Freeze-thaw cycles (FTC) influence soil erodibility (K-r) by altering soil properties. In seasonally frozen regions, the coupling mechanisms between FTC and water erosion obscure the roles of FTC in determining soil erosion resistance. This study combined FTC simulation with water erosion tests to investigate the erosion response mechanisms and key drivers for loess with varying textures. The FTC significantly changed the mechanical and physicochemical characteristics of five loess types (P < 0.05), especially reducing shear strength, cohesion, and internal friction angle, with sandy loam exhibiting more severe deterioration than silt loam. Physicochemical indices showed weaker sensitivity to FTC versus mechanical properties, with coefficients of variation below 5 %. Wuzhong sandy loess retained the highest K-r post-FTC, exceeding that of the others by 1.04 similar to 2.25 times, highlighting the dominant role of texture (21.37 % contribution). Under different initial soil moisture contents (SMC), K-r increased initially and then stabilized with successive FTC, with a threshold effect of FTC on K-r at approximately 10 FTC. Under FTC, the K-r variation rate showed a concave trend with SMC, turning point at 12 % SMC, indicating that SMC regulates freeze-thaw damage. Critical shear stress exhibited an inverse response to FTC compared to K-r, displaying lower sensitivity. The established K-r prediction model achieved high accuracy (R-2 = 0.87, NSE = 0.86), though further validation is required beyond the design conditions. Future research should integrate laboratory and field experiments to expand model applicability. This study lays a theoretical foundation for research on soil erosion dynamics in freeze-thaw-affected areas.

The erosion of cohesive soils is regarded as one of the major threats to the failure of earth structures. The current evaluation of clay erodibility is primarily based on empirical correlations with other physical and mechanical soil properties, which lack a fundamental understanding of multiscale resistance formation under complicated environmental conditions. In this study, the hole erosion test (HET) was conducted using our augmented testing system, which includes sample preparation equipment and a temperature control unit. The kaolinite specimen is prepared following the saturated preconsolidation approach under defined stresses, which significantly improves the test repeatability. In total, 33 specimens are prepared and tested using the enhanced HET system under varying preconsolidation pressures, temperatures, and fines contents with triplicates for each case. The erosion resistance of clay increases with the preconsolidation pressure, and macropores are destructed into micropores, as revealed by the mercury intrusion porosimetry (MIP) test and the specific surface area analyzer. The scanning electron microscopy (SEM) images indicate an anisotropic aggregate structure prepared using the preconsolidation approach, which possesses different erodibility indices in different flow directions. With the increase in temperature from 10 degrees C to 40 degrees C, the critical shear stress decreases from 292 to 131 Pa (or by 55.1%). The addition of quartz sands in the kaolinite clay undermines the soil erosion resistance.

The Sanjiangyuan region, known as the Chinese Water Tower, serves as a crucial ecological zone that is highly sensitive to climate change. In recent years, rising temperatures and increased precipitation have led to permafrost melt and frequent occurrences of thermokarst landslides, exacerbating soil erosion issues. Although studies have explored the impact of freeze-thaw action (FTA) on soil properties, research on this phenomenon within the unique geomorphological unit of thermokarst landslides, formed from degrading permafrost, remains sparse. This study, set against the backdrop of temperature-induced soil landslides, combines field investigations and controlled laboratory experiments on typical thermokarst landslide bodies within the permafrost region of Sanjiangyuan to systematically investigate the effects of FTA on the properties of soils within thermokarst landslides. Furthermore, this study employs the EPIC model to establish an empirical formula for the soil erodibility (SE) factor before and after freeze-thaw cycles (FTCs). The results indicate that: (1) FTCs significantly alter soil particle composition, reducing the content of clay particles in the surface soil while increasing the content of sand particles and the median particle size, thus compromising soil structure and enhancing erodibility. (2) FTA initially significantly increases soil organic matter content (OMC); however, as the number of FTCs increases, the magnitude of these changes diminishes. The initial moisture content of the soil significantly influences the effects of FTA, with more pronounced changes in particle composition and OMC in soils with higher moisture content. (3) With an increasing number of FTCs, the SE K-value first significantly increases and then tends to stabilize, showing significant differences across the cycles (1 to 15) (p < 0.05). This study reveals that FTCs, by altering the physicochemical properties of the soil, significantly increase SE, providing a scientific basis for soil erosion control and ecological environmental protection in the Sanjiangyuan area.

