Erosion Prediction Research Articles

Particle size distribution effects on cavitation erosion in sediment suspensions

Synergistic cavitation–particle erosion often occurs in high-speed sediment-laden flow in hydraulic structures and machines. However, erosion prediction is challenging due to the unclear relationship between erosion and the characteristics of sand- and silt-sized sediments, particularly the sediment particle size distribution (PSDS). In this study, vibratory erosion tests for carbon steel were conducted in suspensions of continuously graded sand–silt mixtures, and the influence of PSDS characteristics, such as the number of modes and sand-to-silt ratios, was investigated. The results indicated that both the total sediment concentration and PSDS parameters had a major impact on synergistic erosion. The changes in the PSDS patterns resulted in different erosion behaviors, even when the sand and silt concentrations were fixed. Based on the viscosity-enhancing effects of silt particles and the impinging effects of sand particles, a new theoretical model for determining the particle impact energy was developed by incorporating PSDS. A deeper understanding of the influence of PSDS and the application of the PSDS-based model can help predict and prevent synergistic erosion.

Isolating climatic, tectonic, and lithologic controls on mountain landscape evolution.

Establishing that climate exerts an important general influence on topography in tectonically active settings has proven an elusive goal. Here, we show that climates ranging from arid to humid consistently influence fluvial erosional efficiency and thus topography, and this effect is captured by a simple metric that combines channel steepness and mean annual rainfall, ksnQ. Accounting for spatial rainfall variability additionally increases the sensitivity of channel steepness to lithologic and tectonic controls on topography, enhancing predictions of erosion and rock uplift rates, and supports the common assumption of a reference concavity near 0.5. In contrast, the standard channel steepness metric, ksn, intrinsically assumes that climate is uniform. Consequently, its use where rainfall varies spatially undermines efforts to distinguish climate from tectonic and lithologic effects, can bias reference concavity estimates, and may ultimately lead to false impressions about rock uplift patterns and other environmental influences. Capturing climate is therefore a precondition to understanding mountain landscape evolution.

Sustainability Analysis of Soil Erosion Control in Rwanda: Case Study of the Sebeya Watershed

Soil erosion is a complex process that results in soil and fertility losses from agricultural land and, ultimately, leads to river sedimentation. This study aimed to assess various influential factors and processes affecting soil erosion and to recommend suitable site-based Soil Erosion Control Measures (SECM) for sustainable agriculture while minimizing the downstream rivers and reservoir sedimentation in the Sebeya watershed of Rwanda. The present research used a literature review, site visits, and focus groups to assess various SECM within the Sebeya watershed. As a result, various site-based SECM were evaluated, recommended, and simulated to alleviate high soil loss rates in the Sebeya watershed using the Universal Soil Erosion Equation (USLE) model. Simulating existing and proposed SECM, soil loss was reduced significantly from 73 t/ha/y to 29 t/ha/y. To highlight the implication of the site-based recommended SECM in improving agricultural productivity, this study suggests field investigations in soil erosion plots and prediction of crop yields from an established linear correlation model between soil loss and crop yields in the Sebeya watershed. For effective action in reducing high soil erosion rates to tolerable rates in the Sebeya watershed, the present research recommends implementing the site-based recommended SECM with mulching and drainage channels on the same farmland. However, lack of money and knowledge are the main limitations in implementing SECM in the Sebeya watershed. Therefore, governmental and non-governmental organizations should technically and financially help farmers in the Sebeya watershed.

Evaluating the applicability of the water erosion prediction project (WEPP) model to runoff and soil loss of sandstone reliefs in the Loess Plateau, China

