Probable Maximum Precipitation

Probable Maximum Precipitation (PMP) Estimates can be produced for any catchment in Australia. There are 3 Generalised Methods used to estimate PMP, appropriate for different locations and durations:

Generalised Short-Duration Method (GSDM)

GSDM downloadable document merges the method and data from Bulletin 53 with recently introduced amendments.

Revised Generalised Tropical Storm Method (GTSMR)

GTSMR guide to the application of the method on compact disc.

Generalised Southeast Australia Method (GSAM)

GSAM guide to the application of the method on compact disc.

Estimates of PMP for catchments overseas can also be provided.

For long durations, for catchments located in western Tasmania, the West Coast of Tasmania Method of Storm Transposition and Maximisation is applicable.

Standard charges apply.

A study into the impact of Climate Change and Probable Maximum Precipitation has been undertaken.

A PMP report provides the PMP depth, averaged over the catchment, as a function of duration, from one hour to a maximum of four days depending on the location; the spatial distribution of the rainfall over the catchment; and the temporal distribution of the rainfall during the period of the PMP storm.

What is PMP?

Probable Maximum Precipitation (PMP) is defined by the Manual for Estimation of Probable Maximum Precipitation (WMO,2009) as:

"...the theoretical maximum precipitation for a given duration under modern meteorological conditions."

Hydrologists use a PMP magnitude, plus its spatial and temporal distributions, to calculate the Probable Maximum Flood (PMF) for the catchment of a dam. The PMF is used to design the dam.

What are Generalised Methods?

Generalised Methods of estimating PMP use data from all available storms over a large region and include adjustments for moisture availability and differing topographic effects on rainfall depth. The adjusted storm data are enveloped by smoothing over a range of areas and durations. Generalised methods also provide design spatial and temporal patterns of PMP for the catchment.


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