Soil Slope Research Articles

Model test study on the rainfall erosion mechanisms and reclamation potential of open-pit coal mine dump soil improved by fly ash and polyacrylamide

Increasing the soil erosion resistance is one of the core issues in slope erosion control and ecological environmental restoration of open-pit coal mine (OPCM) dumps. In this study, fly ash (FA) and polyacrylamide (PAM) were used to improve the soil quality of an OPCM dump, and an indoor physical model was constructed to investigate the water and soil loss characteristics of the improved soil via simulated rainfall experiments. Scanning electron microscopy and Pore and Crack Analysis System software were employed to systematically investigate the erosion resistance mechanisms of the improved soil qualitatively and quantitatively. Finally, the improved technique for order preference by similarity to an ideal solution (TOPSIS) method was adopted to evaluate the reclamation potential of the improved soil. The results revealed that under the action of PAM (PAM and PAM–FA), the average erosion rate of the slope decreased by more than 90 %. Compared with that in the control group, when FA was applied alone, the slope erosion rate first decreased and then increased with increasing FA content. Upon PAM addition, the erosion pattern changed from the splash erosion stage, cave erosion stage, gully erosion stage, and tensile slip stage to the splash erosion stage and cave erosion stage. However, no obvious change in the runoff pattern. Erosion and runoff patterns are generally affected by the amendment type, addition concentration, porosity, pore shape, pore direction and hydrological environment. The erosion resistance mechanism of the improved soil entailed the formation of more stable soil aggregates via filling, cementation, skeleton support generation, and flocculation of FA and PAM. In addition, the optimal soil improvement was achieved when FA and PAM were added at levels of 16 % and 0.01 %, respectively. The obtained research results could be used for erosion control and ecological environmental protection of coarse-grained soil slopes in mining areas, highways and other fields and could be widely applied.

Validation of Soil Detachment Rate Equations on Spring Thaw Period Slopes: Insights From Sediment Concentration and Transport Capacity

AbstractSoil detachment plays a central role in the formulation of soil erosion models, particularly for the simulation and prediction of erosion in cold climates during the thaw period. This research attempts to elucidate the mechanisms of soil detachment on spring thaw period slopes through comprehensive flume experiments, coupled with the application of rare earth element (REE) tracer, investigating the relationships between soil detachment rates, sediment concentration and sediment transport capacity. Observations indicate a nuanced response of soil detachment rate and sediment concentration to scour duration, characterized by an initial increase, subsequent decrease and eventual equilibrium. As thaw depth increases, the primary source of eroded sediment gradually shifts from the upper slope to the mid‐slope. Soil detachment rate was affected by sediment concentration, flow discharge, slope gradient, thawing depth, and slope positions. Furthermore, our analysis reveals a power function relationship (R2 = 0.846) between soil detachment rate, effective shear stress, and sediment transport rate and capacity. These results provide valuable insights into the modeling and prediction of soil erosion processes on brown soil slopes subjected to spring thaw period cycles.

Physics-based time-of-failure determination of rainfall-induced instability in lateritic soil slopes

Conventional time-of-failure estimated from slope surface displacement over time, ignores the crucial geotechnical and environmental causative factors that lead to slope instability. The instrumentation and monitoring are expensive, labour-intensive, and often not feasible for large number of hill slopes. This paper focuses on the physics-based determination of time-of-failure charts for laterite soil slopes prevalent in the Western Ghats of India, under rainfall infiltration. The finite element model was first validated by performing coupled flow deformation analysis of Kondavi soil cutting situated in the Ratnagiri district of Maharashtra, India. The soil samples were collected from the site for basic geotechnical characterisation in the laboratory. In addition, the soil water characteristics curve (SWCC) was determined using the filter paper method, and the unsaturated parameters were obtained using the van Genuchten model. Following the validation of numerical model with the failed Kondavi cutting, the factor of safety (FOS) and time-of-failure (TOF) were studied for varying rainfall intensity, and permeability of the soil. The FOS and TOF charts were then established for varying slope angles (30°, 45°, 60°), effective cohesion (10 kPa, 18 kPa, 25 kPa), effective friction angle (22°, 25°, 28°), water table depth (25 m, 28 m, 30 m, 35 m) and height of slope (15 m, 25 m, 35 m). Results indicate that if rainfall intensity is lower than soil permeability, TOF depends on both the intensity and duration of the rainfall. Higher rainfall intensity leads to a shorter time of failure, and vice versa. Conversely, when rainfall intensity exceeds soil permeability, TOF is determined by the duration of rainfall and the permeability of soil, as the rainfall infiltrates at the saturated permeability rate regardless of its intensity. It is also observed that friction is the dominant parameter for initial FOS, while cohesion is the dominant parameter for the TOF of a rainfall-induced landslide. Finally, charts are proposed that shall serve as a preliminary guide for the determination of the TOF for rainfall-induced instability in the lateritic soil slopes of India. The performance of the charts is further evaluated by comparing the observed and predicted TOF of two other failed laterite cuttings. The implications of these findings are profound, as the proposed TOF charts can be integrated into early warning systems, contributing towards improved disaster mitigation and preparedness with timely decision making for adequate management of landslide associated risks.

