Overland Flow Resistance Research Articles

Design discharge estimation for small urban districts – an analytical approach

ABSTRACT This paper presents a straightforward design discharge estimation procedure for small urban districts. In this approach, the configuration of the small urban district was simplified into either a rectangular porous overland plane or a V-shaped porous overland model. The Horton equation was used to estimate the infiltration on the overland planes, and the kinematic-wave approximation was applied for runoff simulations. In deriving the runoff equation, the Darcy–Weisbach coefficient was adopted to account for the influences of spatially various flow depths on overland flow resistance. The theoretical derivations were applied to a series of cases and verified by numerical models to demonstrate the applicability of the proposed method. The results showed that the design discharges obtained from the analytical equations are close to those simulated by the numerical model. The analysis procedure developed herein can provide a convenient way for engineers to conduct urban sewer designs.

Effects of grass-shrub vegetation and litter on overland flow resistance coefficients

Effects of grass-shrub vegetation and litter on overland flow resistance coefficients

Assessing a transitional and turbulent overland flow resistance law for surfaces with different roughness

The control and management of soil erosion phenomena caused by rainfall and runoff is a significant issue in sloping landscapes, especially if they are scarcely or not vegetated. The study of the relationship between soil roughness and flow resistance is a fundamental step in improving the knowledge of erosion processes. In this study, the suitability of a theoretically deduced flow resistance law, based on a power-velocity profile, was assessed by transitional and turbulent overland flow data obtained in laboratory and available in the literature. These measurements were obtained in a sloping (slope in the range 1–40 %) rectangular flume, testing the effects of six different roughness conditions. At first, for each investigated roughness condition, the available measurements were used to calibrate and test the equation relating the Γ function of the velocity distribution, the flow Froude number, and the channel slope. For all the investigated conditions, this analysis allowed for demonstrating that the flow resistance law gives a reliable estimate of the Darcy–Weisbach friction factor, with errors ≤±5 % for 89.8–100 % of the examined cases with reference to the considered roughness condition. Then, using coefficients b (1.05) and c (0.562) of the Γ function available in the literature, the roughness effect was exclusively attributed to the a coefficient. In this case, the friction factor values calculated by the flow resistance law, with b = 1.05 and c = 0.562 and the a values corresponding to the different roughness conditions, are characterized by errors ≤±5% for 70.4–100 % of the cases. Finally, the power relationships between the calibrated a, b, and c coefficients of the Γ function, and Manning’s n values, corresponding to the roughness of the investigated surfaces, pointed out that the a coefficient is the most affected by the roughness conditions, as the exponent of Manning’s assumes the highest value. The significance of this research is due to the fact that a relevant issue in modeling overland flow is to define the resistance coefficient for variable roughness, especially the vegetated ones.

The role of near‐surface vegetation in modulating overland flow resistance in grasslands of the Chinese Loess Plateau

AbstractVegetation restoration significantly increases overland flow resistance and decreases soil erosion. The cause of soil erosion is unknown, though grain resistance and form resistance are frequently confused with the overall overland flow resistance. The zonal specie of Bothriochloa ischcemum (Linn.). Keng (BI) and the dominant specie of Artemisia vestita Wall. ex Bess (AG) were selected to investigate the effect of vegetation near soil surface characteristics derived by vegetation restoration on overland flow resistance of grain resistance and form resistance. In total, 24 steel tanks were planted at six planting densities of 5, 10, 15, 20, 25, and 30 plants m−2, and two tanks were used as bare soil controls. Their hydraulic characteristics were tested under a constant rainfall intensity (60 mm h−1) on a 26.2% slope. The results showed that the grain resistance (fg) and form resistance (ff) ranged from 0.06 to 0.35 and 18.01 to 95.77 under six planting densities. Vegetation increased overland flow resistance by more than 90%, which was mainly attributed to ff. Vegetation near soil surface factors of the aboveground part, biological soil crusts, and root collar increased ff by 18.71 to 82.13, 0.74 to 11.50, and 1.61 to 3.40, respectively. Compared with BI, the mean value of fg in AG was 48.87% lower, whereas the mean value of ff was 1.36 times greater. The fg decreased with soil organic matter as a power function. The ff decreased with the Reynolds number, Froude number, and flow velocity and increased with vegetation coverage, aboveground biomass, and root collar area as power functions. Soil properties explained the majority of the variation in fg, and near the vegetation soil surface factors explained the majority of the variation in ff. Finally, ff was simulated using the Reynolds number, vegetation coverage, and root collar area. In addition, a simulation equation for the total flow resistance was established by distinguishing the grain resistance and the form resistance, and the performance of the model developed in this study was satisfactory (NSE = 0.97).

