Study: Outdated Stormwater Infrastructure Exacerbates Flooding

A new study from the University of Michigan reveals that stormwater infrastructure in many U.S. cities actually exacerbates flooding due to outdated designs that are no longer effective during extreme weather events, reports Jim Lynch for Tech Xplore.

The problem lies in traditional planning's failure to recognize flood connectivity: how surface runoff from driveways, lawns and streets—and the flows in river channels and pipes—are all interlinked. The result is interactions, often unanticipated, between different stormwater systems that can make flooding worse.

The study used data from flooding in Metro Detroit in 2014, when record-breaking rainfall caused $1.8 billion in damage. According to Vinh Tran, U-M assistant research scientist in civil and environmental engineering and co-first author of the study, “Current flood mapping practices are indicative of outdated thinking that needs to change.” Policy recommendations based on that data include:

• “Stormwater system designs should take a holistic, systemwide approach to flood mitigation, rather than the conventional approach focused on local solutions.”
• “Design guidelines for stormwater systems should be revised to consider connectivity in urban landscapes, including flows in subsurface infrastructure such as pipes and sewers, open channel flows such as rivers and streams, and overland flows over natural and built surfaces.”
• “Advanced computer models that represent the full spectrum of stormwater elements and the behavior of water in them should be mandated.”