Efficacy of Utilizing Stress-Dependent SWRC in the Analysis of a Footing Resting on an Unsaturated Soil Slope

Efficacy of Utilizing Stress-Dependent SWRC in the Analysis of a Footing Resting on an Unsaturated Soil Slope

Volcanic red soil in the tropical mountain region: landscape, parent materials, engineering characteristics, and its use on slope stability (case study: West Lampung, Sumatra, Indonesia)

ABSTRACT The characterization of tropical mountain volcanic red soil in the tropical mountain region, West Lampung area, Sumatra, Indonesia concerning the landslide disaster has been carried out. The research methods used in this research are remote sensing methods, field geological mapping, petrographic analysis (thin section analysis), soil geotechnical analysis, soil geochemical analysis, slope stability analysis, and statistical analysis. The findings indicated that the study area’s volcanic red soil is distinguished by rolling hills with a V-shaped valley, a moderate to severe incline, and an elevation ranging from 850 to 1150 m above sea level. The soil is volcanic residual soil which resulted in wet tropics and from tuff layer and tuffaceous breccias in the felsic composition of the hydrothermal alteration environment. The soil of the study area has a reddish-brown color, and loose characteristic, and belongs to the type of very loose to solid high plasticity uniform inorganic sandy clayey silt. Based on saturated soil slope stability analysis, volcanic red soil has a stable to unstable category if forming a slope. The intrinsic factor that affects the stability of the slope is the percentage of clay content, electrical sensitivity, plasticity index, degree of saturation, and percentage of clay mineral content.

Effects of tillage practices on water storage and soil conservation in red soil slope farmland in Southern China

Under the current conditions of global climate change, many unreasonable tillage practices exacerbate soil erosion and seasonal drought in agriculture. The red soil slope farmland makes up a significant portion of agricultural land in southern China. It is crucial to enhance the water storage and soil conservation effects (WSE) by adopting appropriate agronomic practices on the red soil slope farmland, which ensures regional agriculture’s sustainable development. Therefore, this study employed a combination of experimental plot positioning observations and artificially simulated rainfall experiments to analyze the WSE of four tillage practices: Conventional tillage (CT), Downslope ridge tillage (DT), Cross-slope ridge tillage (RT), and Plastic Mulching (PM). This study proposed the optimal tillage practices based on a comprehensive evaluation of their effects. The results indicate that there is a significant interaction (p < 0.05) between tillage practices and growth stages on soil water retention and infiltration characteristics. Under the same growth stage conditions, PM can reduce soil bulk density by 0.03–14.29% (p < 0.05) and increase temperature, soil moisture content, and total porosity by 4.00–6.67%, 0.68–18.23%, and 1.30–13.47% (p < 0.05), respectively, demonstrating the best water retention capabilities among the four tillage practices. However, during the rainfall-runoff process, the surface runoff amount (SRA) generated by PM and DT accounts for 68.15% and 90.83% of the total runoff, respectively, which is detrimental to soil water infiltration during rainfall. Both practices exhibit poor resistance to soil erosion and demonstrate low water storage and soil conservation effect index (WSEI) values of 0.38 and 0.33, respectively. Secondly, RT’s SRA constitutes only 9.42% of the total runoff, which is beneficial for increasing the cumulative soil water infiltration amount (CIA) during rainfall. Among the three tillage practices, namely RT, DT, and CT, RT demonstrates strong soil water retention capabilities. It can significantly reduce the kinetic energy of soil erosion, enhance soil erosion resistance, and exhibit the highest WSEI of 0.84. Furthermore, CT exhibits a moderate WSEI of 0.75. In summary, from the perspective of WSEI, RT is the tillage practice that should be prioritized for promotion in the cultivation process of red soil slope farmland. Our research results can provide a scientific basis for constructing optimal tillage mode and improving the WSE of southern China’s red soil slope farmland.

