Integration of Green Areas into a Suburban Flood Model

As a result of urbanization, suburban areas are growing. The catchment of this areas is characterized by different land use and sealing types. Due to climate change, there is a tendency towards more intense precipitation events, which causes a respectable increase of overland flow on permeable surfaces (green area). For a detailed flood management a coupled model of runoff, sewer transport and overland flow which also integrate green areas is much more powerful. Available software is usually built as semi-distributed (SD) models whereof the 2D surface module can only convey but not generate grid cell runoff. Fully distributed (FD) models solve this problem but are often not applicable due the required detailed object data. This paper describes a method to integrate green areas into an existing sewer (SD) model by virtual networks. The runoff module is founded on the kinematic wave computation, which includes a module for the infiltration capacity based on the Horton equation. Therefore the additional runoff of the green areas is predictable and the results shows more representative expression of the flood situation. Otherwise, the natural retention effect of green areas is directly implemented and is therefore also quantifiable.