Flood Terms and Definitions
For a better understanding of floods and flood hazard management, take a look at some common terms and definitions.
Designated Flood: means a flood, which may occur in any given year, of such magnitude as to equal a flood having a 200 year recurrence interval, based on a frequency analysis of unregulated historic flood records or by regional analysis where there is inadequate streamflow data available. Where the flow of a large watercourse is controlled by a major dam, the designated flood shall be set on a site specific basis.
Designated Flood Level: means the observed or calculated elevation for the Designated Flood and is used in the calculation of the Flood Construction Level.
Dike: A "dike" is an embankment, wall, fill, piling, pump, gate, floodbox, pipe, sluice, culvert, canal, ditch, drain, or any other thing that is constructed, assembled or installed to prevent the flooding of land.
Diking Authority: a "Diking Authority" is defined as:
- the commissioners of a district to which part 2 of the Drainage, Ditch and dike Act applies,
- a person owning or controlling a dike other than a private dike.
- a public authority designated by the minister as having any responsibility for maintenance of a dike other than a private dike,
- a regional district, a municipality, or an improvement district
Flood: An influx or overflowing of water beyond its normal confines such as a riverbank, lakeshore, flood protection dike, etc.. Floods are part of a river's natural life cycle and can be expected to occur with some predictability.
Freshet: A seasonal rise in river discharge caused by heavy rain or melted snow.
Flood Construction Level: means the Designated Flood Level plus the allowance for freeboard and is used to establish the elevation of the underside of a wood floor system or top of concrete slab or habitable buildings. In the case of a mobile home, the ground level or top of concrete or asphalt pad, on which it is located shall be no lower than the above described elevation. It also establishes the minimum crest level of a Standard Dike. Where the Designated Flood level cannot be determined or where there are overriding factors, an assessed height above the natural boundary of the water body or above the natural ground elevation my be used.
Floodplain: means a lowland area, whether diked, floodproofed, or not which, by reasons of land elevation, is susceptible to flooding from an adjoining watercourse, ocean, lake or other body of water and for administration purposes is taken to be that area submerged by the designated Flood plus freeboard.
Floodproofing: means the alteration of land or structures either physically or in use to reduce or eliminate flood damage and includes the use of building setbacks from water bodies to maintain a floodway and to allow for potential erosion. Floodproofing may be achieved by all or a combination of the following:
- building on fill, provided such fill does not interfere with flood flows of the watercourse, and is adequately protected against floodwater erosion;
- building raised by structural means such as foundation walls, columns, etc.;
- a combination of fill and structural means
Historic Settlement Area: means an area which has been developed or is committed through early settlement to further development either through infilling or redevelopment.
Integrated Flood Management: An integrated approach to flood hazard management includes each of the following management activities as well as strong integration and coordination among all levels of government:
- Management of flood protection works;
- Floodproofing practices and land use planning decisions; and,
- Emergency preparedness, response, and recovery.
