Spatial analysis of future climate change risk to stormwater management infrastructure in the U.S.
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Climate change is expected to result in more intense precipitation events that will affect the performance and design requirements of stormwater management infrastructure. Projected changes will vary regionally, and for events of different magnitude. Potential impacts include altered flow regimes, increased water temperatures and increased pollutant loading to waterbodies. In this poster we discuss a national scale, screening assessment of the potential effects of climate change on precipitation, stormwater runoff, and sizing requirements for urban stormwater management practices. Our methodology combines readily available statistical downscaled climate model output with precipitation intensity-duration-frequency (IDF) analyses explicitly aligned with NOAA Atlas 14 methods. Climate change scenarios are developed by adjusting different IDF events from the Atlas 14 analyses to reflect the ensemble range of mid-century, statistically downscaled climate model projections (LOCA) at approximately 2,504 locations across the CONUS. Precipitation estimates are converted to runoff with EPA’s Storm Water Management Model version 5. Results are spatially interpolated using a geographically conditioned regression kriging approach. The approach provides a flexible, relatively simple way to develop scenarios in a format directly useful to stormwater vulnerability assessment and risk screening. Results show regionally variable changes in stormwater runoff and effects on BMP storage requirements across a range of mid-century precipitation scenarios. The intensity of 24-hour precipitation events with a 2-year or greater recurrence interval is likely to increase in most areas of the U.S. leading to increased stormwater runoff and potential need for increased BMP volume storage requirements. Changes in more frequent, 24-hour events (e.g., the 90th percentile event) commonly used to design urban green infrastructure practices are relatively smaller. While it is not possible to accurately forecast long term, future change, results can be used to help inform the design of resilient, sustainable stormwater management in different regions of the U.S.