Study on the Hydrodynamic Effects of Vegetation in Spur Dike Induced Flow

Abstract

This study investigates the hydraulic influence of localized vegetation introduced upstream of a spur dike in a rectangular channel using a validated computational fluid dynamics (CFD) model. Two scenarios were simulated: one without vegetation and another with a rigid vegetative patch positioned upstream of the spur dike. Analysis focused on flow distributions to assess the impact of vegetation. Results showed that the vegetation considered resulted to a consistent reduction in flow velocity and wall shear stress along both channel banks. The vegetative resistance weakened recirculation zones, attenuated shear layers, and redistributed momentum across the flow domain. Additionally, the presence of vegetation modified the flow structure by promoting more uniform velocity gradients and dampening turbulence intensity near the bed and banks, especially around the spur dike nose. This altered hydrodynamic behavior contributed to a noticeable decline in erosive forces, particularly in zones vulnerable to scour. The simulation outcomes underscore the potential of strategically placed vegetation in reducing local scour and improving bank protection. These findings demonstrate that even limited vegetation placement can effectively reduce erosive forces and enhance flow stability around spur dikes. The study supports the use of targeted vegetation as a nature-based solution in hybrid river training strategies, contributing to sustainable river engineering and flood management practices.