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About 80% of the world's population lives in areas where the fresh water supply is not secure, according to a new global analysis. Researchers compiled a composite index of "water threats" that includes issues such as scarcity and pollution. The most severe threat category encompasses 3.4 billion people. Writing in the journal Nature, they say that in western countries, conserving water for people through reservoirs and dams works for people, but not nature. They urge developing countries not to follow the same path. What we're able to outline is a planet-wide pattern of threat” Charles Vorosmarty City College of New York Instead, they say governments should invest in water management strategies that combine infrastructure with "natural" options such as safeguarding watersheds, wetlands and flood plains. The analysis is a global snapshot, and the research team suggests more people are likely to encounter more severe stress on their water supply in the coming decades, as the climate changes and the human population continues to grow. They have taken data on a variety of different threats, used models of threats where data is scarce, and used expert assessment to combine the various individual threats into a composite index. The result is a map that plots the composite threat to human water security and to biodiversity in squares 50km by 50km (30 miles by 30 miles) across the world. Changing pictures "What we've done is to take a very dispassionate look at the facts on the ground - what is going on with respect to humanity's water security and what the infrastructure that's been thrown at this problem does to the natural world," said study leader Charles Vorosmarty from the City College of New York. "What we're able to outline is a planet-wide pattern of threat, despite the trillions of dollars worth of engineering palliatives that have totally reconfigured the threat landscape." Those "trillions of dollars" are represented by the dams, canals, aqueducts, and pipelines that have been used throughout the developed world to safeguard drinking water supplies. Looking at the "raw threats" to people's water security - the "natural" picture - much of western Europe and North America appears to be under high stress. However, when the impact of the infrastructure that distributes and conserves water is added in - the "managed" picture - most of the serious threat disappears from these regions. Africa, however, moves in the opposite direction. "The problem is, we know that a large proportion of the world's population cannot afford these investments," said Peter McIntyre from the University of Wisconsin, another of the researchers involved. "In fact we show them benefiting less than a billion people, so we're already excluding a large majority of the world's population," he told BBC News. "But even in rich parts of the world, it's not a sensible way to proceed. We could continue to build more dams and exploit deeper and deeper aquifers; but even if you can afford it, it's not a cost-effective way of doing things." According to this analysis, and others, the way water has been managed in the west has left a significant legacy of issues for nature. Whereas Western Europe and the US emerge from this analysis with good scores on water stress facing their citizens, wildlife there that depends on water is much less secure, it concludes. Concrete realities One concept advocated by development organisations nowadays is integrated water management, where the needs of all users are taken into account and where natural features are integrated with human engineering. One widely-cited example concerns the watersheds that supply New York, in the Catskill Mountains and elsewhere around the city. We would argue people should be even more worried if you start to account for climate change and population growth” The city invested in a programme of land protection and conservation; this has maintained quality, and is calculated to have been cheaper than the alternative of building treatment works. Mark Smith, head of the water programme at the International Union for the Conservation of Nature (IUCN) who was not involved in the current study, said this sort of approach was beginning to take hold in the developing world, though "the concrete and steel model remains the default". "One example is the Barotse Floodplain in Zambia, where there was a proposal for draining the wetland and developing an irrigation scheme to replace the wetlands," he related. "Some analysis was then done that showed the economic benefits of the irrigation scheme would have been less than the benefits currently delivered by the wetland in terms of fisheries, agriculture around the flood plain, water supply, water quality and so on. "So it's not a question of saying 'No we don't need any concrete infrastructure' - what we need are portfolios of built infrastructure and natural environment that can address the needs of development, and the ecosystem needs of people and biodiversity." Dollars short This analysis is likely to come in for some scrutiny, not least because it does contain an element of subjectivity in terms of how the various threats to water security are weighted and combined. Developing countries are urged to think carefully about "concrete and steel" solutions. Nevertheless, Mark Smith hailed it as a "potentially powerful synthesis" of existing knowledge; while Gary Jones, chief executive of the eWater Co-operative Research Centre in Canberra, commented: "It's a very important and timely global analysis of the joint threats of declining water security for humans and biodiversity loss for rivers. "This study, for the first time, brings all our knowledge together under one global model of water security and aquatic biodiversity loss." For the team itself, it is a first attempt - a "placeholder", or baseline - and they anticipate improvements as more accurate data emerges, not least from regions such as Africa that are traditionally data-scarce. Already, they say, it provides a powerful indicator that governments and international institutions need to take water issues more seriously. For developed countries and the Bric group - Brazil, Russia, India and China - alone, "$800bn per year will be required by 2015 to cover investments in water infrastructure, a target likely to go unmet," they conclude. For poorer countries, the outlook is considerably more bleak, they say. "In reality this is a snapshot of the world about five or 10 years ago, because that's the data that's coming on line now," said Dr McIntyre. "It's not about the future, but we would argue people should be even more worried if you start to account for climate change and population growth. "Climate change is going to affect the amount of water that comes in as precipitation; and if you overlay that on an already stressed population, we're rolling the dice." For More Information: http://www.bbc.co.uk/news/science-environment-11435522
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Implications in the Southwest U.S.: "Day of Reckoning"
This article begins to create a bleak picture for the Southwestern region of the U.S.
Water Use in Southwest Heads for a Day of Reckoning
LAKE MEAD NATIONAL RECREATION AREA, Nev. — A once-unthinkable day is looming on the Colorado River.
Jim Wilson/The New York Times
Dolores Cormier, 82, of Las Vegas, reconfigured her front and side lawns, installing a rocky cover and drip irrigation.
Barring a sudden end to the Southwest’s 11-year drought, the distribution of the river’s dwindling bounty is likely to be reordered as early as next year because the flow of water cannot keep pace with the region’s demands.
