Managing urban stormwater runoff better

The antidote, Askarizadeh said, is to harvest and reuse as much of the stormwater runoff as possible and allow a portion to infiltrate into the ground to support streams and groundwater.

“Using LIDs to create this kind of localized, widely distributed approach to stormwater management will require individuals and public agencies to be open to significant change,” said co-author David Feldman, professor and chair of UCI’s Department of Planning, Policy & Design. “We expect the government to manage our water supply completely, and in some places, it’s even illegal to harvest rainwater locally. Laws and habits are going to have to change if we are to adapt to new climate and urban realities.”

One of the significant changes the authors argue for is a movement toward distributed infrastructure (rainwater tanks and green roofs) as a complement to the centralized infrastructure (aqueducts, water treatment plants and, more recently, desalination plants) cities have long relied on. “The reason is that in order to protect receiving waters and streams, we need to capture the runoff as close to where it’s generated – for example, your home – as possible,” said co-author Brett Sanders, professor and chair of the Department of Civil & Environmental Engineering at UCI.

“The question then becomes: What do you do with the stormwater once you’ve captured it?” said co-author Megan Rippy, a UCI postdoctoral researcher in civil & environmental engineering. “Our work provides a blueprint for estimating how much of the captured water should be infiltrated into the ground and how much should be harvested for any purpose that keeps it out of the stream, such as for nonpotable purposes in the home. The ratio of those two volumes depends on local climate and what the landscape looked like in pre-industrial times.”

“The bottom line is that these solutions are good for the environment and good for people too; they just require changing habits,” Grant said. “For example, over 2 million people in Australia use rainwater from their roofs to flush toilets – and that makes good sense. Using drinking water to flush toilets is literally washing our future down the drain.”

UCI note that with funding from a National Science Foundation PIRE grant, he and his colleagues were able to spend time in southeastern Australia studying how people there have dealt with their historic drought. “They have had a positive experience implementing LID technologies to manage scarce water resources, and in doing so, they’ve provided a good example of how universities can work with governments and private-sector entities to come up with solutions to water challenges,” Grant said. “And the best part is that after emerging from one of the longest droughts in Australia’s history, Melbourne has been voted year after year as the most livable city in the world. We could definitely use some of their magic.”

— Read more in Asal Askarizadeh et al., “From Rain Tanks to Catchments: Use of Low-Impact Development to Address Hydrologic Symptoms of the Urban Stream Syndrome,” Environmental Science & Technology 49, no. 19 (28 August 2015): 11264-80 (DOI: 10.1021/acs.est.5b01635)