Sediment Depositions in a Submerged Storm Sewer Pipe

Abstract

Sediment depositions in storm sewer systems have received significant attention due to their implications for urban flooding and environmental impacts. However, only limited attention has been paid to sediment deposition in submerged storm sewers. In this study, a laboratory model was used to study the sediment transport and deposition processes in a submerged storm sewer. The growth of the deposition can be divided into two stages: rapid growth (both deposition height and length increase) and equilibrium growth (only deposition length increases). The sediment loading rate determines the duration of the rapid growth stage, and the equilibrium height increases for larger sediment size and higher sediment concentration. The bed shear stress at the equilibrium stage varies from 1.8 to 8.7 N/m2 corresponding to the variation of the bed friction factor from 0.058 to 0.185, which is about 2–4 times that caused by the sediment roughness height alone. This increase in the bed shear stress is mainly due to the significant amount of momentum needed to transport the required sediment loading. A prediction method and its applications are also presented.