With climate change comes more intense storms. This past New Year’s Eve, San Francisco experienced a storm that dropped 5.5 inches of rain. This is more than the total amount of rain the city gets in whole month of December. The unprepared city soon flooded. A staff member had to climb out of the window of a restaurant.
This flooding is largely due to “atmospheric rivers,” which are giant plumes of water vapor in the sky. They can hold the equivalent of 15 Mississippi Rivers in moisture. As climate change continues, the number of severe atmospheric river storms could nearly double by 2100.
To adapt to these heavy storms, cities must make smarter design decisions.
“Sponge Cities” Worldwide
Urban planners around the world are trying out designs to help cities better absorb and store rain. These designs follow the “sponge city” model, which aims to restore soil and greenery that was lost from urban construction.
Below are some examples:
Copenhagen created reservoirs in a public park and added rain gardens to streets to prevent sewers from overflowing.
Rotterdam created a “water square,” which is a sunken basketball court that can hold 0.5 million gallons of rain.
Bangkok created a new park with slopes that divert water into underground storage tanks.
Developments in San Francisco
San Francisco has also taken steps to create more sustainable infrastructure. Projects include:
Rain gardens along Sunset Boulevard to capture rain on streets.
Permeable pavement and planters by the curb at Holloway Avenue.
Beyond reducing flood risk, these design decisions will boost biodiversity and provide shade. These projects are currently in their early stages.
Obstacles to Rolling Out Greener Design
“Sponge City” designs run counter to long-standing practices, which can mean they get less funding. At the moment, San Francisco relies partly on volunteer “Rain Guardians” to keep rain gardens and other green infrastructure running.
Even if the city does roll out these designs on a large scale, not all neighborhoods may avoid flooding. Many were built on former wetlands or floodplains.
Beyond Design
For cities like San Francisco, green designs will be one tool in the toolkit. Some other strategies to use include planting more trees, upgrading sewer systems, and educating the public.
Reference:
https://www.fastcompany.com/90832580/how-sponge-cities-are-redesigning-themselves-for-extreme-rain
