relative error less than 20% compared to the experimental data. In gas-liquid-solid flow conditions, effect of mixture Reynolds number and ratio of the superficial velocities on erosion rate for both churn and annular flows are investigated. A GPR-based framework is demonstrated to predict erosion distributions over the elbow and results are compared with experimental measurements. Results demonstrate that the GPR approach can accurately and reliably predict solid particle erosion.

Uncertainty of Climate Change Impacts on Soil Erosion from Cropland in Central Oklahoma

Impacts of climate change on soil erosion and the potential need for additional conservation actions are typically estimated by applying a hydrologic and soil erosion model under present and potential future climate conditions. Projecting future climate conditions harbors several sources of uncertainty that, in turn, lead to uncertainty in projected soil erosion rates. Awareness of these uncertainties is essential to the development of flexible and affordable conservation and adaptation measures that remain effective over the broad range of climate projections. In this study, three climate-associated sources of uncertainties were selected to examine their effect on projected soil erosion for winter-wheat cropland in central Oklahoma. Forty soil erosion distributions representing various combinations of two emission scenarios, ten climate projection models (incl. downscaling), and two storm intensification alternatives were developed and evaluated. The total uncertainty range of 40 projected soil erosion distributions was 2.1 to 18.2 Mg ha&-1 yr&-1 at the median, and 25.0 to 114.0 Mg ha&-1 yr&-1 at the 10% Probability of Exceedance level. For the selected climate change scenarios, climate models, and Oklahoma climate conditions, the uncertainty due to imperfect prediction tools (climate models, downscaling methods) and model choices (storm intensification) was found to be sizably larger than the inherent uncertainty associated with the realization of a future climate outcome (emission scenario). It was concluded that uncertainties in projected soil erosion rates can potentially be large and should be given full consideration in planning future conservation needs.

Assessment of a numerical model to reproduce event-scale erosion and deposition distributions in a braided river.

Numerical morphological modeling of braided rivers, using a physics‐based approach, is increasingly used as a technique to explore controls on river pattern and, from an applied perspective, to simulate the impact of channel modifications. This paper assesses a depth‐averaged nonuniform sediment model (Delft3D) to predict the morphodynamics of a 2.5 km long reach of the braided Rees River, New Zealand, during a single high‐flow event. Evaluation of model performance primarily focused upon using high‐resolution Digital Elevation Models (DEMs) of Difference, derived from a fusion of terrestrial laser scanning and optical empirical bathymetric mapping, to compare observed and predicted patterns of erosion and deposition and reach‐scale sediment budgets. For the calibrated model, this was supplemented with planform metrics (e.g., braiding intensity). Extensive sensitivity analysis of model functions and parameters was executed, including consideration of numerical scheme for bed load component calculations, hydraulics, bed composition, bed load transport and bed slope effects, bank erosion, and frequency of calculations. Total predicted volumes of erosion and deposition corresponded well to those observed. The difference between predicted and observed volumes of erosion was less than the factor of two that characterizes the accuracy of the Gaeuman et al. bed load transport formula. Grain size distributions were best represented using two φ intervals. For unsteady flows, results were sensitive to the morphological time scale factor. The approach of comparing observed and predicted morphological sediment budgets shows the value of using natural experiment data sets for model testing. Sensitivity results are transferable to guide Delft3D applications to other rivers.

Simultaneous shadowgraph imaging and acceleration pulse measurement of cavitating jet

The variations of cloud structure and erosion characteristics of a cavitating jet are experimentally studied by optical and SEM microscope observations, measurement of erosion characteristics and simultaneous shadowgraph imaging combined with the acceleration pulse measurement. The time difference image analysis of the shadowgraphs allows the detection of the near-wall collapsed bubbles in the periodic development of the cavitating jet, while the simultaneous acceleration pulse measurement indicates the generation of acceleration pulses at the same instant of bubble collapse near specimen surface. These results indicate that the generation of acceleration pulses are highly correlated with the collapsed bubbles behind the cloud in the shrinking motion, which triggers the cavitation bubble collapse and leads to the erosion damage on the specimen. It is found from the image analysis that the erosion distributions on the test specimen are well reproduced in the time-difference images of the shadowgraphs, which indicates the sudden intensity growth near the wall due to the cavitation collapse. This result suggests that the collapse of the cavitation bubbles near the specimen surface is correlated with the erosion distribution on the specimen surface in the cavitating jet.

Numerical prediction of erosion distributions and solid particle trajectories in elbows for gas–solid flow

Erosion caused by particles in pipe bends is a serious problem in the oil and gas industry, which may cause equipment malfunction and even failure. The majority of this work studies the particle trajectories and erosion distributions in pipe bends under different influencing factors by using the computational fluid dynamics (CFD) method. A two-way coupled Eulerian-Lagrangian approach is employed to solve the gas–solid flow in the pipe bend. Eight commonly used erosion models and two particle-wall rebound models are combined to predict the erosion rate on the 90° elbows. The Det Norske Veritas (DNV) erosion model with the Forder et al. particle-wall rebound model is finally chosen as a sample to develop the new CFD-based erosion model after comparing with the experimental data. The accuracy of this presented model is assessed by the experimental data available in previous literature for a range of flow conditions. Good agreement between the predictions and experimental data is observed. Further, the erosion distributions and particle trajectories in pipe bends under different flow velocity, particle mass flow rate and mean curvature radius to diameter (R/D) ratio and pipe diameter are investigated by applying the presented model. The results show that totally two types of erosion scars and three types of particle collisions occur at the elbows with different erosion parameters. These two types of scars may occur alone or occur together due to the combined effect of the particle collisions. Finally, two equations for predicting the maximum erosion location are obtained considering the pipe bend orientation, the particle diameter and the R/D ratio.

Effect of placements (horizontal with vertical) on gas-solid flow and particle impact erosion in gate valve

Gate valve has various placements in the practical usages. Due to the effect of gravity, particle trajectories and erosions are distinct between placements. Thus in this study, gas-solid flow properties and erosion in gate valve for horizontal placement and vertical placement are discussed and compared by using Euler-Lagrange simulation method. The structure of a gate valve and a simplified structure are investigated. The simulation procedure is validated in our published paper by comparing with the experiment data of a pipe and an elbow. The results show that for all investigated open degrees and Stokes numbers (St), there are little difference of gas flow properties and flow coefficients between two placements. It is also found that the trajectories of particles for two placements are mostly identical when St « 1, making the erosion independent of placement. With the increase of St, the distinction of trajectories between placements becomes more obvious, leading to an increasing difference of the erosion distributions. Besides, the total erosion ratio of surface T for horizontal placement is two orders of magnitudes larger than that for vertical placement when the particle diameter is 250μm.