Effects of surface inoculation of biological soil crusts on laminar overland flow resistance

AbstractNotwithstanding the recognized influence of Biological Soil Crusts (BSCs) on surface roughness and its implication for hydrological processes, limited information is currently available on the effect of BSCs on overland flow resistance. The objective of this paper was to investigate the applicability of a theoretically deduced flow resistance equation, based on a power‐velocity profile, using the experimental data set by Jafarpoor et al. (2022) and Sadeghi et al. (2023) for bare soil, which is a control condition, and three inoculated soils (cyanobacteria, bacteria, cyanobacteria+bacteria). In particular, the available data set was used to calibrate the relationship between the velocity profile parameter Γ and the flow Froude number. The developed analysis allowed for stating that (a) the Darcy‐Weisbach friction factor can be accurately estimated using the proposed theoretical approach, and (b) the available measurements do not allow for detecting a trend with the soil treatment.

Effects of root traits on soil detachment capacity driven by farmland abandonment

Vegetation restoration significantly affected root traits during farmland abandonment, thereby considerably altering the soil detachment process. However, few studies have investigated the effects of root traits on soil detachment capacity under different ages of farmland abandonment. To examine the effects of root trait changes caused by vegetation restoration on soil detachment capacity by overland flow (Dc) and soil resistance to erosion under different ages of farmland abandonment, flow scouring tests under five shear stress levels (2.80–12.95 Pa) were conducted on 125 undisturbed soil samples collected using an indoor variable slope flume. The results showed that, compared to slope farmland, the root traits of abandoned farmland (5, 12, 24, and 36 years) increased considerably, and the Dc and erodibility decreased by 51.3–93.9 % and 61.8–94.1 %, respectively. The critical shear stress of abandoned farmland gradually increased with the age of farmland abandonment, but remained less than that of slope farmland. Among hydraulic parameters, stream power was the optimal index for predicting Dc, while among root morphological traits, root surface area density (RSAD) was the best indicator for predicting Dc. The median soil particle size (D50) and cohesion are important factors that affect soil detachment. According to the Water Erosion Prediction Project (WEPP) model, Dc can be predicted using the RSAD and soil cohesion (R2 = 0.95, NSE = 0.95). In addition, a new model was established to estimate the soil detachment capacity based on D50 (R2 = 0.97, NSE = 0.97). In the present study, the performance of the model was improved compared with that of previous studies.

Study on the resistance characteristics of layered vegetation to overland flow

AbstractDifferent types of plants in the vegetation community near the surface of the basin coexist, forming a layered vegetation distribution with high and low plants in the morphology. In order to research the characteristics of flow resistance generated by layered vegetation on slope runoff, a flume experiment was carried out by simulating layered vegetation. The Manning roughness coefficient n was used to characterize the flow resistance of vegetation. Three kinds of vegetation with height combinations of 5 and 7 cm, 6 and 8 cm, and 7 and 9 cm were used for this experiment. By studying the relationship between Manning roughness coefficient n and water depth, it is found that the change of flow resistance of layered vegetation is closely related to the submerged state. The distribution of n shows an inverted “J” type with the increase of water depth. Under the condition of nonsubmerged state and transitional submerged state, n increases with the increase of water depth. The critical point n values of the two states will plummet, and the growth rate of n in the nonsubmerged state is greater than that in the completely submerged state. In the transitional submerged state and completely submerged state, the higher the plant height below the water surface, the higher the corresponding n value and the greater the change rate of n. Formula for predicting overland flow resistance of layered vegetation was established by considering the influence of combined vegetation height and Reynolds number.

