Investigation of Flow and Local Scour Characteristics around a Partially Submerged Permeable Barb

Barbs are wide crested trapezoidal structures, typically constructed of riprap gravel, which project out from the streambank and are oriented upstream into the main flow. Barbs reduce erosion along streambanks by deflecting current into the center of the channel aiding in the protection of bridge piers and abutments. The overall objective of this study is to establish design criteria for permeable barbs within non-navigable mild sloped gravel bed streams. The paper consists of two major parts. Part one focuses on the flow characteristics around a submerged permeable barb to understand the flow regimes "formed" within the vicinity of a barb. Part two utilizes the quantitative data that are gathered in part one and investigates the complex evolution of local scour around the permeable barb under clear-water scour conditions.