Document Type : Research Paper
Authors
1 PhD, Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
2 Assistant Professor, Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
3 Associated Professor, Soil Conservation and Watershed Management Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Trhran, Iran
Abstract
Bedload movement plays an essential role in the process of bedload transport and morphological characteristics of rivers. Slope, flow rate and particle size are important parameters in the amount of bedload transport in the erodible beds. Many studies have been investigated the effects of these parameters on the non-erodible beds. In this research, performing a laboratory model in the erodible substrates, the effects of slope, flow rates, particle size and suspended particle concentration on the amount of bedload transport was investigated. The experiments were carried out in the discharge rate of 0.90 to 4.75 ls-1 with the concentrations of the suspended particles 0, 10gl-1 and the slopes of 2, 3 and 5 percent, on the uniform non cohesive particles with the grain diameter of 1.7 and 3.29 mm. The Froude numbers of these currents were obtained in the range of 0.93 to 1.51 and the non-dimensional bed load discharge was calculated in the range of 0.004-0.131. In the experimental results, the variation of the bedload transport capacity in relation to the discharge was shown in the different slopes and grain sizes. Furthermore, increasing the concentration of suspended particles to 10 gl-1, did not has a significant effect on the bed transport capacity. Applying dimensional analysis, the effective parameters on the non-dimensional bed load discharge (ϕ)were investigated. Moreover, to determine ϕ relation to the shear stress (ϴ), particle size (D*) and slope (S). In the scope of the experiment, an experimental relationship was proposed. Results indicated that for determining the non-dimensional bedload discharge in the steep slopes of erodible beds, considering the slope and dimensionless particle diameters as independent parameters had a better result than shear stress correction. Sensitivity analysis of effective parameters on the experimental relationship showed that the slope parameter had the most effect on the experimental relationship.
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