Probable Maximum Precipitation (PMP)

Synonyms

Continuous Heavy Rain; Flash Flood; Rainstorm

Definition

The WMO defines Probable Maximum Precipitation (PMP) as “... the greatest depth of precipitation for a given duration meteorologically possible for a given size storm area at a particular location at a particular time of year, with no allowance made for long-time climatic trends.” (WMO, 1986).

Discussion

Heavy precipitation and its adverse effects, mostly by floods, are reported from most parts of the world. The reduction of such effects, e.g., through engineering (dams, etc.), requires data on the magnitude and frequency of heavy precipitation events. The information is usually derived from a time series of observed past events. By their nature, such events are infrequent; often a frequency of one such event per 100 years is applied. Observational periods often comprise periods of only a few decades.

Therefore, methods are needed to estimate the probable maximum precipitation occurring in any given set of time-invariant...