Meandering bed development time: Formulation and related experimental testing

•A semi-empirical equation is proposed for the meandering bed development time.•Laboratory tests are used to reveal the form of the equation proportionality factor.•Practical application of the equation is illustrated with natural stream data.

This paper concerns the prediction of the bed development time of alluvial meandering streams. It is assumed that the stream centreline follows a sine-generated curve; the banks are rigid; the flow is turbulent and subcritical; and the width-to-depth ratio is “large”. The bed is flat at the beginning of an “experiment”. The bed development consists of the formation of large-scale, laterally adjacent pool-bar complexes strictly induced by the stream curvature. The paper is to be viewed as an extension of previous work by the writers, who have introduced an equation for the aforementioned bed development time, albeit with a proportionality factor that remains a not yet known function of the stream initial deflection angle. The objective of this paper is to reveal this function, and thus bring the equation for the bed development time into a form suitable for practical applications. This is achieved on the basis of a series of experiments carried out by the writers in three sine-generated meandering streams of varying sinuosity, as well as data from the literature. The paper concludes with examples of application of the resulting equation to real rivers.