Evaluation of the effects of grass and shrub cover on overland flow resistance and its attributes under simulated rainfall

Vegetation plays a crucial role in controlling soil erosion and regulating overland flow connectivity. However, the effects of vegetation coverage on the overland flow resistance mechanisms remain unclear. This study aimed to examine the impact of grass and shrub cover on the resistance to overland flow concerning a random patch distribution pattern. This was achieved through a series of simulated rainfall experiments. Thirty slope surfaces with different vegetation coverages, consisting of complete combinations of five grass and six shrub coverages, were tested under five rainfall intensities (60–120 mm h−1) and three slope gradients (8.75%–26.79%). The results indicated that the Darcy–Weisbach friction factor (f) values on unvegetated slopes ranged from 0.455 to 1.385, whereas those on vegetated slopes ranged from 0.500 to 5.624. Vegetation coverage increased flow resistance on hillslopes, and the relationship between f and the Reynolds number (Re) was influenced by vegetation cover and the slope gradient; thus, it showed a positive correlation when vegetation form resistance was dominant. In contrast, a negative correlation was observed. According to the t-test results, the linear superposition method had limitations in calculating overland flow resistance and was only applicable when the grass coverage was 10%. Moreover, as the coverage increased, significant differences (p < 0.05) emerged between the total resistance and the linear summation of the individual resistance components. Additional vegetation resistance plays a significant role in impeding the water flow, contributing up to 50% of the total resistance. Finally, an equation for calculating additional vegetation resistance was developed using dimensional analysis and multiple nonlinear regression. The accuracy of the equation was validated by comparing it with experimental results (NSE = 0.918, RMSE = 0.144). These findings emphasize the effectiveness of constructing grass-shrub communities and increasing vegetation coverage as measures for soil and water conservation.

Influence of vegetation lodging on the flow regime and resistance characteristic of overland flow

AbstractVegetation lodging downstream under overland flow is a common phenomenon; it changes the characteristics of the overland flow regime and causes the resistance effect. At present, there are few studies on the hydraulic characteristics of the slope flow caused by vegetation lodging, and the problem of the flow resistance of the vegetation morphology has been neglected or simplified, which is likely to cause large deviations in overland flow forecast. To clarify the effect of vegetation lodging on overland flow, under the conditions of slope (0.0%–3.0%) and flow discharge (0.0005–0.008 m3/s), an indoor flume experiment of vegetation gradient lodging combination and lodging angle was carried out, and the resistance mechanism and flow regime characteristics were compared and discussed. The results show that it is reasonable to use a uniform lodging angle to simulate the influence of gradient lodging on the overland flow resistance. The slope and vegetation lodging states are important factors that affect the evolution of flow patterns and turbulence changes. It was found that, as the slope or degree of vegetation lodging increased, the flow patterns evolved from slow to rapid. Under the same flow discharge, the resistance of overland flow decreased with an increase in the vegetation lodging angle. Under unsubmerged conditions, the resistance coefficient f was found to be positively correlated with the Reynolds number Re and the cosine of the lodging angle θ, and negatively correlated with the slope S. Compared with vertical vegetation, the morphological resistance of vegetation with lodging angles of 20°, 40°, 60°, and 80° decreased by 10.28%, 32.53%, 52.45%, and 61.37%, respectively. The morphology of vegetation lodging is the main influencing factor that constitutes flow resistance and controls hydraulic erosion. This study provides a theoretical basis for the prediction of overland flow and soil erosion control.

