Experimental Study on Relationship between Manning’s Roughness Coefficient, Density Vegetation.

Masoud Sajedi Sabegh, Hosna Shafaei, Azim Shirdeli, Nadergholi Ebrahimi

Friday 3 july 2015

12:54 - 12:57h at Europe 1 (level 0)

Themes: (T) Hydro-environment, (ST) Rehabilitation of water systems, Poster pitches

Parallel session: Poster pitches: 15G. Environment - Renewable & Wetland

Roughness coefficient as one of the most important hydraulic parameters in the river is related to _grain size, depth and flow velocity, density and type of vegetation. In this paper, the roughness _changes by changing depth, flow velocity, vegetation density and it was studied with a fixed bed. _The experiments carried out in a flume with a length of 7m and a width of 0.25 m with variable _slopes (0.002, 0.004, 0.006), flow discharges (4,6,8 Lit/S) and vegetation density (50%, 25%, __12%). The shrub vegetation was used in these experiments. The results show that the roughness _coefficient increased by increasing vegetation density and decreased by increasing flow velocity _and increasing depth. Also the results show that there is much difference in roughness coefficient _was estimated under conditions submergence to due differences in water velocity profile and loss _energy. In this study, regression equation for estimating manning’s roughness coefficient of the _river with the conditions of depth, flow velocity and density of vegetation is provided, that it can be _used under the same conditions to estimate the roughness of the river. Also there is a comparison _between roughness coefficients obtained by software solver. The results show that there is _significant difference between observed data and experimental results. In this paper one the _purposes was to investigate how density and placement of vegetation would affect on water depth _and velocity profile. _