Returning to Integrated Landscape Management as an Approach to Counteract Land Degradation in Small Mediterranean Islands: The Case Study of Stromboli (Southern Tyrrhenian Sea, Italy)

The small Mediterranean islands, unique geographical places where coastlines and mountains converge due to volcanic genesis, are among the most threatened environments on Earth. Their marginality, which has historically led to their use as places of detention and punishment, coupled with the extreme climate and rugged geomorphology shaped by terracing practices, has resulted in the loss of systematic land management. This loss stems from the abandonment of cropland in favor of alternative activities and migrations, impacting essential ecosystem services such as the water cycle, soil fertility, and the cultural landscape. The need to counteract the land degradation in these vulnerable areas has been acknowledged for some Mediterranean small islands, including the UNESCO heritage site of Stromboli in the Aeolian Islands, Sicily, Italy—an especially captivating location due to its active volcano. The agricultural abandonment on terraces, intensively cultivated with olives groves and vineyards until the mid-20th century, has rendered the area highly fragile and susceptible to risks such as fires and soil erosion, particularly as a consequence of extreme weather events, as proven in 2022, which saw a destructive fire followed by storms. To mitigate the negative effects of hydrogeological disruptions, the implementation of integrated landscape management—managing ecosystems at the landscape level—has been proposed. Specifically, an agroforestry intervention, coupled with the restoration of dry stone walls, the shaping of soil slopes by recovering the traditional ecological knowledge (TEK), and the design of water-collecting devices incorporated with the traditional hydraulic knowledge, may be proposed as a strategic approach to minimize the soil erosion risks, adapt to climate change, and extensively restore the use of traditional agrobiodiversity to support the local economy and tourism. A pilot intervention by local stakeholders based on these principles is described as an emblematic agrobiodiversity-based landscape design project in a vulnerable area, aiming at the preservation of the cultural landscapes of the small Mediterranean islands.

Assessment of cohesive soil landslide driving forces exerted on piles considering soil arching effects

As known, the reinforcement effect of piles significantly relies on the precise assessment of cohesive soil landslide driving forces exerted on piles. However, the existing methods for estimating the cohesive soil landslide driving forces have scarcely considered the soil arching effects. Generally, this leads to prohibitively conservative approaches for pile stabilization. In this study, according to the Mohr Coulomb theory and the Ito plastic theory, a theoretical analysis method for quantitatively clarifying the distribution of cohesive soil landslide driving forces along piles is presented in detail, considering the vertical and horizontal soil arching effects between two adjacent piles in a pile row above the sliding surface. Centrifuge model test and full scale test of a pile-reinforced cohesive soil slope are introduced for verifying the proposed method, respectively. Compared with previous methods, the proposed method can prospectively produce results in better agreement with the test results. Ultimately, parametric analyses are conducted to investigate the effect of influencing parameters on the landslide driving forces, and the outcomes indicate a rational pile spacing and a small slope angle should be essentially considered for stabilizing a cohesive soil landslide effectively.

Real-time monitoring and numerical analysis of rainfall-induced slope instability

ABSTRACT The study of slope instability includes a detailed study of environmental conditions and soil’s geotechnical and hydrological parameters. In the present study, a thorough understanding of rainfall-induced slope instability is achieved by doing real-time monitoring on an unstable slope located in Shillong, Meghalaya, India. The area selected is prone to landslides due to heavy rainfall and because it is located in the wettest place on earth. The real-time monitoring involves observation of groundwater table variation, intensity of rainfall, soil suction, and their effects on the instability of an unsaturated slope. Boring data show that even if the area is in a hilly region, the groundwater table is very high. The effects of antecedent rain on the matric suction, which indirectly affected the stability of the unsaturated soil slope were noticed. The location of the irrometers helped us in assessing that the slope stability is affected by both the matric suction developed in the unsaturated shallow soil during rainfall and that developed due to the presence of high groundwater level. The displacements along the slope are independent of each other. The results of the numerical analysis show that the slope displacement is positively correlated with the principal strain and maximum shear stress, indicating that the infiltration of rainfall has a significant effect on the stress and strain associated with displacement.

