Sediment transport capacity of concentrated flows on steep loessial slope with erodible beds

Hai Xiao,Puling Liu,Jiaqiong Zhang,Fenli Zheng,Feinan Hu,Gang Liu

doi:10.1038/s41598-017-02565-8

Abstract

Previous research on sediment transport capacity has been inadequate and incomplete in describing the detachment and transport process of concentrated flows on slope farmlands during rill development. An indoor concentrated flow scouring experiment was carried out on steep loessial soil slope with erodible bed to investigate the sediment transport capacity under different flow rates and slope gradients. The results indicated that the sediment transport capacity increases with increasing flow rate and slope gradient, and these relationships can be described by power functions and exponential functions, respectively. Multivariate, nonlinear regression analysis showed that sediment transport capacity was more sensitive to slope gradient than to flow rate, and it was more sensitive to unit discharge per unit width than to slope gradient for sediment transport capacity in this study. When similar soil was used, the results were similar to those of previous research conducted under both erodible and non-erodible bed conditions. However, the equation derived from previous research under non-erodible bed conditions with for river bed sand tends to overestimate sediment transport capacity in our experiment.

Highlights

Soil erosion is a key factor for understanding land degradation processes around the world[1,2,3]
General empirical formula to describe the relationship between sediment transport capacity, slope gradient and unit discharge per unit width as follows: Tc = aSbqc here, a, b and c are coefficients associated with grain size and with laminar and turbulent-flow regimes, respectively; S is the slope gradient (%) and q is unit discharge per unit width (m2 s−1)
The exponents of Eq 4 indicated that the sediment transport capacity was more sensitive to unit discharge per unit width than to slope gradient

Summary

Introduction

Soil erosion is a key factor for understanding land degradation processes around the world[1,2,3]. This is especially relevant in areas where soil erosion is very intense due to low infiltration rates and high erodibility[4]. The Loess Plateau is one part of the world where a better understanding of erosion rates and soil erosion processes is necessary[5]. Sediment transport capacity, defined as the maximum load of sediment that a given flow rate can carry, is essential in many process-based erosion models[10, 11]. General empirical formula to describe the relationship between sediment transport capacity, slope gradient and unit discharge per unit width as follows: Tc = aSbqc (2). Here, a, b and c are coefficients associated with grain size and with laminar and turbulent-flow regimes, respectively; S is the slope gradient (%) and q is unit discharge per unit width (m2 s−1)

Methods

Results

Conclusion