NOAA Atlas 14 - New Precipitation Frequency Studies

Design of hydraulic structures and management of water resources requires rainfall frequency analyses and depth-area-duration curves to determine design storms and storm water runoff. The Hydrometeorological Design Studies Center of the National Weather Service, Office of Hydrology is developing new precipitation frequencies for several regions in the United States. The results for the Semiarid Southwest will be published as NOAA ATLAS 14, Precipitation-frequency Atlas of the United States, Volume 1: Semiarid Southwestern United States: 1.1 - Arizona, 1.2 - Nevada, 1.3 - New Mexico, 1.4 - Utah, and 1.5 - Southeastern California. The Semiarid Study will supersede the previous atlases, NOAA Atlas 2 and Technical Paper 49, for these western States. Frequency studies are also in progress for Ohio River Basin states, and work has been initiated in the Upper Mid-west and New England. The studies for these midwestern and eastern areas will supercede Technical Paper 40, Technical Paper 49, and NWS Hydro 35. NOAA ATLAS 14 includes events from 2-year up to I 000-year return periods, and for durations from 5 minutes to 60 days. These new studies differ from the earlier work in: 1) up to 30 percent more stations, as well as an additional 30 or more years of record; 2) new statistical methods permitting more objective quality control, regionalization of data, and objective curve-fitting techniques; and 3) direct use of partial-duration data series. An important addition to the atlas is seasonality of extreme events. Examples of precipitation frequency study results and applications will be presented. 6 pp., 10 references.