Modelling sediment transport capacity of rill flow for loess sediments on steep slopes

Sediment transport is an important aspect of soil erosion, and sediment transport capacity (T-c) is a key to establishing process -based erosion models. A lot of studies exist that have determined T-c for overland flow, however, few studies have been conducted to determine T-c for loess sediments on steep slopes. Experimental data for this region are thus needed. The objectives of this study are to formulate new equations to describe T-c and evaluate the suitability of these equations for loess sediments on steep slopes. The slope gradients in this study ranged from 10.51% to 38.39%, and flow discharges per unit width varied from 1.11 x 10(-3) m(2) s(-1) to 3.78 x 10(-3) m(2) s(-1). Results showed that 11 increased as a power function with flow discharge and slope gradient, with R-2 = 0.99 and Nash -SuT(c)liffe model efficiency (NSE) = 0.99. T, was more sensitive to flow discharge than slope gradient. T-c increased as a power function with mean flow velocity, which was satisfied to predict T-c with R-2 = 0.99 and NSE = 0.99. Shear stress (R2 = 0.89, NSE = 0.88) was also a good predictor of T-c, and stream power (R-2 = 0.96, NSE = 0.96) was a better predictor of T-c than shear stress. However, unit stream power was not a good predictor to estimate T-c in our study, with R-2 = 0.63 and NSE = 0.62. These findings offer a new approach for predicting T-c for loess sediments on steep slopes. 2016 Elsevier B.V. All rights reserved.