Vegetation restoration is an effective measure for preventing water and soil loss. Although its general effects on runoff have been extensively studied, the comparative efficacy of different restoration patterns specifically in gully catchments of arid and semi-arid regions remains poorly understood. Consequently, through field monitoring of six gully catchments on the Loess Plateau, this study systematically examined the effects of cropland (terrace, as control) and various vegetation restoration patterns (woodland, other woodland, shrubland, grassland, and pastureland) on runoff characteristics. The results demonstrated that vegetation restoration reduced runoff depth (RD) by 67.37-94.24 % and peak flow modulus (PFM) by 44.88-93.89 %. Pastureland exhibited the greatest mitigation effect, with RD and PFM reductions exceeding 90 % and outperforming other woodland (85.07-88.14 %). No significant differences in RD, PFM, and their percentage reductions were observed among woodland, shrubland and grassland (p > 0.05). Runoff variation in the gully catchments was negatively regulated by root mass density and near surface herbaceous stem (cover and diameter) (p < 0.05), but positively correlated with soil water content and physical crust cover (p < 0.05). Tree canopy cover, shrub canopy cover, herbaceous cover, and litter (cover and depth) indirectly regulated runoff characteristics. Vegetation restoration explained 58.2 % of the observed runoff variation. This study provides a scientific basis for guiding vegetation restoration strategies in arid and semi-arid regions like the Loess Plateau.

Watersheds are important inputs in many geospatial applications and watershed delineation is a fundamental task of hydrological processing. Existing efficient watershed delineation algorithms are either designed to exploit the massive parallelism of graphic processing units (GPUs) or rely on specific spatial patterns of watersheds to parallelize efficiently on multicore central processing units. In this study, we propose an efficient flow path traversal algorithm for delineating watersheds from raster flow direction grids. The proposed algorithm employs a novel tracing strategy and traces each cell until a cell with a known watershed label is encountered or the tracing terminates outside the study area. This approach limits the number of times each cell is processed to a constant, does not require any additional data structure, and achieves a time complexity of O(N) regardless of the number of watersheds to be delineated. We conducted three experiments using seven flow direction grids to evaluate the running times, speedups, both strong and weak parallel efficiencies of the algorithms. Our sequential algorithm outperforms two other sequential algorithms on the test DEMs even though those algorithms only process approximately one-third of the DEM cells, while our algorithm processes the entire grid. Our parallel algorithm runs the fastest among all sequential and parallel algorithms evaluated. Combined with highly efficient GPU-based algorithms, the sequential and multicore parallel implementations of our flow path traversal algorithm make it possible to fully leverage the computational capabilities of personal computers for high-performance watershed delineation.

In models simulating soil erosion processes, sediment transport capacity (Tc) precise estimation is crucial for elucidating the mechanisms governing sediment detachment, transport, and deposition. However, the role of surface cover in modulating Tc is not yet fully understood. In particular, whether there is an interaction effect between slope gradient and cover level lacks systematic investigation. In this study, controlled flume experiments were conducted to systematically examine variations in Tc under five slope gradients (3.49–30.9 %), one flow rate (2.70 × 10−3 m2 s−1), and eight cover levels (0, 2.5, 5, 10, 15, 20, 25, and 30 %). Results indicated that Tc increased on steeper slopes and decreased with greater cover extent, with a statistically significant interaction effect between the two factors (p < 0.05). Slope gradient primarily affected Tc by altering flow velocity, whereas cover level mainly influenced Tc through changes in flow depth. Steeper slopes weakened the inhibiting effect for surface cover on Tc; thus, the sediment reduction effect for cover was more pronounced on gentle slopes. The relationship between Tc and cover level followed a negative exponential function (R2 > 0.94). The coefficient associated with cover level (k) decreased from 0.153 to 0.028 as slope gradient increased, indicating that cover becomes less effective at controlling sediment transport on steeper slopes. This study revealed the mechanism by which slope gradient modulates the effect of surface cover on sediment transport capacity, providing a theoretical basis for improving soil erosion process modeling.

