Scour around a Permeable Groin Combined with a Triangular Vane in River Bends

Abstract

River restoration refers to the environmental and ecological aspect of river engineering and aims to improve the natural habitat of a river system using eco-friendly methods. This paper introduces a new river restoration technique for bank protection and restoration of meander bends by combining a permeable groin with a triangular vane. Nine different combinations of permeable groins with triangular vane including three different effective lengths and three angles of vane were investigated in a 180° mild laboratory flume bend in clear water conditions. Based on experimental tests, scour geometrical patterns were analyzed, classified, and compared with each other. This analysis showed that a triangular vane dramatically enhances the performance of the permeable groin to protect the outer bank from erosion. Then, using Buckingham’s theorem of the dimensional analysis and the incomplete self-similarity (ISS) condition, generalized functional relationships for estimating scour main characteristics around an enhanced permeable groin (EPG) were deduced. This analysis showed that scour patterns depend on the upstream densimetric particle Froude number (A50) and the ratio between the effective lengths of the triangular vane and the permeable groin (Lt/Lp). The results showed that scour geometric characteristics estimated by the proposed equations agree reasonably well with the experimental values.