Erosion Model Research Articles

Sensitivity analysis of hydraulic erosion and calibration of the erosion coefficient

Hydraulic erosion may pose a threat to the safety and sustainability of geo-related infrastructure, yet quantifying the intricate process of hydraulic erosion still poses a significant scientific and technical challenge. One important step in meeting this challenge is the formulation of a hydraulic erosion model with the erosion coefficient as a central controlling parameter. Calibration of the erosion coefficient (or rate) remains one of the main obstacles to improving predictive modelling, particularly in scenarios lacking long-term laboratory test data. In this study, sensitivity analysis of the key erosion indicators on the parameters controlling hydraulic erosion is conducted. A novel calibration method for the erosion coefficient is presented based on sensitivity analysis. After validating against simulation results and laboratory test findings, the proposed calibration method is applied to a hypothetical long-term hydraulic erosion case. The results show that the maximum hydraulic erosion time is sensitive to all considered parameters (erosion coefficient, initial fraction of fluidized solid particle, initial porosity and maximum porosity), while the erosion curve shape is only sensitive to the initial porosity and the maximum porosity. The validation by existing simulation results shows that the proposed calibration method is robust and internally consistent. The validation by experimental results indicates that the proposed calibration method also has high external validity. Finally, the proposed calibration method is applied to hypothetical long-term erosion in a grouted area. The results show that the hydraulic erosion effect in the grouted area becomes increasingly severe over time. This study contributes toward a more efficient calibration of the erosion coefficient, especially for scenarios in the absence of testing porosity evolution data. The research outcome provides a theoretical foundation for the safety assessment and sustainability analysis of geotechnical structures that are subject to hydraulic erosion.

Empirical Model of Unconsolidated Tephra Erosion: Verification and Application on Micro Catchment

Erosion is an important process that shapes the earth's surface. Given the complexity of the process, efforts to understand it are essential. Over the last 50 years, numerous models of soil particle erosion by surface runoff emerged, some of which share similar forms and parameters. The differences lie in the coefficient values of the parameters, attributed to the characteristics of the soil material such as texture, structure, and organic matter content. However, these erosion models tend to underpredict in the case of new volcanic deposit erosion. The erosion model for unconsolidated tephra, proposed by Yunita, was developed through laboratory experiments using volcanic material from Merapi Volcano, Indonesia. Nevertheless, the model has not been implemented for other cases. Therefore, this study aims to verify the erosion model for volcanic material in other cases, explore the possibility of broader implementation, identify the factors that influence its accuracy, and determine the model’s limitations. To verify the model’s potential for broader application, we applied it to micro-scale catchments in St. Hellens (USA), Sakurajima (Japan), and a laboratory scale plot in Merapi (Indonesia). The verification yielded satisfactory results for all three cases, especially for new tephra deposits. In the case of St. Helens, the extrapolation of model coefficients was proven to still be applicable even for thicker tephra layers. However, the erosion prediction was overestimated for tephra layer deposits older than 1 year, as the erosion rate decreases over time due to the compaction and stabilization of the tephra layer. In the Sakurajima, the model was also suitable for predicting long-term erosion amounts (daily and monthly). Meanwhile, in Merapi, the model provided accurate predictions for slopes of 20º and 25º but was less accurate for 30º slopes, where the measured erosion was due to both erosion and slope failure. These verification results demonstrate the potential of applying the empirical erosion model to micro catchments with relatively homogenous slopes and tephra properties. The sensitivity test revealed that slope, runoff, rainfall intensity, and volcanic ash thickness are strongly influence the erosion rate. This study also simplified the volcanic ash erosion model as a function of slope (S0), runoff (q), and rainfall (i) by assuming the value of (1-τc/τ0) is equal to 1. Further study using GIS tools is required for its application on several catchments with heterogeneous characteristics. Doi: 10.28991/CEJ-2024-010-07-02 Full Text: PDF

Experimental study on surface erosion of Grade-A marine steel with different curvatures by ultra-high pressure water jet

