Erosion Evolution Research Articles

Ratio of River Channel Bar to Bank Height Sets Bank Erosion Rate

AbstractRiver channel changes during floods, including bank erosion and bar deposition, are difficult to predict but important for infrastructure, river management, and riparian zone health. Upstream dams can also drive disequilibrium changes to channel morphology, potentially changing bar and bank susceptibility to flooding. To understand feedback between bar morphology, flood flow, bank erosion and channel cross‐sectional evolution, we (a) evaluate how bank erosion during natural floods in six gravel‐bed rivers with alternate and/or mid‐channel bars varied with bar and bank height, and (b) conduct laboratory experiments scaled to the Chubetsu River in Japan, a pseudo‐meandering gravel‐bed river that has experienced bank erosion influenced by alternate bars. The field data show a strong correlation between bank erosion during floods and the bar to bank height ratio measured before the respective floods. We also find that rivers with upstream dams tend to have higher bar to bank height ratios. In the experiments, we systematically vary flood discharge, initial bar height, and initial bank height, and measure bank erosion and bar evolution. We experimentally find that bank erosion initially increases with bar height and flood discharge. As bar height evolves, bank erosion rates tend to converge under different initial conditions. Bank erosion rate increases with decreasing bank height. Because bars in natural rivers tend to not be adjusted to the largest floods, our experimental results and field data suggest that surveyed ratios of bar height to bank height could be used to infer relative bank erosion risks prior to large floods.

Understanding Geotechnical Embankment Washout Due to Overtopping: Insights From Physical Tests

Abstract Understanding the erosion process of an earth dam and flood embankment composed of noncohesive, homogeneous soils due to overflow is crucial for determining the quantity and rate of water release. This is necessary to assess the consequences of a failure, analyze the risk, and develop appropriate crisis management procedures. Despite numerous studies in this area, the process of breach evolution is not fully explored. The article presents the results of physical experiments carried out in the field laboratory of the Wrocław University of Science and Technology for a dam with a height of 0.50 m that closes a reservoir with a capacity of 14.4 m3, whose width is significantly greater than the final width of the breach. The scenario analyzed assumes that water overflows the embankment crest, as it is the most common cause of embankment failure based on dam disaster databases. At the same time, the amount of water accumulated in the reservoir is the largest possible for this scenario, suggesting that such a catastrophe may have the most severe consequences. Based on the results obtained from three experiments, four repeatable phases of erosion evolution were identified and described: (I) the initiation phase, (II) the vertical erosion phase, (III) the lateral erosion phase, divided into two cycles, and (IV) the reservoir emptying phase without further propagation of the breach. The outflow rate of the water from the reservoir was also analyzed, allowing the determination of the outflow hydrograph for each test. Hydrographs showed differences between individual experiments; however, the average erosion rate was similar for all tests. Furthermore, the final width of the breach created each time was between 2.2 and 2.5 H (where H is the height of the embankment) and the volume of eroded soil ranged from 0.52 to 0.59 m3. The article also highlights the methodology to calculate the water outflow hydrograph.

Modeling of drug release, erosion and diffusion fronts movement in high viscosity HPMC matrices containing a cellulolytic enzyme

A formerly developed mathematical model describing drug release from hydrophilic matrices (HMs) took into account resistance to drug release given by its dissolution and by the presence of a growing gel layer. Such a model was applied to previously reported release data obtained from HMs made of hydroxypropyl methylcellulose (HPMC), where acetaminophen was used as model drug and a cellulolytic product was added as “active” excipient to attain zero-order release kinetics. The Levich theory applied to acetaminophen intrinsic dissolution rate (IDR) data highlighted the suitability of such a drug for modeling purposes, given its good surface wettability. First assessment of the model ability to describe drug release from the abovementioned systems was carried out on partially coated matrices, representing a simplified physical frame, but results were then confirmed on uncoated systems. Experimental and model release data showed good agreement; therefore, the release-describing equation was combined with that of the global mass balance to obtain two new equations related to erosion and diffusion fronts time evolution. Changes over time in the dissolution and gel contributions to total resistance, calculated using model output parameters, highlighted that the enzyme, through its hydrolytic activity on HPMC, was responsible for a time-dependent reduction of the resistance component related to gel layer.

