In cities that are growing both in size and thirst across the world, sustainability is limited by the grayness of dams and water treatment facilities. In this week Sustainability of nature, research by scientists at Michigan State University advocates going green to secure water supplies.
Scientists have taken new approaches to examine how 317 cities around the world obtain adjacent and distant freshwater and other ecosystem services. It turns out that large-scale built infrastructure – the human means to move water can reduce water quality and damage water supplies at their source.
For sustainability scientist Jianguo “Jack” Liu, the study is yet another example of the need to balance human needs with the impacts of nature. This document highlights the delicate balance between built and green infrastructure and provides policy makers with ways to meet the needs of both.
“Providing adequate water to rapidly growing cities at a time already marked by water insecurity and climate change requires a holistic approach of coupled human and natural systems,” said Liu, MSU chair. Rachel Carson in sustainable development and director of the Center for Systems Integration and Sustainability. . “It is not enough to design ways to move water. You also have to understand how nature reacts and what it can provide.”
Cities impose human will on water supply not only with dams and treatment facilities, but with “impermeable surfaces” which are harsh areas like streets, roofs and parking lots that do not allow water to be supplied. water from seeping into the ground. When water ends up in storm sewers and rivers, it has picked up pollutants. The group deployed the metacoupling framework, a new integrated tool allowing researchers to systematically understand human-nature interactions near and far. This framework expands the science of sustainability from a focus on specific places separately to human-nature interactions across adjacent and distant places.
This is especially important with water, as cities often tap into remote areas and sometimes impose difficulties in the process that can damage the very supplies they covet.
Since the turn of the 20th century, nearly 90% of watersheds supplying water to cities have experienced a reduction in water quality, which directly affects drinking water and recreation in cities.
“Our results indicate that natural infrastructure such as protected forests and wetlands already play an important role in sustaining freshwater flows to cities as well as improving the performance of existing built infrastructure,” said Min Gon Chung, the first author of the article “Natural infrastructure in sustaining urban freshwater ecosystem services globally.”
“These relationships between built infrastructure and natural infrastructure become more complicated as cities increasingly depend not only on surrounding watersheds, but also on distant watersheds as more and more infrastructure like dams and aqueducts are being built, ”added Chung recently receiving his doctorate. at MSU and is a postdoctoral fellow at the University of California, Merced.
In addition to freshwater for consumption and recreation, natural infrastructure also provides many other ecosystem services associated with freshwater, such as sediment regulation, flood mitigation, and hydropower generation.
“This article adapts an analytical technique developed for human social networks to these ‘social networks’ of these ecosystems,” said co-author Kenneth Frank, professor of sociometry at the MSU Foundation. “Just as humans can be supported by a number of friends in different ways, a city can be supported by the freshwater ecosystem services of a number of watersheds. The technique allowed us to estimate whether ecosystem services are due to features of the watershed, such as forest cover, features of the city such as urban population, or features of both, such as the distance from the watershed to the river. city.
The work can help guide policy makers to effectively integrate forest and watershed greens into the water supply chain, as well as bringing more green to cities through parks and green roofs.
In addition to Liu, Chung and Frank, who are members of the SCRS, the document was written by Thomas Dietz, another member of the SCRS and professor of sociology and environmental science and policy; and Yadu Pokhrel, associate professor of civil and environmental engineering.
Cities face dramatic increases in water treatment spending when watersheds are developed
Jianguo Liu, Natural Infrastructure for Maintaining Global Urban Freshwater Ecosystem Services, Sustainability of nature (2021). DOI: 10.1038 / s41893-021-00786-4. www.nature.com/articles/s41893-021-00786-4
Provided by Michigan State University
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