“When it rains, it pours” once was a metaphor for bad things happening in clusters. Now it’s becoming a statement of fact about rainfall in a changing climate.
The 1972 Clean Water Act was designed to make the nation’s waters fishable and swimmable by 1983 but failed to meet that goal. One major reason was that the law initially focused on reducing only point sources – pollution discharges that came from an identifiable source, such as a pipe discharging human or industrial waste.
In hundreds of cities, mainly in the Northeast and Midwest, stormwater and wastewater are carried in the same sewage pipes. Green infrastructure offered a strategy for diverting stormwater away from the sewage system to places where it could soak into the ground. That helped reduce the chances of sewage systems overflowing and sending untreated stormwater and wastewater into local waters.
Every surface matters In my lab at Drexel University we are studying solutions to flooding in the Eastwick section of southwest Philadelphia. This neighborhood sits at the downstream end of a 77-square-mile suburban watershed. When it rains heavily upstream, Eastwick floods. In 2020, Tropical Storm Isaias flooded some homes with more than 4 feet of water.
Depending on where extreme rainfall occurs, these systems could function individually or together, mimicking the modularity and redundancy found in natural ecosystems.