Hydraulic characteristics and sediment generation on slope erosion in the Three Gorges Reservoir Area, China

Abstract

Hydrological processes play important roles in soil erosion processes of the hillslopes. This study was conducted to investigate the hydrological processes and the associated erosional responses on the purple soil slope. Based on a comprehensive survey of the Wangjiaqiao watershed in the Three Gorges Reservoir, four typical slope gradients (5°, 10°, 15°and 20°) were applied to five rainfall intensities (0.6, 1.1, 1.61, 2.12 and 2.54 mm·min -1 ). The results showed that both surface and subsurface runoff varied greatly depending on the rainfall intensity and slope gradient. Surface runoff volume was 48.1 to 280.1 times of that for subsurface runoff. The critical slope gradient was about 10°. The sediment yield rate increased with increases in both rainfall intensity and slope gradient, while the effect of rainfall intensity on the sediment yield rate was greater than slope gradient. There was a good linear relationship between sediment yield rate and Reynolds numbers, flow velocity and stream power, while Froude numbers, Darcy-Weisbach and Manning friction coefficients were not good hydraulic indicators of the sediment yield rate of purple soil erosion. Among the three good indicators (Re, v and w), stream power was the best predictor of sediment yield rate (R 2 = 0.884). Finally, based on the power regression relationship between sediment yield rate, runoff rate, slope gradient and rainfall intensity, an erosion model was proposed to predict the purple soil erosion (R 2 = 0.897). The results can help us to understand the relationship between flow hydraulics and sediment generation of slope erosion and offer useful data for the building of erosion model in purple soil.

Effect of natural rainfall on the migration characteristics of runoff and sediment on purple soil sloping cropland during different planting stages

“…Additionally, purple soil is rich in small rock fragments that are completely incorporated into the topsoil and could considerably influence the percolation, runoff, and soil loss rates of stony soil (Smets et al 2011). Hydrological processes play important roles in hillslope soil migration processes (Qian et al 2016). Runoff is generally the result of unique weather and soil conditions (Douglas et al 1998), while slope runoff is the basic erosion force and sediment transport mechanism of hydraulic erosion.…”

The hydrodynamic mechanism of rainfall runoff from loess slopes treated with incorporated straw

“…For complex underlying surfaces, Re and Fr have been used directly in most studies to analyze the influence that underlying surfaces have on flow regime (Gu et al, 2020; Omidvar, Hajizadeh & Ghasemieh, 2019; Qian, Cheng, Ding, Huang & Liu, 2016; Wang, Lv, Zhang, Li & Meng, 2019; Zhang & Hu, 2019). Many predictive models have been established based on flow velocity, Re , Fr , f , and combinations of their parameters.…”

Equations for predicting interrill erosion on steep slopes in the Three Gorges Reservoir, China

“…Numerous studies have confirmed this finding. (Qian et al, 2016;Wei et al, 2009). The exponents of factors varied in different models.…”

“…As soil erosion by water is largely determined by flow hydraulic characteristics, commonly, concepts were derived from river sediment dynamic theory and applied to interrill erosion. The hydraulic parameters often used to predict interrill erosion rate are flow velocity, shear stress and stream power Qian et al, 2016). Interrill erosion rates are also well correlated with the power functions of flow velocity, shear stress and stream power (Ding and Huang, 2017;Fan and Wu, 1999;Wu et al, 2017).…”