Calculation of Bed Variation in Alluvial Channels

Abstract

A two‐dimensional model is applied to calculate bed variations in alluvial channels. The depth‐averaged flow field is obtained from a steady‐state, two‐dimensional shallow water flow model, and the bed variation is calculated by a continuity equation for bed‐load transport. The model is applied to analyze the symmetric and asymmetric meander loops. Results agreeing with experiments are observed. Applications of the model to the development of meso‐scale bed configuration in straight channels are also shown. The model simulations are conducted for three types of bed configurations: alternating bars, braided bars, and no bars, according to the regime criteria of meso‐scale bed configurations proposed by Kuroki and Kishi (1984). The computed results for alternating bars compare favorably with experiments. The migration velocity of bars in meandering channels is also investigated by the present model. Good agreement with previous experimental and theoretical analyses is found.