Prospects of a water-scarce future on our blue planet seem to loom a little larger, year by year, as researchers better understand how a resource once thought limitless is really consumed and replenished. Now the deepening misery of Cape Town is giving this complex picture a new urban outline.
Big cities aren’t ignored, exactly, when water experts look at places where the buffer between consumption and supply is thinning problematically. But cities generally have extensive infrastructure, and potentially the capability to build more as needed. So they get rather less emphasis than the vast, rural territories whose hamlets are more completely at the mercy of a changing climate and its decreasingly predictable patterns of rainfall and drought.
(See, for example, the 2016 analysis finding that two-thirds of the world’s population now experiences at least a brief period of serious water scarcity each year; although London is mentioned, the main discussion is about the countrysides of Africa, India, China and Australia, along with the southwestern United States.)
When a big city does come under discussion because of its potential water problems, it’s likely to be among the poorer ones: Bangalore, say, where a rapidly expanding population is overwhelming an antiquated water and sewer system. Maybe Jakarta, whose public water system is so tiny compared to demand that people resort to illegal wells, putting uncontrolled demand on a groundwater resource that is also threatened by saltwater intrusion as the land subsides and sea levels rise.
But Cape Town?
Here is South Africa’s gem of a coastal metropolis, seat of its national legislature, wealthy and farsighted enough to keep building up its reservoir system, which was brimful three years ago. Surrounded by desert, the city of 4 million is sometimes described as a vast oasis whose terrain traps moist ocean air and turns it into rain.
Cape Town really seems to have done most everything right, water-wise, and yet is poised to see it all undone in coming weeks by unexpectedly severe drought.
Though the date has been pushed back a bit, it’s generally thought that Cape Town will reach “Day Zero” by mid-May. That’s the point when city water lines will be closed and residents will have to take jugs to one of 200 distribution points, secured by police and soldiers, to receive a daily allotment of about 6 gallons per person. (Many are already practicing for the future by collecting water illegally from natural springs around the city, then running from the cops.)
Traffic per site is expected to average 20,000 visits each day, a flow that will continue until the rains return in sufficient volume to refill the city’s reservoirs. Meanwhile, the city is trying to build desalination plants and pump more groundwater, while reducing allowable daily use from 30 gallons per person to 13.
(According to the U.S. Geological Survey, the average American uses 80 to 100 gallons per day; a newer, efficient shower head will spray 13 gallons in about six minutes; and a modern clothes washer needs twice that to do a load.)
An award-winning system
As with many large cities, Cape Town’s population has been growing (up 80 percent in the last couple of decades) and more rapidly than its water resource (about 15 percent). But it’s not as if the leadership has been lax; the city won a global award in 2015 for managing its water in anticipation of climate change, by adopting an innovative, multipronged
Programme of water conservation and water demand management (WCWDM) aimed at minimising water waste and promoting efficient use of water… that focuses on both technical and behavioural aspects of saving water. The programme includes raising public awareness and the promotion of water use efficiency, the introduction of a “stepped” water tariff designed to encourage water savings, free of charge plumbing repairs for low-income households, training of “community plumbers,” the promotion of alternative water sources such as borehole water and recycled water for irrigation, as well as a range of technical interventions to minimise water losses.
In November, as Cape Town’s situation was beginning to make news outside South Africa, an interesting “myth-busting” analysis emanated from The Conversation, a media project in which academics write on public policy issues, aiming to deliver “academic rigor with journalistic flair.” (It’s based in Melbourne, Australia, a big city that went through its own water crisis in 2006 as part of the country’s decade long Millennium Drought, but was able to keep its system operating at reduced volume.)
Among other points, the piece assesses Cape Town’s water system as one of the world’s best in terms of preventing water loss through leaks, finds there was no way for managers to foresee the severity of the current drought, and praises the city’s efforts to limit the impact of usage restrictions on the poor (while noting, alas, that a lot of Cape Town’s municipal water goes to swimming pools in the wealthier precincts).
The crisis has also focused attention on the other major cities that might be headed for similar trouble. A handful of cities appear on multiple watch lists, and some are in the United States.
Defining ‘water stress’
A 2014 paper in the journal Global Environmental Change is attracting fresh attention for its analysis of “water stress” in the world’s 534 largest cities. The research team, headed by The Nature Conservancy’s Rob McDonald, defined the risk point as using more than 40 percent of all the water available to a city, and listed Los Angeles as among the largest cities at or beyond that metric.
Because it has extended its intake points so far beyond its borders, moving huge volumes across space and time, LA’s sources are vulnerable to climate shifts, drought, decreased snowfall — and wildfire.
Others on the list: Tokyo, Rio de Janeiro, London, Mexico City, Istanbul; Lima, Peru, and Karachi, Pakistan; six cities in China (Beijing, Shanghai, Shenzhen, Chongqing, Wuhan and Tianjin); and five in India (Delhi, Kolkata, Chennai, Bangalore and Hyderabad).
The BBC put together a list of what it considers the 11 cities most likely to follow Cape Town to a Day Zero. The sourcing is a little unclear, but the examples are interesting for the variety of underlying problems they illustrate:
Sao Paulo’s water supply fell to 20 days’ worth in 2015 because of a severe drought, and the city has been criticized for failing to plan and build in anticipation of the next one. Beijing’s water reserves have declined in recent years, even as the population kept growing, and some surface sources are so polluted that the water is useless for farm or factory use.
Cairo and Moscow are also threatened by heavy pollution of surface waters that are their main supply (the Nile, in Cairo’s case). Istanbul and Mexico City are chronically short of water because of an imbalance between consumption and resource; in the latter, one in five residents now gets water for just a few hours a week.
London just doesn’t get enough rain, and forecasts serious supply problems by 2025. Tokyo gets rain in Seattle-like quantities, but only for four months of the year, and collection methods need to be expanded.
Last but hardly least, Miami:
An early 20th century project to drain nearby swamps had an unforeseen result; water from the Atlantic Ocean contaminated the Biscayne Aquifer, the city’s main source of fresh water. Although the problem was detected in the 1930s, seawater still leaks in, especially because the American city has experienced faster rates of sea level rise, with water breaching underground defence barriers installed in recent decades. Neighbouring cities are already struggling. Hallandale Beach, which is just a few miles north of Miami, had to close six of its eight wells due to saltwater intrusion.