Developing Future Projected Intensity-Duration-Frequency (IDF) Curves

The Chesapeake Bay Watershed and Virginia have experienced increases in extreme rainfall events over the past few decades, exacerbating flooding and stormwater challenges throughout the region. Climate change research has also shown that these increases in extreme rainfall are anticipated to continue throughout the 21st century. As a result, urban and coastal flooding could be more severe and more frequent in the future. This presents stormwater engineers and planners with a key challenge: how to incorporate these recent and future changes in rainfall into stormwater infrastructure design and management.

To support entities in the Chesapeake Bay Watershed and Virginia in mitigating these challenges, the authors of this study updated intensity-duration-frequency (IDF) curves, a common tool used for stormwater infrastructure design, to reflect future climate changes. These updated IDF curves are generated from the best-available science and are publicly available in an interactive online tool. Using the online tool, the updated IDF curves can be easily integrated and used across the Chesapeake Bay Watershed and Virginia to plan, design, and build infrastructure assets to be more resilient to climate change.

This technical report describes the project's motivation, data, and methodology and provides an overview of the results and the interactive online tool. The aim of the report is to make the project's approach clear and transparent to those using the interactive online IDF curve tool and to those interested in replicating these methods in other contexts.