Flood

A storm management basin for the temporary storage of runoff water to protect homes and structures during periods of heavy rain.

Phenomenon characterized by a more or less abrupt rise in the level of a watercourse, related to a flow growth. Flood is not always an overflow of the riverbed. Floods are also characterized by their return period: the five-year flood (frequency one year out of 5 - Return period 5), the ten-year flood (frequency one year out of 10 - Return period 10), the hundred-year flood (frequency, one year out of 100 - return period 100). Seasonal floods are natural phenomena. They are essential to maintaining the diversity of water systems and services provided by nature.

Violent swell of the sea caused by sudden underwater tectonic disturbances: earthquake, underwater collapse, etc. The waves thus generated propagate at high speed (several hundred km/h) with wavelengths of several kilometres and can have amplitudes of several tens of metres, causing major damage to the coastline they strike.

Document that defines the measures to take for dealing with a major crisis (accidental pollution or catastrophic event), and which aims at planning rescue, organizing the flow of information between the services concerned, informing the public with the necessary instructions, delimiting possible evacuation areas, etc. The

Measuring the effects of a hazard in an area. Risk significance therefore depends on the hazard but also on exposed challenges (populations, property and the environment) and on their vulnerability. There is no risk when the area exposed to a hazard is devoid of human, material and environmental challenges.

Action to eliminate or reduce an immediate risk to an acceptable level (e.g. through removal or disposal of hazardous products and wastes from a site, by prohibiting or limiting access to the site, or by eliminating the risks of fire and explosion, etc).

Risk which is characterized by both a low probability of occurrence and huge seriousness of a given event should it occurs (many casualties, extensive damage to property and the environment).

Area where overflows can spread in the floodplain and which plays a significant role in flood control. Mapping these flood-storage areas allows better land use management in the valleys.

More or less likely danger or inconvenience (immediate or long-term) to which public health is exposed. The identification and analysis of risks related to a phenomenon (flooding, contamination, etc) usually allows predicting its impact on public…

Injury to life, health or damage that may occur in floodplains. In those, we can distinguish several levels of risk depending on the severity of damage to be feared, taking into account the flooding height, flow velocity (for the flooding considered) and the vulnerability of exposed sites.