Watershed Grouping Based on Suspended Sediment Yield Using Morphological Criteria: A Comparison of Hierarchical and Nonhierarchical Techniques

ABSTRACTRegional sediment analysis methods have traditionally been used to reliably estimate sediment yield in ungauged watersheds with adequate hydrometric stations. Watershed‐grouping techniques are a suitable approach for estimating sediment load, which can be used to assess erosion processes, and surface water quality, and plan soil and water conservation measures. Additionally, the relationship between sediment yield and watershed characteristics can be used to identify different stages of erosion evolution and prioritize watersheds for conservation efforts. To this end, this study aimed to assess the applicability of various analytical hierarchy process (AHP) methods, including Ward's, Single linkage, and β‐flexible methods, as well as the nonhierarchical fuzzy C‐means (FCM) method in the Gorganroud and Qareh‐Sou watersheds of northern Iran based on hydrological, geological, climatic, physiographical, and land‐use characteristics. Furthermore, the study evaluated clustering methods to determine the optimal number of subwatershed clusters. The AHP methods identified two, three, or four clusters, while the FCM method identified three clusters as the best number of clusters. The results indicated that the FCM method had a well‐regionalized estimation in the study area with the maximum amount of validation indices (The highest Dunn coefficient 0.31–0.65, the lowest TESS 16.62–36.8, and acceptable Pseudo‐F coefficient 8.1–10.4). Notably, the fuzzy clustering methods associated each input sample with two or more clusters, which reduced the uncertainty of sediment yield estimation. The recommended clustering method can be used for regional sediment analysis in ungauged watersheds and evaluated against other hydrological variables in the study area.

State-of-the-Art Review of Continuum Mechanics-Based Modelling of Soil Surface Erosion

AbstractSoil surface erosion can shape the morphography of rivers and estuaries in the natural environment and induce high potential risks to structures in engineering. Numerical simulations based on continuum mechanics theory can provide reliable assessments of the evolution of surface erosion from the perspective of a large-scale view. However, current studies on continuum mechanics-based modelling are still limited. This paper comprehensively reviews such numerical simulations of soil surface erosion. This review begins by discussing the fundamental physical mechanisms of surface erosion. Subsequently, it explores the basic physics-based conservation equations controlling soils and fluids in surface erosion. Then, the empirical formulae depicting the different stages of surface erosion are presented. Building on these mathematical foundations, this paper reviews various numerical methods for surface erosion modelling from a continuum mechanics perspective. Finally, this paper discusses the advantages and limitations of the numerical methods. This work can provide researchers convenience for using numerical models on surface erosion simulations.

Quantitative analysis of impact of human activities on soil erosion using the RUSLE model in a typical karst area in Guizhou, China.

Human activities have significant influence on soil erosion in karst areas. The spatial and temporal evolution of soil erosion in Guizhou Province was evaluated using the Revised Universal Soil Loss Equation (RUSLE), which revealed an increasing trend in the initial data analysis for the soil erosion modulus. To disclose the impact of human activities on regional soil erosion, the soil erosion in 2000, 2010, and 2020 was analyzed. The results show the following: (1) The average values of the soil erosion modulus in the study area for 2000, 2010, and 2020 were 4.479, 4.945, and 5.806 t·hm-2·a-1, respectively; when considering human activities without the influence of rainfall erosivity, these values were 4.679, 4.963, and 4.799 t·hm-2·a-1. The influence of human activities on soil erosion is gradually becoming a positive force. (2) According to the Spearman regression analysis, the top four factors related to soil erosion in 2000 and 2010 were soil loss risk (E, 0.721 and 0.737), anti-erosion factors (Pr, - 0.236 and - 0.221), rock exposure rate (0.222 and 0.279), and altitude (0.210 and 0.195). In 2020, the top four factors were Pr (0.725), land surface temperature (LST, 0.268), NDVI (- 0.232), and E (0.186). In the first two stages, soil erosion is closely related to natural factors, while in 2020, soil erosion is more closely related to human activities. (3) The geographically weighted regression (GWR) showed the highest range of regression coefficients for Pr (150), followed by E and NDVI (25), rock exposure rate (10), and land surface temperature (LST) (1.5). The rainfall erosivity is increasing annually as a consequence of global climate change. This rise in rainfall erosivity has resulted in a corresponding increase in soil erosion in the study area, which obscures the positive impact of human activities in the reduction of soil erosion.

