The global development community is gearing up to adopt the Sustainable Development Goals (SDGs) in September, illustrating a key shift in development priorities. Rather than focusing purely on goals and indicators, as the MDGs did, this new set of goals will additionally focus on the sustainability of development. One huge task is to provide global water security. Amidst rapid urbanization, water security in cities is a growing struggle, and providing water sustainably is even more of a challenge. A possible solution to this lies in “green infrastructure.”

“Green infrastructure” refers to a type of infrastructure engineered to maximize natural processes to manage water, mainly for cities and urban areas. These natural processes can include filtration through certain soils, flows of water through aqueducts and other gravity-based processes, or storing run-off water in certain specified land areas. These “green” processes can help control polluted run-off and erosion, as well as helping to sustainably and continually provide clean water for cities. Green infrastructure is distinguished from “gray infrastructure,” which includes the more typical basins, sewage systems, pipes, and filtration centers. Gray infrastructure can be expensive, cumbersome, and often subject to degradation over time. In many cases “green infrastructure” offers a sustainable way to manage, store, and distribute water because it utilizes natural processes instead of imposing artificial systems.

Lima, Peru is revitalizing a pre-Incan canal system for more effective and sustainable water management and treatment.

One example of green infrastructure was recently in the news for its innovative approach to providing water to Peru’s desert capital city, Lima. In response to a growing water shortage, Lima has dedicated $22 million to restore an ancient, pre-Incan canal system. The canals funnel water from mountain streams into the mountain itself, where it percolates, filtrates, and releases slowly over the course of the dry season. “Gray infrastructure” water management techniques would send the water too quickly to Lima, which would result in mudslides and erosion in the wet season and severe water shortages in the dry season. The green infrastructure solution adds at least 1 cubic meter per second of water to the city. This solution is also cheaper than building a canal or storage facilities, especially in light of the rapid urbanization of the region. Lima is expected to grow by at least 700,000 people in the next five years, and green infrastructure solutions are flexible and sustainable even with that growth.

Another important example of a green infrastructure project can be found in the United States. In New York City, the Catskill Mountains provide water for the 8.4 million people. In 2007, the Environmental Protection Agency decided that the city of New York did not need to build an $8 billion filtration plant to provide clean water to the city, but instead they could invest in $300 million over the next 10 years to acquire land and prevent development where the water originates. This smaller, greener investment would keep the water from contamination from runoff and other pollutants connected to infrastructure development processes. This solution secured clean drinking water for the city, protected the environment, and saved the city billions.

In developed cities, storm water runoff is the newest area where green infrastructure investment makes the most sense. Instead of soaking into the ground, rainwater in urban areas hits impervious concrete and gets forced through pipes and drains out into rivers and other water sources, carrying with it sediment, metals, and other pollutants that then enter our water supply and then need to be filtered out.  Green infrastructure solutions use natural soils and vegetation to filter and store the water before recycling it back into a drinking supply.

Environmental sustainability is not the only benefit of green infrastructure. Many economic studies and cases have shown that investing in green infrastructure is more cost-effective than investing in gray infrastructure projects. The projects often require smaller investments at the start, there are lower energy costs associated with the projects, and they require less general maintenance. In terms of secondary economic benefits, green infrastructure projects protect from much flood damage and erosion, recovery from which is expensive. By providing clean water that doesn’t sit in the open anywhere, they also help prevent diseases and associated public health costs. An EPA study in Lancaster, PA found that green infrastructure saved the city over $120 million up front in avoided gray infrastructure costs and provided over $4.8 million in annual benefits.

Green infrastructure lets the earth do some of the work for us, and in many cases it makes more sense to capitalize on natural systems already in place. Green and gray infrastructure can be combined to create innovative and cost-effective water management in many cities around the world. Doing so will allow for sustainability to truly be a central component of economic growth and development in the coming decades.

Elizabeth Melampy is a researcher on the Project for US Leadership in Development.

Photo courtesy of Flickr user Imperial94 under a Creative Commons Attribution-ShareAlike 2.0 Generic license.