Soil erosion is one of the most serious environmental issues, especially in vulnerable areas such as the Pisha sandstone regions located in the Loess Plateau (China). In these types of reliefs, long-term studies monitoring runoff and soil loss are scarce, and even more considering the efficiency of different soil management techniques applied to reduce land degradation. In this study, seven years (2014–2020) of in-situ measurements of surface runoff and soil loss for different land uses (forestland, shrubland, grassland, farmland, and bare land) in a Pisha Sandstone environment at the Loess Plateau were conducted. We applied the Water Erosion Prediction Project (WEPP) model combining the large database with the precipitation regimes. Our results showed that runoff volume coming from observed and simulated data exhibited significant differences among them depending on the different vegetation types. Runoff and soil loss were different among diverse land use types as follows: farmland > grassland > shrubland > forestland. After conducting a calibration, we found satisfactorily simulated surface runoff and sediment yield based on precipitation regimes and land uses at sandstone reliefs. Simulation performance of surface runoff was better than sediment yield. The range of standard error of the model simulation for event and annual values of runoff were 4.71 mm and 12.19 mm, respectively. The standard error for event and annual values of soil loss were 4.19 t/hm2 and 21.86 t/hm2. In the calibration group, R2 of runoff and soil loss were 0.92 and 0.86 respectively, while Nash-Sutcliffe coefficient (E) reached 0.90 and 0.85, respectively. In the validation group, the R2 for both runoff and soil loss were 0.82 and 0.56, respectively. Nash-Sutcliffe coefficient (E) were 0.77 and 0.54 for the runoff and sediment yield. We concluded that using a detailed monitoring dataset, the WEPP model could accurately simulate and predict water erosion in the hillslopes of Pisha sandstone area.

Impacts of slope morphological evolution on subsequent erosion for a coarse-textured soil

Assessing impacts of erosion-induced slope morphological evolution on subsequent erosion based on erosion feedback system is crucial for prevention and control of slope erosion in coarse-textured soil regions. This work aimed to reveal the effect of the evolving erosion morphology on subsequent erosion processes on the granite red soil slope through quantitative analysis. Specifically, we achieved it by conducting long-duration (120 h) simulated rainfall experiments under constant rainfall intensity of 90 mm h−1 and fixed slope gradient of 16.7 % on the soil flume packed with granite red soils to simulate field slope. Results showed that (1) with the evolution of erosion, three erosion phases (sheet erosion, rill erosion, and ephemeral gully erosion phases) varied as the dominant erosion forms; (2) with erosion development, the coverage of quartz gravels enriched on the slope surface increased first (4.60 %-49.17 %), followed by a trend of dynamic erosion–deposition equilibrium (47.68 %-56.74 %); (3) the quartz gravel cover on the surface restrained the slope erosion degree, resulting in loss of fine particles and erosive-reduction in vertical depth of inter-rill and sheet erosion areas; (4) quartz gravels entering the channels inhibited downward erosion, forcing the runoff to intensify lateral erosion, leading to gradual degradation of soil layers and the exposure of erodible subsoils under an accelerated trend. This work provides a reference for the prediction and control of slope erosion in granite red soil regions.

Measuring and Modeling Impacts of Gravel Road Design on Sediment Generation in the Southeastern U.S.

