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Soil erosion is a pressing environmental issue with significant agricultural productivity and ecosystem stability implications. In recent years, biochar, a carbon-rich product of biomass pyrolysis, has emerged as a promising soil amendment tool for erosion control due to its ability to improve soil quality and stability. This review paper aims to comprehensively analyze the effectiveness of biochar role in mitigation of soil erosion and sustainable land management practices. By examining a wide range of research studies, this paper elucidates the impact of biochar on key soil erosion parameters as it directly affects the soil structure, water-holding capacity, and nutrient retention. The paper discusses how biochar interacts with soil particles and aggregates to enhance their stability and resistance to erosive forces. It also assesses the influence of biochar properties, such as feedstock type, pyrolysis temperature, and application rate, on its erosion control efficacy. Furthermore, this review explores the role of biochar in promoting plant growth and root development, thereby reinforcing the vegetation cover and further reducing erosion susceptibility. Finally, an outline of potential challenges and opportunities for the widespread adoption of biochar-based erosion control strategies in different agricultural and environmental contexts is presented. Overall, this review provides valuable insights into the multifacet role of biochar in sustainable soil management and offers recommendations for future research directions on direct and indirect application on soil erosion control.

Margin lateral erosion is arguably the main mechanism leading to marsh loss in estuaries and lagoons worldwide. Our understanding of the mechanisms controlling marsh edge erosion is currently quite limited and current predictive models rely on empirical laws with limited general applicability. We propose here a simple theoretical treatment of the problem based on dimensional analysis. The identification of the variables controlling the problem and the application of Buckingham's theorem show, purely on dimensional grounds, that the rate of edge erosion and the incident wave power density are linearly related. The predictive ability of the derived relationship is then evaluated, positively, using new long‐term observations from the Venice lagoon (Italy) and by re‐interpreting data available in previous literature. Key Points Marsh edge erosion rate is a linear function of wave power density Marsh edge erosion rate is a function of marsh cliff height Traditional, power‐law, formulas are inconsistent with theory and observations

Planar erosion is an important mode of soil erosion, which occurs in the process of loess slope erosion, gully erosion, and cave erosion. It is of great significance to understand the characteristics and mechanism of planar erosion to reveal the mechanism of loess erosion and the prevention and treatment of soil and water loss. In this paper, a series of loess planar erosion tests have been carried out through self-developed large-scale loess scour instrument. The erosion process and stage characteristics of subsurface erosion under different conditions have been analyzed and summarized, and the internal mechanism of the loess planar erosion process in different erosion characteristic stages has been revealed. Furthermore, based on the special \"core (powder) + coat\" microstructure characteristics of loess, a numerical model of inter particle linkage was established to characterize the characteristics of loess microstructure and anti-erosion properties. The numerical simulation results carried out based on the numerical model of inter particle linkage established in this paper are in good agreement with the main results of the physical simulation of planar erosion. The results all show that the loess planar erosion at the scale of large test blocks can be divided into three characteristic stages: uniform planar erosion stage, micro gully erosion stage, and collapse failure stage. This indicates that the fluid–solid coupling simulation method of CFD–DEM proposed in this paper has high simulation accuracy and has great application potential in the research and application of loess erosion. This provides a new and feasible idea for the study of loess slope erosion and hydraulic loss control on the Loess Plateau, which is worthy of further promotion.

Soil erosion is a natural process; it adversely impacts natural resources, agricultural activities, ecological systems, and environmental quality as it degrades landscapes and water quality, disrupts ecosystems, and intensifies hazards. Management strategies are needed that protect soil erosion in agricultural watersheds to achieve the sustainable land-use planning. This study maps soil erosion susceptibility using two GIS-based machine-learning approaches—analytical hierarchy process (AHP) and fuzzy logic modeling in the Kunur River Basin, West Bengal, India. Fifteen soil erosion conditioning variables were integrated with the modeling methods, remote sensing data, and GIS analysis. The relative importance of the conditioning variables was assessed for their capacities to predict susceptibility of locations to soil erosion. The soil erosion susceptibility maps generated from the two models used 70% of surveyed soil erosion sites. These models’ maps were validated with the characteristics of the remaining 30% of the soil erosion sites to produce a receiver operating characteristics curve. The results indicated that the fuzzy logic model has the higher prediction accuracy; the area under the curve (AUC) value was 91.4%. The AUC value of the AHP model was 89.7%. Both models indicated that study area contains regions of high to severe soil erosion susceptibility. Logistic regression was used to discern the variables’ importance in the assessment. Relief, NDVI, distance from a river, rainfall erosivity, and soil types were the most important variables. TWI, SPI, aspect, and a sediment transportation index were of least importance. Fuzzy-logic-generated SESMs can be effective tools to guide protective actions and land managers’ measures during the primary stages of soil erosion to control the development of soil degradation.

