Proven, Cost-Effective Solutions that Can Help Communities Reduce Flood Damage
Posted September 30, 2011
The flooding and punishing storms that ravaged so many communities this year have left their mark not only in water-logged basements but also in strained dams, cracked earthen levees, eroded riverbanks and many other systems we rely upon to manage flood waters.
Repairing this strained infrastructure comes with a staggering price tag. The Army Corps of Engineers announced it needs more than $2 billion repair damage from this year’s flooding.
That number is far higher than $150 million the Corps had budgeted. Worse yet, it doesn’t include the cost of cleaning up after Hurricane Irene and Tropical Storm Lee pounded states from Virginia to Vermont.
If this were an isolated spike in the budget, it might be easier to deal with it, but it looks instead like the beginning of a steady climb. Scientists say that many regions of the country will experience increased rains and more powerful storms as a result of climate change.
New York State is already witnessing the acceleration of rainwater. After Tropical Storm Lee caused the Susquehanna River to crest at 41-feet, one woman in nearby Binghamton, said, “In 2005, we had the 100-year flood, and in 2006, we had the 500-year flood,” she said. “What-year flood is this?”
Each new wave of flooding will put added strain on communities’ water infrastructure—and on their budgets. But even as we make much needed repairs to dams and concrete canals, we can also start investing in a set of solutions that could make us even better prepared to minimize flooding damage.
Green infrastructure is a set of design strategies that mimic nature's own hydrology and allow rain to filter back into the ground right where it falls.
Instead of rain hitting huge swaths of concrete in our cities, we can use things like porous pavement, planted swales around parking lots, rain gardens planted along sidewalks, green roofs, and additional trees to help absorb the water like sponges. Under natural conditions, the amount of rain that is converted to runoff is less than 10 percent of rainfall volume.
If a 1-inch rainstorm fell on a 1-acre natural meadow, it would typically produce about 218 cubic feet of runoff. That’s enough to fill 28 standard bathtubs. The same storm falling on a 1-acre paved parking lot would produce roughly 3,450 cubic feet of runoff—nearly 16 times more than the natural meadow, and enough to fill 448 bathtubs.
Obviously we can’t return our built environments into grassy meadows, but green infrastructure allows us to create a similar effect throughout our communities. Using permeable pavement instead of conventional asphalt or concrete, for instance, can make a significant difference—even in the face of powerful storms like Irene.
Philadelphia has become a national leader in green infrastructure. The city recently installed its first block-long permeable street, and its Water Commissioner Howard Neukrug said that after the recent storms that hit the city, they “couldn’t find any water there” despite major flooding elsewhere in the city.
Green infrastructure may not capture all the runoff in a hurricane, but it will reduce the volume of flood waters and decrease the damage done to our aging dams, levees, and canals. It will also make us ready to receive the wave of more frequent and more intense rainfalls that will be hitting some many communities across the nation in the coming years.
In a recent report called Thirsty for Answers: Preparing for the Water-related Impacts of Climate Change in American Cities, NRDC described how different cities are applying these same techniques. Most found that not only were they a cost-effective way to manage stormwater, but they were also welcomed by residents who enjoyed the added green space.
If we update our approaches to urban development and redevelopment to make them greener today, we won’t be scrambling to find as much emergency funding in every budget cycle.
The EPA can help the nation move in this much needed direction this fall, when it updates its own 20-year-old rules for managing urban runoff. Fortunately, the agency—including Administrator Lisa Jackson—is interested in green infrastructure techniques. By making green infrastructure standard operating procedure, the EPA’s rules can help prepare the nation for the sort of challenges we have experienced this spring and summer. The EPA shouldn’t miss this opportunity.