Sediment morphology and the flow velocity field in a gully pot

Sediment morphology and the flow velocity field in a gully pot: An experimental study

Rietveld, M.W.J. (TU Delft Sanitary Engineering)
de Rijke, D. (TU Delft Sanitary Engineering)
Langeveld, J.G. (TU Delft Sanitary Engineering; Partners4UrbanWater)
Clemens, F.H.L.R. (Deltares; Norwegian University of Science and Technology (NTNU))

2020

Urban runoff (re)mobilises solids present on the street surface and transport them to urban drainage systems. The solids reduce the hydraulic capacity of the drainage system due to sedimentation and on the quality of receiving water bodies due to discharges via outfalls and combined sewer overflows (CSOs) of solids and associated pollutants. To reduce these impacts, gully pots, the entry points of the drainage system, are typically equipped with a sand trap, which acts as a small settling tank to remove suspended solids. This study presents data obtained using Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) measurements in a scale 1:1 gully to quantify the relation between parameters such as the gully pot geometry, discharge, sand trap depth, and sediment bed level on the flow field and subsequently the settling and erosion processes. The results show that the dynamics of the morphology of the sediment bed influences the flow pattern and the removal efficiency in a significant manner, prohibiting the conceptualization of a gully pot as a completely mixed reactor. Resuspension is initiated by the combination of both high turbulent fluctuations and high mean flow, which is present when a substantial bed level is present. In case of low bed levels, the overlaying water protects the sediment bed from erosion.

3D printing
Gully pot
Hydraulics
LDA
Multiphase flow
PIV
SPIV
Stereo photography
Urban drainage

http://resolver.tudelft.nl/uuid:095dadf1-b052-4dfb-a1df-a5b167d469b2

https://doi.org/10.3390/w12102937

2073-4441

Water, 12 (10), 1-26

Institutional Repository

journal article

© 2020 M.W.J. Rietveld, D. de Rijke, J.G. Langeveld, F.H.L.R. Clemens