Urban hydrological applications require high resolution precipitation and catchment information in
order to well represent the spatial variability, fast runoff processes and short response times of
urban catchments (Berne et al., 2004). Although fast progress has been made over the last few
decades in high resolution measurement of rainfall at urban scales, including increasing use of
weather radars, recent studies suggest that the resolution of the currently available rainfall
estimates (typically 1 x 1 km2
in space and 5 min in time) may still be too coarse to meet the
stringent requirements of urban hydrology (Gires et al., 2012). What is more, current evidence is
still insufficient to provide a concrete answer regarding the added value of higher resolution rainfall
estimates and actual rainfall input resolution requirements for urban hydrological applications. With
the aim of providing further evidence in this regard, a collaborative study was conducted which
investigated the impact of rainfall input resolutions on the outputs of the operational urban drainage
models of four urban catchments in the UK and Belgium (Figure 1).