Given that the development of the scour downstream of hydraulic structures increases the risk of structural damages, it is important to find cost-effective and environmental approaches to reduce this risk. This study aimed to experimentally evaluate the effect of synthetic fibers on the scour profile downstream of a sluice gate with a rigid apron. Experiments were performed with the same Froude number and with different weight percentages of synthetic fibers in both non-cohesive and cohesive sediments. One uniform sand was used as the non-cohesive sediment, and three different cohesive sediments were prepared through mixing different percentages of Kaolinite soil (KCC) with the used sand. The scouring experiments showed that the presence of synthetic fibers did not considerably affect the scour hole dimension in non-cohesive sediments. Evaluation of the scour in the cohesive sediments in silty sand (SM) texture found that an increase in the percentage of silt reduced the scour hole dimension. The effect of synthetic fibers on scour of SM-texture-based sediments was also investigated, and the results showed that increasing the percentage of synthetic fibers decreased the scour hole dimension. In addition, the cohesive sediments in SM texture did not have the similar non-dimensional scour profile, and the presence of synthetic fibers did not significantly affect the scour hole.
