Climate Change and Storm Water Infrastructure in the Mid-Atlantic Region: Design Mismatch Coming?

Climate change is anticipated to result in changes to the statistical properties of both precipitation depths and precipitation intensity. As a general representative for storm water infrastructure, this work examines changes in detention basin performance under several different climate change model scenarios at the study location north of Washington, DC. Frequency analysis of simulated climate model precipitation data indicates that both precipitation depths and intensities are predicted to change under future climate. The magnitude and direction of these changes vary from one climate model to the next. 24-h design storms consistent with the future climate precipitation data are used to drive a rainfall-runoff model simulating a watershed/detention basin system. In most cases, the performance of a detention basin design based on present climate is inadequate under future climate conditions. This work explores detention basin performance based on future precipitation depths only, storm intensity only, and both depth and intensity acting jointly. Results are interpreted in terms of the adequacy of current infrastructure to carry future flood loads, and in terms of potential strategies for design of infrastructure, in the face of a nonstationary climate. (C) 2014 American Society of Civil Engineers.