Highlights The erodibility of heavily trafficked gravel roads can be much greater than that of low volume forest roads. Improved designs of heavily trafficked gravel roads can decrease sediment generation by more than 90 percent. The WEPP Model can be successfully parameterized for high traffic gravel roads to reflect the effects of weather, road design, and topography. Abstract. The purposes of this study were to support a watershed modeling analysis by evaluating the ability to the Water Erosion Prediction Project (WEPP) model to estimate sediment generated by high traffic gravel roads, and to determine the erodibility of two designs of high-traffic gravel roads. In many watersheds, the road network can be a major source of sediment. The ability to predict erosion from roads, evaluate the effects of design and management on road sedimentation, and compare sediment from roads to other sources of sediment in the watershed is an ongoing need by watershed managers. The Water Erosion Prediction Project (WEPP) model is a widely used model for predicting sediment from forest roads. There has, however, been little information published on erosion from high traffic gravel roads and WEPP applications to such roads. To evaluate road erosion predictions, a study was conducted incorporating two road designs at Fort Benning, Georgia, U.S. One design followed a common practice of starting with a native material road and adding gravel and grading as required. Erosion and rutting on the road surface were common occurrences on this type of road. The improved design was a “graded aggregate base” design, built with compacted aggregate layers. To evaluate erosion risks for these two road designs, runoff and sediment delivery were measured from ten plots ranging in size from 63 to 150 m2. Runoff depths up to 50 mm occurred from daily rainfall amounts up to nearly 60 mm, with least square mean event runoff values of 6.5 mm from unimproved plots and 14.9 mm from improved road plots. Delivered sediment ranged from zero to 18 Mg ha-1 from individual storms with least square mean amounts of 2.27 Mg ha-1 of sediment delivered from unimproved road plots compared to only 0.026 Mg ha-1 delivered from improved road design plots for a given runoff event. Hydraulic conductivity was found by calibration to be 3.0 mm h-1 for unimproved roads and 1.3 mm h-1 for improved road segments. Rill erodibility was 0.09 s m-1 for unimproved roads and 0.0008 s m-1 for improved roads, values that were greater than had been measured on road erosion studies elsewhere that were typically less than 0.0004 s m-1. The critical shear for the unimproved roads was the minimum that the WEPP model would accept, 0.0001 Pa, but was a more typical value of 1.5 Pa for the improved road segments. When applying the calibrated erodibility values to a validation data set, the Willmott indices of agreement were 0.62 and 0.82 for runoff for unimproved and improved roads, respectively, and 0.67 and 0.66 for sediment delivery from unimproved and improved roads, respectively, indicating good agreement between observed and WEPP-estimated runoff and erosion rates. A sensitivity analysis and calibration analysis found that the WEPP model was not sensitive to interrill erosion for this application. A sensitivity analysis coupled with a WEPP validation analysis showed that WEPP could incorporate weather, topography, soil, and road design features to predict sediment delivery from highly erodible road segments. The study suggests that there is a need for a simulated runoff study to determine high values of rill erodibility more precisely on unimproved high traffic roads, and that there is a need to incorporate more erodible road erodibility values into the online WEPP:Road interface for the WEPP model. The road erosion rates and effectiveness of improved road designs for reducing off-road sediment reported in this study will be useful to managers seeking to quantify and reduce road erosion rates from high-traffic gravel roads in sensitive watersheds. Keywords: Erodibility, Gravel Roads, Soil Erosion, WEPP.

Outer cortex thyroid cartilage invasion vs gross extrathyroidal extension in T4a carcinoma larynx: Are they the same entity?

We read the article by Dwivedi et al.[1] with great interest. In the past, total laryngectomy was considered the gold standard treatment for carcinoma larynx regardless of the stage. As the science of conservation laryngectomy, and organ preservation by non-surgical modalities[2] has evolved, total laryngectomy was deemed suitable for very advanced, i.e., T4a lesions of the larynx. T4a is any erosion of the outer cortex of the thyroid cartilage or beyond. This outer cortex erosion can be minimal or gross with soft tissue involvement. The accuracy of computed tomography for detecting gross extrathyroidal extension will obviously be 100%.[3] Now, the question arises as to how to accurately identify early outer cortex erosion of the thyroid cartilage when there is no soft tissue involvement. Guo et al.[4] have beautifully described the computed tomography-based radiomics features for the prediction of thyroid cartilage erosion in laryngeal cancer. A mention of the cases of early outer thyroid cartilage erosion in the study by Dwivedi et al.[1] and their true detection on histopathology would have been appreciated. Of the 30 patients included in this study, nine patients had T2 disease and four had T3 disease. As all patients included in the study underwent total laryngectomy, could they have been offered organ preservation, either medically or surgically? Additionally, the role of computed tomography scans in accurately identifying outer cortex erosion with gross extrathyroidal extension in patients who are post-chemoradiation should be carefully assessed, in view of post-chemoradiation changes in the larynx. Magnetic resonance imaging and a positron emission tomography-computed tomography scan would be valuable to help differentiate edema from tumor in the salvage setting. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Prediction of cavitation dynamics and cavitation erosion around a three-dimensional twisted hydrofoil with an LES method

The Large Eddy Simulation (LES) method coupled with a Schnerr and Sauer cavitation model was adopted to simulate the unsteady cavitating flow around a Delft Twist 11 (Twist11) hydrofoil. We proposed a novel aggressiveness indicator to predict the risk of cavitation erosion on the hydrofoil surface by utilizing LES simulations as input. The proposed aggressiveness indicator introduces the time-averaged pressure, the hypotheses of Nohmi et al. and the concept of the power exponent into the energy balance approach. The results show that the current numerical method integrally reproduces the evolution of the cloud cavity observed in the cavitation tunnel. The cavitation erosion risk predicted by the aggressiveness indicator ⟨e1⟩n=5′ agrees well with the erosion pattern obtained from the paint test. The predicted erosion risk regions are located in the “hoof” positions (region 2 and region 3) of the horse-shoe-shaped cloudy cavity and the positions (region 1) near the cavity closure line.