To investigate the erosion mechanism and model of ultra-high pressure (200 MPa) water jet on grade–A marine steel with different curvatures. The ultra-high pressure water jet was induced by plunger pump. The dynamic strain was collected by dynamic strain gauge during impact to explore the mechanical effect. The microstructure was analyzed using three-dimensional topography and a scanning electron microscope. The results show that the average microstrains of samples with the curvature of 1/4 m−1, 3/4 m−1, and 5/4 m−1 impacted by ultra-high pressure water jet are 707, 952 and 1053, respectively, and the strain amplitudes are 300∼700, 300–600 and 300–560 respectively. The force exerted on the surface of the curved samples manifested as cyclic, pulsating, and alternating stress. With the curvature increase, the roughness decreases by 19.22%, 48.64%, and 21.31%, respectively. Meanwhile, surface damage, material removal, pits, holes, and cracks decrease. Finally, the erosion mechanism is clarified, and the erosion model of the ultra-high pressure water jet on grade–A marine steel with different curvatures is established.}

Synergy effects of cavitation and particle erosion based on the Erosion/Corrosion Research Center erosion model

This study presents a new synergy model that incorporates the accelerated motion of particles resulting from bubble collapse. The model uses the Erosion/Corrosion Research Center erosion model to predict the combined effect of cavitation and particle erosion on wall surfaces. The results show that, compared with the conventional erosion model, the synergy model reduces the error in the erosion mass loss by up to 24.60%. The significant improvement in prediction accuracy confirms the effectiveness of the synergy model. The severity of sample erosion is positively correlated with the cavitation-inducer angle. The synergy effect leads to an increase in the extent and severity of erosion. Smaller particles demonstrate a more pronounced synergy effect, resulting in significantly accelerated motion and a highly concentrated particle distribution. High erosion rates are associated with high-speed impacts and small-angle impact zones, primarily caused by high-speed cutting erosion. This study presents a novel prediction method for exploring the synergy effect of cavitation and particles on wall erosion and investigates the motion characteristics of particles under this effect.

Estimation of Soil Loss using Remote Sensing Data in a Regional Tropical Humid Catchment Area

Soil erosion has been and continue to be a major threat to environmental degradation especially in the developing countries. Accurate estimation of soil loss will provide reliable information in the management and mitigation solutions to soil erosion. In this study, the soil loss in an erosion prone Anambra State of South East region of Nigeria was estimated. Due to the complex nature of the catchment characteristics of Anambra State, soil loss cannot be estimated precisely by mere application of conventional soil erosion model. Hence a site-specific methodology was developed and applied. Revised Universal Soil Loss Equation (RUSLE) was integrated with the Geographic Information System (GIS) of the environment using remote sensing to build the model. 40-years rainfall data was collated from the Nigeria Meteorological Agency and analyzed. The various parameter of RUSLE which includes: Rainfall Erosivity (R), Soil Erodibility (K), Topography (LS), Land Use and Land Cover (C), and Erosion Control practices (P) were developed and imposed into ArcGIS 10.6 to estimate the amount of annual soil loss in the area. The result indicated that about 27.58km2 (0.59%) of the study area have very low erosion rate of 0 – 5 t ha1year-1 , while the rates of erosion in 1311.52km2 (28.01%), 538.59km2 (11.50%), 1649.08km2 (35.22%), 959.09km2 (20.48%), and 196.76km2 (4.20%) of the study area are 5–10, 10–15, 15–25, 25–50 and >50 t ha-1year-1respectively. This knowledge will help decision makers in managing the land degradation problems in Anambra State of Nigeria. Doi: 10.28991/CEJ-2024-010-07-014 Full Text: PDF

Dynamic Analysis of Changes in Jambu Riverbed and Banks: Case Study Around Cikuya Bridge

Several cross-sections of the Jambu River, particularly around the Cikuya Bridge, have experienced bank collapse phenomena. This paper interprets the issues related to bank collapse and its impact on the flow capacity of the Jambu River, especially around the Cikuya Bridge. Morphological changes were simulated using a sediment transport model implemented in the Hydrologic Engineering Center's River Analysis System (HEC-RAS) 6.3.1, integrated with the ARS-USDA Bank Stability and Toe Erosion Model (BSTEM). The simulation results indicate that over a period of 10 years, the thalweg elevation (the lowest point of a riverbed) of the Jambu River around the Cikuya Bridge is predicted to experience deposition in 17 cross-sections and erosion in 15 cross-sections. The highest deposition occurs at the cross-section below the Cikuya Bridge, with a thalweg elevation change of 0.59 m. This warrants attention as the storage capacity of the cross-section decreases by 7% from the initial condition. Predictions indicate that bank collapse will occur in 7 cross-sections over the next 10 years. This is attributed to the steep slopes of silt and clay banks, exceeding 45 degrees, and the reduced safety factor of bank stability due to groundwater pressure influenced by river discharge fluctuations and tidal effects reaching the Jambu River. Bank collapse impacts the elevation change of the riverbed and adds load to the sediment transport model from the collapsing cross-sections to the downstream sections. Keywords: Jambu River, Cikuya Bridge, Cilacap, sediment transport, bank stability and toe erosion model

