Erosion Coefficient Research Articles

Susceptibility of hydraulic structures to internal erosion: modeling of suffusion process

Internal erosion is a primary cause of hydraulic structure failure, manifesting as two key phenomena: piping erosion and suffusion. These processes differ in their geometrical and hydraulic boundary conditions, resulting in varying levels of failure risk. Piping erosion is the more hazardous and rapid process, often leading to immediate failure if not promptly addressed. In contrast, suffusion gradually alters the permeability of the medium, potentially culminating in failure after a prolonged period of development. In this study, we propose a model for suffusion based on Darcy’s law, Papamichos' erosion law, and Einstein's viscosity evolution relation. The model describes the temporal evolution of the average porosity in the porous medium, the concentration of eroded particles in the fluid, and the mass of particles eroded, while highlighting the impact of hydraulic and mechanical parameters, such as the erosion coefficient and maximum porosity, on this evolution. The numerical solution is obtained using the finite difference method, with the sample discretized into elementary layers. For discretization, an explicit off-centered scheme was adopted. The simulation results reveal that suffusion is strongly influenced by soil hydraulic and mechanical parameters, particularly the erosion coefficient (λ) and final porosity (Ømax).

Durability of a Metakaolin-Incorporated Cement-Based Grouting Material in High Geothermal Tunnels.

To improve the durability of cement-based grout in high geothermal tunnel grouting projects, metakaolin was incorporated to replace 8% of the cement. The permeability, chloride penetration, and sulfate and carbonate erosion tests were carried out on the grout cured at varying temperatures (20, 30, 40, 50, and 60 °C). It was shown that with the increase in curing temperature, the impermeability and resistance to chloride penetration initially increased and then decreased, reaching the highest values at 40 °C. Furthermore, the incorporation of metakaolin into grout enhanced the impermeability by 11.11-38.91% and resistance to chloride penetration by 12.23-12.77%. As attacked by sulfate, the surface spalling of the specimen was more obvious with the increase in the curing temperature and immersion time. Conversely, the appearance remained almost unchanged under carbonate erosion. As immersion time increased, both the antisulfate and anticarbonate erosion coefficients declined. The effect of curing temperature on erosion resistance was assessed via the relative antierosion coefficient. When immersed in sulfate, the coefficient achieved the highest value of 1.08 as cured at 30 °C, and in carbonate, the coefficient reached a maximum of 0.99 as cured at 40 °C. Through scanning electron microscopy and binarized images, it was verified that gypsum and ettringite were formed during sulfate attack, leading to volume expansion and cracking, consequently reducing the strength. Meanwhile, in the case of carbonate erosion, calcium hydroxide (CH) and calcium silicate hydrate gel (C-S-H) were dissolved and degraded, resulting in a large number and size of pores in the grout. The research results have certain theoretical significances and reference values for the application of cement-based grouting materials in high geothermal environments.

Multi-hazard modeling of erosion and landslide susceptibility at the national scale in the example of North Macedonia

Abstract Due to favorable natural conditions and human impact, the territory of North Macedonia is very susceptible to natural hazards. Steep hillslopes combined with soft rocks (schists on the mountains; sands and sandstones in depressions), erodible soils, semiarid continental climate, and sparse vegetation cover give a high potential for soil erosion and landslides. For this reason, this study presents a multi-hazard approach to geohazard modeling on the national extent in the example of North Macedonia. Utilizing Geographic Information Systems, relevant data about the entire research area were employed to analyze and assess soil erosion and susceptibility to landslides and identify areas prone to both hazards. Using the Gavrilović Erosion Potential Method (EPM), an average value of 0.36 was obtained for the erosion coefficient Z, indicating low to moderate susceptibility to erosion. However, a significant area of the country (9.6%) is susceptible to high and excess erosion rates. For the landslide susceptibility assessment (LSA), the Analytical hierarchy process approach is combined with the statistical method (frequency ratio), showing that 29.3% of the territory belongs to the zone of high and very high landslide susceptibility. Then, the accuracy assessment is performed for both procedures (EPM and LSA), showing acceptable reliability. By overlapping both models, a multi-hazard map is prepared, indicating that 22.3% of North Macedonia territory is highly susceptible to erosion and landslides. The primary objective of multi-hazard modeling is to identify and delineate hazardous areas, thereby aiding in activities to reduce the hazards and mitigate future damage. This becomes particularly significant when considering the impact of climate change, which is associated with increased landslide and erosion susceptibility. The approach based on a national level presented in this work can provide valuable information for regional planning and decision-making processes.

