By Theresa Pinto M.S., Contributing Reporter
MIAMI BEACH, FLORIDA – Since 2014, China’s Sponge City initiative has been in place but the funding is set to end in 2020. It requires that eighty percent or more of all urban areas are capable of absorbing or reusing seventy percent of all stormwater. Thus far, China has hard engineered some solutions but also relocated millions of people.
Analysts report that 4 out of 5 people impacted by sea level rise by 2050 will live in coastal Asian regions. Nearly every one of China’s 654 largest cities are affected by regular flooding, and over 4,000 people were killed when the worst flooding seen in over half a century caused the Yangtze River to overflow in 1998.
As part of the initiative, thirty cities were selected for a pilot program to test adaptive strategies. Shanghai has been declared the most vulnerable major city in the world to flooding and built nearly 325 miles of seawall so far as one measure in the pilot.
“Shanghai is completely gone – I’d have to move to Tibet!” resident Wang Liubin told The Guardian in 2017, after seeing what three degrees of global warming will do.
Urban landscapes disrupt the natural flow of rainwater, causing not only flooding and storm surges, but also stormwater runoff pollution and urban heat island effects. Absorbing rainwater, allowing natural processes to take place, and repurposing what’s left is at the heart of the Sponge City Concept.
Or as the journal ‘Water‘ explains, Sponge cities “should have the appropriate planning and legal frameworks and tools in place to implement, maintain and adapt the infrastructure systems to collect, store and treat (excess) rainwater….[And] also reuse rain water to help to mitigate the impacts of “too little” and “too dirty” water.”
The Sponge City Concept in practice is not new. Rummelsburg, Germany was built twenty years ago and has become a prime example of a ‘sponge city’ in the meantime. The buildings are covered in green roofs 2-3 inches deep in dirt and the majority of the rainwater is captured and used to cool the city.
Since then, Berlin has adopted and implemented the concept in total. “The basic idea of a Sponge City is that we want to keep the rainwater in the city. When water evaporates, the city is cooled accordingly,” says Carlo Becker, the landscape architect responsible for engineering Berlin’s transition. For Germany, Sponge Cities manage heat and rain.
In the U.S., New Jersey adopted a Sponge City policy after Hurricane Sandy made landfall there in 2012, causing massive destruction and flooding. The Southwest Resiliency Park in Hoboken showcases green infrastructure with Sponge City adaptations including rain gardens and pervious pavement, which allow absorption of rainwater rather than runoff into storm drains or nearby bodies of water.
Locally, the Perez Art Museum of Miami has been awarded for its green design, including some Sponge City measures. The “lush vegetation is sustained with rainwater collected in cisterns, and a drip-chain system that irrigates greenery from canopy to garage…signature hanging gardens create a microclimate…that filters sunlight and cools outdoor display areas,” according to the PAMM website.
But no regional municipality has adopted the concept as a whole. Miami Beach adopted its current Stormwater Management Master Plan in 2014, but it is less about sponginess and more about elevating roads 2-3 feet and pumping stormwater into the Biscayne Bay.
Miami-Dade County’s Department of Environmental Resources Management admonished Miami Beach in April about water quality issues and pollution in Biscayne Bay caused by its stormwater pumps however. According to DERM, the pumps are incorrectly designed and allow “oil, dirt, debris, dog feces, pesticides, and other runoff into the water.”