Modifying 2D surface models in urban flood analysis.

Hydraulic models in urban flood analysis play a decisive role, as they obtain information about flood extension, flow patterns on the surface and in the pipe network comes at cost of time consuming model set up and computing time. Dual drainage models do have the advantage of more accurate results as they consider bidirectional interaction between surface and sewers. This can be crucial as for certain rainfall events the sewer system can have a decisive impact. The aim of this paper is to modify 2D surface models and consider the performance of the sewers according to design standards for sewer systems, without the actual coupling process. Therefore a time varying approach, as inflow capacity into the sewers, was designed which reduces the rainfall depth before surface run off occurs. For a one-hour storm event, the novel approach indicates a higher performance (about 13 %) of the sewer system in the first half of the rainfall event compared to using a constant drainage removal rate. The presented approach in this paper will be tested in further research. • Considering performance of sewers in 2D surface models increases quality of results. • Accuracy of dual drainage models comes at costs of model set-up and computing time. • Novel Approach to modify 2D-surface models according to design standards of sewers. [ABSTRACT FROM AUTHOR]