Overland flow hydrodynamic characteristics in rough beds at low Reynolds numbers

This paper considers overland flow resistance at low Reynolds numbers through analysis of experimental runs carried out using water only and water/glycerol mixtures. We first examined the power relationship between the Darcy–Weisbach friction factor f and the Reynolds number Re to obtain the values of the K coefficient and b exponent. These results confirmed the applicability of the values of b suggested in literature, while K required a specific calibration for laminar open-channel flows. The analysis revealed that transition from a laminar to turbulent flow regime for water only flows occurred at a threshold value of Re equal to 500 as described historically. The estimate of f by the power relationship and the calibrated b and K values were reliable for water only runs when Re ≥ 500. The measurements were also used to test a theoretical flow resistance law based on a power-velocity distribution. The calibrated theoretical relationship between the velocity profile parameter Γv, bed slope, flow Froude number and Re enabled a good estimate of f for water flows. For mixed fluid flows, the effect of the velocity profile shape was considered calibrating this relationship by two datasets obtained setting a threshold Reynolds number equal to 7. For flows with Re < 7, the shape of the velocity profile can be linear or convex while for flows at Re ≥ 7 the shape of the velocity distribution is always concave. The theoretical flow resistance allowed an accurate estimate also for mixed fluid flows, even at Re < 7. The different shape of the power-velocity distribution highlighted that mixed flows behave differently as compared to water only flows.

A theoretically-based overland flow resistance law for upland grassland habitats

Sediments conveyed from interrill areas to rills are transported by a thin flow (overland flow) and the knowledge of overland flow resistance is useful to evaluate overland flow velocity and sediment transport capacity.The aim of this paper was to verify the applicability of a theoretical overland flow resistance law, based on a power-velocity distribution, using field measurements for four upland grassland types used in different management strategies (Hay Meadows, Low-density Grazing, Rushes and Rank Grassland). Particular attention was deserved to the effects of vegetation growth cycles on the surface roughness and the corresponding reduction of overland flow velocity.The relationship between the parameter Γ of the power velocity profile, the flow Froude number and the Reynolds number, obtained by dimensional analysis, was calibrated using the available data. A specific calibration for each upland grassland type and taking into account the temporal phases of the vegetation growth was also carried out.The theoretical approach, checked by the available field measurements, allowed to establish that a) the proposed theoretical flow resistance law, which considers also the effect of the flow Reynolds number, allows an accurate estimate of the Darcy–Weisbach friction factor, b) the theoretical overland flow resistance law considers the temporal variability of vegetation characteristics, c) this flow resistance law can be specifically calibrated for taking into account for each upland grassland type the effect of the vegetation temporal variability and d) a low effect of the seasonal variation of roughness in grassland environments is detected.The interrill soil erosion processes are strongly related to hillslope hydraulics and the proposed overland flow resistance law is useful to model soil erosion processes.

