REVIS ITING PMPs

摘要

Many dam safety officials use probable maximum precipitation (PMP) for dam safety evaluations and design requirements. But the series of federal publications that provides PMP estimates is rapidly becoming outdated. When should a dam owner consider a new study?rnProbable maximum precipitation, or PMP, has been used as a design basis for many state- and federally-regulated dams since the 1930s. Combined with a rainfall-runoff model for converting precipitation to a streamfiow hydrograph, PMP is used to predict the timing, volume, and peak flow associated with extreme flood events at a dam. Designers obtain PMP values from a patchwork of hydrometeorological reports (HMRs) produced by the U.S. Weather Bureau or its successor, the National Weather Service (NWS), or from site-specific studies performed by private contractors.