Application of Remote Sensing for Identifying Soil Erosion Processes on a Regional Scale: An Innovative Approach to Enhance the Erosion Potential Model

Soil erosion represents a complex ecological issue that is present on a global level, with negative consequences for environmental quality, the conservation and availability of natural resources, population safety, and material security, both in rural and urban areas. To mitigate the harmful effects of soil erosion, a soil erosion map can be created. Broadly applied in the Balkan Peninsula region (Serbia, Bosnia and Herzegovina, Croatia, Slovenia, Montenegro, North Macedonia, Romania, Bulgaria, and Greece), the Erosion Potential Method (EPM) is an empirical erosion model that is widely applied in the process of creating soil erosion maps. In this study, an innovation in the process of the identification and mapping of erosion processes was made, creating a coefficient of the types and extent of erosion and slumps (φ), representing one of the most sensitive parameters in the EPM. The process of creating the coefficient (φ) consisted of applying remote sensing methods and satellite images from a Landsat mission. The research area for which the satellite images were obtained and thematic maps of erosion processes (coefficient φ) were created is the area of the Federation of Bosnia and Herzegovina and the Brčko District (situated in Bosnia and Herzegovina). The Google Earth Engine (GEE) platform was employed to process and retrieve Landsat 7 Enhanced Thematic Mapper plus (ETM+) and Landsat 8 Operational Land Imager and Thermal Infrared Sensor (OLI/TIRS) satellite imagery over a period of ten years (from 1 January 2010 to 31 December 2020). The mapping and identification of erosion processes were performed based on the Bare Soil Index (BSI) and by applying the equation for fractional bare soil cover. The spatial–temporal distribution of fractional bare soil cover enabled the definition of coefficient (φ) values in the field. An accuracy assessment was conducted based on 190 reference samples from the field using a confusion matrix, overall accuracy (OA), user accuracy (UA), producer accuracy (PA), and the Kappa statistic. Using the confusion matrix, an OA of 85.79% was obtained, while UA ranged from 33% to 100%, and PA ranged from 50% to 100%. Applying the Kappa statistic, an accuracy of 0.82 was obtained, indicating a high level of accuracy. The availability of a time series of multispectral satellite images for each month is a crucial element in monitoring the occurrence of erosion processes of various types (surface, mixed, and deep) in the field. Additionally, it contributes significantly to decision-making, strategies, and plans in the domain of erosion control work, the development of plans for identifying erosion-prone areas, plans for defense against torrential floods, and the creation of soil erosion maps at local, regional, and national levels.

Modeling soil erosion dynamic processes along hillslopes with vegetation impact across different land uses on the Loess Plateau of China

Developing a process-based soil erosion model that comprehensively considers the effects of vegetation is complex but crucial for evaluating sediment reduction during vegetation restoration. Current understanding of the effect of vegetation on sediment reduction along hillslopes across different land uses is limited. In this paper, we developed a dynamic model of hillslope erosion that integrates the effects of vegetation on soil detachability and hydrodynamics (VED) based on the feedback mechanism between soil detachment and sediment transport. The VED was calibrated and validated with runoff plot data for woodland, grassland, and farmland in the Wuding, Yan, Jing and Wei Rivers of the Loess Plateau in China. Unified baseline parameters and decay coefficients of vegetation were obtained. The model validation results indicated that the coefficient of determination, Nash–Sutcliffe simulation efficiency and relative error ranged from 0.59 to 0.99, 0.56 to 0.90, and −45.99 % to 46.36 %, respectively. The decay coefficients for soil detachment capacity (Φ), sediment transport capacity (Tc), and the sediment reduction effect of vegetation exhibited the following order: woodland > grassland > farmland. Compared with VED, existing process-based soil erosion models failed to effectively characterize the influence of vegetation on Φ and Tc on the Loess Plateau, with differences of several orders of magnitude. The individual contributions of runoff, soil detachability, and hydrodynamics with vegetation impact on sediment yield were quantified by VED. The contribution rates of vegetation to sediment reduction decreased gradually with increasing slope length because the soil detachment capacity of bare slopes exceeded that of vegetated slopes, resulting in a faster increase in sediment yield. The contribution rates of vegetation to sediment reduction for woodland, grassland, and farmland with 20 %–60 % vegetation covers were 66.75 %–99.95 %, 57.43 %–99.63 %, and 27.91 %–88.63 % in the boundary conditions of this study, respectively. The results reveal the potential for integrating VED into other distributed watershed hydrological and sediment models to assess the effects of vegetation restoration on sediment reduction at a watershed scale.

