Abstract: The main streamline of Jingjiang reach changes in the form of alternation of main & tributary branches and radius of thalweg in bends.To describe the characteristics of mainstream line in bifurcated and curved reaches,this paper presents a dimensionless coefficient: sinuosity eigenvalue r.Correlation between r and other eigenvalues(such as dispersion of flood flow,sediment transport index,etc.) obtained by hydrological statistics reveals that less of average flood,uniformity of flow and incoming sediment wi...