A case study for integrated modeling in urban drainage facilitating the interface approach

Late research and developments show a trend towards in-tegrated models to simulate the urban drainage cycle to offer a complete picture of the system’s performance. However, in regard to integrated models considering wa-ter quality, only few actual case studies exist. We devel-oped such a model for the urban drainage system of Graz, Austria containing runoff generation, a sewer system, ac-tuators and the wastewater treatment plant (WWTP) of the city. This integrated model uses an interface ap-proach, which connects commonly known sub-models of the various subsystems by automated scripts. Following this methodology results in the advantage of an under-standable and easier to maintain integrated model for the sewer operator.
So far the model has been used to evaluate the impact of a newly constructed combined sewer storage tunnel (cen-tral storage tunnel – CST) on the existing WWTP and to derive best management practices (BMPs) for the inte-grated operation of the system in regard to minimizing the total emission load to the receiving water.