WEPP interrill erodibility for clay soils in the crop lands of Northern NSW and Southern Queensland, Australia

Context Water Erosion Prediction Project (WEPP) soil erosion model parameters are rare for cultivated cropping soils in Australia. Aims Measure WEPP interrill erodibility (Ki) for cropping soils. Methods Plots were 50% side-slopes of row-crop furrows. Rainfall was applied for 30 min at 107 mm h−1 under a rainfall simulator, then at higher and lower rainfall intensities for 10 or 6 min. Several of these rainfall sequences were performed with drying between (events). Runoff, sediment concentrations and sediment sizes in runoff and the soil surface after rain and sediment settling velocities were measured. Soils were well-aggregated Vertosols and a Dermosol: clay 31–69%, silt ~20%. Settling velocities and undispersed particle size distributions for rainfall wet soil are provided for a range of soils in Supplemental Data, for use by WEPP users. Key results Runoff during 30 min and 54 mm of rain was 28–44 mm or 50–86% rainfall. Soil losses were 26–61 t ha−1 and sediment concentrations 67–127 g L−1. Infiltration, runoff, sediment concentration and soil losses were sometimes different for soils and events. Gatton and Emerald soils had lower soil losses and Cecilvale, Mywybilla and Narrabri soils had higher soil losses. Conclusions Mean Ki for Emerald and Gatton soils were significantly lower, 2 960 000 and 3 209 600 kg.s m−4, respectively. Ki values were not significantly different for the Cecilvale, Narrabri and Mywybilla soils, 3 900 000 kg.s m−4. Implications WEPP Ki values were like values found for USA cropping on clay soils. Sizes in the soil surface and sediment, and settling velocity distributions, were similar between soils but sediment sizes were finer.

The effects of typical grass cover combined with biocrusts on slope hydrology and soil erosion during rainstorms on the Loess Plateau of China: An experimental study

AbstractBiological soil crust (BSC), as a groundcover, is widely intergrown with grass. The effects of grass combined with BSCs on slope hydrology and soil erosion during rainfall are still unclear. In this study, simulated rainfall experiments were applied to a soil flume with four different slope cover treatments, namely, bare soil (CK), grass cover (GC), BSC, and GC + BSC, to observe the processes of runoff and sediment yield. Additionally, the soil moisture at different depths during infiltration was observed. The results showed that the runoff generated by rainfall for all treatments was in the following order: BSC > GC + BSC > CK > GC. Compared with CK, GC promoted infiltration, and BSC inhibited infiltration. The BSCs obviously inhibited infiltration at a depth of 8 cm. When the rainfall continued to infiltrate down to 16 and 24 cm, the effects of grass on promoting infiltration were stronger than those of BSCs on inhibiting infiltration. Compared with CK, the flow velocity of the BSC, GC and GC + BSC treatments was reduced by 62.8%, 32.3% and 68.3%, respectively. The BSCs and grass increased the critical shear stress by increasing the resistance. Additionally, the average sediment yield of GC and both treatments with BSCs was reduced by 80.8% and >99%, respectively, compared with CK. The soil erosion process was dominated by the soil detachment capacity in the CK, BSC and GC + BSC treatments, while the GC treatment showed a transport‐limited process. This study provides a scientific basis for the reasonable spatial allocation of vegetation in arid and semiarid areas and the correction of vegetation cover factors in soil erosion prediction models.

Gully erosion prediction method from geoenvironmental data and supervised machine learning techniques

Predictive models are statistical representations that indicate, based on the historical data analysis, the probability of triggering a given phenomenon in the future. In geosciences, such models have been essential to predict the occurrence of adverse phenomena commonly associated with environmental disasters, such as gully erosion. Therefore, this paper presents a method for producing gully erosion predictive models based on geoenvironmental data and machine learning techniques. The method's effectiveness test was produced in a region of approximately 40,000 km² in southeastern Brazil and compared the predictive performance of four models designed with different machine learning algorithms. The results demonstrated that the technique is capable of producing models with high predictive ability, with emphasis on the random forest algorithm, which, in addition to having achieved the highest levels of accuracy, also produced highly realistic maps for the study area.•The method is straightforward and may be applied to predict other geological processes.•The application of the method does not require knowledge of programming language.•The models produced achieved high predictive performance.

