To prevent extreme rainfall, flooding and other severe weather from causing major damage, urban planning efforts should take a more comprehensive approach, according to a March 29 presentation by The Ohio State University’s Center for Urban Research and Analysis and the Byrd Polar and Climate Research Center.
During the presentation, Chris Zevenbergen, a professor of flood resilience at the Delft University of Technology in Delft, Netherlands, outlined strategies that integrate traditional stormwater management with innovative solutions that complement the natural environment.
“In the past 15 years, he’s accumulated an extensive national and international experience with integrated approaches to flood management in urban environments,” Jason Cervenec, education and outreach director for the Byrd Polar and Climate Research Center, said of Zevenbergen.
Several cities around the world have begun adopting the Three Points Approach (3PA) to stormwater management, Zevenbergen said. The 3PA divides stormwater management into three domains: the design domain, extreme domain and everyday domain.
In the design domain, “that’s the traditional domain where engineers are working with designs and producing an engineering solution,” he said.
The extreme domain addresses how municipalities and other government entities respond to severe weather events, including planning for the potential failure of traditional stormwater infrastructure.
“We take into account our design failure, then we build in flexibility through nature-based solutions,” Zevenbergen said.
The everyday domain addresses how municipalities approach water management when there is little or no rain. Rather than the traditional approach in which water management systems are administered separately by various government agencies, the 3PA approach integrates city, regional and river-basin management into one system, Zevenbergen said.
“Cities have to look beyond the city boundaries and have to reach out to the provinces [or county and state governments] and the national government to really align the strategies,” he said. “Managing extremes means managing the systems as a whole. Cities are becoming part of our national policies regarding water management.”
Zevenbergen cited the city of Philadelphia’s Green Stormwater Infrastructure plan, which manages stormwater runoff with nature-based solutions such as plants, soil and stone to reduce the amount of water that enters sewer systems while protecting rivers and streams. The plan is administered at the city level following state and federal regulations.
In Ohio, the Ohio Environmental Protection Agency encourages businesses, organizations and individuals to prevent excess stormwater runoff with practices such as using rain barrels or planting rain gardens to absorb excess rainfall and controlling soil erosion by placing additional soil on erosion-prone areas, according to the agency’s website.
Nature-based solutions to stormwater management have been implemented across the United States and Europe for many years, Zevenbergen said.
“What I think is new is the scale on which this is happening,” he said. “This requires, on the one hand, a vision to imagine an appealing future of the city ̶ and it should be a collective imagination ̶ but it also requires policies in place to make this happen.”
A European city that is using the 3PA strategy is Copenhagen, Denmark, Zevenbergen said. Copenhagen’s Cloudburst Management Plan is a citywide strategy for dealing with extreme rainfall events. Copenhagen drafted the plan after a 1,000-year storm on July 2, 2011, left the city under 3 feet of water and caused an estimated $1 billion in damage, according to the Urban Government Atlas, an online database of environmental solutions.
The Cloudburst plan comprises 300 projects, with nature-based solutions such as constructing new canals and developing more green spaces that can absorb water.
“Of course, those projects cannot be implemented overnight,” Zevenbergen said. “They are really embedded in a strategy which will be implemented within, say, 30 to 50 years’ time.”
Adapting stormwater management systems to withstand extreme weather events more effectively will require multipronged, decades-long efforts and collaboration between the public and private sectors, Zevenbergen said.
“There are no single measures. There is no silver bullet,” he said. “You have to use a portfolio, a raft of measures to really make a system resilient.”
Zevenbergen’s talk was part of a series this spring presented by CURA and the Byrd Polar and Climate Research Center featuring research by international scholars and practitioners. For information about upcoming events, visit CURA’s website.