Abstract—This study uses two of numerical modeling approaches to represent the urban catchment, and assess the flood risk of an urban catchment; hydrological surface routing approach and hydraulic 2D surface routing approach. Both approaches were combined with 1D hydraulic stormwater drainage network. XPSWMM was used as the modeling tool. This comparison leads to select most suitable approach to assess the possible flood inundations in the study area. Comparison of results of two approaches shows that the both approaches are suitable to represent urban catchment’s hydrological behavior, but the results of hydrological surface routing are more close to observation data. Model was calibrated to one sub catchment and used to generate flood vulnerability maps for whole catchment. These maps will be used as water sensitive urban design guide lines in the future developments of the area, while structural and non structural measures are to be implemented.

Index Terms—Flooding, Hydrological modeling, Stormwater, Urban environment.

A. P. Basnayaka, R. Sarukkalige are with Department of Civil Engineering, Curtin University, GPO Box U1987, Perth, Australia. (e-mail: a.basnayak@postgrad.curtin.edu.au; r.sarukkalige@curtin.edu.au).
D. R. I. B. Werellagama served as a senior lecturer of the Department of Civil Engineering University of Peradeniya, Sri Lanka (e-mail: indukaw@gmail.com) and presently works as an Environmental Consultantin Auckland, New Zealand.

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Cite: Amila P. Basnayaka, Ranjan Sarukkalige and Induka Werellagama, "Numerical Modeling of Flood Vulnerability in Urban Catchments for Flood Forecasting," International Journal of Environmental Science and Development vol. 2, no. 5, pp. 383-387, 2011.