Scour Characteristics Downstream of a Gabion Weir

Rectangular broad-crested gabions are economical- and environmental-friendly structures that are constructed to manage the transport of sediment in steep slope rivers. This study aims to study the pattern and extent of scour downstream of a gabion weir and impermeable weir to solve the existing problem of excessive scour by impermeable structures. Laboratory experiments were conducted for scouring at downstream of the gabion weirs and impermeable weirs under free flow conditions. The experimental setup consists of a rectangular channel with dimensions of 9.6 m in length, 0.5 m in width, and 0.6 m in height. The data range for the present study includes a densimetric Froude number from 0.72 to 1.47, a ratio of downstream depth to crest height of the weir from 0.44 to 0.94, and a porosity ranging from 0.37 to 0.395. The collected data were analyzed to propose relationships for the gabion weir’s maximum scour depth, length, dune height, and nondimensional scour profile. The maximum scour depth was observed as a function of porosity, densimetric Froude number, and the downstream water depth ratio to the gabion weir crest height. The range of validation of the proposed relationship for scour depth shows an error within the range of ±20%. Sensitivity analysis shows that porosity is the most significant input parameter for scour depth.