Canonical Rainfall Distributions in the United States

Abstract

This study identifies five normalized depth-duration functions (NDDFs) that can be used to represent the rainfall characteristics in various regions of the United States. An analysis of the NDDFs at 9,24 hydrometeorological stations showed that most local rainfall distributions are within one standard error of the five canonical NDDFs identified in this study. The geographic regions corresponding to each of the five NDDFs are identified. Comparison of the normalized temporal rainfall distributions with the conventional Types I, IA, II, and III rainfall distributions shows fairly close agreement; however, the corresponding geographic areas were not in agreement, indicating that continued use of the type curves in engineering practice should be discouraged.