An Assessment of Stormwater Management criteria for the Humber River Watershed Using Radar Generated Rainfall Data

When developing sites in Southern Ontario, to mitigate the potential impact of impervious surface creation on downstream flood risk it is typically required to provide “post-development to pre-development” water quantity control through the implementation of stormwater management infrastructure. Under conventional practice, the stormwater infrastructure designs are typically designed based upon analyses which apply rainfall data generated by synthetic design storm events that correspond to particular statistical return periods. Issues and limitations surrounding the application of synthetic design storm events for sizing stormwater management infrastructure have been recognized in previous studies and research literature. While continuous hydrological simulation using long-term, locally recorded meteorological data is generally considered to be a more rigourous technique for completing hydrologic design analyses, this approach is often precluded from application due to limitations in the available data.

This paper presents a case study for the Humber River Watershed, for which radar-generated rainfall was used to support evaluation of stormwater management practices for quantity (flood) control. The PCSWMM modelling software, developed by demonstrate SUSTAIN applications using examples from engineering projects in and around Pittsburgh, Pennsylvania. The main focus of the paper will be on SUSTAIN's BMP siting tool which supports selection of suitable BMP locations that meet user defined site suitability criteria such as size of drainage area, slope, hydrological soil group, groundwater table depth, property type, and buffer distance from buildings, roads, and streams.