School of Civil and Environmental Engineering, Ningbo University, Ningbo 315211, China E-mail:
Water Sci Technol. 2022 Nov;86(9):2454-2464. doi: 10.2166/wst.2022.329.
Sumps are commonly used in urban stormwater systems, which can be considered as a simple pretreatment device for stormwater quality control. However, they may function as pollution sources due to sediment washout under high flow conditions. An experimental study was conducted to investigate the scour process of predeposited sediments from a sump and its influencing parameters. Under conditions with large inflows or high sediment deposit, the sediment particles could be resuspended, entrained and flushed out. The washout mass decreased exponentially with time if the sediment bed surface depth was larger than a threshold value; otherwise, the amount of washout would be much smaller. The same scour pattern was observed for all the testing cases, of which the largest scour depth always occurred below the outlet. The deposit below the inlet might increase under conditions with high flow rates and low levels of sediment bed. Dimension analysis was performed and principal non-dimensional parameters were found, including the Péclet number, the pipe Froude number, and the dimensionless particle diameter, which can be used to determine whether the washout would occur and its intensity in a stormwater sump under given conditions.
集水池常用于城市雨水系统中，可被视为雨水水质控制的一种简单预处理装置。然而，在高流量条件下，集水池可能会因泥沙冲刷而成为污染源。本实验研究了集水池中预沉积泥沙的冲刷过程及其影响参数。在大流量或高泥沙沉积条件下，泥沙颗粒可能会被再次悬浮、夹带并冲刷出去。如果泥沙床表面深度大于阈值，则冲刷质量随时间呈指数衰减；否则，冲刷量会小得多。所有测试案例均观察到相同的冲刷模式，其中最大冲刷深度始终发生在出口下方。在高流速和低泥沙床条件下，进口下方的沉积物可能会增加。进行了量纲分析，找到了主要的无量纲参数，包括皮克列数、管弗劳德数和无量纲粒径，可用于确定在给定条件下雨水集水池中是否会发生冲刷以及冲刷强度。