Erosional Response to Pleistocene Climate Changes in the Brazilian Highlands

AbstractPlio‐Quaternary climatic changes are considered to be a key driver of landscape evolution, but many unresolved questions remain, such as the extent of the impact of major climatic shifts such as the Mid‐Pleistocene Transition (MPT). Various geochronological methods are available to infer changes in surface processes over the Plio‐Quaternary, and Terrestrial Cosmogenic Nuclides (TCN) have proven to be one of the most efficient tools to reconstruct paleo‐denudation. Implementing these approaches requires very specific conditions, such as well‐preserved and extensive sediment sequences. Developing alternative methods to document the evolution of denudation is thus of major interest to retrieve information on the evolution of denudation in places where recent detrital sediment records are absent. We explore the evolution of landscape erosion over a 1 Ma timescale in an intra‐cratonic setting, the Espinhaço mountain range (Brazil), with a new data set of detrital cosmogenic nuclide concentrations (26Al–10Be). We observe a systematic disequilibrium in the 26Al/10Be ratio, which we interpret as resulting from the combination of soil mixing and a significant increase in the intensity of surface processes, close to the MPT. We discuss the different scenarios with respect to available local and global data concerning the relationships between climate evolution and erosion over this time period. Our results have important implications for the interpretation of the denudation rates derived from TCN concentrations under steady states assumption, in landscapes with low erosion rates, which have a long memory for surface processes history.

Quantitative Evaluation of Soil Erosion in Loess Hilly Area of Western Henan Based on Sampling Approach

The terrain in the loess hilly area of western Henan is fragmented, with steep slopes and weak soil erosion resistance. The substantial soil erosion in this region results in plenty of problems, including decreased soil productivity and ecological degradation. These problems significantly hinder the social and economic development in the region. Soil conservation planning and ecological development require accurate soil erosion surveys. However, the studies of spatio-temporal patterns, evolution, and the driving force of soil erosion in this region are insufficient. Therefore, based on a multi-stage, unequal probability, systematic area sampling method and field investigation, the soil erosion of the loess hilly area of western Henan was quantitatively evaluated by the Chinese Soil Loss Equation (CSLE) in 2022. The impact forces of soil erosion were analyzed by means of a geographic detector and multiple linear regression analysis, and the key driving factors of the spatio-temporal evolution of soil erosion in this region were revealed. The results were as follows. (1) The average soil erosion rate of the loess hilly area in western Henan in 2022 was 5.94 t⋅ha−1⋅a−1, with a percentage of soil erosion area of 29.10%. (2) High soil erosion rates mainly appeared in the west of Shangjie, Xingyang, and Jiyuan, which are related to the development of production and construction projects in these areas. The areas with a high percentage of soil erosion area were in the north (Xinan and Yima), west (Lushi), and southeast (Songxian and Ruyang) of the study area. Moreover, areas with the most erosion were found in forest land, cultivated land, and areas with a slope above 25°. (3) At the landscape level, the number and density of patches of all land types, except orchard land, increased significantly, and the boundary perimeter, landscape pattern segmentation, and degree of fragmentation increased. (4) The geographical detector and multiple linear regression analysis indicated that the driving forces of soil erosion are mainly topographic and climatic (slope length, elevation, precipitation, and temperature). Soil erosion was significantly influenced by the density of landscape patches. These maps and factors influencing soil erosion can serve as valuable sources of information for regional soil conservation plans and ecological environment improvements.

Terminal glacial overdeepenings: Patterns of erosion, infilling and new constraints on the glaciation history of Northern Switzerland