Determination of Organic Carbon Content of the Soils within the Greenhouses Built on Pyroclastic Deposits in Isparta Settlement Area

Soil organic carbon (SOC) is an important indication of soil health and helps to sustain soil fertility. As a result, determining its composition and the factors that influence it is critical for long-term soil nutrient management, especially in controlled conditions such as greenhouses. This study utilizes machine learning to classify SOC content in greenhouses built on pyroclastic deposits in the Isparta region. A dataset of 276 samples and eight variables—clay (%), silt (%), sand (%), soil electrical conductivity (EC), pH, elevation, slope, and aspect—were used to model SOC values. SOC content was classified into five classifications: very low (2.3%). In this study, five machine learning models—Logistic Regression (LR), K-Nearest Neighbors (KNN), Support Vector Machine (SVM), Decision Tree (DT), and Random Forest (RF)—were evaluated using cross-validation to determine their classification accuracy, precision, recall, F-score, and ROC area. Random Forest (RF) and Decision Tree (DT) outperformed the other models, with RF achieving the highest overall accuracy (76.4%), precision (77.3%), and AUC (0.904), followed by DT at 75.4% and AUC of 0.874. This study shows the practicality of machine learning models in categorizing SOC content, highlighting their importance for long-term soil health and fertility control in greenhouse conditions. To improve model efficacy, future studies should include more auxiliary variables, such as soil physical and chemical qualities and lithological data, as well as a wider range of soil types.

Mixed Grass Species Enhances Root Production and Plant–Soil Reinforcement

ABSTRACTVegetation is a widely used eco‐friendly approach for slope reinforcement and ecological restoration. As a potential planting strategy, mixed planting of plants is often recommended to improve biodiversity, but the effects of mixed planting on soil reinforcement and slope stability are not yet clear. To address this issue, a study on two typical herbaceous slope protection plants, Chrysopogon zizanioides and Cynodon dactylon, were conducted. The biomechanical characteristics of different herbaceous plants were analyzed, and their root distribution and soil reinforcement performance under single and mixed planting were explored. Results show that mixed planting could significantly increase the number and root area ratio of root systems. At 0.1 cm depth after 42 days, the root number under mixed planting increased by 111.42% compared to vetiver grass monoculture and by 19.57% compared to bermuda grass monoculture. Mixed planting can provide stronger soil reinforcement by increasing apparent cohesion, with a maximum increase in apparent cohesion of 47.9%. The results of slope stability analysis showed that vegetation mainly relied on mechanical reinforcement in the root zone and hydrological reinforcement outside the root zone. After 42 days of growth, mixed planting at 0.1 m depth increased slope stability by 11.94% compared to vetiver grass monoculture and by 27.12% compared to bermuda grass monoculture, with both mechanical and hydrological effects of vegetation significantly enhanced. These findings suggest that mixed planting can promote plant development and growth, improve root production, and enhance plant–soil reinforcement and slope stability during the early establishment of vegetation. Therefore, in formulating slope reinforcement and ecological restoration strategies, more consideration can be given to mixed planting of plants, maximizing the utilization of competition characteristics between plants, and reducing the risk of shallow landslides while improving biodiversity.

Parametric Study of Rainfall-Induced Instability in Fine-Grained Sandy Soil

This study investigates the stability of fine-grained sandy soil slopes under varying rainfall intensities, durations, and geotechnical properties using a parametric analysis within GeoStudio. A total of 4416 unique parameter combinations were analyzed, incorporating variations in unit weight, cohesion, friction angle, slope inclination, slope height, rainfall intensity, and duration. Results reveal that rainfall intensity is the most influential variable on the factor of safety (FS), with higher intensities (e.g., 360 mm/h) on steeper slopes (e.g., 45°) leading to critical FS values below 1, indicating an imminent risk of failure. Under moderate conditions (e.g., 9 mm/h rainfall on slopes of 26.6°), the FS remains above 2. This dataset provides a valuable foundation for training machine learning models to predict slope stability under diverse environmental conditions, contributing to the development of early warning systems for rainfall-induced landslides.

