Urban Drainage Modelling - Comparison and Capabilities 1D & 2D

Urban drainage is a prevailing issue within today’s modern societies. Rapiddevelopment of dense urban areas has increased the demand on designers to quicklyand accurately model complex drainage networks. Computer modelling has allowed forcomplex drainage networks to be designed and assessed, promoting the development ofnew softwares and their capabilities. The most recent development has been twodimensionalanalysis techniques incorporated into leading drainage programs. As thetechnology is relatively new, few assessments have been conducted to explore theprograms’ capabilities and limitations. Research and testing provided valuableinformation for future drainage modelling, and gave consideration to legal obligationsand responsibilities.An investigation into the modelling techniques employed by three common drainageprograms (DRAINS, 12d and XPStorm) was undertaken in this project. The programsvary in their complexity and capabilities, with DRAINS and 12d being limited to a onedimensionalanalysis, and XPStorm being capable of performing a two‐dimensionalanalysis. A one‐dimensional comparison of all three programs highlighted differences intheir modelling techniques and subsequent results. Major differences in infiltration lossresults indicated that there are technical issues, which have significant impacts on thehydrological flow calculations.Additionally, a two dimensional scenario investigated the capabilities and accuracy ofthe XPStorm software. The scenario primarily focused on the interaction of surface flowwith common urban surroundings/obstructions along a road surface. The limitations ofthe program’s accuracy and ability to model complex scenarios were discovered,relating to the 2D finite element grid sizing. The program was restricted to relativelylarge grids and also experienced issues when modelling steep sections of road.Reviewing the programs highlighted their capabilities and differences.Recommendations were made for further investigation into the loss methods and theirtechniques for all three programs. Consultation with program developers concerningthe limitations of XPStorm grid spacing is required for greater accuracy and detailswithin future models.