Glacially overdeepened basins are a common landform of subglacial erosion. However, the controlling erosional–depositional processes and their age remain poorly understood on a global scale. Terminal overdeepenings near the former glacier margins are critical for the understanding of subglacial processes and their development over time. This study examines the geomorphology and sedimentology of buried terminal overdeepenings eroded below the Rhein Glacier and adjacent lobes in the distal northern foreland of the European Alps. The evolution of erosion and infilling in the overdeepened troughs over time is investigated using high-quality drill cores (∼1463 m of core in total) that were logged for lithofacies, petrophysical, geotechnical and compositional properties. The drill data is integrated with 2D-reflection seismics (∼41 km in total) and supplementary subsurface data. This extensive dataset reveals that the studied overdeepened basins include twelve typical facies associations (partially emplaced in characteristic sequences) and characteristic architectural elements. These categories serve as effective tools to reduce the high facies variability and facilitate easier comparison and correlation of the valley fill. Our analysis shows that the formation of terminal overdeepenings on soft sedimentary bedrock (Molasse) is the result of a combination of erosional processes. Subglacial water erosion and evacuation are the dominant processes and active during periods of glacier–bed decoupling and flushing. Direct subglacial erosion occurs during glacier–bed coupling and is documented by bedrock glacitectonites. The valley fill architecture shows that the studied overdeepenings typically undergo a multiphase evolution, with several phases of overdeepening erosion, deposition and partial re-erosion (or re-activation). The combined dataset (including geochronological data) suggests that the overdeepenings were eroded during many, if not all, extensive glaciations during the Middle–Late Pleistocene that reached the distal foreland. These are findings relevant for the large number of overdeepenings known from the Northern Alpine foreland and overdeepened features worldwide. They corroborate the importance of overdeepenings as archives for the paleoenvironmental change and landscape evolution during the Quaternary.

Spatio-temporal evolution of water erosion in the western Songnen Plain: Analysis of its response to land use dynamics and climate change

Preventing water erosion is crucial for maintaining ecosystems and ensuring food security, necessitating a comprehensive understanding of the spatial and temporal patterns of water erosion and its underlying drivers. In the context of global warming, analyzing the impacts of land use dynamics and climate change on water erosion contributes to effective land management and sustainability of both industry and agriculture. This study aims to analyze the spatial distribution of water erosion in the western Songnen Plain from 1990 to 2020 using the Revised Universal Soil Loss Equation (RUSLE), with a focus on assessing the impacts of land use and climate on water erosion. The results revealed a 7.1 % increase in the area experiencing water erosion above light levels in the western Songnen Plain. The hotspots for water erosion were located in the southeast and northwest of the study area. The rapid expansion of farmland and land salinization, leading to reduced vegetation cover and soil property deterioration, were the main causes of intensified water erosion in the region before 2000. Although water erosion was slightly alleviated after 2000, the further expansion of farmland, the worsened water erosion intensity in alkaline land and frequent extreme weather still posed serious threats to water erosion in the study area. Water erosion was positively correlated with temperature and dry/wet alternation events, including frequency, duration, and severity. In addition, land use type was the main factor influencing the heterogeneous distribution of water erosion in the western Songnen Plain, whose interaction with dry/wet alternation events had the strongest explanatory power. Therefore, this study calls for the implementation of soil and water conservation measures to mitigate the impacts of land cultivation, salinization, and climate change on water erosion.

Bank erosion under the impacts of fluvial erosion, frost heaving/freeze-thaw process of rivers in seasonal frozen regions

Bank erosion is a key feature of channel evolution in alluvial rivers, and will occur under the combined effect of hydraulic erosion and frost heave/freeze-thaw process of rivers in seasonal frozen regions. However, most research on bank erosion modeling has seldom considered the impact of the frost heave/freeze-thaw process. Therefore, the variation in the mechanical characteristics of riverbank soil under the freeze-thaw cycle was investigated firstly in the current research and then used in the modeling of bank erosion processes at typical sections of the Songhua River. Additionally, a sensitivity analysis of riverbank stability was conducted using orthogonal experiments. The results indicate that after 7 freeze-thaw cycles, the soil cohesion and internal friction angle of bank soil decreased by about 10%–47 % and 9%–19 %, respectively. Unlike lowland rivers, bank erosion of rivers in seasonal frozen regions is more likely to occur during the rising water period. The frost heaving/freeze-thaw process will make the bank stability safety coefficient Fs more quickly decrease to the unstable critical value. As compared with the case without considering the frost heaving/freeze-thaw process, the mass failure occurred in advance when the frost heaving/freeze-thaw process was considered, and the calculated bank erosion volume was increased by 11%–51 %, agreeing better with the measured value. The sensitivity ranking of the four influencing factors on riverbank stability under freezing-thawing conditions is as follows: river stage > groundwater level > cohesion > internal friction angle. The current study can provide a reference for research on bank erosion and channel evolution of rivers in seasonal frozen regions.