Application of remote sensing in monitoring land degradation: A case study of Stanari municipality (Bosnia and Herzegovina)

Abstract The subject of the research represents the application of remote sensing in monitoring land degradation in the municipality of Stanari in Bosnia and Herzegovina (B&H). The aim of the study is to identify spatial changes during the research period (2017–2023) by processing remote sensing “products.” Within the changes in land use, the focus is placed on alterations resulting from surface mineral resource mining activities. The total approved exploitation area amounts to 3841.08 ha, covering almost a quarter of the municipality (23.89%). Monitoring changes in land use was conducted through the processing of Sentinel-2 images using supervised classification (SC). The classification results were compared with the Dynamic World (DW) dataset. Results indicate significant losses in forested areas, reduced by −7.23% (DW) or −2.43% (SC) at the municipal level and −11.48% (DW) or −5.90% (SC) within the exploitation area. Spatial extents of deforestation were identified and analyzed based on processing the Hansen Global Forest Data Change dataset. The deforestation area, caused by mining activity in B&H over the research period (2001–2021), amounts to 977.94 ha, with 264.25 ha (27.02%) within the Stanari municipality. Over 90% of the cleared forest area is within the exploitation area. High erosion coefficient values (Z) were recorded within the approved exploitation area, coinciding with the spatial coverage of deforestation. Additionally, results obtained using an empirical method for studying mechanical water erosion (W y) indicate a high intensity within the exploitation area. For the approved exploitation area, possibilities for the restoration of degraded land were analyzed, including an overview of activities conducted so far and mapping some of the previously reclaimed areas. The research contributes to a better understanding of spatial changes resulting from mining activities, and the presented data are significant for numerous practical issues, such as sustainable land use planning, spatial planning, protection of forest ecosystems, and the environment.

Flow-induced erosion modelling of cohesive material with coupled CFD-DEM approach

Erosion is one of the continuous wear mechanisms in cohesive materials caused by the shear stress applied by the fluid flow at the liquid–solid interface. The erosion resistance of cohesive materials is significantly influenced by the strength of the cohesive bonds that hold the particles together, increasing the complexity of the mechanism. The erosion rate of cohesive materials depends on the critical shear stress (CSS) and the erodibility coefficient at the surface. The current understanding of the relationship among the inter-particle bond strength, CSS, erodibility coefficient, and their respective contributions to the flow-induced erosion process is still lacking; therefore, it cannot be adequately described mathematically. The present research offers a coupled computational fluid dynamics (CFD)–discrete element method (DEM) approach to visualize and quantitatively analyze the flow-induced erosion in cohesive materials. The capability and accuracy of the developed model were validated using experimental data available in the literature. A cohesion model was then employed to describe the strength of the cohesive bond, and the effects of the cohesion energy density (CED) on the CSS and erodibility coefficient were investigated. The analysis indicated that for cohesive materials, the non-dimensional CSS not only is affected by the particle Reynolds number but also strongly depends on CED. The simulation results indicated that by increasing the CED value from 500 to 900kJ/m3, the CSS increased by 25 %, and the erodibility coefficient decreased by 62 %. The proposed CFD–DEM approach can effectively estimate the erosion initiation and erosion rate of cohesive materials in different applications and geometries.

Investigating the internal erosion behavior and microscopic mechanisms of chemically stabilized soil: an experimental study

IntroductionInternal erosion triggered by water pipeline leaks seriously threatens the stability of the urban ground. Hangzhou, a city in Zhejiang Province, China, is facing critical challenges due to urban ground collapse (UGC) caused by internal erosion. However, there is a lack of research on the prevention of UGC by improving the internal erodibility of underground soil. Addressing this issue is of utmost importance to ensure the city’s stability and safety. This paper proposes to improve the internal erodibility of typical sandy silt soils with chemical stabilisers.MethodsThe effects of three chemical stabilisers, lignosulphonate (LS), lime (LI), and lignin fibre (LF), on the critical shear stress (τc) and erosion coefficient (kd) of sandy silt soils were investigated, which from Hangzhou, Zhejiang, China, by the hole erosion test (HET) at different mixing amounts and at different conservation times.ResultsThe findings indicate that LF mainly improves the erosion resistance of sandy silt by increasing τc, and the maximum increase is 2.38 times; LI mainly improves the erosion resistance by decreasing kd, and the maximum decrease is 2.18 times. After adding LS, τc and kd did not change significantly. The scanning electron microscope (SEM) test revealed that the inclusion of LF led to the formation of larger agglomerates in the sandy silt soil. The microstructure of sandy silt soil remained dispersed even after adding LS. Various chemical stabilisers used to improve sandy silt soils exhibited distinct erosion mechanisms. Sandy silt soils improved with LF exfoliated into agglomerates, displaying high resistance to erosion. On the other hand, the sandy silt treated with LF still lacks a protective layer and shows minimal improvements in its ability to withstand erosion. In contrast, the LS-amended sandy silt remains stripped with individual soil particles with insignificant changes in erosion resistance.DiscussionThis study can provide a conceptual framework for choosing foundation treatment techniques in future urban development projects.

