Investigating Velocity Profiles in Rivers with Submerged Vegetation Patch in the Bed and Emergent in the Bank (Case Study: Fars and Bushehr Rivers)

Understanding how velocity profile changes in vegetated rivers are important in accurately estimating discharge, shear velocity, and flow resistance. Therefore, in this study, velocity profiles of four direct reaches of mountain rivers with vegetation patches in Fars and Bushehr provinces have been investigated. Data collection in this study started in March 2021 and ended in May 2021. Measurements in this study include surveying, velocity measurement, and bed sampling. Investigation of 71 velocity profiles measured in the selected reaches showed that despite the high aspect ratio () in the studied reaches, in 39% of the profiles, the Dip phenomenon occurred, indicating that the aspect ratio is not the only factor influencing the Dip phenomenon. In addition, The Dip parameter was higher in profiles near to vegetastion pacthes.  Also, by investigating the logarithmic law in velocity profiles, it was found that the logarithmic law is well applicable in reaches with vegetation patches, and the upper limit of the validity of the logarithmic law up to 58% of the flow depth was obtained. This value has been reported in laboratories for velocity data up to 20% of flow depth.