Abstract Understanding how surface combined covers influence hydraulic parameters of overland flow is essential for optimizing soil erosion control measures. Surface combined covers significantly alter overland flow hydraulics, yet interactions between upright/non‐upright covers remain poorly quantified. This study systematically investigated the effects of combined cover types (upright stems, non‐upright stems, and their mixtures) and varying coverage percentages on flow hydraulics under controlled laboratory conditions, with a fixed flow discharge of 1 × 10−3 m3 s−1 and constant slope gradient of 15°. The results demonstrated that surface combined covers significantly altered key hydraulic parameters. Specifically, increasing total coverage (Ct) led to substantial decreases in Froude number (Fr), stream power (ω), and unit stream power (P), accompanied by significant increases in Manning's coefficient (n). Regression analyses indicated that Ct reliably predicted shear stress (τ), Fr, n, and P (R2 > 0.7) in combined‐cover scenarios without upright stems, whereas individual coverage elements provided greater explanatory power when upright stems were present. Among the tested hydraulic parameters, Reynolds number (Re) and ω were poorly described by total coverage alone, suggesting the necessity of considering individual cover elements for accurate predictions. Upright stems exhibited a dominant role in influencing hydraulic behavior by generating localized vortices, enhancing turbulence, and increasing bed friction and flow resistance. The findings contribute to understanding the hydrodynamic mechanisms by which composite covers influence soil erosion.

Slope gradient and surface cover are key factors controlling soil erosion, but how their interaction influences the erosion control effectiveness of rock fragments remains unclear. In the commonly used exponential function that describes this effect (C = a.exp(- b.R-c)), the coefficient b determines the rate at which soil loss decreases with rock fragment coverage, but how b varies with slope is largely unknown. To address this, rainfall simulation experiments were conducted under 30 combinations of slope gradients (8.7%similar to 70.0%) and rock fragment coverage levels (0%similar to 80%) to investigate the slope-dependent erosion control by rock fragments. The results showed that rock fragment coverage and slope gradient had significant interactive effects on runoff and sediment concentration. Runoff and sediment concentration generally decreased with increasing coverage, while at steep slope and low coverage, the reduction efficiency was significantly weakened or even reversed. Soil loss rate exhibited a consistent exponential decline with increasing coverage across all slope gradients. However, the rate of this decline, represented by the coefficient b, systematically decreased from 0.0102 at slope 8.7% to 0.0032 at slope 70.0%. Further curve fitting revealed a significant exponential relationship between b and slope gradient. This study systematically quantifies the control of slope gradient on the erosion-reducing effectiveness of rock fragments and develops a slope-dependent formulation for the coefficient b. These findings provide a clear parameterization basis for improving the cover factor in existing soil erosion prediction models and help enhance the accuracy of erosion assessments in complex terrain regions.

Overland flow velocity is an important parameter in soil erosion models. However, most existing flow velocity equations are mainly derived from laboratory simulation experiments using artificial vegetation. The purposes of this study were to evaluate the applicability of current overland flow velocity models and to develop and calibrate a field-based overland flow velocity prediction equation for the Loess Plateau. In-situ scouring experiments were carried out in the Zhifanggou small watershed under a fixed 10° slope, with five flow rates (0.06—1 L s⁻1) and five stem cover levels (0—15

Vegetation plays a critical role in controlling gully erosion. However, few studies have clarified the effects of shrub and its components on gully bed erosion processes by altering the flow hydraulics and soil loss. In this study, a series of in situ scouring experiments were conducted to investigate the influence of shrub stem and litter on the concentrated flow pathway characteristics, hydraulic properties, and sediment yield during gully bed erosion. The experiments involved a typical shrub named Leucaena leucocephala, with five stem coverage (0 %, 0.15 %, 0.30 %, 0.60 %, and 1.20 %) and five litter amounts (0, 100, 200, 300, and 400 g m-2). Four different treatments were applied: stem and litter (SL), stem only (OS), litter only (OL), and a control bare gully bed (BG). The results showed that, compared to the bare gully bed, the various treatments significantly enhanced concentrated flow branching, increased Darcy-Weisbach friction factor (f), and reduced flow rate, velocity, shear stress, and soil loss rate. The combined effect produced by SL treatment on runoff and erosion was the strongest. Stems were most effective in reducing flow velocity and shear stress, contributing an average of 21.23 % and 7.54 %, respectively. Litter primarily increased the flow resistance f and reduced flow rate and soil loss rate, with average contributions of 123.59 %, 20.60 %, and 27.67 %, respectively. Increasing stem coverage and litter amount increased their contribution of controlling runoff and erosion. When the litter amount exceeded 200 g m-2, it gradually replaced stems as the dominant role in increasing flow resistance f and reducing concentrated flow and erosion in the both stems and litter covered gully beds. These findings enhance the understanding of how shrub and its components control gully development and highlight the importance of maintaining litter in the gully beds to mitigate gully erosion.