Experimental Study on the Physical Properties of Autoclaved Bricks Made from Desert Sand and Their Resistance to Sulfate Attacks

In order to optimize the application of desert sand autoclaved bricks in rural construction in Xinjiang, this study focuses on the research and development of MU15-grade desert sand autoclaved bricks. Experimental investigations were conducted to examine the relationship between the water absorption rate of desert sand autoclaved bricks and the duration of water absorption while analyzing the impact of the water absorption rate on the compressive strength of these bricks. Additionally, experimental research was carried out to evaluate the appearance, compressive strength, and pore structure of autoclaved bricks after sulfate erosion. The results indicate the following. (1) With an increasing immersion time, the water absorption rate of desert sand-based autoclaved bricks initially rises and then declines, reaching approximately 14.74% when immersed for 4 h, which is close to the saturation water absorption rate. (2) The compressive strength of desert sand-based autoclaved bricks gradually decreases with an increasing water absorption rate, reaching its lowest point when saturation is attained, with a strength loss rate of approximately 33.18%. (3) Finally, after sulfate erosion, cracks and detachment appear on the surface of desert sand-based autoclaved bricks, and these cracks extend and propagate with the continuous accumulation of eroded products. Simultaneously, this process leads to an increase in the proportion of harmful pores by 0.96%, thereby causing a deterioration in strength. Through data analysis, a decay curve of the compressive strength erosion coefficient of desert sand-based autoclaved bricks with the number of sulfate erosion cycles was established, with good accuracy. This study provides theoretical references and technical support for the performance characteristics of desert sand-based autoclaved bricks and their application in rural construction in Xinjiang.

Finite Element Method-Peridynamics Coupled Analysis of Slope Stability Affected by Rainfall Erosion

Rainfall is a pivotal factor resulting in the cause of slope instability. The traditional finite element method often fails to converge when dealing with the strongly nonlinear fluid–solid coupling problems, making it impossible to fully analyze the sliding process under the state of slope instability. Therefore, this paper uses the coupling of peridynamics (PD) and the finite element method (FEM) to propose a data exchange mode between the seepage field and the deformation field. The influencing factors of fine particle erosion during rainfall are further considered. According to the damage mechanism of the slope sliding process to the original structure of the soil, a modified erosion constitutive relationship is proposed, which takes into account the destructive effect of plastic deformation on coarse particles. Then, the influence of rainfall duration, rainfall intensity, erosion, and initial saturated permeability coefficient on slope stability was simulated and analyzed. This paper provides a novel concept for slope stability analysis and safety evaluation under rainfall conditions.

Evaluation and Comparison of Breach Parametric Model for Embankment Dams

Reliable approximations for breach parameters using a parametric model due to embankment dam failure are very significant factors in dam safety and mitigation measures. Therefore, utilizing information on historically unsuccessful embankment dams, several empirical models have been formulated by different researchers. There is still no universal method for calculating the occurrence of dam breaches. The main objective of this research is to evaluate and compare the selected parametric dam breach models that are available in the literature. Four models (Xu et al., Vescher et al., Froehlich, and USB Reclamation) were chosen to forecast the breach event's parameters and peak discharges. Historically, 59 failed embankment dams’ data in various countries around the world were used. In order to assess and compare the breach models and recommend the best-performing model for predicting the peak discharge, breach width, and failure time, ten (10) statistical quantitative indicators were used. The breach model developed by Xu et al. has good performance. Finally, to show the impacts of erodibility, validation, and sensitivity of the selected model, it was checked using eight dams’ data. During the validation, the calculated and observed results were in agreement. Sensitivity revealed that large fluctuations in the breach parameter and peak discharge were seen when the erodibility coefficient increased or decreased.

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.