Late Holocene rapid paleoenvironmental changes and anthropogenic impacts in central Yunnan, southwest China

Understanding long-term anthropogenic impact on the Earth's surface system is crucial for establishing reference conditions and potentially allowing future trajectories to be more rigorous and tightly constrained. In this study, the evolution of catchment erosion, chemical weathering and bottom-water hypoxia during the late Holocene are investigated using multi-proxy records from an accurately-dated sediment core from Lake Qilu in central Yunnan, southwest China. Through the comparison of our results with other paleoenvironmental records from the study region, we are able to see that the increase in anthropogenic impact on the catchment of Lake Qilu began in 780 CE, which is associated with the large scale expansion of agriculture in China. In the early stages of vegetation disturbance and agricultural land use, soil erosion and chemical weathering within in the catchment was significantly intensified, while the lake gradually changed to a state of anoxia until the period of accelerating eutrophication in 1945 CE. However, the extremely high rate of soil erosion and weak chemical weathering suggest the beginning of a new phase in terms of anthropogenic impact on the landscape. Furthermore, the late Holocene intensification of chemical weathering in monsoonal China can also be linked to increased anthropogenic activities rather than spatial differences in hydroclimate changes. This study highlights the fact that humans have been shaping the Earth's surface for millennia, which means that it is essential to place present environmental concerns into a long-term context.

Evolution features and a prediction model of casing perforation erosion during multi-staged horizontal well fracturing

Large-displacement high-intensity sanding hydraulic fracturing operations often cause casing perforation erosion and thus temporary plugging failures, exacerbate the unevenness of fracture initiation and expansion, and induce casing damage. In order to clarify the dynamic evolution of perforation erosion and predict perforation diameter, the effects of different types of proppants, the viscosity of sand-carrying liquids, and large sand-passing quantities on perforation erosion rate were experimentally explored in the study. The evolution of perforation erosion and the particle size distribution of quartz sand and ceramsite were analyzed in the experiment and a prediction model for perforation erosion under various fracturing parameters was established. Compared to ceramsite, quartz sand had the more significant effect on perforation erosion and the more serious particle abrasion and fragmentation under the same sand-passing quantity. Increasing the viscosity of the sand-carrying liquid slowed down perforation erosion and made the edge of perforation entrance more uniform. As the sand-passing quantity through the perforation increased, perforation erosion in the initial stage was concentrated at the perforation edge. Then, the inner wall of the perforation was also eroded, but the average erosion rate was reduced. A prediction model of perforation erosion considering multiple fracturing parameters was established based on the principle of fluid similarity. The errors between predicted values and downhole eagle-eye observation values were less than 15 %. The model provides an important basis for the optimization of fracturing parameters and downhole casing strength design.

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

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

Influence of drainage flow velocity on microscopic cohesive soil erosion and macroscopic road collapse evolution: A case study in Beijing, China

Drainage pipe leakage is the primary cause of road collapse in Beijing, where cohesive soils are prevalent. Nevertheless, the influence of drainage flow velocity on cohesive soil erosion and road collapse remains unclear. Using the tracer technology, this study analyzes the microscopic erosion process of the cohesive soil under different drainage flow velocities, whereas the macroscopic evolution characteristics of road collapse were examined through camera images, soil settlement, and soil dry density. Based on the results, the microscopic cohesive soil erosion and macroscopic road collapse evolution can be categorized into five phases. As the drainage flow velocity increased from 0.045 to 0.067 and 0.089 m/s, the critical seepage range within the fluorescent tracer images decreased by 6.76 % and 9.32 %, respectively, demonstrating a power–law decline. Additionally, the settlement ring exhibited characteristics of upstream inward convergence and downstream outward divergence. These results can enhance the comprehension of road collapse mechanisms.