Surface cover can effectively prevent soil erosion, serving as one of the essential soil and water conservation measures. Accurately estimating the sediment transport capacity is critical to developing soil erosion models. However, current research on the mechanism of the effect of surface cover on the sediment transport capacity is still inadequate. Therefore, the flume experiments were conducted with one slope gradient (25.88 %), one flow discharge (1.0 x 10-3 m3/s), three surface cover types (corn residue, rock fragment, and sweet potato) and seven cover levels (0, 5, 10, 20, 30, 50, and 70 %) to investigate the effect of different surface covers on the sediment transport capacity. The results showed that the sediment transport capacity had a significantly negative correlation with the Manning coefficient and surface coverage. The reduction rate in sediment transport capacity tended to stabilize when surface coverage exceeded 30 %. Surface cover type and cover level played a significant role in reducing sediment transport capacity. The effect of cover type on reducing the sediment transport capacity is greater in a complete submersion state than that in a partial submersion state. The Manning coefficient was a comprehensive factor reflecting the effect of surface cover type and coverage on sediment transport capacity. The power function equation with the Manning coefficient provided the best simulation of sediment transport capacity. The findings will be helpful for understanding the mechanism of soil erosion under surface cover conditions and improving the predictive accuracy of soil erosion process models.

Sediment transport capacity (Tc) is a critical parameter in predicting soil erosion, and surface cover has been found to be an effective means for reducing Tc. However, limited research exists regarding the influence of surface cover types on Tc, and the sediment retardation benefits (SRB) of surface cover types are unknown. The aim of this study was to investigate the impact of different surface cover types on Tc and SRB. Therefore, a sets of flume experiment were conducted under controlled conditions, featuring a fixed slope gradient (S = 25.88 %), a constant unit flow discharge (q = 2.70 x10-3 m2 s-1), and three common types of surface cover commonly found on slope farmland: corn residue, rock fragment, and sweet potato). These experiments also included seven coverage levels (C = 0, 5, 10, 20, 30, 50 and 70 %) with water and sediment samples collected at regular intervals. The results showed that the relative sediment transport capacity (RT) had a negative exponential function with a C under different surface cover types (R2>0.8). Sweet potato exhibited the most effective SRB under the same C. SRB stabilized when the C of different surface cover types reached 30 %. The equations for predicting sediment transport capacity were improved. The results may contribute to the theoretical understanding of sediment transport processes under surface cover conditions and provide a foundation for the informed selection of soil and water conservation measures.

Sediment transport capacity (Tc) serves as a crucial determinant in soil erosion models. While surface cover types are recognized as key factors influencing sediment transport capacity, their effects have not been systematically quantified. This study provides mechanistic insights into the pathways through which surface cover modulates sediment transport capacity and quantitatively establishes the combined effects of cover type and coverage. The flume experiments were conducted using four cover types (corn residue, rock fragment, sweet potato, and corn stem) with coverage ranging from 2.5 % to 70 %, under a fixed slope gradient (15(degrees)) and a constant flow discharge (1 x 10(-3 )m(3 )s_ 1). The results showed that sediment transport capacity was significantly correlated (p <0.05) with flow velocity (v), flow depth (h), and coverage (C) across different cover types. A significant power function increase was observed between sediment transport capacity and flow velocity for all cover types (p < 0.01, R-2 > 0.93). When estimating sediment transport capacity using a single flow velocity, coverage effects can be disregarded, but the velocity exponent must be adjusted based on cover type. Surface cover type primarily influences sediment transport capacity by altering flow velocity and flow depth. Flow velocity, flow depth, and coverage can be jointly used to describe sediment transport capacity under different cover conditions, thereby quantifying the effects of cover type. The findings of this study elucidate the pathways through which surface cover types affect sediment transport capacity, providing insights into the hydrodynamic mechanisms underlying this influence.

