Author(s): Zhi Yang; Biao Huang; David Zhu

Linked Author(s):

Keywords: Equal mobility; Erosion rate; Flushing; Non-cohesive sediment; Storm sewer

Abstract: This study investigated the hydraulic flushing behavior of sediment deposits in storm sewers through systematic laboratory experiments examining two distinct deposition types: continuous sediment beds and localized deposits. Experimental observations revealed three principal bedforms during flushing -- rippled, flat, and dune -- with formation primarily governed by particle Reynolds number. The cumulative sediment removal ratio demonstrated positive correlation with flow rate and negative correlation with sediment height and particle size for both deposition morphologies. For localized deposits specifically, deposition length and location significantly influenced removal efficiency. Sediment transport rates exhibited similar parametric dependencies but consistently decreased over time during flushing operations. For continuous beds, the flushing process manifested as two distinct phases: an initial stage characterized by rapid sediment mobilization followed by a stable stage with gradual transport. A refined dimensionless model was developed to predict erosion rates under various hydraulic conditions, enhancing predictive capabilities for sediment removal processes. The investigation of mixed-size sediment flushing revealed equal mobility across different particle fractions, indicating that relative transport rates remain proportional to particle abundance in the deposit. These findings provide quantitative relationships and modeling frameworks that advance understanding of sediment transport mechanics in storm sewers and offer practical guidance for optimizing flushing operations in urban drainage maintenance programs.

DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P1745-cd

Year: 2025