Erosion, deposition and breach evolution of landslide dams composed of various dam material types based on flume tests

The accurate and rapid prediction of breach outflow rates of landslide dams is crucial for effective risk assessment and mitigation strategies. However, challenges arise due to the complexities associated with breaching mechanisms. In this study, 12 flume tests were conducted on landslide dams composed of various material types, including fine-grained, coarse-grained, well-graded, and gap-graded materials, each with two dry densities. This study comprehensively investigated erosion, deposition, and breach evolution, providing the foundation for the development of breach evolution models. A comprehensive logic diagram, focusing on shear stress and grain size distribution, was proposed to forecast the failure modes of landslide dams. The study also suggested a method to assess the longitudinal breach evolution based on the prediction of the Erosion Point (EP) and Deposition Point (DP), and to assess the lateral breach evolution by considering both steep and gentle breach side slopes. Our findings indicate that fine-grained materials undergo layer erosion, coarse-grained materials remain stable, well-graded materials develop erosion pits, and gap-graded materials are prone to piping. The existence of an interface can result in piping channels, even when the overall hydraulic gradient is insufficient to initiate piping. Incorporating the longitudinal slope angle and its influence on both driving and resisting forces into the traditional erosion rate equation can significantly enhance its accuracy, especially when coarse particles are present. Coarse particles play a pivotal role in erosion and deposition behavior and reshaping the breach evolution as the initiation of coarse particles is dominated by rolling instead of slipping in fine particles. Deposition on the downstream slope of a dam can significantly influence the longitudinal breach process, leading to changes in the downstream topography and grain size distribution. The proposed method for assessing longitudinal breach evolution unifies the previous methodologies by predicting the positions of EP and DP based on erosion and deposition.

Numerical Simulation of Rainfall-Induced Erosion on Infiltration and Slope Stability

In slopes where a mixture of coarse and fine particles is present, the infiltration of rainfall can cause the migration of fine particles. This migration alters the hydraulic properties of the soil and has implications for slope stability. In this study, the slope under investigation is a tailings dam composed of loosely consolidated soil with a wide particle size distribution. Due to rainfall infiltration, fine particles tend to migrate within the voids of the coarse particle framework, leading to changes in hydraulic properties and inducing slope instability. The classical internal erosion constitutive model, known as the Cividini and Gioda erosion criterion, is commonly used to predict the behavior and effects of fine particle erosion in geotechnical engineering. However, certain parameters in this erosion criterion equation, such as long-term density, are challenging to obtain through experiments. To investigate the coupled evolution of seepage and erosion within landfill slopes under the influence of rainfall infiltration and to understand the mechanisms of slope instability, this research assumes the erosion of fine particle suspension and adopts the Worman and Olafsdottir erosion criterion to establish a coupled model of unsaturated seepage and internal erosion. The developed model simulates the coupled response of seepage and erosion in unsaturated landfill slopes under three different rainfall intensities. It is then combined with the infinite slope model to quantitatively analyze the impact of fine particle migration on soil permeability and slope stability. The numerical simulations provide the following findings: The Worman and Olafsdottir erosion criterion, unlike the Cividini and Gioda erosion criterion, only requires the determination of the soil’s gradation curve to estimate the erosion rate. Internal erosion primarily occurs within the leading edge of moisture penetration, accelerating the advancement of the wetting front and reducing slope stability. When the rainfall intensity is lower than the saturated permeability coefficient, the influence of internal erosion can be disregarded. However, under rainfall intensities equal to or greater than the saturated permeability coefficient, considering internal erosion results in a difference in the depth of the wetting front of up to 34.2 cm after 6 h in the R2 scenario. The safety factor without considering internal erosion is 1.12, whereas considering internal erosion yields safety factors between 1.08 and 1.09. In the R3 scenario, the difference in the depth of the wetting front reaches 53.8 cm after 6 h, with a safety factor of 1.12 without considering internal erosion and safety factors between 1.06 and 1.07 when considering internal erosion.

Solid–Liquid Two-Phase Flowmeter Flow-Passage Wall Erosion Evolution Characteristics and Calibration of Measurement Accuracy

Solid–liquid two-phase flowmeters are widely used in critical sectors, such as petrochemicals, energy, manufacturing, the environment, and various other fields. They are indispensable devices for measuring flow. Currently, research has primarily focused on gas–liquid two-phase flow within the flowmeter, giving limited attention to the impact of solid phases. In practical applications, crude oil frequently contains solid particles and other impurities, leading to equipment deformation and a subsequent reduction in measuring accuracy. This paper investigates how particle dynamic parameters affect the erosion evolution characteristics of flowmeters operating in solid–liquid two-phase conditions, employing the dynamic boundary erosion prediction method. The results indicate that the erosion range and peak erosion position on the overcurrent wall of the solid–liquid two-phase flowmeter vary with different particle dynamic parameters. Erosion mainly occurs at the contraction section of the solid–liquid two-phase flowmeter. When the particle inflow velocity increases, the erosion range shows no significant change, but the peak erosion position shifts to the right, primarily due to the evolution of the erosion process. With an increase in particle diameter, the erosion range expands along the inlet direction due to turbulent diffusion, as particles with lower kinetic energy exhibit better followability. There is no significant change in the erosion range and peak erosion position with an increase in particle volume fraction and particle sphericity. With a particle inflow velocity of 8.4 m/s, the maximum erosion depth reaches 750 μm. In contrast, at a particle sphericity of 0.58, the minimum erosion depth is 251 μm. Furthermore, a particle volume fraction of 0.5 results in a maximum flow coefficient increase of 1.99 × 10−3.