Field measurement of wind erosion linked to soil properties improves our understanding of erosion processes in arid and semiarid regions to combat this environmental threat. The aim of this study was to investigate wind erosion and threshold velocity (Vt) in relation to soil properties using a portable wind tunnel in 60 sites of Kerman, the largest province of Iran. The result indicated that wind erosion rates ranged from 0.03 g m−2 min−1 to 3.41 g m−2 min−1, indicating a wide variability in the erodibility of soils. Wind erosion was inversely attributed to Vt following a power function. In all cases, the influence of soil properties on wind erosion was supported by their opposite effect on threshold velocity. Clay and silt fractions, mean weight diameter (MWD) of aggregates, dry stable aggregates (DSA), shear strength, surface gravel, the concentrations of K+, Ca2+, and Mg2+, soil organic carbon (SOC) and calcium carbonate equivalent (CCE) were inversely proportional to wind erosion rates following nonlinear functions. Wind erosion was significantly increased as electrical conductivity (EC) and sodium adsorption ratio (SAR) increased. Critical values of 5.7–8.9 m s−1 at 10-m height for Vt, 7% for clay content, .3 mm for MWD, 25% for DSA, and 5% for surface gravel were recognized, approximately. Multiple regression analysis indicated that SAR and MWD were the best predictors of wind erosion rate. Meanwhile, MWD, surface gravel, clay content, and SOC had the best estimation for threshold velocity.

The wind wave erosion is one of the main factors of the soil bank slope retreat in plain irrigation reservoirs, which plays an important role in the bank profile evolution and seriously affects the agricultural irrigation. To study the failure mechanism induced by the wind wave erosion, a reservoir soil bank slope is taken as a research object. Through the field investigations, laboratory tests and prototype observations, a mechanical model of the bank slope recession under the wind wave erosion is established and verified by the field observation results. On this basis, the finite element method is utilized to analyze its stability in different erosion periods, and the evolution law of the safety factors with erosion time is revealed quantitatively. The results show that the lateral retreat of the slope foot will lead to local collapse and form vertical surfaces when eroded by wind waves. Based on the monitoring data in April 2019, the calculated lateral erosion distance is 1.29 m after the wind wave erosion lasts for 9 h, and the vertical surface height reaches 3.10 m, resulting in the bank slope failure. After failure, it is reshaped, and the stability is significantly improved. However, the new slope will face the instability risk of the former one when eroded by wind waves again. The stability safety factors generally show cyclical variation with the wave erosion time. The failure and retreat of the bank slope repeat the above cycle annually.

One of the prevalent material removal mechanisms in vibratory ultrasonic machining (USM) is cavitation erosion. The slurry-used USM process contains a mixture of water and abrasive particles—hence, strictly not pure cavitation. Cavitation erosion is the process of surface modification by generation and collapse of vapor bubbles on the workpiece surface inside a liquid medium. Although considerable research has been devoted in finding the material removal mechanism, rather less attention has been paid on the effect of pressure and temperature in cavitation erosion. Hence, efforts have been taken in this investigation to identify the mechanism of cavitation collapse at various ambient pressures and fluid temperatures and to investigate their effects in machining using AISI 304 stainless steel and aluminum 6061-T4 with wire EDM surface. Ambient pressure and temperature were varied from 100 to 400 kPa and 10 to 90 °C respectively. The outcomes showed that mass loss increased until 400 kPa and 50 °C and then declined with increase in liquid temperature. Scanning electron microscope (SEM) images showed that most of the test surface deformed plastically with surface undulations and material removal was by micro-pitting. Further, suggestions are provided to control the machining conditions from the identified cavitation collapse mechanism. Optimal conditions to accelerate the machining process were found to be 50 °C and 400 kPa.

