Impact of Climate Change on Extreme Rainfall across the United States

Abstract

Changes in climate may alter extreme rainfall intensity in most regions. In order to incorporate potential future changes, tools for planning and design should be capable of considering nonstationary climate conditions. In this study, potential changes in intensity-duration-frequency (IDF) curves, which are often used for assessment of extreme rainfall events, were explored using climate model historic runs, reanalysis runs, and future climate projections. The concept of the adjustment factor, which represents the general ability of climate models in representing the reanalysis data that is a reasonable estimate of actual gridded historical climate at the model grid scale, was applied to investigate potential impacts of climate change on IDF curves. For most of the study regions, future climate projections suggested an increase in the intensity of extreme storms for a given return period and duration with strong regional variations. The results also revealed the dependence of the adjustment factor values on return period and storm durations as related to the characteristics of extreme rainfalls, as it varied significantly with region, storm duration, and return period.