The relationships between soil aggregates, aggregate-associated carbon (C), and soil compaction indices in pomegranate orchards of varying ages (0-30 years) in Assiut, Egypt, were investigated. Soil bulk density (Bd) and organic carbon (OC) content increased with orchard age in both the surface (0.00-0.20 m) and subsurface (0.20-0.40 m) layers 0.20-0.40 m). The percentage of macroaggregates (R-0.25) and their OC content in the aggregate fraction > 0.250 mm increased as the pomegranate orchard ages increased in the surface layer (0.00-0.20 m). Older pomegranate orchards show improved soil structure, indicated by higher mean weight diameter (MWD) and geometric mean diameter (GMD), alongside reduced fractal dimension (D) and erodibility (K). As orchard ages increased, maximum bulk density (BMax) decreased due to an increase in OC, while the degree of compactness (DC) increased, reaching a maximum at both soil layers for the 30 Y orchards. Soil organic carbon and aggregate-associated C significantly influenced BMax, which led to reducing the soil compaction risk. Multivariate analyses identified the >2 mm aggregate fraction as the most critical factor influencing the DC, soil compaction, and K indices in pomegranate orchards. The OC content in the >2 mm aggregates negatively correlated with BMax, DC, and K but was positively associated with MWD and GMD. Moreover, DC and Bd decreased with higher proportions of >2 mm aggregates, whereas DC increased with a higher fraction of 2-0.250 mm aggregation. These findings highlight the role of aggregate size fractions and their associated C in enhancing soil structure stability, mitigating compaction, and reducing erosion risks in pomegranate orchards.

The changing climate raised more concerns about the durability of aged slopes and embankments due to the increased frequency of extreme rainfall events. Recently, there has been a growing interest in the utilization of biopolymer as a biomediated soil improvement method. However, challenges, such as, strength loss due to exposure to adverse environmental conditions and limitations on the suitability of soils for effective treatment, can be problematic in practice. Therefore, this study introduces an innovative approach by combining biopolymer with another eco-friendly material, biochar. The erodibility of the reinforced soil was examined through both wetting and drying tests and slope-rainfall simulation tests with the consideration of different rainfall intensities and slope inclinations. The findings suggest that cyclic wetting and drying conditions can lead to a progressive degradation (decrease in strength) of soils reinforced with biopolymer, starting from the initial cycle. Conversely, incorporating biochar into the biopolymer-reinforced soils successfully postponed this decline in both compressive and shear strength, prolonging the soil's resilience by two to three cycles. In addition, soil slopes reinforced with the combined treatment exhibited reduced soil runoff and increased durability under both light and heavy rainfall compared to slopes reinforced with either biopolymer or biochar alone. The findings of this study provide an innovative method for controlling soil erosion on sandy soil, suggesting its potential application in slope stabilization and restoration.

Freeze-thaw cycles (FTCs) influence soil erodibility through alterations in soil structure and mechanical properties. Despite existing studies, the quantitative relationship between soil erodibility and the number of freeze-thaw cycles (FTCs) at different initial soil water contents (ISWC) is still not fully understood. This study employed direct shear tests, soil disintegration tests, and pore size distribution (PSD) tests to quantify soil erodibility indices and soil structure characteristics for brown soil in Northeast China. Five FTCs (zero, one, five, ten, and fifteen) and five ISWC (10, 15, 20, 25, and 35%) were considered. The results revealed that as ISWC increased, soil cohesion generally declined, particularly with the rise in FTCs, making the difference in cohesion between high and low ISWC more pronounced. In contrast, the differences in internal friction angles between different ISWC gradually decreased as the FTCs increased. The soil disintegration rate was significantly affected by ISWC, showing an initial increase followed by a decrease as ISWC rose (p < 0.05). Notably, the range of 10-15% ISWC was the most easily disintegrated ISWC. FTCs could decrease the soil pore volume of lower ISWC and increase the soil pore volume of higher ISWC. 0.4 mu m radius pores were a critical threshold for pore changes in soil under FTCs and five FTCs might be the critical value for influencing macropores. FTCs could affect 0.1-4 mu m radius pores indirectly influencing the internal friction angle, and affect 4-25 mu m radius pores indirectly influencing the cohesion and disintegration rate. This paper introduces novel insights into the erosion characteristics and micro-mechanisms of brown soil under freeze-thaw conditions.

