Photo: Donald Milne
That the news is familiar makes it no less alarming: 1.1 billion people, about one-sixth of the world's population, lack access to safe drinking water. Aquifers under Beijing, Delhi, Bangkok, and dozens of other rapidly growing urban areas are drying up. The rivers Ganges, Jordan, Nile, and Yangtze — all dwindle to a trickle for much of the year. In the former Soviet Union, the Aral Sea has shrunk to a quarter of its former size, leaving behind a salt-crusted waste.
Water has been a serious issue in the developing world for so long that dire reports of shortages in Cairo or Karachi barely register. But the scarcity of freshwater is no longer a problem restricted to poor countries. Shortages are reaching crisis proportions in even the most highly developed regions, and they're quickly becoming commonplace in our own backyard, from the bleached-white bathtub ring around the Southwest's half-empty Lake Mead to the parched state of Georgia, where the governor prays for rain. Crops are collapsing, groundwater is disappearing, rivers are failing to reach the sea. Call it peak water, the point at which the renewable supply is forever outstripped by unquenchable demand.
This is not to say the world is running out of water. The same amount exists on Earth today as millions of years ago — roughly 360 quintillion gallons. It evaporates, coalesces in clouds, falls as rain, seeps into the earth, and emerges in springs to feed rivers and lakes, an endless hydrologic cycle ordained by immutable laws of chemistry. But 97 percent of it is in the oceans, where it's useless unless the salt can be removed — a process that consumes enormous quantities of energy. Water fit for drinking, irrigation, husbandry, and other human uses can't always be found where people need it, and it's heavy and expensive to transport. Like oil, water is not equitably distributed or respectful of political boundaries; about 50 percent of the world's freshwater lies in a half-dozen lucky countries.
Freshwater is the ultimate renewable resource, but humanity is extracting and polluting it faster than it can be replenished. Rampant economic growth — more homes, more businesses, more water-intensive products and processes, a rising standard of living — has simply outstripped the ready supply, especially in historically dry regions. Compounding the problem, the hydrologic cycle is growing less predictable as climate change alters established temperature patterns around the globe.
One barrier to better management of water resources is simply lack of data — where the water is, where it's going, how much is being used and for what purposes, how much might be saved by doing things differently. In this way, the water problem is largely an information problem. The information we can assemble has a huge bearing on how we cope with a world at peak water.
That data already shows the era of easy water is ending. Even economically advanced regions face unavoidable pressures — on their industrial output, the quality of life in their cities, their food supply. Wired visited three such areas: the American Southwest, southeastern England, and southeastern Australia. The difficulties these places face today are harbingers of the dawning era of peak water, and their struggles to find solutions offer a glimpse of the challenge ahead.
On the descent into Sky Harbor International Airport, Phoenix's endless grid of streets and tract homes is etched into the desert floor like the imprinted surface of a microchip. When the sunlight hits at the right angle, the canals that zigzag across the landscape light up like semiconductor traces surging with electricity.
And Phoenix is sprawling at a rate that seems to rival Moore's law. In the 1990s, the metro area was growing at the rate of an acre every three hours. The population is expected to nearly double in the next 20 years. But cities, unlike microchips, don't double in efficiency every 18 months. A 2007 government report stated that staggering growth in the American Southwest "will inevitably result in increasingly costly, controversial, and unavoidable trade-off choices." The issue: how to parcel out a dwindling water supply.
The city's chief water sources are the Salt River Project and the Central Arizona Project, two massive water systems that bookend a century-long effort to hydrate the region. The Salt River Project began in 1903 with the Roosevelt Dam, which reined in the flood-prone waterway. Today, the SRP is a vast network of reservoirs, hydroelectric dams, and channels. As for the Central Arizona Project, it's one of the largest and most expensive aqueducts in the US, completed in 1993 at a cost of $3.6 billion. The 336-mile CAP canal diverts 489 billion gallons a year from the Colorado River, irrigating more than 300,000 acres of farmland and slaking the thirst of Phoenix and Tucson.
By Matthew Power
http://www.wired.com/science/planetearth/magazine/16-05/ff_peakwater#
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