Floodline_TRCA_Polygon

*NOTE: For proper evaluation of this feature, please download the feature ‘Floodline_TRCA_Line’ here, as it contains attributed line segments that identify spill, spill screening area, undefined flood plain, pending updates etc. The regulatory flood plain is the approved standard used in a particular watershed to define the limit of the flood plain for regulatory purposes. This standard is defined by the Ontario Ministry of Natural Resources and Forestry. Within TRCA’s jurisdiction, the regulatory flood plain is based on the more severe of the Regional Storm (Hurricane Hazel), or the 100 year storm; whichever is greater. For most of our jurisdiction, it is Hurricane Hazel. A hydrology model simulates the effect of this amount of rainfall as if it were over each watershed, taking into account the topography, soil type, land-use, and other characteristics to determine how much water would end up in our rivers and streams. A hydraulic model then looks at where this water would go, and what areas would be inundated. The inundated area for the regulatory storm is called the regulatory flood plain.