A recently published analysis of how land cover and climate change will affect watersheds across the United States, provides options for the management of runoff, storm water and floods that can be implemented by decision-makers to manage water quality.

The study, which was recently published in the Journal of Geophysical Research Biogeosciences, was conducted by scientists from the University of Massachusetts Amherst, who hope that the models and simulations produced will provide managers with practical ways to encourage land developers to implement water quality and conservation measures and to incorporate green infrastructure into their projects.

Using data collected from satellite images, field stations, temperature gauges, stream gauges and water flow observations across the United States, the study connects the dots between land use and climate (notably temperature and rainfall/precipitation) to runoff and flooding within a watershed drainage system at a much larger scale than ever before.

According to co-author, Timothy Randhir, of the Department of Environmental Conservation at the University of Massachusetts Amherst, this new information will give us a clearer understanding of the mechanisms and runoff processes in large watersheds.

“We also want to highlight the importance of natural systems such as forest cover and open space when a town is considering new parking lots or shopping centers, for example. You can't just take away such ecosystem services and expect everything to be OK,” said Randhir. “All towns now have a big problem dealing with storm water, and with climate change it's going to get worse. In the past, the problems just flowed away to become some other town's problem, but that isn't going to work anymore.”

Randhir hopes that this will encourage a new approach to the way managers manage water resources, moving away from the current reactive approach, where managers deal with stormwater and runoff issues after they have become problematic, to a more active approach where they take preventative measures before problems arise.

“There seems to be a better understanding now that water flowing away from you doesn't just disappear, it affects someone else, and a problem in the system above you will affect you,” said Randhir. “This kind of systems thinking has to take over, and cooperation has to be used more often.”

The report suggests recommendations on how to utilize tools such as improving infiltration or urban greening as mitigation measures to reduce flooding. According to Randhir, by combining green infrastructure with best management practices watersheds can made more resilient. It is in a town or city’s own best interests to encourage these measures by offering incentives to developers who install pervious surfaces that promote rainwater infiltration rather than impervious concrete that promote stormwater runoff; or water retention features such as drainage basins or rain gardens that capture runoff that is contaminated with heavy metals, grease and oil washed off road surfaces as well as sediments from soil surfaces.

Land managers can also introduce incentives to farmers and private landowners to encourage them to take measures to prevent runoff on their properties. Randhir hopes that town and city managers make use of this new information to initiate changes to their land use practices. By doing so, flooding will be reduced, and water quality will improve for users downstream.

Journal Reference

Paul Ekness, Timothy O. Randhir. Effect of climate and land cover changes on watershed runoff: A multivariate assessment for storm water management. Journal of Geophysical Research: Biogeosciences, 2015; DOI: 10.1002/2015JG002981

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