Investigation of Effective Parameters on Manning Coefficient in Rivers and Obtain the New Relation for Estimate it (Case Study: Ferizi River)

In river engineering، determination of flow resistance is essential. Various empirical methods have been suggested for estimating bed roughness coefficient by researchers. However، these methods can only be applied to Special River. In this study، flow conditions and river geometry data were obtained from the Ferizi river. In this section flow must be uniform، turbulent، hydraulically roughness and without vegetations or obstacles and bed forms، until could ignore from effects of this cases and could assume that the flow resistance is only due size of particle sediment. The result showed in addition particle sediment the hydraulic behavior is effective on calculating for flow resistance coefficient. For this reason after the dimensional analysis the flow resistance coefficient (n) will be inversely proportional to the Froude number. Also the relation is obtained estimate the flow resistance coefficient (n) with more accuracy (R2=0. 993).