REGIONAL RAINFALL INTENSITY‐DURATION‐FREQUENCY CURVES FOR PENNSYLVANIA¹

Abstract

ABSTRACT: A statistical analysis of all available continuous hourly and 15‐minute duration rainfall records for Pennsylvania was performed to develop an updated procedure to estimate design storms. As a resuit of this study, Pennsylvania was divided into five homogeneous rainfall regions and a set of rainfall intensity‐duration curves developed for each region, for return periods of 1 to 100 years and durations ranging from 5 minutes to 24 hours. The PDT‐IDF curves were judged to be a better representation of Pennsylvania rainfall than the nationwide TP‐40 maps, particularly for storm events of 10‐years and lower return periods. The average time distribution of 24‐hour storms in Pennsylvania was found to be well represented by the SCS Type II distribution. The Corps of Engineers SPS 24‐hour distribution was found to differ appreciably from both the SCS Type H and the Pennsylvania 24‐hour storm distribution. For storm durations between 15 and 90 minutes the standard Yarnell intensity‐duration curves closely resemble Pennsylvania storm distributions.