Much Ado About Flooding – Using Green Infrastructure to Reduce A Growing Problem

Stormwater in Washington, DC

Stormwater in Washington, DC | Lynette Batt

Perhaps it’s my age, but everyday I’m astounded by how much I’ve come to rely on my smartphone for everything, it seems, except making phone calls.  One of the most useful features is the weather app that tells me each day’s forecast for the town where I live, wherever I happen to be at the moment, and for San Francisco, my “home away from home.” 

Over the past few months, it seems that every other day brings an alert from this app about yet another coastal flooding advisory in these places. Consecutive waves of heavy rain have lashed the Bay Area for weeks now, flooding neighborhood streets and cafes and causing sewer overflows.  The heavily developed reaches of northern New Jersey have seen local creeks and rivers rise over their banks.  Serious storms, like those deluging the West Coast, can eventually overwhelm the capacity of most storm sewer systems, and even smaller storms can cause flooded basements, streets and businesses. 

To a considerable extent, the repeated crisis of local flooding is a result of the way we’ve historically built our storm sewer systems to move rainfall away from our communities in gutters, tunnels, and ditches. However, as more land is built and paved over with rooftops and parking lots, more rainfall flows into the storm sewer system in ever greater volumes.

The Federal Emergency Management Agency (FEMA), the agency responsible for managing federal flood response efforts, estimates that at least a quarter of the economic damages caused by flooding are caused by urban drainage problems.

Here at American Rivers, we are working to advance natural solutions to both the way we protect our communities against damage from large scale flooding and how we build our communities to prevent recurring, local flooding damage.  As we detailed in a recent report [PDF], there are different ways to build office parks, shopping centers, and residential neighborhoods that prevent rainfall from draining into overburdened sewers and streams.

Hard surfaces like roads and rooftops interrupt the natural “water cycle” that most of us learned in grade school by preventing water from infiltrating into the ground or used by trees and plants. Green infrastructure counteracts this impact, preventing flooding by slowing down runoff and capturing and infiltrating rainwater where it falls.

This approach has proven particularly effective at the neighborhood scale flooding; our collaboration with the City of Toledo and the consulting firm TetraTech in Toledo, Ohio rebuilt a block of Maywood Avenue [PDF] with green infrastructure that captured rainfall in rain gardens, porous pavement, and street edge swales.  After the project was completed in 2012, residents experienced no basement flooding, even when a major storm dumped seven inches of rain on the city.

Examples in Toledo and others across the country are making the case for green infrastructure’s flood reduction advantages. As cities and towns deal with shifting precipitation patterns and a changing climate, green infrastructure can offer a cost-effective approach to protecting clean water and mitigating localized flooding that may become more common in certain areas. At American Rivers, we continue to make the case for the economic advantages of this approach as well as its community benefits and advocate for new stormwater standards and regulations that encourage green infrastructure.