Abstract
In rivers which formed multi-row bars or braided rivers, riverbanks often have wavy shape on a scale of several times of river width. In such rivers, a wide width part (anti-node) and a narrow part (node) appear by turns in the longitudinal direction. The elucidation of this phenomenon accompanied by bank erosion is very important on river management works. However, the formation mechanism of a gourd type channel has not been clarified. This research conducts a linear stability analysis as the first step which clarifies the formation mechanism of such channels. As a result, it became clear that a gourd type wavelength is changed with hydraulic conditions.
