Storm Intensification: Implications for Environmental Design in Maryland

Abstract

Extreme precipitation is predicted to increase over the 21st century. Stormwater infrastructure designs based on historic climate experience will have reduced margins of safety and could fail to provide intended levels of services. Climate-adjusted rainfall intensity-duration-frequency curves were estimated at locations throughout Maryland for multiple climate models and land cover assumptions and linked to rainfall-runoff models with green and gray stormwater control measures (SCMs). These data are used to evaluate three classes of responses: highway flooding, stream stability, and performance of SCMs. Results suggest greater changes for larger, low recurrence events. Current guidance for road culverts may be inadequate to prevent flooding over their expected design life. Impacts on stream stability and water quality SCMs may be less severe due to smaller anticipated changes in high recurrence events; however, the large variability and incomplete knowledge of uncertainty bounds on future storm event magnitudes create challenges for planning. Given uncertainty in prediction of future precipitation it will be important to choose resilient management strategies that can be adapted as climate evolves.