10.4122/1.1000001518 Achleitner, S. Rauch, W. CITY DRAIN \302\251 - A simulation software for integrated modeling of urban drainage systems DTU Library, Technical University of Denmark (DTU) 2005 sewer system RTC receiving water integrated urban drainage modelling CSO CITY DRAIN \302\251 Simulink \302\251 water quality University of Innsbruck, Institute of Environmental Engineering en Conference full text 10.4122/1.1000001517 application/pdf 1 Over the last years design procedures of urban drainage systems are subject to a shift from end of pipe design criteria to ambient water quality approaches. Emphasis is nowadays put on the improvement of the receiving water quality by an overall management of river basins, which is a core element of the water framework directive (WFD) as well. For the application in practice software tools are required that are capable of modelling urban drainage systems (including the receiving water) in an integrated way having rainfall as the elementary input. For use in the daily engineering work such software tools are required to be simple in handling and to provide a certain flexibility to be adjustable for different scenarios. CITY DRAIN is developed in a Matlab/Simulink \302\251 environment for simulation of urban drainage systems. The different parts of an urban drainage system (catchment, sewer system, storage devises, receiving water,\342\200\246) are built in blocks representing dynamic subsystems with different underlying modelling approaches for hydraulics and mass transport. These blocks can be freely arranged and connected to each other in order to describe an integrated urban drainage system and the fluxes of water and matter. The underlying models in CITY DRAIN are kept simple on purpose, using fixed discrete time steps for dynamic simulation. Still, the open structure of the software allows to add own blocks and/or modify blocks, being necessary to model specific aspects or processes.