Determination of Friction Factor over a Pool Reach by Double-average Method

Abstract

Bed-form characteristics have been investigated because of the close relation to hydraulic friction. Pool is one of the most important bed forms in coarse-bed rivers. The form friction factor should be considered in determining many river engineering projects including stable channel design, the scour depth along bank protection and at bridges piers. This study was conducted in the coarse-bed, Saymareh river, in western Iran. Two reaches, with Froude number less than 1.0, were selected to investigate the contribution of the double-average method in determining friction factor, one with pool bed form, range of Reynolds numberfrom 1.325×10