Slab Driven Quaternary Rock‐Uplift and Topographic Evolution in the Northern‐Central Apennines From Linear Inversion of the Drainage System

AbstractInvestigating rock‐uplift variations in time and space provides insights into the processes driving mountain‐belt evolution. The Apennine Mountains of Italy underwent substantial Quaternary rock uplift that shaped the present‐day topography. Here, we present linear river‐profile inversions for 28 catchments draining the eastern flank of the Northern‐Central Apennines to reconstruct rock‐uplift histories. We calibrated these results by estimating an erodibility coefficient (K) from incision rates and catchment‐averaged erosion rates obtained from cosmogenic‐nuclide data, and we tested whether a uniform or variable K produces a rock‐uplift model that satisfactorily fits independent geochronological constraints. We employ a landscape‐evolution model to demonstrate that our inversion results are reliable despite substantial seaward lengthening of the catchments during uplift. Our findings suggest that a rock‐uplift pulse started around 3.0–2.5 Ma, coinciding with the onset of extension in the Apennines, and migrated southward at a rate of ∼90 km/Myr. The highest reconstructed rock‐uplift rates (>1 km/Myr) occur in the region encompassing the highest Apennine massifs. These results are consistent with numerical models and field evidence from other regions exhibiting rapid rock‐uplift pulses and uplift migration related to slab break‐off. Our results support the hypothesis of break‐off of the Adria slab under the central Apennines and its southward propagation during the Quaternary. Moreover, the results suggest a renewed increase in rock‐uplift rates after the Middle Pleistocene along the Adriatic coast, coeval with recent uplift acceleration along the eastern coast of southern Italy in the Apulian foreland.

GIS-Based Integrated Multi-Hazard Vulnerability Assessment in Makedonska Kamenica Municipality, North Macedonia

This study presents a comprehensive analysis of natural hazard susceptibility in the Makedonska Kamenica municipality of North Macedonia, encompassing erosion assessment, landslides, flash floods, and forest fire vulnerability. Employing advanced GIS and remote sensing (RS) methodologies, hazard models were meticulously developed and integrated to discern areas facing concurrent vulnerabilities. Findings unveil substantial vulnerabilities prevalent across the area, notably along steep terrain gradients, river valleys, and deforested landscapes. Erosion assessment reveals elevated rates, with a mean erosion coefficient (Z) of 0.61 and an annual erosion production of 182,712.9 m3, equivalent to a specific erosion rate of 961.6 m3/km2/year. Landslide susceptibility analysis identifies 31.8% of the municipality exhibiting a very high probability of landslides, while flash flood susceptibility models depict 3.3% of the area prone to very high flash flood potential. Forest fire susceptibility mapping emphasizes slightly less than one-third of the municipality’s forested area is highly or very highly susceptible to fires. Integration of these hazard models elucidates multi-hazard zones, revealing that 11.0% of the municipality’s territory faces concurrent vulnerabilities from excessive erosion, landslides, flash floods, and forest fires. These zones are predominantly located in upstream areas, valleys of river tributaries, and the estuary region. The identification of multi-hazard zones underscores the critical need for targeted preventive measures and robust land management strategies to mitigate potential disasters and safeguard both human infrastructure and natural ecosystems. Recommendations include the implementation of enhanced monitoring systems, validation methodologies, and community engagement initiatives to bolster hazard preparedness and response capabilities effectively.

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.

Estimating the Extent of Water Erosion in Darbandikhan Lake Using a Model Gavrilović Method (EPM) (Erosion Potential Method)

Through the research, it became evident that the soil erosion protection index (Xa) in the very severe category appears to correlate with the spatial distribution of vegetation cover. It covers an area of 80.73 km2, accounting for 17.54%. However, the very weak category is among the weakest in soil protection, occupying areas characterized by water bodies, covering an area of 49.65 km2, or 10.79%. The probability erosion coefficient (Z) indicates a very weak probability of erosion, covering an area of 143.19 km2, or 31.11%. Thes means that 31.11% of the total study area of 460.21 km2 is subject to very weak erosion. The last category, very severe potential erosion, is the least extensive, covering an area of 21.06 km 2, or 4.58%. Regarding the amount of soil lost in the study area, apparent erosion ranges from 0.29 to 50 m3/km2/year. This category is prevalent in the northeastern and northwestern parts, with a clear concentration in the northern parts, covering an area of 35.04 km2, or 7.61%. Severe erosion ranges from 501 to 1500 m3/km2/year, making it the least extensive category in the region, covering the smallest area among the categories, at 19.92 km2, or 4.33%.

