Urban stormwater models comprise four main components: rainfall, rainfall-runoff, overland flow
and sewer flow modules. They can be considered semi-distributed (SD) or fully distributed (FD)
according to the rainfall-runoff module definition. SD models are based on sub-catchments units
through which rainfall is applied to the model and at which runoff volumes are estimated. In FD
models, the runoff volumes are estimated and applied directly on every element of a twodimensional
(2D) model of the surface. This poster presents a comparison of SD and FD models
based on two case studies: Zona Central catchment at Coimbra, Portugal, and Cranbrook
catchment at London, UK. SD and FD modelling results are compared against water depth and
flow records in sewers, and photographic records of a flood event. In general, FD models are
theoretically more realistic and physically-based, but the results of this study suggest that the
implementation of these models requires higher resolution (more detailed) elevation, land use and
sewer network data than is normally used in the implementation of SD models. Failing to use
higher resolution data for the implementation of FD models could result in poor-performing
models. In cases when high resolution data are not available, the use of SD models could be a
better choice.