The reliable prediction of sediment transport capacity ( Tc ) is essential for soil erosion models. Although rock fragments are a common surface cover type, quantitative studies on their relationship with Tc are limited. Tc typically follows a power function with slope gradient ( S ) and flow discharge ( q ) under bare flumes, but varying exponents complicate practical application. This study aims to investigate the effect of rock fragment cover on Tc , explore the interactive effects of S , q , and cover on Tc , and ultimately develop a universal Tc prediction equation and assess its feasibility for different scenarios. Flume experiments on Tc with rock fragment cover have been conducted, and many existing Tc prediction equations have been reviewed. The results revealed that the effects of S and q on the relationship between rock fragment cover and Tc were minor and that the impact of rock fragment cover on the relationships of S and q with Tc was also not significant. Consequently, a new universal equation for Tc incorporating cover was developed. This equation featured fixed exponents of 1.66 for S and 1.22 for q and was applicable across various slope gradient, flow discharge, coverage and cover type conditions. Moreover, the impact of rock fragment cover on Tc reduction was significantly less than those of litter cover and stem basal cover ( P < 0.05). Therefore, the role of rock fragments should be considered separately in soil erosion models. These findings could significantly advance the practical application of the Tc prediction equation.

The flow velocity is an important variable in the simulation of runoff processes and soil erosion models. Previous research has indicated that slope gradient will affect flow velocity when the flow lacks sufficient erosive capacity to alter the morphology of eroding rills. Cultivated furrows are unique rills, and during the snowmelt period, soil erodibility is low. It is unclear how slope gradient affects flow velocity under these conditions. The purpose of this study was to investigate whether slope gradient truly has an effect on flow velocity in the cultivated furrow when snowmelt runoff occurs. Experiments were conducted in the cultivated furrows in Jiusan Farm, Nenjiang County, Heilongjiang Province, China. The flow rate and velocity of furrows on slopes ranging from 0.5 degrees to 2.0 degrees were monitored during the snowmelt period. A total of 109 events were recorded. The measured flow velocity ranged from 0.07 to 0.71 m/s, and the flow rate ranged from 0.008 to 1.831 x 10-3 m3/s. The results indicate that during the snowmelt period, flow velocity is positively correlated with slope gradient at the significance level of 0.05. Slope gradient significantly affects the relationship between flow velocity and flow rate. The Manning formula can be used to calculate flow velocity in the furrows, and the Reynolds number is not the optimal indicator for calculating the Darcy-Weisbach friction factor. The variation in the resistance coefficient with flow depth in the furrow differs from that of thin-layer flows on slopes. The results can assist hydrological and soil erosion simulations of snowmelt runoff in the cultivated furrows.

Grass, shrubs and tree stems can increase flow depth and resistance and prevent soil erosion, and it is necessary to quantify the relationship between flow depth and hydraulic parameters for high surface roughness of vegetation stem. Therefore, the experimental design included flow depth, velocity and transport capacity, which were measured for different stem covers (bare flume to cover 30%), diameters (2, 10, and 36 mm), and arrangements (bead, tessellation, stagger, random, and stripe) to clarify the relationship between flow depth and the hydraulic radius, Reynolds number Re, Manning coefficient nm, Darcy-Weisbach resistance f and transport capacity Tc. The result shows that flow depth could be effectively predicted by stem cover and stem diameter; the greater the surface roughness was, the more the difference between flow depth and hydraulic radius; and flow depth could not be used as the hydraulic radius to calculate hydraulic parameters for high surface roughness. Re, nm, and f were significantly impacted by flow depth. The linear relationship between flow depth and Re, nm, and f became stronger as stem cover decreased and stem diameter increased, and they were more affected by stem cover than by diameter. The relationship between flow depth and f was less impacted by high surface roughness of vegetation stem. Tc was not significantly impacted by flow depth; the Manning coefficient and Darcy-Weisbach resistance were not appropriate for predicting transport capacity; and the Reynolds number could illustrate the mechanism of sediment transport capacity affected by vegetation stem cover from the perspective of flow resistance.

Permanent gully (PG) erosion is a critical form of soil degradation on the Loess Plateau of China, yet its response to individual rainfall events remains poorly understood. The purposes of this study were to investigate the influences of event rainfall properties on PG erosion and identify the most dominant factors of rainfall properties driving PG erosion on the Loess Plateau of China. Thirteen PGs were selected, and their elevations were measured by real-time kinematic with Global Navigation Satellite System in May 2023 and 2024 and after each erosive rainfall event. The key parameters reflecting PG evolution, including gully length, perimeter, projected area, erosion rate, deposition rate, were calculated from the established digital elevation model. The results showed that the maximum erosion rate of PG reached 683 t.ha-1 in a single rainfall event, surpassing many reported annual erosion rates. The ratio of erosion from PG sidewall-floor to total erosion ranged from 91.2 % to 100 %, highlighting the dominant role of sidewall-floor erosion in overall gully erosion. PG erosion was significantly influenced by rainfall amount (P) and rainfall energy (E) at event scale. The antecedent rainfall over 3 or 5 days also importantly affected gully erosion. These findings enhance the understanding the influencing mechanisms of rainfall properties on PG erosion and contribute to land management strategies in erosion-prone regions.

