Document Type : Research Paper
MSc. Student, Soil Science Dep., Faculty of Agricultural Sciences, University of Guilan, Iran
Assistance Professor, Soil Science Dep., Faculty of Agricultural Sciences, University of Guilan, Iran
Irrigation Eng. Dep., Faculty of Agricultural Sciences, University of Guilan, Iran
The understanding soil erosion processes and the development of accurate erosion prediction models require understanding of detachment, deposition and sediment transport in rills. To evaluate the effect of soil type and flow stream power on the relative importance of flow driven processes of sediment transport, and on the boundary between the processes regarding to particle size, experiments were performed under six flow stream powers at the slope of 2% in the laboratory condition. A 0.05 × 0.05 × 2.5 m flume was used and time changes in sediment size distribution were measured during 40 minutes to evaluate sediment transport processes. The results supported: i) a hydraulically-dependent size selective pattern for particle transportation, and ii) transportation of different sizes of particles by different mechanisms including Suspension-saltation and Rolling. The results also showed that the particle size with minimum transportation, which has been considered as boundary between the suspension-saltation and rolling processes is unique for each soil, depends on its particle size distribution. This boundary is not changed by increasing flow stream power from 0.12 to 0.8 Wm-2.