Flow–sediment interaction and experimental design of screen plates for scour mitigation downstream of hydraulic structures

ABSTRACT This study examines scour development downstream of hydraulic structures, focusing on screen plates as a mitigation measure. To function as energy dissipators, screen plates with varying aperture ratios were strategically placed at a specified distance from the sluice gate. In particular, the maximum and minimum depths and lengths of scour holes were observed for screens with aperture ratios of 40 and 50%, respectively. A moving bed with particles of different sizes was then selected. Results show that maximum scour depths ranged from 8 to 23 cm, while scour lengths varied between 30 and 85 cm, with finer sediments producing deeper and longer scour holes. Increasing the screen aperture ratio and thickness generally reduced scour intensity, and optimally positioned screens enhanced energy dissipation, decreasing sediment transport by up to 40 %. Consequently, increasing the aperture ratio and the thickness of the screens correlates with a decrease in scour hole size, suggesting, e.g., potential strategies to improve the bridge's resistance to scour. These findings provide valuable insights for the design and optimization of scour protection measures, offering practical guidance for enhancing the stability and longevity of hydraulic structures in real-world applications.