Bulk Flow Characteristics of a Gravel Bed River with Instream Emergent Vegetation

Abstract

ABSTRACT Aquatic vegetation and morphology are integral components of fluvial systems, study of which is important due to ecological and engineering projects. Often, studies in fluvial systems are carried out in the laboratory as collecting data in the field is expensive and difficult, and even risky. A field study was carried out to measure the hydraulic and geometric parameters of the bed and the banks of a gravel bed river with instream emergent vegetation in northern Iran. The aim of this study was to gain insight into the effect of bed forms and vegetation patches on flow resistance and distribution of velocity and bed shear stress. The boundary layer characteristics method was employed to calculate the shear velocity and friction factor, the resulted friction values are compared with that of Manning’s equation. The friction of bed forms was estimated using a linear superposition of friction. Results showed that the boundary layer characteristics method was suitable for calculating the shear velocity under various conditions, moreover, the distribution of velocity and bed shear stress were discussed. The findings of this study will be useful in river management and restoration.