Determination of C-factor for conventional cultivation and soil conservation technique used in hop gardens

Abstract The research presented in the article was focused on determining the C-factor for hops for conventional cultivation (CT) and soil conservation technique, which is based on the presence of cover crops (CC) in the inter-rows. The values of the soil loss ratio, which are the basis for the calculation of the C-factor, are also presented. The research activities were carried out between 2016 and 2023 and a field rainfall simulator was used for the measurements. Rainfall simulations were conducted at three developmental stages of CC. The results show a high C-factor value for CT (0.73), which indicates insufficient erosion control efficiency. In contrast, a C-factor of 0.16 was determined for the cover crop technique. This means that cover crops in the inter-rows of hop gardens can effectively reduce the risk of water erosion. The values reported in the article can be used as input parameters in various erosion models and equations to refine the subsequent calculation.

Współczynnik erozji gleby przy użyciu wielospektralnych wskaźników roślinności: Przykład zlewni rzeki Sarayardere (wschodnie Rodopy, Bułgaria)Wpływ zmian klimatu na środowisko zbudowane

Land cover/land use is one of the main factors influencing the development of soil erosion. It has been included in the calculation and modelling of erosion and sediment transport in many studies. In the current research NDVI (normalized difference vegetation index) and NDRE (normalized difference red edge index) are used for quantifying the cover management factor (C-factor). They are calculated on the base of Sentinel 2 multispectral images. Taking into account the vegetation phenology two time points were analyzed: end of May - June – active vegetation and September (beginning of October) – late vegetation. The changes in the values of the indices were considered for 2018, 2021 and 2022. The study area is the watershed of the river Sarayardere, located in the southern part of Bulgaria. This is a hilly to low-mountain area, prone to erosion due to rare vegetation, high slope gradients and a relatively long dry period followed by intensive rainfall. The calculated values of the C-factor are indicators for higher susceptibility to erosion in September than it is in June. The spatial distribution of the C-factor shows different patterns. The results, received on the base of the image of September 2021, show increasing the areas with C-factor < 0.1 and these ones > 0.5, in comparison with the results of September 2018. C-factor values calculated on the image of October 2022 indicate the highest susceptibility to erosion. Using NDRE instead NDVI results in slightly higher values of the C-factor. The advantage of the NDRE index is that it provides information on the content of chlorophyll in the vegetation during the end of the vegetation period and allows a more accurate assessment of the state of the separate plants, regarding the determination of diseased or damaged plants. In addition to the vegetation indices, an expert evaluation of the state of vegetation was done. The results of the current study show that the watershed of the river Sarayardere is in a relatively good condition regarding the development of erosion processes. The attention should be directed to the possible increase of erosion on deforested slopes and the availability of loose materials, in case of intense rainfall.

Integrating Erosion Models Into Land Health Assessments to Better Understand Landscape Condition

Wind and water erosion can severely impact natural resources and ecosystem services, making soil erosion management essential to sustaining agroecosystems. Land health assessment protocols, such as Interpreting Indicators of Rangeland Health (IIRH), provide valuable information to make decisions on managing soil erosion in vulnerable drylands. Using quantitative erosion models with land health assessments can further inform management decisions. For example, sediment transport estimates from the Aeolian EROsion (AERO) model and Rangeland Hydrology and Erosion Model (RHEM) can help in understanding the impacts of differences in soil and vegetation on wind and water erosion risk. In this article, we provide a conceptual basis for using AERO and RHEM to support IIRH assessments that are used extensively by managers across United States rangelands. We describe how using erosion models with IIRH can (1) improve understanding about potential erosion rates for different types of storm events; (2) support identifying areas at risk of erosion where erosion evidence is not (yet) significant; (3) increase land health assessment consistency by providing reproducible erosion indicators; (4) provide another line of evidence to support assessment conclusions about land health; and (5) improve understanding about potential erosion rates across ecologically similar sites and over time. Effectively using erosion models to support land health assessments will improve wind and water erosion management in drylands, thus helping to protect and restore these ecosystems.