Slope threshold for overland flow resistance on sandy soils

AbstractRecent research on rill flows recognised that an 18% slope can be used to distinguish between ‘gentle’ and ‘steep’ slope cases for the detected differences in hydraulic (flow depth and velocity) and sediment transport variables (flow transport capacity, actual sediment load). The effects of slope on flow velocity, friction factor and transport capacity and their interactions affect process‐based erosion modelling. The main aim of this paper is to investigate, for the first time, how slope affects the overland flow resistance on sandy soils, which are characterised by loose particles readily available to be transported and deposited. Using literature measurements carried out in sandy soils for both gentle and steep slopes, a theoretical overland flow resistance equation, based on the integration of the power velocity distribution, is tested. The relationship between the velocity profile parameter Γ, the channel slope, the Reynolds and Froude number is calibrated using measurements characterized by a wide range of hydraulic conditions and distinguishing between gentle (5.2%–13.2%) and steep (17.4%–42.3%) slope conditions. The analysis demonstrated that: (1) the parameter Γ can be accurately estimated by Equation (15) in which the exponents are independent of slope condition; (2) the coefficient a of Equation (15) is equal to 0.8750 and 0.8984 for the gentle and steep slope condition, respectively; (3) the estimations of the Darcy–Weisbach friction factor f (Equation 19) are accurate and characterised by errors less than or equal to ±5% for 97.2% of cases; and (4) in the range of steep slopes, the flow resistance law calibrated for the gentle slope condition (Equation (19) with a = 0.8750) systematically overestimates the f value. In conclusion, this study allowed the recognition, for an unlimited soil detachment condition and an overland flow, of how the energy dissipation processes and the estimate of the friction factor are affected by slope.Highlights A theoretical overland flow resistance law is tested by data obtained on sandy soils. Differences between gentle and steep slope conditions are investigated. The Darcy–Weisbach friction factor estimate by the flow resistance law is accurate. The law calibrated for gentle slopes overestimates f in the range of steep slopes.

Overland flow resistance and its components for slope surfaces covered with gravel and grass

Overland flow resistance plays an important role in predicting hillslope hydrological and erosion processes on hillslopes. Soil surfaces covered with grass and/or gravel may increase hydraulic resistance to overland flow, but there is little information on the determination on these resistance components in a composite slopeland. In this study, the smooth and sand-bed surfaces covered with different gravel or/and grass (cover degree = 2.5%, 5%, 10%, 15%, 20%) under five slope gradients (3°, 6°, 9°, 12°, 15°) were subjected to inflows to investigate the hydraulic resistance and validate the sum law of resistance components. The results showed that, the overland flow mainly belonged to transition or turbulent and supercritical flow regime with 150 < Re < 2050 and 0.4 < Fr < 6.9. As the gravel or grass cover increased, Darcy-Weisbach resistance coefficient (f) significantly increased. The resistance can be well predicted by flow discharge, gravel or grass cover using a power equation. The flow discharge had a greater influence on flow resistance than gravel or grass cover, and the impact of flow discharge weakened with the increasing bed slopes. The total resistance was generally greater than the sum of resistance components, and there existed a positive additional resistance for the composite surfaces. The additional resistance accounted for 37.4%, 4.2% and 16.6% to the total resistance for the sand surfaces covered with gravel, grass and both of them, respectively. These results can help to understand the rainfall-runoff processes and improve the design of soil and water conservation measures in the rocky and mountainous areas.

Testing a theoretically-based overland flow resistance law by Emmett’s database

The main aim of this paper was to test a recently theoretically deduced flow resistance equation, based on a power-velocity profile, using a wide database of available measurements carried out in laboratory and field experimental runs with overland flow under simulated rainfall. In comparison with previous calibrations and validations of this theoretically deduced flow resistance equation, the used database by Emmett is characterized by a wide range of rainfall intensities (from 79.2 to 303.5 mm h−1 for laboratory runs and from 178.3 to 215.9 mm h−1 for field investigations) and bed slopes (from 0.33 to 17% for laboratory runs and from 2.9 to 33.2% for field investigations). For the first time, the wide Emmett’s database of laboratory runs carried out by an overland flow subjected to rainfall in a rough-bed-flume was used for testing the theoretical resistance law. Furthermore, the seven investigated field vegetated plots allowed to broaden the range of examined subcritical flows and rainfall intensity. Laboratory data were divided into two datasets (calibration and testing), and the overland flow measurements on a smooth bed by Yoon and Wenzel were added to the testing dataset to assess the applicability of the calibrated equation for different bed roughness conditions. The available laboratory measurements of flow velocity, water depth, hydraulic cross-section area, wetted perimeter and bed slope allowed both to calibrate and test the relationship between the velocity profile parameter Γ, the bed slope, the flow Froude number, and the rainfall Reynolds number, which is a dimensionless group representing the effect of rainfall intensity on flow resistance. The field data were used to calibrate the same flow resistance law and evaluate the effect of different types of vegetation, adapting the relationship obtained by Nicosia et al. The developed analysis showed that: i) the theoretical flow resistance equation gave an accurate estimate of the Darcy–Weisbach friction factor for overland flow under simulated rainfall on rough bed both in laboratory and in field condition; ii) the flow resistance increased with rainfall intensity for the investigated laminar overland flow; iii) the flow resistance relationship is able to take into account different vegetation types characterized by different roughness.