Estimating WEPP Cropland Erodibility Values From Soil Properties

Highlights Very fine sand is the single most important variable for predicting rill and interrill erodibility values. Slope steepness is the most important property for predicting critical shear for rill erosion. Erodibility prediction equations with the best goodness-of-fits have both soil texture and mineralogy terms. Equations to predict erodibility from texture, organic carbon, cation exchange, slope, and taxonomy are proposed. Abstract. In the late 1980s, the USDA Agricultural Research Service, along with other federal agencies and multiple universities, collaborated to develop a new physically based soil erosion model, the Water Erosion Prediction Project (WEPP) Model. The WEPP model was intended to replace the Universal Soil Loss Equation and was to include estimates for upland runoff and erosion, sediment delivery to first order channels, and runoff and sediment routing through a downstream channel network. The WEPP technology estimated erosion from raindrop splash and sheet flow (interrill erosion) and concentrated channel flow (rill erosion). To make these erosion estimates, WEPP required new soil erodibility values for interrill erodibility (Ki). rill erodibility (Kr), and critical shear (𝜏c) for concentrated flow erosion. The WEPP Core team determined that they needed to estimate these three erodibility values from measurable soil properties for a wide range of soil conditions. To develop relationships between WEPP soil erodibility variables and other soil properties, a field study was carried out using rainfall and runoff simulation to measure the three erodibility values for 36 soils. Sites were identified on croplands from Washington to Georgia and Maine to California, USA for erodibility measurement. Concurrently, the USDA Soil Conservation Service (SCS) carried out detailed soil surveys and laboratory analyses for all sites to provide a large database of soil physical, chemical, and engineering properties. Correlation and regression analyses were carried out to develop relationships between SCS measurable soil properties and WEPP soil erodibility values. This article provides a summary of the field procedures, data analyses, and subsequent predictive equations that were developed. The predictive equations that were finalized in the WEPP User Summary used sand, very fine sand, clay, and organic carbon contents to predict cropland soil erodibility, but the Coefficient of Determination (r2) values were 0.55 or less. More complex predictive equations were developed with soil physical, chemical, mineralogical, and geomorphic properties, with r2 values up to 0.81. Most of the better predictive equations included terms for soil texture and clay mineralogy, often with additional chemical properties. A set of simplified erodibility equations using only the readily available properties of soil texture, organic carbon, cation exchange capacity, slope steepness, and taxonomic order were derived for use within the WEPP Model, with r2 values greater than 0.5 for all three equations for estimating soil erodibility from measurable soil properties. Keywords: Critical Shear, Interrill Erodibility, Rill Erodibility, Soil Properties, WEPP.

Soil erosion prediction and risk assessment using RUSLE model and GIS techniques in the Nangka watershed

Soil erosion in the Nangka watershed has always been a matter of concern. Over the last decade, soil erosion has led to continuous environmental problems. A thorough examination of the extent of the problem was required to identify an appropriate soil conservation strategy within the watershed. This study was conducted to observe erosion rates and map out the erosion hazard level. Erosion predictions were analysed by using the Revised Universal Soil Loss Equation (RUSLE) model with the help of ArcGIS software. RUSLE was selected because of its quantitative ability to estimate average annual soil erosion and its compatibility with the GIS interface. The potential hazard of soil erosion was classified and ranked into five class categories as set by the national authority. The results reveal that the Nangka watershed is prone to soil erosion with the annual average values ranging from 1.33 Mg·ha –1·y –1 to 2472.29 Mg·ha –1·y –1. High soil erosion rates of 9.8% are in severe (class IV) and very severe (class V) conditions, primarily in the upper course of the watershed. The low annual average of soil erosion (class I and class II), which accounted for 75.95% of the total erosion, mostly took place in the steepness below 35%. The remaining area of 14.25% within the watershed is in moderate condition (class III). It is expected that the results of this study will help the authority in the implementation of soil conservation measures.

