Tracking the hydrodynamic behavior of fine sediment using particle image velocimetry

Siltation, or sediment pollution, is a cause for water pollution by fine particles, which are categorized as clay and silt. With the increasing concentration and accumulation of suspended sediments (<63 µm) siltation occurs, which is most often caused by soil erosion or sediment spill. The high rate of suspended particles causes the ecological degradation of water ecosystems. Thus, studying the hydrodynamic behavior of fine sediments is essential. Directly evaluating fine particle suspension and deposition can be expensive and limiting. The aim of this study is to present a novel, direct view of the hydrodynamic behavior of fine sediment in retention structures with different hydraulic features using particle image velocimetry (PIV). The setup is designed to identify fine particle displacement by capturing images with a charge-coupled device camera and Nd-YAG laser lighting. The results were obtained from a designed sediment basin, to which water with 15 % fine soil (<63 µm) concentration was added and which was subsequently seeded with fluorescent polymer particles (20–50 µm). New knowledge of a direct map of the hydraulic behavior of fine sediment is presented. According to the results, the flow rate modifies the velocity and direction of fine particles, while at the bottom of the basin towards the outlet, the re-suspension rate increases at a higher flow rate.