The megacity . . . 10 to 20 million inhabitants residing within the walls of an urban über metropolis where resources are scarce and clean water is a luxury. The UN estimates that within the next two decades, two-thirds of the world’s population will live in an urban environment—most in the developing world—and many will call one of the world’s 39 megacities home. As I’ve said before, Megacities are the perfect test case for water resource management issues because the sheer numbers amplify the issues faced by many traditional urban communities, including pollution, dwindling groundwater supplies, aging and poorly maintained infrastructure, scarce freshwater and inefficient wastewater, and stormwater control and disposal. And according to a new report by the World Wildlife Fund (WWF), resource management at 50-million m3 (cubic meters) is about to get a whole lot more complicated.
In a report entitled “Big Cities, Big Water, Big Challenges: Water in an Urbanizing World,” WWF that by 2050, 70% of the world’s population will live in urban areas—with most of that rapid population growth taking place in the developing world (about 5 million new residents per month on average). More critical—in terms of water quality and resource scarcity—because urban growth is “inextricably linked with slum expansion and poverty”, megacity infrastructure “cannot keep pace with massive urban growth, [and] many people are left without adequate access to drinking water and sanitation.” The sheer volume of residents, combined with under-funded and barely maintained conveyance systems, also impacts the megacity’s ability to navigate changes to the water cycle, including the severe weather events and damaged ecosystems resulting from a rapidly changing climate.
As you might expect, water loss in a megacity is breathtaking. The UN estimates that in megacities throughout the world, over 45 million cubic meters of drinking water are lost every day. The report focuses on the implications of poor water management and challenged water supplies in five megacities: Mexico City, Mexico; Buenos Aires, Argentina; Nairobi, Kenya; Shanghai, China; and Karachi, Pakistan. These cities are dealing with a variety of challenges—including over-exploitation of aquifers, water pollution, wastewater discharge and contamination, and populations expanding beyond the cities original conveyance borders.
In a statement about the report, Martin Geiger, Head of Freshwater, WWF Germany, said: “It’s vital for cities to protect and restore ecosystems that are important water sources. As well as reducing unnecessary consumption, successful water and wastewater management is also essential to support agriculture. Cities must begin conducting vulnerability tests and ensuring government and stakeholder involvement to assess risk, and prepare for the increased populations we are expecting in the future.”
The report also spends a significant amount of time discussing urban water footprints, saying, “A city’s water footprint would help further investigate the impacts a city has on water resources at a local, as well as, global level.” The report defines an urban water footprint as water quantity and quality, plus the “hydrological cycle of both groundwater and surface water, utilities, connectivity to the water network, and, to a certain extent, land use/settlements.” Because most megacities have an external footprint beyond their direct boundaries,” the report emphasizes that applying an expanding water footprint terminology can “help determine the diverse impacts of urban populations’ consumption and therefore their indirect water footprint and where these effects are felt.”
“Better understanding the wider water risks that urban areas and the regions supplying products, water, and services are facing, provides the cities and regional governments and population the necessary information to take action in order to reduce, mitigate, or avoid those risks.”
The report also lays out several urban water resource management suggestions:
*Cities must protect and restore ecosystems that are important water sources for surface waters and aquifers. The adoption of a multi-sectoral approach to water and wastewater management at the national level is a matter of urgency.
*Successful and sustainable wastewater management that supports peri-urban agriculture is crucial for reducing water consumption.
*In order to better understand their vulnerabilities, prepare for climate change impacts, and make informed political and financial decisions, cities must conduct vulnerability and water risk assessments covering the core urban and peri-urban areas. Local stakeholder involvement is key to any vulnerability and risk assessment and adaptation strategy development and implementation.
*Innovative financing of water and wastewater infrastructure should take into account livelihoods, involve the private sector, and institutionalize payment and cost recovery systems.
*An inventory of critical infrastructure at-risk to flooding, droughts, or sea level rise is fundamental to inform longer-term planning, construction, funding, and other resiliency goals.
*The incorporation of green infrastructure and low-impact development, such as rain gardens, capture-and-use systems (rain barrels and cisterns), or urban agriculture, should be encouraged in local planning.
So what do you think? How can we best provide clean water and sanitation to the world’s megacities and their ever-expanding populations of poverty-level residents? Can political will loosen the purse strings for infrastructure financing not only internationally, but domestically as well? With our own megacities to contend with (including New York and Los Angeles for starters), should we be paying more attention to urban water resource management at the international level?