Response of seasonal variation in soil detachment capacity to straw incorporation in sloping farmland on the Loess Plateau

AbstractSoil detachment capacity by rill flow (Dc) is sensitive to changes in topsoil properties generated by crop straw incorporation. In the present study, we investigated the effect of crop straw incorporation on the seasonal variation in Dc, the knowledge regarding which is limited currently, and identified the key influencing factors. Three typical crop straw types (wheat, soybean, and maize) were selected for this study. Soil samples incorporated with crop straw and without crop straw were collected over 375 days (from October 1, 2020 to October 10, 2021) and were subjected to a hydraulic flume (length, 4.0 m; width, 0.2 m) to determine Dc. The topsoil properties soil bulk density (BD), soil cohesion (Coh), soil penetration resistance (PR), soil organic matter content (SOM), mean weight diameter (MWD), and straw decomposition rate (SDR) were measured to explain the seasonal variation in Dc. The results showed that crop straw incorporation effectively reduced Dc, and the Dc for the soil incorporated with straw decreased by 25.92%–38.76% compared with that without straw incorporation. Dc exhibited a significant decreasing trend over time, and the Dc at the end stage decreased by 83.00%–88.31%, compared with the initial stage. Seasonal variation in Dc was significantly correlated with BD, Coh, PR, SOM, MWD, and SDR. The measured Dc decreased with BD and Coh as a power function and with SOM and MWD as an exponential function. The influence of straw incorporation on Dc is time‐dependent and can be divided into short‐term and long‐term effects. Natural soil consolidation gradually masked the effect of straw residue with the decomposition of the incorporated straw. The comprehensive response of seasonal variation in Dc to straw incorporation was described by a power combination equation (Dc = 1.23 τ1.65 BD−2.63 Coh−1.33 SOM−0.70; R2 = 0.96). Thus, the seasonal variations in Dc with straw incorporation were mainly controlled by the changes in soil properties triggered by the decomposition of incorporated straw and natural soil consolidation. The results of this study provided a scientific reference for soil erosion prediction and control in sloping farmlands.

Bibliometric Analysis of Black Soil Protection from the Perspective of Land-Use Monitoring

Land use affects ecosystem stability and agricultural ecological security in black soil regions. Additional attention is required regarding the impact of different land-use patterns on black soil. However, the construction of sustainable agricultural ecological security in black soil environments is a dynamic process that depends on the reviews of experts and statistical analyses of literature data. This study quantitatively reviewed the past 20 years of the literature regarding black soil. Using the superposition of the expert knowledge map and machine clustering, knowledge regarding land use in black soil fields was classified structurally. Further, studies directly related to the spatiotemporal pattern of land use were identified, and frequently cited works of the literature were screened to build a dynamic knowledge network of black soil research. The results show that (1) the cooperative relationship among China, the United States, and Canada is the strongest, but the density of cooperation networks between other countries is low; (2) land-use research regarding black soil is divided into four research areas: soil microbial community and activity, soil erosion and ecological processes, ecological management of land use, soil organic matter, and element cycling; (3) the monitoring and management mode of land use in black soil areas should be established to include information management that incorporates knowledge of the cultivated land factor potential, grain production capacity assessment, soil erosion evaluation and prediction, and farmland landscape planning.

Integrated modeling for simulating sediment production and transport in agricultural landscapes

A new modeling platform was developed to simulate spatially distributed sediment production and transport in agricultural landscapes. The sediment production at the grid scale was computed using the stand-alone Water Erosion Prediction Project-Hillslope Erosion code, while an advection-dispersion equation represented sediment transport. The model's performance was tested in the Water Resources and Erosion watersheds at the Oklahoma and Central Plains Agricultural Research Center, El Reno, OK, USA. Results showed that this modeling approach could capture the complex behavior of sediment under different management practices in the watersheds. The modeling framework provides mechanistic processes to simulate the fate and transport of sediment across the watershed at spatio-temporal scales that are useful in assessing the environmental impacts of management schemes. Therefore, this study is expected to help advance the current approaches to estimating soil erosion by bridging scale differences to capture the large-scale effects of small-scale soil erosion processes.

