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Flood Glossary

Term Definition
Adaptation The practice of adjusting or taking actions to limit or reduce vulnerability to changing hazard risk. In the context of climate change impacts on coastal flood hazard risk, specific adaptation actions might include improved coastal zone management, changes to planning, permitting, codes and standards, structural design, and social preparedness.
Annual Exceedance Probability (AEP) The probability, expressed in percentage, of a flood of a given size being equalled or exceeded in any year. Accordingly, a flood that is estimated to recur once in 100 years (on average) has an AEP of 1/100 or .01 (1% AEP meaning a 1% chance of occurring in any year). A flood estimated to recur once in 500 years on average has an AEP of 1/500 or 0.002 (.2% AEP).
Atmospheric Rivers Long, narrow flows of moisture-laden air that can carry large amounts of water in short periods of time and release this moisture as either snow or rain.  Atmospheric rivers can be hundreds of kilometres long and extend from tropical ocean areas to mid-latitude coastal locations, such as the BC coast.
Coastal Flood Hazard A potentially damaging flood event (or multiple events) in coastal regions, which may cause damage to buildings and infrastructure, and/or the loss of life, injury, property damage, social and economic disruption, or environmental degradation.
Coastal Flood Risk The combination of the probability of a coastal flood hazard event (or multiple events) and the associated negative consequences.
Contents Damages The damages to the contents within a building, such as appliances, furniture and electronics.
Critical Infrastructure  (CI) Processes, systems, facilities, technologies, networks, assets, and services essential to the health, safety, security, or economic well-being of Canadians and the effective functioning of government.
Damages The financial and non-financial impacts/consequences of a hazard event. For buildings and infrastructure, this may include structural damage or loss of performance, or damages due to loss of serviceability/operability.
Design or Designated Flood
In BC, a given flood magnitude that is used as a standard for designating flood levels (e.g., for use in the calculation of flood construction levels) or dike design and construction. In most parts of the province, it refers to a 200-year (or 0.5% AEP) flood. Along the Lower Fraser, the design flood for dike construction is the estimated flow during the 1894 Fraser River flood. In select areas elsewhere, it is set on a site-specific basis.
Dike (or Dyke) An embankment designed and constructed to prevent the flooding of land. A dike is supported by related works, such as floodboxes, gates and pumps, that serve to hold back floodwaters while continuing to discharge water from behind the dike. To learn more see Dikes and Related Works.
Direct Damages The financial costs to repair or replace an asset to its pre-flood condition. Direct damages include structure and contents damages.
Disaster A serious disruption of the functioning of a community or a society at any scale due to hazardous events interacting with conditions of exposure, vulnerability and capacity, leading to human, material, economic and environmental losses and impacts.
Exposure The presence of people, infrastructure, housing, or other assets-at-risk in places that could be adversely affected by hazards.
Flood The presence of water on land that is normally dry. Often used to describe a watercourse or body of water that overtops its natural or artificial confines. See Flood 101 for a look at different types of flooding.
Floodplain A floodplain is flat or nearly flat land that is susceptible to flooding from a watercourse, lake or other body of water.
Floodplain Management Floodplain management includes policies and regulations intended to reduce flood risks associated with land use and development in floodplains and flood hazard areas.
Floodproofing In reference to development, actions taken at the site or property level that reduce the vulnerability of buildings and their contents to flood damage. Learn more about floodproofing in communities.
Floodwall A vertical artificial barrier designed to temporarily contain the waters of a river, sea, or other waterway or water body.
Flood Construction Level (FCL) The minimum height required for a development to protect habitable living space from flood damage.
Flood Hazard A potentially damaging flood event that may cause the loss of life, injury, property damage, social and economic disruption, or environmental degradation.
Flood Maps Maps that display information related to a flood, such as the estimated extent of flooding, water depths, water velocities, flood duration or other information. See Flood Maps for more on the types of maps and the information they display.
Flood Mitigation Steps to reduce flood damage by structural measures (such as dikes), non-structural measures (such as keeping populations and assets away from flood-prone areas or requiring floodproofing), or a combination of these measures.
Flood Risk Assessment Evaluation of a flood hazard (including the expected flood extent, depth and direction of flow) together with information about assets and people that are vulnerable to flooding to identify potential economic, social, cultural and environmental losses from flooding.
Hazard A potentially damaging physical event, phenomenon, or human activity that may cause the loss of life, injury, property damage, social and economic disruption, or environmental degradation.
Hazard Assessment  A process to acquire information about the nature, extent, intensity, frequency and probability of a hazard.
Hundred-Year Flood A flood of a given size that is estimated to recur once in 100 years on average. This is an older term — the probability of flood recurrence is now more often expressed in terms of Annual Exceedance Probability (AEP).
Light Detection And Ranging (LiDAR) A remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the earth. LiDAR is increasingly used to collected detailed topographic data to support flood modeling and mapping.
Natural Hazard Natural process or phenomenon that may cause loss of life, injury, other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage.
Peak Flow The maximum rate of water discharge during a flood at a given location on a river or other watercourse.
Resilience The ability of a system (such as individual or multiple buildings or infrastructure assets), community, or society exposed to hazards to resist, absorb, accommodate, and recover from the effects of a hazard in a timely and efficient manner, including through the preservation and restoration of its essential basic structures and functions.
Risk The combination of the probability of a hazard event and its negative consequences.
Storm Surge The increase in still water level at a coastal site due to meteorological conditions. To learn how storm surge contributes to coastal flood hazard, see Coastal Flood.
Structural Damages Damages to the structural systems of a building or infrastructure, such as walls, floors, and heating and cooling systems.
Tsunami A series of waves caused by a rapid, large-scale disturbance of water. Tsunamis can be triggered by earthquakes, landslides, volcanic eruptions, meteor impacts, human activities (e.g., explosions), and meteorological/atmospheric phenomena (meteo-tsunamis).
Vulnerability The characteristics and circumstances of a community, system, or asset that make it susceptible to the damaging effects of a hazard. For buildings and infrastructure assets, vulnerability is a product of both exposure and susceptibility to damage.