Influence of Vegetated Banks on Turbulent Characteristics of Non-uniform Flow in Gravel Bed River

摘要

Diverse bedforms are observed in river beds. Pools and riffles occur in the bed due to the nonuniformity of flow, cross-section and the straight path of rivers and natural channels. From a hydraulic point of view, the variation in roughness is due to variations of flow depth and flow cross-section in pools and riffles, leading to energy losses and local erosion. Vegetated banks have a significant effect on the sustainability of banks and flow resistance, increasing the roughness coefficient in banks and floodplain. Due to the adjustment of environmental conditions and energy loss caused by vegetated banks and bedforms, their interaction plays a significant role in river restoration projects. Consequently, it is necessary to investigate the interactions of bedforms, flow, and vegetation on the stability and fluvial processes. The present study was conducted in Plusjan River in the central Iran to investigate the influence of vegetated banks, and accelerating and decelerating flows (non-uniform flows) on turbulent flow characteristics in the gravel-bed river. Results show that interactions between vegetated banks, flow nonuniformity, and bedforms lead to irregular patterns of velocity, Reynolds stress, and turbulence intensity distributions.