This paper presents the implementation and application of a semi-distributed hydrological model enabling the simulation of flow among multiple linked sustainable urban drainage systems (SUDS) and multipurpose spaces for water retention. These measures are considered as appropriate strategies to adapt to the uncertainties in future climate change and urban growth scenarios. Of particular concern is the control of exceedance flow for urban flood modelling in case of storm events. The objectives of the tool are the detailed hydrological simulation of the water balance processes, the integration of SUDS elements with water receiving and sending functionality in the model net as well as the integration of the model into a flood-risk mapping tool. The model was applied to quantify the impacts of land use and climate change impacts for 2050 in a river catchment in Hamburg. The results offer a better understanding of the mitigating performance efficiency in urban flooding that can be achieved by using SUDS and multipurpose retention spaces in urban catchments. However, there are still considerable uncertainties associated with the extraction and interpretation of data of climate change scenarios, land use change scenarios as well as for the hydrological model results.
