Testing a simple 2D hydraulic model in an urban flood experiment

Hydraulic modelling of flood events involving urban areas constitutes a difficult challenge due to the complexity of topography and flow dynamics that characterize such an environment. Despite the increasing availability of detailed, high‐resolution topographic data, the assessment of model performance is still hampered by the scarcity of observed data describing the development of flood events. In the present paper, a simple two‐dimensional (2D) diffusive model is tested by reproducing a number of experiments carried out using an urban district physical model. The availability of measured water level data allows us to evaluate the model performance in detail and to investigate its limitations in reproducing complex flow dynamics. In addition, simplified approaches to represent urban areas within the model grid are considered and tested, and their influence on model results is assessed. The tested approaches include a simplified porosity‐based approach and the increase of roughness for urban grid cells. Overall results show that the proposed diffusive model is able to reproduce main flow processes, although some localized flow dynamics were poorly simulated. Simplified methods for representing the urban district provided similar results to detailed grid representations, suggesting that they could be proficiently used in combination with reduced complexity models.