Rare and Abundant phoD‐Harboring Bacteria Mediate the Mineralization of Organic Phosphorus Fractions in Soil Aggregates During Cut Slope Restoration

ABSTRACTPhosphorus (P) is the key nutritional element in the soil of cut road slopes undergoing ecological restoration, and the transformation of organic P (Po) is a crucial part of the P cycle. However, the role of phoD‐harboring bacteria in driving the mineralization of Po fractions in road slope soil aggregates is unclear. This study analyzed road slope soils that had undergone 7, 11, and 14 years of restoration in the western Sichuan Plateau of China. We examined the differences and associations between the Po fraction content, alkaline phosphatase (ALP) activity, and community composition of rare and abundant phoD‐harboring bacteria in soil aggregates of four particle sizes (0.053–0.25, 0.25–2, 0.053–0.25, and, &gt; 2 mm). The results showed that NaHCO3‐extracted Po (NaHCO3‐Po) content in soil aggregates increased with restoration years, while NaOH‐extracted Po (NaOH‐Po) content decreased. ALP activity in soil aggregates increased with restoration years, but there was no significant relationship between ALP activity with the phoD‐harboring bacterial community. There were significant differences in the composition of rare and abundant phoD‐harboring bacterial communities during slope restoration. Soil moisture, pH, organic carbon, and the C:P ratio in soil aggregates were the primary factors affecting the distribution of the Po fractions and the phoD‐harboring bacterial community. NaHCO3‐Po and NaOH‐Po in soil aggregates were likely the main substrates for ALP‐mediated Po mineralization. More genera were involved in Po mineralization in slope soils restored for 14 years than in soils restored for 7 and 11 years, and rare phoD‐harboring genera were more actively involved in Po mineralization than abundant phoD‐harboring genera. This study provides some theoretical basis for P effectiveness enhancement and P management during slope soil restoration.

Analytical assessment of dynamic stability in 2D unsaturated soil slopes reinforced with piles

Analytical assessment of dynamic stability in 2D unsaturated soil slopes reinforced with piles

Seismic Loading and Reinforcement Effects on the Dynamic Behavior of Soil Slopes

Seismic Loading and Reinforcement Effects on the Dynamic Behavior of Soil Slopes

Soil surface roughness impacts erosion behavior through selective regulation of flow properties in rainfall-seepage scenarios

Soil surface roughness (SSR) impacts runoff dynamics of surface-subsurface and the magnitude of soil erosion, limited attention has been paid to how SSR governs runoff hydrodynamics to affect erosion behavior and the effectiveness of erosion reduction under rainfall-seepage scenarios on low-permeability purple soil slopes. Herein the seepage rates of 2, 4, and 8 L min⁻¹ were sequentially simulated under a rainfall intensity of 1.0 mm min⁻¹ among different microrelief treatments (CT: conventional tillage; AD: artificial digging; RT: ridge tillage) on purple soil slopes with gradients of 5°, 10°, and 15°. These simulations aimed to investigate the mechanisms underlying the erosion reduction benefits associated with flow properties due to microrelief. The results showed that increased SSR altered erosion kinetic energy under rainfall-seepage conditions. The benefits of rough slopes to control erosion decreased as rainfall-seepage intensity and slope gradient increased. During rainfall-seepage events, the variation in runoff behavior was regulated positively by the effect of SSR on unit stream power. However, the increasing net output power of runoff due to flow turbulence altered sediment output, thereby affecting sediment control benefits. Overall, the impact of rainfall-seepage intensity on surface roughness became more significant with increasing slope gradient. Our findings suggest the capable of integrating for interrelated microrelief and runoff processes in factors analysis of driving soil erosion at rainfall-seepage hydrologic states to elucidate erosion effect.

Indoor tests of sensor-enabled piezoelectric geocable–geogrid composite structure for slope rehabilitation and monitoring

Sensor-enabled piezoelectric geocables were combined with a geogrid to acquire a sensor-enabled piezoelectric geogrid (SPGG) based on the impedance–strain relationship. Tension, pullout, and straight shear tests were conducted on this SPGG configuration. The tension test results indicated that the tensile strain–normalized impedance curves were exponential in form within the first 7 % of strain and the rate of shift in impedance was independent of the tension loading rate. An excellent correspondence between the peak strength and impedance inflection point was observed in the results of the pullout and straight shear tests. Additional validation of the proposed SPGG was conducted through a collapse test of the reinforced soil slope model. The results indicated that the SPGG-obtained strains were similar to actual strain gauge measurements but provided a larger measurement range and that the SPGG was able to sense real-time vibrations during the slope collapse using a voltage analysis, confirming that the proposed SPGG can simultaneously provide soil reinforcement, strain monitoring of reinforcement materials, and vibration sensing. This research is expected to inform the development of a dynamic and static monitoring, large range, and accurate method for monitoring the conditions of reinforced soil over their entire lifecycles.

