Experimental Study of the Effect of non-Submerged Rigid Vegetation on Flow Force in Symmetrical Rectangular Compound Channel by Direct Measurement Method

In this research, using direct measurement method, the flow pressure in the composite channel with vegetation has been measured. The vegetation used in this study was made of PVC. Five different diameters with values ​​of 20, 25, 30, 40 and 50 mm, two longitudinal distances of 12 and 15 cm and two transverse distances of 6 and 8 cm according to the regular and irregular arrangement and the location of vegetation as the proposed variables were used in this study. For direct measurement of force, a special type of hydraulic flume called "knife edge hydraulic flume" was used. Based on the results of the experiment, it was found that with increasing vegetation diameter, the flow force increases, which is due to increasing the volume and reduction of the cross-sectional area of the vegetation. In addition, due to the effect of longitudinal and transverse distances of vegetation, it can be said by increasing these distances, the flow force rate showed a decreasing trend. This is due to the reduction of vegetation volume and the secondary flows caused by vegetation cover.