Freeze–thaw cycles alter soil properties markedly and cause a subsequent change in soil erosion, however previous studies about freeze–thaw cycles’ influence on soil physical properties were restricted to simulating runoff and soil loss on cropping slopes in cold regions and failed to invoke responses of soils under different degraded conditions to freeze–thaw cycles. This study was designed to compare and quantify the responses of different degraded soils to freeze–thaw cycles in laboratory setting. The soil conditions were divided into five types: original profile, degraded profile, parent profile, deposited profile and compacted surface. Samples were collected from the black soil region in Northeast China and were frozen (− 12 °C for 12 h) and then thawed (8 °C for 12 h) for certain times. Samples without freeze–thaw cycles were treated as control group. Porosity, aggregate mean weight diameter, saturated hydraulic conductivity and water retention curves were tested for control and experimental samples. Results showed that porosity and saturated hydraulic conductivity significantly increased (maximum for degraded profile), while mean weight diameter decreased (maximum for compacted surface) compared with control group. After 30 freeze–thaw cycles, remaining water contents increased in deposited and original profiles, while decreased in compacted surface. Generally, well-structured soils are more difficult to be broken by repeated FTCs. The first freeze–thaw cycle displayed evident influence on soil physical properties under original profile, and at least one threshold of cycle time (between 5 and 20) existed. These findings may help improve understanding the functional mechanism of freeze–thaw cycles on soil erosion processes.

Soil erosion is a major threat to soil functioning. The use of vegetation to control erosion has long been a topic for research. Much of this research has focused on the above-ground properties of plants, demonstrating the important role that canopy structure and cover plays in the reduction of water erosion processes. Less attention has been paid to plant roots. Plant roots are a crucial yet under-researched factor for reducing water erosion through their ability to alter soil properties, such as aggregate stability, hydraulic function and shear strength. However, there have been few attempts to specifically manipulate plant root system properties to reduce soil erosion. Therefore, this review aims to explore the effects that plant roots have on soil erosion and hydrological processes, and how plant root architecture might be manipulated to enhance its erosion control properties. We demonstrate the importance of root system architecture for the control of soil erosion. We also show that some plant species respond to nutrient-enriched patches by increasing lateral root proliferation. The erosional response to root proliferation will depend upon its location: at the soil surface dense mats of roots may reduce soil erodibility but block soil pores thereby limiting infiltration, enhancing runoff. Additionally, in nutrient-deprived regions, root hair development may be stimulated and larger amounts of root exudates released, thereby improving aggregate stability and decreasing erodibility. Utilizing nutrient placement at specific depths may represent a potentially new, easily implemented, management strategy on nutrient-poor agricultural land or constructed slopes to control erosion, and further research in this area is needed.

Waterfall retreat transmits base‐level perturbations upstream, thereby providing markers of changing climate and tectonics. In homogeneous rock, waterfalls often retreat either by direct waterfall‐face erosion or incision from repeating (‘cyclic’) steps formed above waterfalls. We lack knowledge on the conditions driving these different erosion styles, limiting our ability to predict waterfall retreat. We address this knowledge gap through flume experiments assessing how changing flow hydraulics modulates bedrock erosion. We show that, under large discharges, changes in flow hydraulics cause spatial variability in particle impact velocity, leading to cyclic step formation. As discharge decreases, both the magnitude and spatial variability of particle impact velocity decreases, causing more uniform erosion, limiting cyclic step development and potentially allowing direct erosion of the waterfall face to become the dominant retreat mechanism. These results suggest climate change and water‐resource management can alter the rate and style of waterfall retreat. Plain Language Summary Waterfalls retreat upstream as they erode and, due to their rapid erosion, waterfalls can set erosion rates within landscapes. Waterfall retreat rates depend, in part, on the physical processes driving waterfall erosion. Waterfalls typically retreat either via direct waterfall‐face erosion or via forming smaller steps (called ‘cyclic steps’) which form immediately upstream of waterfalls and erode vertically. However, the conditions that cause one of these erosion mechanisms to dominate over the other are not well known. We performed laboratory experiments simulating waterfall erosion under variable water discharge while measuring changes in flow velocity and the velocity of sediment impacting the bedrock river bed. We pay particular attention to particle impacts because, like sandblasting, it is the impacts from sediment that drive bedrock erosion. Our experiments show that sediment impact velocity is sensitive to water discharge, and that this should lead to waterfalls retreating via cyclic step formation for rivers for relatively large floods, whereas for relatively small floods, waterfalls are more likely to retreat via direct erosion of the waterfall face. Key Points The spatial distribution of particle impact velocity above waterfalls is sensitive to flow hydraulics At large discharges, increased spatial variability in particle impact velocity drives cyclic step formation above waterfalls At low discharges, reduced variability in impact velocity limits cyclic step formation and promotes retreat via waterfall‐face erosion