The erodibility of clay exhibits significant variability across different influencing factors. The existing research using compaction approach for specimen preparation neglected the non-uniformity in soil specimens and is unsuitable for high plasticity clay. In this study, the saturated preconsolidation approach was used to prepare uniform kaolinite specimens to simulate natural consolidating conditions. The prepared specimens were then analyzed using a hole erosion analyzer, and the surface morphology of the eroded hole was quantified using a 3D scanner. A total of 18 hole erosion tests were conducted under various preconsolidation pressures and erosion directions. The erosion resistances were found to increase with higher prestress, and the variation of critical shear stress across different erosion directions reached 29%. The SEM images reveal a stack-packing microstructure in the consolidated specimens, with a denser clay aggregate packing observed under higher pre-stress conditions. The anisotropic erosion property is properly described by the radial anisotropic coefficient kr and the roughness anisotropic coefficient k(pr), and the critical shear stress tau(c) is negatively correlated with k(r), while its correlation with k(pr) is not obvious.

Erosion causes significant damage to life and nature every year; therefore, controlling erosion is of great importance. Therefore, maintaining the balance between soil, plants, and water plays a vital role in controlling erosion. Aim of this study was to estimate some erodability parameters (structural stability index-SSI, aggregate stability-AS, and erosion ratio-ER) with indices and reflectance obtained via TripleSat satellite imagery using machine learning algorithms (support vector regression-SVR, artificial neural network-ANN, and K-nearest neighbors-KNN) in Samsun Province, Vezirkopru, Turkiye. Various interpolation methods (inverse distance weighting-IDW, radial basis function-RBF, and kriging) were also used to create spatial distribution maps of the study area for observed and predicted values. Estimates were made using NDVI, SAVI, and ASVI indices obtained from satellite images and NIR reflectance. Accordingly, the ANN algorithm yielded the lowest MAE (2.86%), MAPE (9.46%), and highest R2 (0.82) for SSI estimation. For AS and ER estimation, SVR had the highest predictive accuracy. Given the RMSE values in spatial distribution maps for observed and estimated values (SSI 7.861-7.248%, AS 14.485-14.536%, and ER 4.919-3.742%), the highest predictive accuracy was obtained with kriging. Thus, it was concluded that erosion parameters can be successfully estimated with reflectance and index values obtained from satellite images using SVR and ANN algorithms, and low-error distribution maps can be created using the kriging method.

Burn severity maps are typically generated using spectral indices and used in classifying the spatial distribution of damage caused by fires. In densely vegetated forests, even when overstory crowns are severely affected by the high-intensity fire, the topsoil may not experience high temperatures which makes spectral indices inadequate for assessing soil burn severity. On the other hand, field observations of soil burn severity can be subjective. For this reason, horizon-based soil sampling and extensive soil testing (physical, hydrological, chemical, mineralogical, and mechanical properties) were conducted in this study. Statistical tests have been employed to identify the most representative soil parameters of soil burn severity in the area. The remote sensing data (differential spectral indices and land surface temperature), field observations, and site-specific burned soil data were combined through weighted overlay analysis in the Geographical Information System (GIS). Accordingly, an improved soil burn severity map for the area affected by a forest fire in Kavaklidere, Mugla, Turkiye was produced to show the post-fire soil erodibility potential. The findings of this study indicated that the effect of fire on soil properties was limited to the upper 0-4 cm of the soil profile with surface temperatures reaching a maximum of 300 degrees C for the high burn severity. The liquid limit, shear strength, organic matter, water repellency, and mean grain size were determined to be promising parameters to represent the soil burn severity. The map produced using the novel approach outperformed conventional burn severity maps. In addition, the high soil burn severity class can serve as a parameter to indicate erosion susceptibility after a wildfire.

Monitoring erosion is an important part of understanding the causes of this geotechnical and geological phenomenon. In order to monitor them, it is necessary to develop equipment that is sophisticated enough to resist the sun and water without damage, that is self-mechanized, and that can support the amount of data collected. This article introduces a rain-triggered field erosion monitoring device composed of three main modules: control, capture, and sensing. The control module comprises both hardware and firmware with embedded software. The capture module integrates a camera for recording, while the sensing module includes rain sensors. By filming experimental soil samples under simulated rain events, the device demonstrated satisfactory performance in terms of activation and deactivation programming times, daytime image quality without artificial lighting, and equipment protection. The great differences about this monitoring device are its ease of use, low cost, and the quality it offers. These results suggest its potential effectiveness in capturing the progression of field erosive processes.