Kengo Osada

NUMERICAL STUDY ON THE FORMATION OF LOW-WATER COURSE IN A STRAIGHT CHANNEL WITH ALTERNATE BARS

As recent channel characteristics of gravel-bed river, bed degradation, immobilization of the lowwater course, local scour near river bank, extension of relative elevation, and overgrowth of vegetation are mentioned. These figures are produced as results of the morphological change under the medium-size floods in the low-water course affected by alternate bars. In this study, we discuss the low-water channel formation where recent river channel characteristics of the gravel-bed river are reflected, and the process of morphological change was examined from numerical calculation. First, a channel with alternate bar was made, afterwards, the flow discharge was lowered and the meandering low-water channel, which brings about the bank erosion and local scour, was formed. These processes were investigated from the results of present numerical calculation.