Effects of sheet flow rate and slope gradient on sediment load

Sirjani, Elham; Mahmoodabadi, Majid

doi:10.1007/s12517-012-0728-x

Cited by 54 publications

(31 citation statements)

References 28 publications

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“…Slope is an important control of sediment loss [29], as is also shown by the data presented herein. Soil detachment is strongly influenced by the raindrop impact, whereas the detached soil particles are transported by the combined action of the thin sheet flow and raindrop impact [45]. Moreover, the presence of a water layer on the soil surface controls the detachment rate [46].…”

Section: Sediment Lossesmentioning

confidence: 99%

“…Thus, increase in slope steepness significantly increased sediment losses at steeper slopes for all rainfall intensities (Table 3). Furthermore, detached soil particles are easily entrained by higher flow velocity and stream power on steeper slopes [45,[48][49][50]. Comparing the effect of increasing rainfall intensity at a specific slope level (Table 2), data show that an increase in sediment losses by increasing rainfall intensity were maximum at the lowest slope; it created more sediment loss, whereas this effect decreased, at steeper slopes.…”

Section: Sediment Lossesmentioning

confidence: 99%

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Effect of Slope, Rainfall Intensity and Mulch on Erosion and Infiltration under Simulated Rain on Purple Soil of South-Western Sichuan Province, China

Khan

Gong

Ting-xing

et al. 2016

Water

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Purple soil is widely distributed in the hilly areas of the Sichuan basin, southwest China, and is highly susceptible to water erosion. The triggering of this process is related to slope, rainfall intensity and surface cover. Therefore, this study assesses the effects of different simulated rainfall intensities with different slopes on hydrological and erosional processes in un-mulched and mulched purple soils. Results show that the sediment and water losses increased with an increase of rainfall intensity and slope steepness. Generally, the slope contribution (Sc) on water and sediment losses decreased with increasing rainfall intensity and slope steepness under both un-mulched and mulched soil. In un-mulched conditions, water losses were independent of slope steepness (Sc < 50%) during the highest rainfall intensity. However, in mulched soil, the higher contributions of slope (Sc) and rainfall (Rc) were found for water and sediment losses, respectively, i.e., >50%, except during the increase in slope steepness from 15 • to 25 • under the highest rainfall intensity (120 mm·h −1 ). The effectiveness of mulch was more pronounced in reducing sediment losses (81%-100%) compared with water losses (14%-100%). The conservation effectiveness of mulch both decreased and increased with slope steepness for water and sediment losses, respectively, under higher rainfall intensities. Water infiltration and recharge coefficient (RC) decreased with an increase of slope steepness, while with an increase in rainfall intensity, the water infiltration and RC were increased and decreased, respectively, in both un-mulched and mulched soil. On the other hand, mulched soil maintained a significantly (α = 0.05) higher infiltration capacity and RC compared to that of the un-mulched soil.

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Section: Sediment Lossesmentioning

confidence: 99%

Section: Sediment Lossesmentioning

confidence: 99%

Effect of Slope, Rainfall Intensity and Mulch on Erosion and Infiltration under Simulated Rain on Purple Soil of South-Western Sichuan Province, China

Khan

Gong

Ting-xing

et al. 2016

Water

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“…In addition, slope gradient is considered to play a key role in controlling IR and erosion rate (Essig et al, 2009;Mahmoodabadi and Cerdà, 2013). Ekwue et al (2009) and Sirjani and Mahmoodabadi (2014) reported that soil erosion increased with increasing slope gradient as a result of reduced IR and greater runoff rate. Janeau et al (2003) observed a reduction in IR when slope gradient increased.…”

Section: Introductionmentioning

confidence: 99%

Aggregate breakdown and surface seal development influenced by rain intensity, slope gradient and soil particle size