Validation of the ERO2.0 code using W7-X and JET experiments and predictions for ITER operation

The paper provides an overview of recent modelling of global material erosion and deposition in the fusion devices Wendelstein 7-X (W7-X), JET and ITER using the Monte-Carlo code ERO2.0. For validating the modelling tool in a three-dimensional environment, W7-X simulations are performed to describe carbon erosion from the graphite test divertor units, which were equipped in operational phase OP 1.2 and analysed post-mortem. Synthetic spectroscopy of carbon line emission is compared with experimental results from the divertor spectrometer measurement system, showing a good agreement in the e-folding lengths in the radial intensity profiles of carbon. In the case of metallic wall materials, earlier modelling of the Be/W environment in JET and ITER is revisited and extended with an updated set of sputtering and reflection data, as well as including the mixing model for describing the Be/W dynamics in the divertor. Motivated by recent H/D/T isotope experiments in JET, limited and diverted configuration pulses are modelled, showing the expected trend of both Be and W erosion increasing with isotope mass. For the JET diverted configuration pulses, it is shown that Be migrates predominantly to the upper part of the inner divertor where it initially leads to strong W erosion. With longer exposure time, the growth of a Be deposited layer leads to a reduction of W erosion in that region. A similar trend is observed in simulations of the ITER baseline Q = 10 scenario, however with a more symmetric Be migration pattern leading to deposition also on the outer divertor.

Multiphase flow and nozzle wear with CFD-DEM in high-pressure abrasive water jet

The issue of wear failure in High-Pressure Abrasive Water Jet (HP-AWJ) nozzles is an unavoidable challenge, and studying methods to enhance and predict the effective lifetime of nozzles is worth deep exploration. This paper employs a CFD-DEM coupling numerical approach to investigate wear phenomena inside the HP-AWJ nozzle, aiming to capture the realistic particle wear and erosion failure issues at the focusing tube region, which is a high-wear area of the HP-AWJ nozzle. Furthermore, the study considers realistic particles and nozzle wall constitutive models, incorporating material properties into the physical model, and employs computer-aided design methods to reflect wear failure conditions at different time intervals in the inner wall of the focusing tube at the nozzle. The results demonstrate that the number of realistic particles and initial inlet velocity has no impact on the particle exit kinetic energy. However, the particle-wall restitution coefficient affects the average particle kinetic energy at the outlet in the AWJ nozzle. The equivalent model of the realistic particles reflects the influence of the particle roundness on particle kinetic energy, acceleration, and stress concentration variations in the nozzle. These variations further affect the particle erosion rate on the nozzle wall and the actual wear failure problems on the wall surface. Finally, by combining the proposed erosion and wear model, a representative erosion profile at the AWJ focusing tube location comparable to experimental results is obtained, and the wear depth of the focusing tube changing with time is also studied. The results and methodologies presented in this paper provide valuable guidance for controlling the effective service lifetime of the AWJ nozzle, improving machining efficiency, and extending the lifespan of the AWJ nozzle.

Post-fire soil erosion: Two years of monitoring − First time detected implications between extremely intense consecutive rainfall events and erosion rates

The research was carried out in one of the most important suburban forests of Greece, after a wildfire (2021). The objectives include the estimation of the annual soil erosion, the effect of extremely intense and consecutive rainfalls on erosion process, the correlation among erosion, rainfall intensity and other factors. To monitor soil erosion in burned and unburned areas, erosion measurements were obtained installing silt fences. The results showed that the main factor affecting annual erosion is the presence or not of vegetation. Rainfall intensity is a major determinant of erosion, especially when it exceeds 6–7 mm/30 min. However, it was revealed that erosion does not increase significantly in burned areas, despite the increase of rainfall intensity. In unburned area the erosion was significantly increased, above a rainfall intensity threshold (>10 mm/30 min). For the first time, it was shown that in cases of two consecutive and very heavy rainfalls, the second and more intense rain caused significantly lower erosion than the first one. A 690 % average increase in R factor during the 2nd storm, showed an average decrease in soil erosion of 20 % (burned and unburned areas). The present study also revealed that the high increase of R factor in the 2nd post-fire year did not trigger a significant increase of soil erosion, since the extreme erosive events occurred very close to each other in time. These findings highlight that the use of R factor in RUSLE, to calculate the annual erosion in burned or unburned areas, detached from the respective field data establishment to validate the model, involves high uncertainties, which could possibly result in wrong erosion rates calculations. Researches and stakeholders, who use the R factor in erosion modeling, should previously examine in detail the exact dates of erosive events, before the implementation of the erosion model.