Assessing an overland flow resistance approach under equilibrium sediment transport conditions

In this study, for the first time, a theoretically deduced flow resistance equation was tested for an overland flow under equilibrium sediment transport conditions using available experimental data by Liu et al. for five Chinese soils. Initially the relationship among the velocity profile parameter Γ, the channel slope, the flow Reynolds number, the Froude number and the sediment concentration was calibrated using 90 measurements of the available database (Loessial, Cinnamon and Black soil) and tested by other 60 measurements (Red and Purple soil). The results proved that the Darcy–Weisbach friction factor can be accurately estimated by the proposed theoretical approach, with errors that are always less than or equal to ± 5%. Then, using mean values of the exponents of Froude number, slope, sediment concentration and Reynolds number (Eq. 7), the calibration was carried out for each soil type to attribute the soil effect on the velocity profile parameter and flow resistance to the scale factor a. This analysis demonstrated that the a coefficient increases with the transportability of soil particles, which is associated to a decrease of both the flow energy required for sediment transport and the Darcy–Weisbach friction factor.

Overland Flow Resistance Law under Sparse Stem Vegetation Coverage

To explore the characteristics of overland flow resistance under the condition of sparse vegetative stem coverage and improve the basic theoretical research of overland flow, the resistance characteristics of overland flow were systematically investigated under four slope gradients (S), seven flow discharges (Q), and six degrees of vegetation coverage (Cr). The results show that the Manning roughness coefficient (n) changes with the ratio of water depth to vegetation height (h/hv) while the Reynolds number (Re), Froude number (Fr), and slope (S) are closely related to vegetation coverage. Meanwhile, h/hv, Re, and Cr have strong positive correlations with n, while Fr and S have strong negative correlations with n. Through data regression analysis, a power function relationship between n and hydraulic parameters was observed and sensitivity analysis was performed. It was concluded that the relationship between n and h/hv, Re, Cr, Q, and S shows the same law; in particular, for sparse stem vegetation coverage, Cr is the dominant factor affecting overland flow resistance under zero slope condition, while Cr is no longer the first dominant factor affecting overland flow resistance under non-zero slope condition. In the relationship between n and Fr, Cr has the least effect on overland flow resistance. This indicates that when Manning roughness coefficient is correlated with different hydraulic parameters, the same vegetation coverage has different effects on overland flow resistance. Therefore, it is necessary to study overland flow resistance under the condition of sparse stalk vegetation coverage.

Comment on “Overland runoff erosion dynamics on steep slopes with forages under field simulated rainfall and inflow by C. Li and C. Pan”

AbstractManaging sloping landscapes to control soil erosion processes due to rainfall and runoff is a relevant problem, especially when the vegetation is absent or sparse. The aim of this paper was to investigate the applicability of a theoretically resistance law for overland flow under simulated rainfall, based on a power‐velocity profile, using field measurements carried out by Li and Pan for three plots with planted forage species (Astragalus adsurgens, Medicago sativa and Cosmos bipinnatus).The relationship between the velocity profile parameter Γ, the flow Froude number and the rain Reynolds number was calibrated using the data by Li and Pan. The obtained overland flow resistance law was also verified by independent field measurements carried out by Li and Pan in the same plots with the same forage species subjected to three different treatments (intact grass control IG, no litter or leaves NLL (only the grass stems and roots were reserved) and only roots remaining OR).The theoretical approach and the measurements carried out in the investigated conditions allowed to state that a) the Darcy‐Weisbach friction factor can be accurately estimated using the proposed theoretical approach, b) the Darcy‐Weisbach friction factor varies with rainfall intensity and c) for the investigated forage species, the vegetation treatment (IG, NLL, OR) does not significantly affect the flow resistance in laminar regime.