Rainfall and snowmelt runoff are the primary drivers of soil detachment in cold regions. Understanding how hydraulic properties influence the soil detachment rate ( D r ) is essential for accurately modelling soil erosion during the spring thaw period. This study aimed to clarify the relationship between hydraulic parameters and D r at different slope positions. Experiments were conducted under four flow discharge conditions (4.5, 6.5, 8.5 and 10.5 L min −1 ), two slope gradients (10° and 15°) and four thawing depths (2, 5, 10 and 15 cm). Results indicated Dr could be adequately described as a power function of the flow discharges increasing with shear stress, the resistance coefficient and stream power. Shear stress was identified as the most effective hydrodynamic parameter for predicting D r at upslope (first slope) and midslope (second slope) positions, whereas stream power best predicted D r at the downslope (third slope) position. Unit stream power was not a reliable predictor of D r . These findings enhance the mechanistic understanding of soil erosion processes occurring during the spring thaw period and improve the predictive capabilities of soil erosion models.

Surface cover influences the hydraulic parameters of overland flow, subsequently affecting soil erosion. Therefore, exploring the flow dynamic mechanisms under different surface cover types is crucial. A series of flume experiments were conducted to investigate the impact of surface cover on the hydraulic parameters of overland flow. The specific experimental conditions were as follows: one slope gradient (15°) and one flow discharge (1.0 × 10 −3 m 3 s −1 ), four cover types (corn residue, rock fragment, sweet potato, and corn stem), and seven coverage percentages ranging from 0% to 70%. The results indicated that the cover of non‐submerged state was the most effective at reducing flow velocity, with cover of submerged state being the least effective. Under the four cover conditions, flow velocity, Froude number, flow depth, and shear stress exhibited significant power function relationships with coverage ( R 2 > 0.91). The relationships between Reynolds number and stream power with coverage were not significant under corn residue and rock fragment cover ( P > 0.05), but showed significant power function relationships under sweet potato cover ( R 2 > 0.88). The cover type alters the form of the cover and the flow submergence degree, leading to the change of hydraulic radius, thereby influencing the hydraulic parameters of overland flow. The findings provide scientific evidence for understanding the flow dynamic mechanisms under surface cover and improving the predictive accuracy of soil erosion process models.

The problem of unpaved road erosion is prominent in the Loess Plateau hilly and gully region. Unpaved roads contribute substantially to watershed sediment due to their high soil bulk density, low infiltration rates and extensive network. In this study, a field investigation was conducted on typical unpaved roads within a typical watershed in this region, focusing on assessing the damage state, annual soil loss and the factors influencing erosion in a comparatively wet year. The results showed that the soil erosion from unpaved roads was very severe, with an annual erosion intensity of 470 t hm(-2), following three heavy rain events and two rainstorm events in the summer of 2022. The main unpaved roads (MUR) suffered the most severe road erosion, with 22.2 % of road segments experiencing severe erosion with classical gullies. The erosion gullies on the road had an average depth of 16.1 cm and an average width of 36.5 cm, with the widest being 146.0 cm and the deepest being 174.0 cm. The road erosion intensity was significantly related to drainage area, road area, road length and coverage. Road erosion reduced significantly when the land use in the drainage areas of the road was covered with shrub or grass, or road surface was covered with grass or gravel. Our findings offer valuable insights for road construction and erosion prevention in similar terrains.

