Urban stormwater models cover the main physical processes related with stormwater along urban catchments, from runoff generation to routing along overland surface and flow in the sewer networks. These models have been widely used to manage drainage networks in urban areas and have been increasing application for the analysis of floods in urban areas.
Urban stormwater models are based on coupling three main modules: rainfall-runoff, overland flow and sewer flow. The rainfall-runoff transform inputs such as rainfall into runoff, which is then applied to the overland flow module to route over the urban surface area or applied to the sewer flow module which represent the flow in the sewer system.
The present research intends to improve urban stormwater modelling tools, with respect to the analysis of different overland modules setup and formulations, and their interactions with sewer flow modules. The overland module setup can be based on semi-distributed models where rainfall is applied to subcatchments, or fully distributed models where rainfall is applied directly to the overland surface in the overland module; These two different overland modules setup were compared based on two real models implemented in InfoWorks ICM and a model setup that enabled their direct comparison. The interactions between the overland and sewer flow modules were analysed with an innovative approach to delineate stochastic flood hazard maps considering operational conditions of sewer inlets. The overland module was also formulated with the proposed Quasi-2D concept that to represent continuous surfaces based on a 1D scheme.