Validation of a 2D flow model using high-resolution experimental data sets for sub/surface flow interactions

Flood risk in urban environments has undoubtedly increased over the past decade due to accelerated urbanisation and land use changes [1] and more frequent extreme rainfall, induced by climate change, have exacerbated this convoluted issue [2]. Effective contemporary urban flood risk analysis requires detailed computational modelling techniques which, to date, have been widely adopted to investigate behaviours of urban floods and their impacts (e.g. microbial risk assessments [3], flood risk zoning [4], property damage [5], in order to develop countermeasures in flood mitigation decision making [6]). Two systems are always considered for modelling purposes: the minor system refers to subterranean pipes and manholes and the major system represents flow pathways over a surface (e.g., street). The minor system is often simulated via one-dimensional (1D) sewer network models, while the major system can be modelled via either 1D channel networks or two-dimensional (2D) overland flow models. The interactions between subsurface and surface systems are analysed via 1D-1D or 1D-2D modelling approaches [7], where the coefficients for linking the two models require careful calibration to accurately reflect the flow dynamics between them. In this study, experimental datasets collected within a facility that replicates urban flooding scenarios are used to calibrate a 1D sewer and 2D overflow hydraulic model such that it can increase its accuracy and therefore be applied with more confidence to analyse a wider range of flooding conditions.