HORIZON 2020: Understanding the transport and fate of ejected sewer sediments during flood events

This research project presents a comprehensive investigation into sediment transport dynamics during flood events within urban drainage systems. A meticulously designed physical model, featuring a scaled "floodplain" with dimensions akin to real-world scenarios, linked to a sewer system via a manhole, serves as the experimental platform. Sediments representative of road runoff (d50 between 63 and 300 µm) are introduced into the drainage system via controlled injection. The study will focus on the transport of these sediments in flood conditions, and specifically the propensity of sediments to be transported from sewers to surface flows during sewer surcharge events. This type of events are expected to become more frequent and severe in the future due to climate change, urbanization, and degraded existing sewer systems.
A range of experiments, totalling 45, systematically vary pipe flow rates, surface flow conditions, and granulometries to examine their impact on sediment behaviour will be performed. Advanced particle tracking techniques, including 3D Particle Tracking Velocimetry (PTV) and overhead camera observations, will provide granular insights into sediment dynamics. To complement the physical experiments, numerical simulations will be conducted employing 3D Computational Fluid Dynamics (CFD) models. This comparison between experimental data and simulations enhances our understanding of urban drainage
processes. Subsequently, simplified 1D/2D urban flood models are developed and calibrated, incorporating sediment and pollutant transport modules.
The project's results are anticipated to yield a deep and sound knowledge into sediment transport mechanisms during flood events, with applications related to the understanding of public health risks from exposure to contaminated sediments. The combination of detailed experiments and advanced modelling approaches is expected to advance our ability to simulate real-world scenarios accurately. This research contributes to sustainable urban planning and water management practices, with potential implications for enhancing flood resilience in urban areas and it is in line with Sustainable Development Goal 11
(Make cities and human settlements inclusive, safe, resilient and sustainable) and 13 (Take urgent action to combat climate change and its impacts).