Comparison of urban overland flow dynamics on sealed and partially permeable surfaces across a European transect

This study has analysed the extent to which overland flow dynamics, simulated with sub-hourly rainfall data for two scenarios of fully sealed and partially permeable urban streets, varies for 10 European cities across the Cfb climate zone. The cities showed similar behaviour in terms of frequency, total, peak flow and seasonality, with the exception of the western end of the Cfb transect. Introducing SUDS such as the partially permeable scenario reduced medium and large events in all cities; however; they were more pronounced in the central and north-eastern cities of transect. Long dry spells followed by large, flashier runoff events are prominent in some cities, increasing surface-water issues from diffuse pollution due to prolonged pollutant accumulation. The effects of temporal scaling of sub-hourly and hourly rainfall data on overland flow and the usability of ERA rain data were assessed to enable a coherent urban overland flow analysis relevant for pollution transport.