[Objective]Rainfall erosivity serves as an indicator to assess the potential impact of rainfall on soil erosion,playing a crucial role in evaluating regional soil erosion risk.Therefore,analyzing the temporal and spatial variations of rainfall erosivity in Beijing from 1981 to 2020 holds significant importance for scientifically assessing and preventing regional soil erosion risks.[Methods]This study employed Kriging interpolation,Mann-Kendall non-parametric test,and wavelet analysis based on daily precipitation data collected from 119 rainfall stations in Beijing and its surrounding areas between 1981 and 2020.These methods were utilized to analyze the spatial distribution,trend changes,and periodic fluctuations of annual rainfall erosivity as well as erosivity associated with moderate rain(10～25 mm),heavy rain(25～50 mm),and extreme rain(≥50 mm)in Beijing.[Results]The annual rainfall erosivity in Beijing ranged from 1 691.51 to 3 914.89(MJ·mm)/(hm2·h·a)during the period from 1991 to 2020.The spatial distribution characteristics of annual rainfall erosivity exhibited similarities with heavy rain and rainstorm but differed from moderate rain patterns.Overall,there was a decreasing trend observed from northeast regions towards the surrounding areas.Over the past four decades,moderate rainfall erosivity demonstrated a significant increasing trend in Beijing;however,no significant mutations or trends were observed for annual rainfall erosivity,heavy rain events,rainstorms or July-August summer precipitation erosivity.Notably large decreasing trends were identified for annual rainfall erosivity within local areas such as Miyun and Pinggu districts.The main cycle for both annual rainfall erosivity and medium-to-heavy intensity precipitation lasted approximately twenty-five years with two to three alternating"low-high"changes.[Conclusion]The study can offer a scientific foundation for soil and water conservation,agricultural practices,and ecological preservation in Beijing.

[Objective]Slope and slope length are essential topographic factors,and their calculation accuracy directly affects the evaluation accuracy of slope soil erosion model.The high-precision elevation measurement capability of Gaofen-7 satellite has great potential in the accurate extraction of terrain factors,and it is expected that it can be used in the extraction of slope and slope length to achieve accurate expression of terrain.It is necessary to evaluate the accuracy of the results of slope length extraction using the DEM of Gaofen-7 satellite.[Methods]The slope and slope length of DEM generated by Gaofen-7 satellite,1∶10000 topographic map and LiDAR images in 4 small basins in Wubu County,Shaanxi Province were extracted by using the terrain factor(LS)calculation tool.Correlation coefficient(r),relative deviation(RE)and absolute deviation were used as evaluation indexes to evaluate the accuracy of extraction of topographic factors by Gaofen-7.[Results]Compared with the slope and slope length of LiDAR and 1∶10 000 topographic map,the average slope extracted by GF-7 was 7.50％～9.02％lower,and the slope length was 1.83％～19.35％larger.However,the area distributions of slope length and slope derived from the three data sources had no significant difference.Comparing the results of slope and slope length,the discrepancy in slope(RE:16.46％～44.26％)derived from different sources is significantly lower than that(RE:75.25％～140.87％)was slope length.The discrepancy between different sources was enhanced in gully areas(RE of slope 15.48％～56.63％,slope length:50.02％～130.79％),while being decreased in inter-gully areas(RE of slope 21.28％～63.61％,RE of slope length 93.01％～192.51％).[Conclusion]It was feasible to obtain areal grading characters of slope or slope length and slope of specified locations using DEMs generated from Gaofen-7 satellite,while the results of slope length for specified locations were less reliable.In conclusion,the Gaofen-7 satellite had a great advantage in describing the spatial distribution of slope length and slope at the watershed scale,while being less capable of capturing slope length and slope at a specific site.

The transport of sediments is a crucial part of soil erosion. Accurately calculating the sediment transport capacity is key to the construction of soil erosion process models. Research on Tc has focused mainly on the dynamics of a single particle of sediment and hydraulic variables. There have been few studies of the impact of soil aggregates on the Tc. To clarify how sediment characteristics, including those for single particles and aggregates, affect the Tc of overland flow with no raindrop import, flume experiments were implemented at slope gradients varying from 5.24% to 26.80% and flow discharges ranging from 0.68 to 5.41 × 10−3 m2 s−1. The experimental materials were five typical soils in China. The results indicated that the correlation between the measured Tc and sediment mechanical composition indexes of the five soils was indistinctive in this study. The sediment settling velocity with aggregates has a significant correlation with the measured Tc. New equations, including for the sediment settling velocity with aggregates ωud75, were established to calculate the Tc. The empirical equation that included ωud75, slope gradient and unit discharge performed greatly in predicting Tc (R2 = 0.93, NSE = 0.90). ωud75 can effectively improve the calculation accuracy of Tc. The new equation including flow and sediment properties obtained through dimensional analysis performed well in predicting Tc (R2 = 0.99, NSE = 0.91), and the calculation accuracy was better than that of the empirical model derived in this study. These findings indicate that the sediment settling velocity is an important variable in the equation for predicting sediment transport capacity of overland flow.