Potential Impacts of Climate Change on Intensity-Duration-Frequency Relationships for Locations in the United States

The increasing number of extreme hydrological events such as floods that has been observed in recent decades worldwide has put a focus on changes in extreme weather characteristics due to anthropogenic impacts. Projected changes in climate due to increased greenhouse gas emissions is expected to lead to further changes in the characteristics of precipitation events, with an expected increase in extreme rainfall event frequency in many regions. In order for government agencies and engineering firms to address any trends and changes, methods are needed to incorporate anthropogenic impacts on the natural environment into design and assessment. In this work, we project changes in intensity-duration-frequency curves, often used for assessment and design, using historical records and future climate projections from the North American Regional Climate Change Assessment Program. We provide a method for calculating intensity-duration-frequency relationships that incorporate projected changes in rainfall intensity at a range of locations in the continental United States. Design storm intensities are calculated using the Gumbel (Extreme Value Type I) distribution. Various trends and changes are observed at different locations. In addition, areal to point relationships for these design storm events are explored. This work illustrates that projected changes in design storm intensities vary substantially for different locations, and assessments of changes in extreme precipitation events should be location specific.