Impact of extreme rainfall events on soil erosion on karst Slopes: A study of hydrodynamic mechanisms

As global warming intensifies, frequent extreme rainfall events cause severe soil erosion. ​However, the impact of extreme rainfall on erosion on karst slopes and its hydrodynamic mechanisms are still poorly understood. This study aims to examine how extreme rainfall events and slope gradient affect soil erosion on karst slopes and its underlying dynamic mechanisms. Simulation experiments were performed in a steel tank that mimicked the dual hydrological structure of a karst slope, using various rainfall intensities (50, 105, 115, 125, and 145 mm·h−1) and slope gradients (5°, 15°, and 25°). The results show that in the event of extreme rainfall (105 – 145 mm·h−1), there was a substantial increase in the surface runoff coefficient, rising from 48.85 % to 89.79 %, representing an 83.81 % increase. Surface erosion was found to be the predominant factor on the slope, contributing to 98.74 % to 99.98 % of the overall sediment output, while underground sediment coefficient ranged from only 0.02 % to 1.26 % under same conditions. The unit stream power emerged as the most suitable hydrodynamic parameter for characterizing surface sediment yield (SS), with a critical threshold of unit water flow power for surface erosion identified at 0.006 m·s−1. Constructing a surface erosion model (R2 = 0.969) based on runoff velocity, rain intensity, and slope yields higher accuracy than the model (R2 = 0.966) based solely on runoff modulus, rain intensity, and slope. For the most precise predictions, it is recommended to combine runoff modulus and velocity with rainfall intensity and slope when constructing the surface erosion prediction model(R2 > 0.999). This study enhances understanding of extreme rainfall’s effect on soil erosion in karst slopes and backs the creation of prediction models for such events. Our insights offer fresh perspectives for soil and water conservation, aiding in the formulation of precise erosion control strategies for karst slopes.

Predicting the coupling effects of grass and shrub with biological crust on splash and sheet erosion

Vegetation plays an important role in preventing soil erosion in arid and semi-arid regions. However, the current research on soil erosion under vegetation conditions neglected the role of biological crusts (BSC). The impact of different combinations of grass and shrub vegetation with BSC on the soil erosion process were investigated in this study through indoor simulated rainfall experiments and field experiments. Additionally, the calculation formula for the splash and sheet erodibility coefficients (KSS) in the Rangeland Hydrology and Erosion Model (RHEM) model was revised and validated. The results showed that the ability of BSC to reduce erosion was gradually enhanced with an increase in BSC coverage. The significant erosion reduction effect of BSC under different vegetation coverages was found. As the BSC coverage increased to 40 %, the soil erosion process changed from transport-limited to detach-limited. When grass and shrub was combined with BSC, the average flow velocity was smaller than that of the individual vegetation treatments. Moreover, the proportion of BSC resistance was the highest among the various vegetation combinations consistently. When the coverage of the combined BSC exceeded that of the vegetation, the BSC dominated the soil erosion process through its direct physical protection and indirect alteration of soil properties. When the BSC coverage was incorporated into KSS, the determination coefficients of the revised KSS were all above 0.8. This study deepened the understanding of the coupling effects of grass and shrub with BSC on slope erosion processes, and improved the predictive accuracy of the RHEM model.