Landscape patches influencing hillslope erosion processes and flow hydrodynamics

Exploring overland flow resistance and sediment delivery capacity under different landscape vegetation conditions is critical for better understanding hydrodynamic mechanisms of soil erosion processes and hydrological connectivity on hillslopes. To evaluate flow resistance relations and sediment transport for landscape vegetation coverage and combinate effect of vegetation patches, field simulated rainfall experiments were conducted using a series of overland runoff and sediment transport rates in 3 m (L) × 2 m (W) experimental plots with coverages of 0%, 20%, 40%, 60% and 90% in a uniformly distributed condition and composited flow paths of different patches (horizonal path, vertical path, random patches and S-shaped path) in the same coverage (40% and 60%). The runoff rates for the grassland with coverages of 20–90% were decreased by 19.3–61.4% (P < 0.05), and the sediment concentrations were reduced by 81.7–97.8% (P < 0.05) compared to the bare land. The Darcy-Weisbach resistance coefficient doubled and the stream power declined by 60.0% when grassland coverage increases to 90%. The runoff rates varied little among the conditions of horizontal, vertical, random and S-shaped flow paths at the coverage of 60%, while the rate apparently reduced by 34.1% (P < 0.05) when the vertical flow path became horizontal under the same coverage of 40%. The sediments for poorly connected flow paths could reduce sediment >90% either on high-coverage or low-coverage grassland. Our field experiments confirmed that the increase of vegetation coverage and the combination of landscape patches could significantly reduce runoff rates, sediment yields and flow velocities, increase surface roughness, promote flow resistance and diminish hydraulic shear stress and the stream power. The poorly-connected paths (horizontal and random) exhibited a stronger flow resistance and weaker sediment transport capacity than the well-connected paths (vertical and S-shaped).

On the Fixed Rainfall Intensity: Effects on Overland Flow Resistance, Shear Velocity and on Soil Erosion

On the Fixed Rainfall Intensity: Effects on Overland Flow Resistance, Shear Velocity and on Soil Erosion

The effects of varied soil properties induced by natural grassland succession on the process of soil detachment

The changes in soil properties caused by vegetation succession might have great effects on the process of soil detachment by overland flow. This study was carried out to quantify the effects of varied soil properties induced by natural grass succession on soil detachment capacity by overland flow and soil resistance to flowing water erosion on the Loess Plateau. 300 undisturbed soil samples (without roots) were collected from ten typical grasslands, and subjected to flow scouring under six shear stresses ranging from 4.98 to 16.37 pa. The results showed that the maximum soil detachment capacity (3.80 kg m−2 s−1) was found in Astragalus melilotoides Pall. grassland, where it was 49.0 times greater than that of the minimum found in Poa sphondylodes Trin. grassland. Soil properties induced by fibrous root herbage have strong effects on the process of soil detachment. In comparison to grasslands with tap root systems, grasslands with fibrous root herbage have lower soil detachment and rill erodibility by 84.6% and 84.3%, respectively, and critical shear stress which is higher by 15.2%. Stream power was a better parameter than velocity, shear stress or unit stream power for simulating soil detachment capacity. Soil cohesion, bulk density, organic matter and median soil grain size were the main factors affecting the process of soil detachment. Rill erodibility decreased with cohesion or clay content as an exponential or power function, and increased with the median soil grain size as an exponential function. A model was developed to estimate soil detachment capacity based on hydraulic parameters and soil properties on the Loess Plateau. The result was satisfactory and the performance of model was greatly improved in comparison to previous studies (R2 = 0.77; NSE = 0.61; p < 0.01).