Experimental Study on the Effects of Bed Channel Vegetation Density on Flow Hydraulic Characteristics

In this paper, the effects of bed vegetation density, inflow rate and slope on some hydraulic properties of flow was studied in a laboratory environment. For this purpose, a trapezoidal flume with 3m long was established and some hydraulic characteristics of flow such as water level, manning roughness coefficient, longitudinal velocity, deep velocity and bed shear stress were recorded in different flexible artificial bed cover densities (VD= 0,20%,30%,50%) inflow rate (Q= 5,10,15,20,25 lit/se) and slope (S=0, 0.5%,1%). Final results analysis showed that behavior of hydraulic parameters depends on the interaction between inflow rate and slope and vegetation density. Water level and manning roughness coefficient increased nonlinearly with increasing bed vegetation density at a constant inflow rate. Maximum water level and roughness coefficient were observed in S=0, VD=50%, Q=25, 5 lit/se respectively. Also, with increasing bed vegetation density at a constant inflow rate, deep velocity and shear stress decreased nonlinearly and longitudinal velocity decreased linearly. Minimum longitudinal velocity and shear stress were observed in S=0, VD=50%, Q=5, 25 lit/se respectively. Froude number decreased with increasing vegetation density at a constant inflow rate. Maximum Froude number was seen in VD=0, Q=25 lit/se.