Areas that are vulnerable to flooding are called ‘floodplains’ or ‘flood hazard lands’. These are lands adjoining a river, lake or other watercourse, which has been, or may be, covered by floodwaters.
In Ontario, floodplains are managed to reduce damage and loss. Floodplain management has three components:
- Prevention – land use planning and regulation of development, increasing public awareness of potential risks;
- Protection – structural/protective works such as dams and dykes, purchasing of hazardous land to convert them into park lands; and
- Emergency preparedness and response – flood preparedness, forecasting, warning and combat.
Within Ontario there are three concepts of floodplain management:
- one-zone concept,
- two-zone concept and
- in a few exceptional situations, a special policy area concept.
Regardless of the concept applied, the overall intent of the policies governing public health and safety should be assured.
One-zone concept: Using this, planning authorities determine the flooding hazards limit, and prohibit all development or site alteration within those boundaries. This is the most effective way of minimizing threats to public health or safety or property damage. Where the one zone concept is applied, the entire flood plain or the entire flooding hazard limit defines the floodway.
Two-zone concept: This concept identifies the floodway and the flood fringe. The floodway refers to that portion of the floodplain where development and site alteration would cause a threat to public health and safety and property damage. The flood fringe is the portion of the flood plain where development may be permitted subject to certain established standards and procedures.
Special Policy Areas: In some unique or exceptional situations, communities are allowed to continue uses in a flood plain if the area is officially designated as a Special Policy Area (SPA). The application of the SPA concept is really limited to those areas, which are essential for the continued viability of existing uses; e.g. historical sites or old neighbourhoods built before flood plain policies came into effect.