Experimental and numerical investigation of erosion in plugged tees for liquid-solid flow

Sand particle erosion is a prevalent issue that cannot be ignored in oil field development and may lead to leakage accidents. Consequently, it is significant to investigate and quantify erosion in pipelines. In this study, a flow loop is utilized to study the erosion of plugged tees in liquid‒solid flow. Then, computational fluid dynamics (CFD) software ANSYS Fluent is used to develop an erosion prediction numerical model, and the numerical erosion profile is validated with the experiments. Through particle trajectory analysis, three representative particle movement paths are selected, which provides a deeper understanding of erosion generation. Additionally, the erosion damage mechanism is analyzed through the surface morphology of the samples and particle impact behavior. The findings reveal that particles can follow the secondary flow to impact the inside of the downstream pipe under the experimental flow conditions. As the particle size or liquid velocity increases, the particles begin to erode the outside of the pipe under the action of inertial force. Due to the low-angle impact of the particles, the corresponding erosion damage mechanism is micro-cutting.

Prediction of Soil Erodibility by Diffuse Reflectance Spectroscopy in a Neotropical Dry Forest Biome

The USLE and the RUSLE are two common erosion prediction models that are used worldwide, and soil erodibility (K-factor) is one parameter used to calculate them. The objectives of this study were to investigate the variability of soil-erodibility factors under different soil-texture classes and evaluate the efficiency of diffuse reflectance spectroscopy (DRS) in the near-infrared range at predicting the USLE and RUSLE K-factors using a partial least squares regression analysis. The study was conducted in Fluvisols in dry tropical forest (the Caatinga). Sampling was undertaken in the first 20 cm of soil at 80 sites distributed 15 m apart on a 70 m × 320 m spatial grid. Results show that the clay fraction is represented mainly by 2:1 phyllosilicates. Soil organic matter content is low (<0.2%), which is typical of tropical dry forests, and this is reflected in the high values of the calculated USLE and RUSLE K-factors. An empirical semivariogram was used to investigate the spatial dependence of both K-factors. Pedometric modeling showed that DRS can be used to predict both USLE (R2adj = 0.53; RMSE = 8.37 10−3 t h MJ−1 mm−1) and RUSLE (R2adj = 0.58; RMSE = 6.78 10−3 t h MJ−1 mm−1) K-factors.

Future Rainfall Erosivity over Iran Based on CMIP5 Climate Models

Soil erosion affects agricultural production, and industrial and socioeconomic development. Changes in rainfall intensity lead to changes in rainfall erosivity (R-factor) energy and consequently changes soil erosion rate. Prediction of soil erosion is therefore important for soil and water conservation. The purpose of this study is to investigate the effect of changes in climatic parameters (precipitation) on soil erosion rates in the near future (2046–2065) and far future (2081–2100). For this purpose, the CMIP5 series models under two scenarios RCP2.6 and RCP8.5 were used to predict precipitation and the R-factor using the Revised Universal Soil Loss Equation (RUSLE) model. Rainfall data from synoptic stations for 30 years were used to estimate the R- factor in the RUSLE model. Results showed that Iran’s climate in the future would face increasing rainfall, specially in west and decreasing rainfall in the central and northern parts. Therefore, there is an increased possibility of more frequent occurrences of heavy and torrential rains. Results also showed that the transformation of annual rainfall was not related to the spatial change of erosion. In the central and southern parts, the intensity of rainfall would increase. Therefore, erosion would be more in the south and central areas.

Numerical prediction of vibration-induced cavitation erosion in high-speed gears using erosion risk indicators

Cavitation erosion in gear transmissions is lack of study at present, but closely correlating to the damage on tooth surface due to the high impact pressure generated by collapsing bubbles. In this study, combined the gear dynamics and two-phase flow simulations, the cavitation erosion risk indicators (CERI) are used for predicting the tooth erosion. In the proposed computational fluid dynamics model considering vibration and cavitation, the gear displacement from finite element model is employed as boundary condition, and the moving mesh technology is used to adapt deformed fluid domain. Subsequently, this method is validated by the available experiments. The erosion on meshing surface is estimated by twelve different CERIs, and the three most reasonable indicators are remained.