GIS integrated SWMM modeling - A case study in Lethbridge

SWMM modelling for municipal stormwater systems has evolved with asset management and the prevalence of detailed GIS databases.  Structured GIS information allows for the economical development of larger and more detailed models.  This additional detail can provide a more precise picture of the causes and effects of local conditions that result in stormwater flooding. This approach provides a more comprehensive understanding of stormwater flooding and will allow a modeller to identify cost effective improvement projects.

Associated Engineering has developed spatial queries and scripting to automate traditional model building tasks.  This automation, combined with parallel processing software and powerful computers, allows for faster processing of large GIS databases allowing for the development of more  detailed models.  Some examples of formerly time consuming modeling building tasks are: interpolation and gap filling of missing data; locating topographic high and low points; and dynamic connection of the major and minor systems.

Automation allows for standardized, efficient and expeditious development of stormwater models; however, it also allows for comprehensive quality control amidst large datasets.  By integrating standardized, automated procedures with engineered quality control, modellers are able to focus their efforts on the most critical parts of the stormwater systems delivering additional value and higher quality products.

Associated Engineering will present on a modelling project commissioned by the City of Lethbridge.  The scope of work was to build and analyze a detailed 1D/1D dual drainage model for the entire City.  The automation was customized for the City of Lethbridge to better accommodate the steep riverine valleys and flat upland areas.  The resulting models  incorporate nearly all of the stormwater infrastructure with pipe sizes as low as 150 mm.  The stormwater models include approximately 20,000 nodes and 35,000 links.  The project included GIS data review, database normalization and standardization, GIS stormwater mapping, model building and analysis, and identification of improvement projects

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