In recent years, the terms, “once-in-a-century” and 100-year, have been attached to various rare and catastrophic events; recent examples are the rains associated with Hurricane Agnes and the 1972 Rapid City storm. The background for the use of these terms is examined from the points of view of both the professional and nonprofessional user. A brief review is presented of the methods of analysis of extreme values with applications to rainfalls. The main unsolved problem in rainfall frequency analysis is the lack of a satisfactory procedure for determining the frequency of various rainfall patterns over a fixed geographical area.

This content is only available as a PDF.