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Public-images-osm logo.svg hazard_return_period
Group: Hazards
Used on these elements
may be used on nodesmay be used on waysshould not be used on areasmay be used on relations
Status: undefined

The purpose of this key is to store the approximate return period (in years) of a known hazard. As this information is never known precisely, very broad categories are defined:

  • Return period < 3 years: All seasonal hazards that are very well known by the local communities and that happen virtually every year. Communities are usually not threatened by such hazards, as they often have efficient resilience strategies. Potential disturbances in the usual activities are still possible, which is why they must be mapped as well.
  • Return period 3 - 50 years: All hazards that are considered as exceptional and that happen more than once in a lifetime. Such hazards pose certain threats, as the communities tend to "forget" about them, because of their seldom recurrence.
  • Return period > 50 years: All hazards that are considered as highly exceptional and that happen once (or less) in a lifetime. Such hazards pose heavy threats to the communities, as they tend to have very high intensity and are not easily foreseeable.


To be completed... Probably need to accept various forms of values: return period in years, return period category...