Future Climate Impacts on Stormwater Management Facilities in Wisconsin

This webinar will describe the impact of changing rainfall frequency and intensity on stormwater management facilities, focusing on Wisconsin. Rainfall data from the Wisconsin Rainfall Project, which provides rainfall statistics from NOAA Atlas 14, and Rainy Day software analyses of updated current and future conditions under climate change was used to test sensitivity of storm sewer sizing, detention basin sizing, impacts on stormwater quality systems, and impacts on individual and community-wide stormwater detention facilities. Storm sewer and detention basin sizing impact analyses were conducted for four locations across Wisconsin. Results indicate modest changes in calculated storm sewer sizes, but more substantial impacts on detention basin volume. Analysis of a “depaving” approach to reducing runoff partially offset increases in runoff. Impact analyses for stormwater quality designs were in some cases substantial, mainly due to the hydraulics of the outlet structures. The existing detention basin analyses indicated reduction in the performance of the detention basin with respect to return period, and more substantial overtopping flow, due to larger peak inflow and runoff volume. Approaches for existing detention basin retrofit and risk assessment of detention facilities are presented.

Rob Montgomery, P.E. has over 40 years of experience as a water resources engineer with areas of expertise in lake management, water resources engineering, and using climate impacted data in infrastructure design. Rob served as the Co-Chair of the WICCI Infrastructure Working Group from its inception (2020) through 2024. Rob has worked on diverse projects, including the Monroe County Climate Action Plan, flood management strategies for the upper Rock River watershed, Green Lake Management District phosphorus control study, and shoreline protection for Whistling Straits golf course.