Quantifying flood model accuracy under varying surface complexities

•Experimental facilities provided effective datasets for numerical model calibration and validation.•Model performance decreased when pipe and surface inflows increased, and when the surface increased in complexity.•It is plausible to calibrate models in lower resolution due to lower simulation times and acceptable error ranges. Floods in urban areas which feature interactions between piped and surface networks are hydraulically complex. Further, obtaining in situ calibration data, although necessary for robust simulations, can be very challenging. The aim of this research is to evaluate the performance of a commonly used deterministic 1D-2D flood model, calibrated using low resolution data, against a higher resolution dataset containing flows, depths and velocity fields; which are replicated from an experimental scale model water facility. Calibration of the numerical model was conducted using a lower resolution dataset, which consisted of a simple rectangular profile. The model was then evaluated against a dataset that was higher in spatial resolution and more complex in geometry (a street profile containing parking spaces). The findings show that when the model increased in scenario complexity model performance was reduced, though most of the simulation error was