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Research Project Title: Modelling Site-Scale SuDS at the Street-Scale

Sustainable Drainage Systems (SuDS) are used to manage the runoff from rainfall events, and can contribute to flood risk mitigation in urban areas. Vegetated SuDS, such as green roofs and bioretention cells, are increasingly utilised as part of urban Green Infrastructure or (in China) Sponge Cities. This project relates to the modelling of rainfall-runoff responses for SuDS. Existing physically-based modelling tools such as SWMM allow us to model individual SuDS devices directly. However, it may not be practical to work at the same level of detail when we want to understand street (and city) scale drainage systems comprising multiple SuDS, conventional drainage components and other elements. Simplifications are made to allow models to function at large scales, for example by amalgamating all the components in a street into a single node and then dividing the node appropriately into permeable and impermeable contributing fractions. This type of approach is likely to over-simplify the dynamic nature of SuDS responses, where wetting and drying processes, over the timescale of days and weeks, have a critical impact on the system response. The aim of this project would be to develop a lumped modelling approach that captures the detail of the SuDS coverage and hydrological impact (retention and detention) in a sub-catchment, for use in large-scale continuous simulation modelling. The outcomes of the project would be modelling tools for stormwater engineers to design/size SuDS installations appropriately.