TP – 1238 An Introduction to Hydrometeorology for Professional Engineers

Description

The “design storm” is the estimate of the rainfall amount and its distribution over a particular drainage basin, with respect to both time and area that is used in the development of a PMF hydrograph or; in some instances, a flood hydrograph representing a specific frequency event. The purpose of this technical paper is to provide the hydrology engineer a basic familiarity with the atmospheric processes that produce extreme precipitation events, and the methods by which these processes are used in computing individual drainage PMS (Probable Maximum Storm) values and in developing regionalized criteria used to compute such values for particular drainage basins. In 1981, agencies adopted a mutually acceptable, uniform definition of the widely used term PMP (Probable Maximum Precipitation) as “theoretically, the greatest depth of precipitation for a given duration that is physically possible over a given size storm area at a particular geographical location at a certain time of the year.