Response of Hydrodynamic Characteristics to Tillage-Induced Microtopography of Rill Erosion Processes under Heavy Rainfalls

The occurrence and development of rill erosion depends on the hydraulic characteristics of water flow and underlying soil surface features. Our experiments include one-rainfall-intensity treatments (2.0 mm min−1) and various microtopographic levels based on different tillage practices with smooth slope (CK), artificial digging (AD), and ridge tillage (RT) on a 15° slope. The results indicate the following: (1) The soil roughness index values were in the order of CK < AD < RT, and the spatial variability of different tillage practices had strong autocorrelations during different rill erosive stages. The codomain values decreased with the increase in microtopography. (2) The multifractal dimension values of tillage practices in various erosive stages were in the order of RT > AD > CT. The microtopography of different tilled slopes showed strong multifractal characteristics, and the multifractal characteristics were stronger as the microrelief heterogeneity increased. For the CK slope, the generalized fractal dimension span (ΔD) ranged between 0.0019 and 0.0058. For the AD slope, ΔD was between 0.2901 and 0.5112. And, for the RT slope, ΔD was between 0.4235 and 0.7626. (3) With the evolution of rill erosion, the flow pattern on different tilled slopes changed from subcritical transition flow to supercritical transition flow. (4) Soil roughness index and ΔD had good correlations with hydrodynamic parameters. The stronger the erosive energy of runoff was, the higher the spatial heterogeneity of microtopography was. This study is expected to provide a theoretical basis for revealing the hydrodynamic mechanism of rill erosion in slope farmland.

Soil erosion prediction and spatiotemporal heterogeneity in driving effects of precipitation and vegetation on the northern slope of Tianshan Mountain

Soil erosion changes become more unclear in the future due to climate change and increased human activity. However, the spatiotemporal heterogeneity in the driving effects of key factors on soil erosion remains inadequately understood on the northern slope of the Tianshan Mountains (NSTM). In this paper, the spatiotemporal evolution of soil erosion on the NSTM was evaluated in the historical period (2000–2015) by the Revised Universal Soil Loss Equation (RUSLE) model. Subsequently, the FLUS-CMIP6-RUSLE model was employed to predict soil erosion in the future period (2030–2050). Then, the GTWR model was used to dissect the spatiotemporal heterogeneity in the driving effects of precipitation and vegetation. The results indicated that soil erosion on the NSTM fluctuated from 2000 to 2015, increasing by 1.77 t ha −1 yr −1. Soil erosion areas mainly occurred in Changji City, Fukang City, Hutubi County, Mulei County, Qitai County, and Turpan City. The soil erosion modulus in 2030, 2040, and 2050 under different climate scenarios will be 26.56,28.83, and 37.49 t ha −1 yr −1, respectively. The spatial pattern of soil erosion is similar to the historical period. Precipitation was the main factor intensifying soil erosion in the eastern and western counties from 2000 to 2020, while the soil erosion change in central counties was affected by vegetation. In the future, soil erosion change in the counties (i.e., Karamay, Yili, Tacheng, Shihezi, Manas, Qitai, and Mulei) will be driven by precipitation. The vegetation will be the main driver of soil erosion change in central and eastern counties (i.e., Urumqi, Turpan, Fukang City, Jimsar County, and Changji City). This study firstly attempts to explore the spatiotemporal heterogeneity in the driving effects of precipitation and vegetation using Spatial-Temporal Geographically Weighted Regression (GTWR) in urban agglomerations of NSTM. It is meaningful to explore erosion-prone regions and to implement rational soil conservation measures in the study region and similar regions in the world.