Investigation on critical erosion of gas production channel for sand carrying during injection and production process in gas storage

Gas wells on underground gas storage typically are operated in high-load mode, with a large working displacement injection and high-strength production. Erosion-corrosion caused by solid particles could cause serious damage to the gas well, leading to tubing column failure and security risks. The influence factors on the tubing column geometry, the fluid properties and particle properties were investigated by the indoor erosion experiments and numerical simulation respectively. Five different erosion models were applied to predict the erosion rate. The Generic model was selected to calculate the influencing value by a range of parameters after comparing the predicted results with the experimental data. The results indicated that the sand production rate, the gas production rate and the production pressure played a crucial role on the tubing column erosion. The error of Generic model is less than 20%. The product of the quadratic power of daily gas production, the negative quadratic power of production pressure and the first power of sand production rate was directly proportional to the erosion rate of tubing column. The sequence of the maximum erosion rate on different sites from high to low was obtained: No-Go Landing Nipple, Safety Valve, integral Y-type wellhead. The erosion effect on Y-type wellhead should be considered emphatically considering the long-term operation. The chart of Critical Erosion Coefficient (C value) was established according to the design criterion of API RP 14E, which is suitable for gas storage production channel. The reasonable C value should be set as 180.0 to ensure the gas storage to meet the service life. Meanwhile, the recommendatory C value range was set between 175.0 and 200.0 for considering the maximum productivity of gas storage. The research results provided a key guidance for judging the service safety of injection-production channel in gas storage.

Estimating the extent of erosion using the RUSLE coefficient for Wadi Al-Karmashiya, northeast of Wasit Province

Soil loss is a major cause of land degradation all over the world, especially in large areas of arid and semi-arid regions. The objectives of the study were to estimate the extent of erosion and soil erosion using several indicators, especially the effect of rain coefficient, soil erodibility coefficient, slope coefficient, and cover coefficient. Plant and soil conservation factors, through RUSLE laboratories, as well as employing geographical information systems to obtain results related to soil erosion in the Karmashiya Basin, as the study showed that the volume of erosion in the basin ranged between 5-265 tons/ha/year, and that the areas most affected by erosion Those extending along the waterways, especially the central and southern regions of the basin, as well as the agricultural areas spread over a diverse area of the basin’s lands, especially those that do not follow modern methods of tillage and irrigation.

OPTIMIZATION OF AGRICULTURAL LAND IN CHERKASY REGION THROUGH ALTERNATIVE FARMING SYSTEMS

In recent years, much attention has been paid to preserving soil fertility and preventing soil degradation, driven by public interest in the environment and growing awareness of the role of soil cover in ensuring environmental and food security in any country. A negative consequence of anthropogenic impact is the deterioration of the ecological function of soils in the ecosystem. There are processes of compaction and disruption of water, air and nutrient regimes. The goal of article is to soil erosion is the main destabilizing factor of the ecological situation in the agricultural landscapes of Cherkasy region, and this publication is aimed at studying it. To determine the qualitative characteristic of the soil cover, namely the actual state of water erosion, the erodibility coefficient (CEr) and data on the distribution of eroded soils by gradations of erodibility are used. The soil erosion coefficient is calculated as a weighted average for each soil based on the coefficients (non-eroded - 1; slightly eroded - 1.2; medium eroded - 1.4; highly eroded - 1.6), which indicate a corresponding decrease in fertility compared to the full profile soil. The erodibility coefficient, together with the data on the distribution of eroded soils by gradations of erodibility, is used as an important qualitative characteristic of the soil cover. Agricultural land occupies about 70% of Ukraine's territory, which is more than 60 million hectares. Overdevelopment of agriculture and a large amount of arable land are the main environmental problems associated with agriculture. The average plowed area reaches 70%, and 90% in Vinnytsia, Cherkasy, Kherson, Kirovohrad, and Zaporizhzhia regions. The article describes the negative effects of water erosion on agricultural landscapes of Cherkasy region. The definition of the qualitative characteristics of the soil cover, namely the actual state of erosion processes using the erodibility coefficient, is given.

