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Simplified hydraulic models for urban inundation modelling. Based on research by : Paul D. Bates 1 , Timothy J. Fewtrell 1 , Jeffrey C. Neal 1 , Mark A. Trigg 1 , Guy J-P. Schumann 1 and Matthew S. Horritt 2
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Simplified hydraulic models for urban inundation modelling Based on research by: Paul D. Bates1, Timothy J. Fewtrell1, Jeffrey C. Neal1, Mark A. Trigg1, Guy J-P. Schumann1 and Matthew S. Horritt2 1School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK 2Halcrow Ltd., Burderop Park, Swindon, Wiltshire SN4 0QD, UK
Reduced complexity models of flooding • Storage cell models originally created using irregular floodplain units (Zanobetti et al., 1970) • Increased resolution of topographic data proliferated the development of regular grid versions in 2 dimensions • Models either solve uniform flow formulae (e.g. Manning’s eqn) or finite difference approximation of diffusion wave (e.g. Bradbrook et al., 2004) • Hunter et al. (2004) noted a number of problems with storage cell model type approach • If the time step was too large, “chequerboard” oscillations will develop • Hunter et al. (2005) proposed a solution to these problems by a von Neumann stability analysis of the diffusion wave equation • However, as a result of the stability condition, computation time increases quadratically with increasing grid resolution Computationally intractable for high resolution grids required for urban flood modelling
Testing: Model efficiency Over 600x increase in time step → 1000x increase in computational speed