Probable Maximum Precipitation

Probable Maximum Precipitation (PMP)

Probable Maximum Precipitation (PMP) is used in the design of high hazard and critical infrastructure that must be able to withstand the largest physically possible flood (often referred to as the Probable Maximum Flood)

Probable Maximum Precipitation (PMP) is used in the design of high hazard and critical infrastructure that must be able to withstand the largest physically possible flood (often referred to as the Probable Maximum Flood). PMP is most often estimated with a storm-based approach to calculate a deterministic (single maximum) value. However, in recent years, AWA has also developed a process to calculate Annual Exceedance Probabilities (AEPs) that extend to the PMP event and probability estimate of the PMP depths. This information is extremely valuable when evaluating critical infrastructure from a risk perspective and in combination with deterministically derived PMP depths.

AWA has completed hundreds of PMP studies worldwide, analyzing all types of meteorological and topographical combinations from tropical rainforest and glaciated regions to the driest locations on earth. With advanced analysis, AWA is able to account for barrier effects from mountains, the availability of moisture and the impacts of elevation changes when determining possible precipitation values. AWA PMP studies have been accepted by the appropriate dam safety regulators and independent review boards.