Infiltration-Based Variability of Soil Erodibility Parameters Evaluated with the Jet Erosion Test

Soil erosion by water on agricultural hillslopes leads to numerous environmental problems including reservoir sedimentation, loss of agricultural land, declines in drinking water quality, and requires deep understanding of underlying physical processes for better mitigation. It is imperative to accurately predict soil erosion caused by overland flow processes so that soil conservation efforts can be undertaken proactively before large-scale sedimentation problems arise. Soil detachment is often described by the excess shear stress equation that contains two physical soil erodibility parameters, erodibility coefficient, and critical shear stress. These parameters are normally assumed to be constant but can change across varying soil texture classes as well as during surface runoff events due to changes in soil cohesion and potential dependency on soil moisture content. These changes may significantly affect soil erosion rates at the field and watershed scale. In this study, the erodibility parameters of three soil types (sandy loam, clay loam, and silty clay loam) were analyzed using a laboratory mini-Jet Erosion Test (JET) to determine the effect of soil sample infiltration and moisture condition. Results from the experiments depicted a dynamic relationship between the soil erodibility parameters and amount of infiltrated mass of water. Data analysis displayed that for soils of different texture critical shear stress exhibited local minimum with higher values for very dry and saturated soils, while erodibility coefficient tended to increase with the increase of mass of soil water. Utilizing these dynamic soil erodibility parameters did not result in a significant difference in soil erosion rates when compared to using the averaged soil erodibility parameters taken from the experiment but the range of potential erosion rates increases with the increase of applied sheer stress to soil surface. The erosion rates with the experiment-based coefficients were found to be higher than with the baseline WEPP-based coefficients. These results highlight the importance of evaluating the effect of intrastorm dependent factors during surface runoff events, such as antecedent soil moisture content, time to peak from the start of runoff, soil cohesion, etc., on soil erodibility parameters to accurately calculate erosion rates, especially for initially dry soils or during earlier stages of surface runoff when critical shear stresses were highly affected. Further assessment of such factors with JET or other laboratory and field tests is recommended.

Effects of Erosion Control Works: Case Study–Reservoir Celije, Rasina River Basin, the Zapadna Morava River (Serbia)

The aim of this research was to analyze the impact of implemented erosion control works (ECW) on soil erosion intensity in the watershed of the Ćelije reservoir (Rasina River) in the period between 1968 and 2022. The Erosion Potential Method was used to calculate the annual gross erosion (W), sediment transport (G), and erosion coefficient (Z) in the study area. As a result of the performed ECW there was a general decreasing trend in the intensity of soil erosion processes in the last 54 years. The specific annual gross erosion was 1189.12 m3/km−2/year−1 in 1968, while in 2022 it was 554.20 m3/km−2/year−1. The specific sediment transport was 540.18 m3/km−2/year−1 in 1968 and 253.55 m3/km−2/year−1 in 2022. Due to the changes in the intensity of erosion processes, the specific annual gross erosion decreased by 634.92 m3/km−2/year−1 and the specific sediment transport decreased by 286.63 m3/km−2/year−1. The erosion coefficient was reduced from Z = 0.62 to Z = 0.35. A dependence between the slope of siltation and the natural bed slope was defined. The results show a significant correlation between erosion intensity and performed ECW, providing a basis for future watershed management and defining a strategy for soil erosion control in the Ćelije reservoir watershed.

Application of the tidally averaged equilibrium cohesive sediment concentration for determination of physical parameters in the erosion-deposition fluxes

A puzzling fact for the Partheniades-Krone formula is the adoption of very contrasting values for the empirical parameters (e.g., the erosion coefficient and the critical shear stresses) but satisfactory reproduction of the suspended sediment concentration (SSC). Here, a theoretical equation for the tidally-averaged equilibrium (TAE) condition is derived by setting the integrated erosion flux throughout a tidal period equivalent to the integrated deposition flux throughout the same tidal period, leading to a new constraint condition on these parameters if values of the TAE-SSC are available. A preliminary check using the measured data of the Yangtze Estuary shows that a larger critical shear stress for erosion would require a smaller critical shear stress for deposition, both of which must be enhanced if the erosion coefficient further increases. Contrasting sets of parameter values derived by this constraint are fed into a coupled hydro-sediment-morphodynamic model to simulate cohesive sediment transport in the Yangtze Estuary. The results confirm that very contrasting parameter values can indeed lead to satisfactory reproduction of the temporal variations of the SSC (e.g., those in July 2016, including both spring tide and neap tide). This is further demonstrated by the numerical modelling of cohesive sediment transport in an idealized symmetrical estuary. These results indicate that the TAE condition can be used as a constraint for determining the erosion coefficient and the critical shear stresses for erosion and deposition. In addition, two simplified equations of the bed sediment mass conservation (no erosion version and the no deposition version) are derived as complements for obtaining a unique set of the three parameter values, provided that the simultaneous measured time series of SSC, bed shear stress and bed level can be collected at the same gauging station.