Author(s): Jiongxin Xu

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Keywords: Sand-bed river; Gravel-bed river; Channel width; Channel depth; Channel slope; Flow velocity; Hydraulic geometry

Abstract: Hydraulic geometry is an important subject in the study of alluvial rivers. So far, little research has been devoted to the comparison of hydraulic geometries between sand-and gravel-bed rivers. Based on a large database composed of the data from 270 rivers, this comparative study has been made. The bankfull width (B) –discharge (Q bf) relationship of sand-bed rivers shows basically no difference from that of gravel-bed rivers, and the grain size of bed material has little influence on the B-Q bf relationship. When the discharge is given, the bankfull depth of sand-bed rivers is significantly larger than that of gravel-bed rivers, the bankfull slope is gentler, and the flow velocity at bankfull discharge is lower. When all data are put together without differentiating sand-and gravel-bed rivers, the relationship between flow velocity and bankfull discharge shows some non-linear variation. The flow velocity increases with the increased discharge to some peak, followed by a decline. This non-linearity may be attributed to the different manners for the sand-and gravel-bed rivers in which the flow velocity is adjusted to the changing discharge.

DOI:

Year: 2004