A laboratory study of sediment transport capacity in the dynamic process of rill erosion

The transport capacity of flowing water in a rill is one of the important parameters in soil erosion, especially in soil erosion prediction and soil erosion process modeling. Theory suggests that under steady flow, sediment yield will increase with slope length and will approach its limit: the highest possible sediment concentration at transport capacity of the flow. The objective of this study was to develop a method to measure transport capacity of flow. A series of 405 flume experiments were conducted with a silty-clay (loess) soil. A mathematical expression was presented to estimate transport capacity from the experimental data under five slopes (5°, 10°, 15°, 20°, 25°), and three flow rates (2, 4, 8 l/min). The transport capacity is simply given as the product of unit-width flow rate with the limit value of the sediment function with rill length. Transport capacity was found to be related to slope and flow rate. For practical purposes, a method was suggested to estimate the rill length required for determining transport capacity at different slope and flow rate.