Climate Change Impact on the Stability of Soil Slopes from a Hydrological and Geotechnical Perspective

Climate change (CC) is expected to cause significant changes in weather patterns, leading to extreme phenomena. Specifically, the intensity of precipitation extremes is continuously escalating, even in regions with decreasing average precipitation levels. Given that CC leads to long-term shifts in weather patterns and may affect the precipitation characteristics (i.e., frequency, duration, and intensity) directly related to groundwater table fluctuations and soil erosion phenomena, it has the potential to significantly affect soil slope instabilities. In turn, slope stability and the structural integrity of nearby structures and infrastructure will be affected. Accordingly, the present paper focuses on the impact of CC on the geohazard of soil slope instability by considering both hydrological aspects, i.e., the impact on rainfall intensity on the groundwater table and the geotechnical aspects of this complex problem. The findings reveal that the impact of CC on potential slope instabilities can be detrimental or even beneficial, depending on the specific site and water conditions. Therefore, it is essential to do the following: (a) collect all the available data of the area of interest, (b) assess their variations over time, and (c) examine each potentially unstable slope on a case-by-case basis to properly mitigate this geohazard.

An evolutionary approach to predict slope displacement of earth embankments under earthquake ground motions

Accurate slope stability analysis of earth embankments under ground shaking is of great importance for practical use in earthquake geotechnics. This study aims to predict soil slope displacements of earth embankments subjected to earthquake loading using evolutionary algorithms. Comprehensive real case histories of slope displacement of earth embankments under past earthquakes in different areas of the world were gathered and analyzed. A robust model was then developed to predict earthquake induced soil slope displacements using gene expression programming (GEP). Characteristics of earthquake ground motion including earthquake magnitude, earthquake predominant period, maximum earthquake acceleration and also geotechnical specifications of earth embankment including yield acceleration and fundamental period of earth embankment were taken as most influential factors on the slope displacements of earth embankments under earthquakes. Subsequently, performance of developed GEP-based predictive model was assessed using a sensitivity analysis under various effective factors. Finally, the accuracy of the predictive model was evaluated through comparison with the available relationships for estimation of seismic soil slope displacements. The results clearly indicate favorable accuracy of developed GEP-based model to predict slope displacements of earth embankments subjected to earthquake ground motions.

Rainfall depth dominates overland flow and sediment yields of the coarse-textured soil: A case study in Southern China

Soil degradation, particularly due to water erosion, is a significant issue in many regions, including the mountainous areas of Southern China. This study investigated the response of overland flow and sediment yield to different rainfall patterns on a coarse-textured soil slope in Southern China. Three distinct rainfall regimes were identified through K-means clustering analysis, based on event rainfall depth, duration, and maximum 30-min intensity (I30). The results showed that rainfall regime II, characterized by moderate rainfall depth, duration, and I30, generated the highest accumulated surface runoff (97.3 mm) and soil erosion (1584.9 t km−2). Further analysis revealed that overland flow and sediment yield were positively correlated with various rainfall characteristics, including rainfall depth, mean intensity, duration, I30, rainfall energy, and rainfall erosivity. However, rainfall depth was identified as the dominant factor, exhibiting the stronger correlations with both the runoff depth (R2 = 0.77, RMSE = 0.396) and the erosion (R2 = 0.58, RMSE = 0.658) than did the mean rainfall intensity, I30, and duration. Note that RMSE values were expressed in logarithmic units in this study. Piecewise regression models were developed to predict overland flow and sediment yield based on rainfall depth, and these models were validated through in-situ rainfall simulation experiments. The results showed that these models produced acceptable soil and water loss predictions, with a mean bias of −0.093 mm and RMSE of 0.197 mm for the runoff depth, and a mean bias of −0.156 t km−2 and RMSE of 0.456 t km−2 for the sediment yield. Thus, rainfall depth is the dominant driver of soil and water loss in the coarse-textured soils of Southern China, and the developed regression models can be used to estimate overland flow and sediment yield in similar environments.