Sajjadi

Mahmoodabadi

2015

Solid Earth

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Abstract. Aggregate breakdown is an important process which controls infiltration rate (IR) and the availability of fine materials necessary for structural sealing under rainfall. The purpose of this study was to investigate the effects of different slope gradients, rain intensities and particle size distributions on aggregate breakdown and IR to describe the formation of surface seal. To address this issue, 60 experiments were carried out in a 35 × 30 × 10 cm detachment tray using a rainfall simulator. By sieving a sandy loam soil, two sub-samples with different maximum aggregate sizes of 2 mm (D max 2 mm) and 4.75 mm (D max 4.75 mm) were prepared. The soils were exposed to two different rain intensities (57 and 80 mm h −1 ) on several slopes (0.5, 2.5, 5, 10 and 20 %) each at three replicates. The result showed that for all slope gradients and rain intensities, the most fraction percentages in soils D max 2 and D max 4.75 mm were in the finest size classes of 0.02 and 0.043 mm, respectively. The soil containing finer aggregates exhibited higher transportability of pre-detached material than the soil containing larger aggregates. Also, IR increased with increasing slope gradient, rain intensity and aggregate size under unsteady state conditions because of less development of surface seal. However, under steady state conditions, no significant relationship was found between slope and IR. The findings of this study revealed the importance of rain intensity, slope steepness and soil aggregate size on aggregate breakdown and seal formation, which can control infiltration rate and the consequent runoff and erosion rates.

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“…Also, several hydraulic parameters (e.g., flow depth, flow velocity, shear stress, stream power, and unit stream power) are used to characterize the erosive power of the overland flow for determining sediment concentration (Trout and Neibling 1993;Shih and Yang 2009). In situations of higher erosive powers, due to greater flow rates, sediment concentration increases (Sirjani and Mahmoodabadi 2012a). In addition, slope steepness has an important role in controlling stream power.…”

Section: Introductionmentioning

confidence: 99%

Sediment concentration and hydraulic characteristics of rain-induced overland flows in arid land soils

Sajjadi

Mahmoodabadi

2015

J Soils Sediments

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Purpose Rain-induced overland flow involves the detachment of soil particles by raindrop impact and the transportation by the resultant overland flow. The purpose of this study was to investigate the relationship between sediment concentration and different hydraulic parameters including flow depth, flow velocity, shear stress, stream power, and unit stream power. The effects of soil particle size distribution, rain intensity, and slope steepness on measured sediment concentration in rain-induced sheet flow were also examined. Materials and methods Two arid land soils with different particles size distributions (D 2mm and D 4.75mm ) were subjected to simulated rains using a detachment tray under infiltration conditions. Two rain intensities of 57 and 80 mm h −1 were simulated on slope gradients ranging from 0.5 to 20 %, resulting in rain-induced overland flows. After pre-wetting each soil, the sediment-laden overland flow was sampled at several time intervals (2, 5, 15, 20, 30, and 40 min) and the sediment concentration was determined. Different hydraulic parameters including flow depth, flow velocity, shear stress, stream power, and unit stream power were measured. The hydraulic parameters were used to model the sediment concentration, and the model performance was evaluated. Results and discussion The result showed that the measured sediment concentration was greater in the higher rainfall intensity and at steeper slopes. With increasing slope steepness, sediment concentration increased from 4.3 to 15.5 kg m −3 and from 3.8 to 12.5 kg m −3 for soils D 2mm and D 4.75mm , respectively. There was a direct relationship between sediment concentration and the rain-induced flow velocity, shear stress, stream power, and unit stream power. Nevertheless, the values of sediment concentration increased as flow depth decreased on steeper slopes. Also, sediment concentration was lower in the soil containing larger aggregates than in the finer soil. The hydraulic parameters tended to overestimate low amounts of sediment concentration and underestimate high values. Conclusions In general, the accuracy of the hydraulic parameters in predicting sediment concentration was: flow velocity > stream power > shear stress > unit stream power > flow depth. Flow velocity was the best predictor of sediment concentration with a linear relationship, whereas the other parameters showed nonlinear relationships. This study revealed that rain-induced sediment concentration at small scales can be modeled precisely on the basis of the flow velocity parameter.

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Effects of sheet flow rate and slope gradient on sediment load

Cited by 54 publications

References 28 publications

Effect of Slope, Rainfall Intensity and Mulch on Erosion and Infiltration under Simulated Rain on Purple Soil of South-Western Sichuan Province, China

Effect of Slope, Rainfall Intensity and Mulch on Erosion and Infiltration under Simulated Rain on Purple Soil of South-Western Sichuan Province, China

Aggregate breakdown and surface seal development influenced by rain intensity, slope gradient and soil particle size

Sediment concentration and hydraulic characteristics of rain-induced overland flows in arid land soils

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