For the first time, federal estimates issued in August indicate that Lake Mead, the heart of the lower Colorado basin’s water system — irrigating lettuce, onions and wheat in reclaimed corners of the Sonoran Desert, and lawns and golf courses from Las Vegas to Los Angeles — could drop below a crucial demarcation line of 1,075 feet.
If it does, that will set in motion a temporary distribution plan approved in 2007 by the seven states with claims to the river and by the federal Bureau of Reclamation, and water deliveries to Arizona and Nevada would be reduced.
This could mean more dry lawns, shorter showers and fallow fields in those states, although conservation efforts might help them adjust to the cutbacks. California, which has first call on the Colorado River flows in the lower basin, would not be affected.
But the operating plan also lays out a proposal to prevent Lake Mead from dropping below the trigger point. It allows water managers to send 40 percent more water than usual downstream to Lake Mead from Lake Powell in Utah, the river’s other big reservoir, which now contains about 50 percent more water than Lake Mead.
In that case, the shortage declaration would be avoided and Lake Mead’s levels restored to 1,100 feet or so.
Lake Powell, fed by rain and snowmelt that create the Colorado and tributaries, has risen more than 60 feet from a 2004 low because the upper basin states, Colorado, New Mexico, Wyoming and Utah, do not use their full allocations. The upper basin provides a minimum annual flow of 8.23 million acre feet to Arizona, Nevada and California. (An acre-foot of water is generally considered the amount two families of four use annually.)
In its August report the Bureau of Reclamation said the extra replenishment from Lake Powell was the likeliest outcome. Nonetheless, said Terry Fulp, the bureau’s deputy regional director for the Lower Colorado Region, it is the first time ever that the bureau has judged a critical shortage to be remotely possible in the near future.
“We’re approaching the magical line that would trigger shortage,” Mr. Fulp said. “We have the lowest 11-year average in the 100-year-plus recorded history of flows on the basin.”
The reservoir is now less than 15 inches above the all-time low of 1,083.2 feet set in 1956.
But back then, while the demand from California farmland was similar, if not greater, the population was far smaller. Perhaps 9.5 million people in the three states in the lower Colorado River basin depended on the supply in the late 1950s; today more than 28 million people do.
The impact of the declining water level is visible in the alkaline bathtub rings on the reservoir’s walls and the warning lights for mariners high on its rocky outcroppings. National Park Service employees have repeatedly moved marinas, chasing the receding waterline.
Adding to water managers’ unease, scientists predict that prolonged droughts will be more frequent in decades to come as the Southwest’s climate warms. As Lake Mead’s level drops, Hoover Dam’s capacity to generate electricity, which, like the Colorado River water, is sent around the Southwest, diminishes with it. If Lake Mead levels fall to 1,050 feet, it may be impossible to use the dam’s turbines, and the flow of electricity could cease.
The fretting that dominates today’s discussions about the river contrasts with the old-style optimism about the Colorado’s plenitude that has usually prevailed since Hoover Dam — then called Boulder Dam — was completed 75 years ago, impounding the water from Lake Mead.
The worries have provoked action: cities like Phoenix and Las Vegas have undertaken extensive conservation programs. Between 2000 and 2009, Phoenix’s average per-capita daily household use has dropped almost 20 percent; Las Vegas’s has dropped 21.3 percent.
Nonetheless, “if the river flow continues downward and we can’t build back up supply, Las Vegas is in big trouble,” Pat Mulroy, general manager of the Southern Nevada Water Authority, said in an interview.
While Las Vegas is one of the Colorado River’s smaller clients — it consumes 2 percent of the river’s allocated deliveries— the city relies on Lake Mead for 90 percent of its water supply. From 2002 to 2009, the metropolitan area’s population mushroomed by nearly 40 percent, to 1.9 million from 1.37 million.
In response to the population boom and the drought, which began in 1999, the authority began an aggressive effort to encourage water conservation in 2002.
Now it is expanding its options: it is tunneling under the bottom of Lake Mead to install a third intake valve that could continue operating until lake levels dropped below 1,000 feet.
Saddle Island, the construction staging site on the reservoir, looks like an abstract painting, its dusty russet ground covered with interlacing segments of the 2,500 concrete rings that will make up the three-mile-long pipe.
Ms. Mulroy has also pushed aggressively for pipelines to carry distant groundwater to the Las Vegas area; most contentious is a planned 285-mile pipeline that would cross the state diagonally and take groundwater from the Snake Valley, on the Nevada-Utah border, to Las Vegas.
The authority has also spent about $147 million on a program to encourage homeowners and businesses to eliminate their lawns in favor of the rock, grass and cactus landscaping known as xeriscaping. More than 70 percent of household water usage is attributed to outdoor use, Ms. Mulroy said.
Residents can now water their yards only three days a week, before 11 a.m. and after 7 p.m., and the restrictions are to tighten this winter.
Dolores Cormier, 82, who lives on Monterrey Avenue on the southern side of Las Vegas, reconfigured her front and side lawns, installing a rocky cover and drip irrigation. Under a water authority program known as Water Smart Landscapes (colloquially, Cash for Grass), she has received $2,689 in utility subsidies that will offset the $5,600 or so she said the xeriscaping cost her.
She is pleased with the new look but said her average monthly water bill of $45 or so has yet to decline, perhaps because she still tends grass in her small backyard. “I need some lawn,” she confessed.
If the 1,075 level is broken at Lake Mead next year, more drastic conservation measures will be needed, officials warn.
“We have a very finite resource and demand which increases and enlarges every day,” said John A. Zebre, a Wyoming lawyer and the president of the Colorado River Water Users Association.
“The problem is always going to be there,” he said. “Everything is driven by that problem.”
For More Information:
http://www.nytimes.com/2010/09/28/science/earth/28mead.html?_r=1