Author(s): A. Nazari G.
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Keywords: Sediment; Erosion; Channel junction; Chamfer; Physical model
Abstract: Channel junction is a phenomenon that occur in rivers, irrigation and drainage channels. It causes erosion and deposition which become a part of river morphological changes. Different factors affect junction changes, such as; channel and sediment geometry, discharge of main and tributary channel, downstream Froude number. In this research erosion at 45°and 90°angle junction (using two experimental set-ups) is considered. The hydraulic parameters such as different discharge ratio of tributary branch to total discharge for three different tributary branch widths, five sediment size and two geometry for the connection at junctions were tested. The results show that the depth of maximum scour does not occur at the junction mouth but happens upstream of the main channel. Also, erosion depth is decreased from its maximum value into downstream of main channel with a mild slope. With decreasing width of the tributary branch, the depth of maximum scour was decreased but the width of scour hole was increased. Also, the depth of scour has an inverse relation with bed material diameter, the width of tributary branch to main channel and the tributary channel discharge to total discharge.
Year: 2010