1D and 2D modelling of urban drainage systems using XP-SWMM and TUFLOW

Abstract

The release of a revised NSW Floodplain Management Manual in 2001 established a new direction for urban flood management in NSW by redefining the floodplain as the area bounded by the PMF and the removal of the distinction between \342\200\234mainstream flooding\342\200\235 and \342\200\234local flooding\342\200\235. This new direction and the increasing availability of aerial laser scanning have ramifications for urban flood studies. The trend in NSW and elsewhere has been for the growing adoption of 2D models as the new benchmark for urban flood studies. To enhance its capability to model urban drainage systems the TUFLOW 2D hydrodynamic model is being incorporated as a layer into an XP-SWMM2D package. Two case studies that demonstrate the new 1D/2D modeling capability of TUFLOW and XP-SWMM2D are described. The first case study is of a reach of Prospect Creek in the City of Fairfield. A 2D and a combined 1D/2D models of the floodplain were assembled and run. A comparison of 1D, 1D/2D and 2D results is given. The second case study is of a local drainage subcatchment that demonstrates the interaction between the piped drainage system and 2D surface overland flows. It is concluded that the 2D hydrodynamic modeling layer in the XP-SWMM package offers users new opportunities to undertake more detailed investigations of urban drainage systems and of urban waterways and floodplains. It also demonstrates the on-going evolution of the XP-SWMM package in response to the changing needs of stormwater managers.