Probable Maximum Flood (PMF)

Synonyms

Extreme Flood; Maximum Flood

Definition

According to the US Federal Energy Regulatory Commission (2001), the Probable Maximum Flood (PMF) is the theoretically largest flood resulting from a combination of the most severe meteorological and hydrologic conditions that could conceivably occur in a given area. PMF is mainly used as a security assessment for existing dams and other impounding structures, and as a design criterion for proposed similar hydraulic structures, in order to avoid dam failures and catastrophic floods.

Discussion

Dams are often built to control floods in areas occupied by people and must be able to store floodwaters, in order to avoid costly disasters in life and economy. Computer models are used to assess the water storage capabilities of these hydraulic structures, without overtopping under flood conditions. The height of future floods is often predicted in reference with a time interval. For example, a 100-year flood level is considered as the level of a...