Transverse vibration analysis and active disturbance rejection decoupling control of rain erosion whirling arm

The transverse vibration caused by the mass eccentricity of the whirling arm and the unbalanced magnetic pull of the motor rotor is a critical factor that affects the stability and safety of the rain erosion whirling arm. To investigate the transverse vibration characteristics of the rain erosion whirling arm during operation, a four-degree-of-freedom transverse vibration model of the rotor-rain erosion whirling arm is established using the lumped mass method. The differential equation of motion of the rotor-rain erosion whirling arm, considering the influence of mass eccentricity and unbalanced magnetic pull, is then established based on the Lagrange equation. This equation is numerically solved using the Runge-Kutta algorithm to investigate the axis trajectory and amplitude distribution of the rotor-rain erosion whirling arm. To reduce the fatigue damage caused by vibration, the active disturbance rejection decoupling control method is employed. Furthermore, the parameters of the extended state observer are adjusted using pole assignment and bandwidth. The simulation results reveal that the vibration amplitude of the rotating blade can be reduced to within 0.2 mm, referring to the BSS7393 test standard. Additionally, experimental research is conducted to compare the vibration of the rain erosion whirling arm before and after implementing the active disturbance rejection decoupling control. The results demonstrate that the active disturbance rejection decoupling control method effectively suppresses the vibration of the rain erosion whirling arm, illustrating its feasibility and effectiveness for system vibration control.

A comparative study on the modeling of soil erosion by USLE, RUSLE, and USPED

ABSTRACT Soil erosion is considered to be a prominent problem, and its regular spatial assessment in the watershed is required. Thus, for the present study, the Kodar river basin in Chhattisgarh, India, was chosen for the investigation. Three different models, namely Universal Soil Loss Equation (USLE), Revised Universal Soil Loss Equation (RUSLE), and Unit Power-Based Soil Erosion and Deposition (USPED), were chosen by incorporating remote sensing and GIS platforms and their performance were compared. On the basis of area’s varied slope and land usage, the erosion rate was calculated. It was noted that a difference of 33,68632 t, −11570.08 t, and 1023.99 t in the sedimentation values of the USLE, RUSLE, and USPED models, respectively were observed. The observed sedimentation data was validated, and the USPED model was found to be the most authentic model among the selected three models. Hence, the present study will be helpful in better understanding of the complex interactions of the variables involved in predicting net erosion of soil.

Improving the reliability of using rare earth elements as soil erosion tracers

Rare earth elements (REEs) have been successfully used as tracers in field-scale erosion experiments to provide spatially distributed erosion data for process-based soil erosion models. This study aimed to demonstrate how differences in the erodibility of individual REEs naturally present in the soil affect the evaluation of data from such experiments.A four-year field experiment was carried out at an experimental site used for arable farming to investigate soil erosion. The concentrations of tracer REEs (Pr, Sm, Gd, Ho, Er, and Yb) and reference REEs (all other REEs) were evaluated and compared both in the soil and eroded sediment.The tracer REE concentrations in the eroded sediments were consistently significantly higher than the average background soil concentrations. Even when compared with the maximum values of background soil concentrations, enrichment of Er, Sm, and Ho in the sediment was still evident. However, in some cases, the reference REE concentrations in the sediment were often higher than the maximum soil background concentrations by more than 10%. These enrichment differences indicate the varying erodibility of individual REEs during erosion. The elements chosen as tracers could also be enriched in the sediment from their natural background sources, thus influencing the measured concentration values in the sediment after tagging.This study demonstrated that different REEs naturally present in soil exhibit varying degrees of erodibility, which affects data evaluation in soil erosion tracing experiments using REE oxides as tracers. Therefore, the reliable application of the REE tracer method can only be suggested under certain requirements defined in this study.

Erosion behaviors and mechanisms of Ti3AlC2 material under arc discharge in various mixed atmospheres

The present study establishes an experimental platform for investigating arc erosion and explores the erosion characteristics of Ti3AlC2 material under a voltage of 10 kV in SF6/N2, SF6/CO2, and N2/CO2 environments. Our findings reveal that the arc energy and duration exhibit a gradual increase in the sequence of SF6/N2, SF6/CO2, and N2/CO2, while the breakdown strength decreases. Scanning electron microscopy (SEM) and a three-dimensional laser confocal microscope were employed to observe uneven erosion morphology. Additionally, high-speed camera footage captures the arc bending and drifting phenomenon caused by Rayleigh-Taylor instability between the arc and gas. X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analysis were utilized to characterize the composition of eroded surfaces. Erosion models were proposed for each mixed atmosphere along with comprehensive discussions on their underlying mechanisms. This work expands the application scope of MAX phase materials while providing a theoretical foundation for designing electrical contact materials.