Water resources and how they are managed impact almost all aspects of society and the economy, in particular health, food production and security, domestic water supply and sanitation, energy, industry, and the functioning of ecosystems. Under present climate variability, water stress is already high, particularly in many developing countries, and climate change adds even more urgency for action. Without improved water resources management, the progress towards poverty reduction targets, the Millennium Development Goals, and sustainable development in all its economic, social and environ- mental dimensions, will be jeopardized. UN Water.Org
A Landmark California Plan Puts Floodplains Back in Business — Water Deeply
SOMETHING MONUMENTAL HAPPENED on August 25 in California water management that received almost no media attention: It became official policy to reconnect the state’s major rivers with their floodplains.
The action by the Central Valley Flood Protection Board, an obscure panel appointed by the governor, clears the way for the state to embrace projects that allow floods to recharge groundwater. This could include projects like breaching levees, building setback levees and creating flood bypass structures so rivers can inundate historic floodplains for the first time in a century.
In short, it means rivers must no longer be confined within levees as a standard practice.
The result could be not only reduced flood risk, but reviving severely depleted groundwater aquifers, restoring wildlife habitat and improving the capabilities of existing water storage reservoirs.
The state calls these “multibenefit” flood-control projects, said Mike Mierzwa, chief of the office of flood planning at the California Department of Water Resources. They’re a major focus of the Central Valley Flood Protection Plan, a massive policy document the board adopted at its August 25 meeting. Read More
On the March 21st, International Day of Forests, FAO HQ will host a special celebration in recognition of ‘Forests and Water’. During the event the Land and Water Division will present ‘Forests and Water in Practice’ with examples of watershed management dealing with changes in rural production processes in a framework of market-driven agricultural development.
Fifty years ago Singapore had to ration water, and its smelly rivers were devoid of fish and choked with waste from shipbuilding, pig farms and toilets that emptied directly into streams.
But it’s a very different story today. The world’s most densely populated country now collects rainwater from two-thirds of its land, recycles wastewater and is even developing technology that mimics human kidneys to desalinate seawater.
“In about a lifetime, we have transformed Singapore,” said George Madhavan, an engineer who has worked for the national PUB water agency for 30 years and is now communications director.
“It’s not rocket science – it is more political will … The key success factor is really government – the leadership to pull different agencies together to come up with a plan.”
As governments around the world wrestle with water crises from droughts to floods, many are looking to the tiny Asian city-state of Singapore for solutions.
In many countries, a flood prevention agency focuses on quickly draining away storm water, while another manages drinking water.
In Singapore, PUB “manages the entire water loop”, Madhavan told the Thomson Reuters Foundation.
Its aim is to capture every drop of rain it can and recycle as much used water as possible.
“That means that ideally, we don’t sell you water. We rent you water. We take it back, we clean it. We’re like a laundry service. Then you can multiply your supply of water many, many times,” Madhavan said.
“The water that you drink today is the same water that dinosaurs drank. We don’t create or destroy water. It just goes around. So we are using engineering to shorten the loop.”
Beware of crocodiles
Following independence on August 9, 1965, the new 700 sq km country relied on three reservoirs and water imported from neighbouring Malaysia.
Today, it collects rainwater through an 8,000-km drain network that empties into 17 reservoirs, and reclaims used water from a deep tunnel sewerage system up to 60 metres below ground.
Singapore, which is recognised as a global leader in water technology, set up a water planning unit in 1972. Unlike Bangkok, Kuala Lumpur and Tokyo, it does not have land outside the city to act as huge catchment areas.
Eleven government agencies joined up from 1977 to 1987 to clean the heavily polluted Singapore River and Kallang Basin in the main commercial area.
The city relocated 610 pig farms and 500 duck farms (later barring such farms), transferred 5,000 street hawkers to food centres, and moved boats east to the Pasir Panjang area.
Madhavan said the biggest challenge was relocating 46,000 squatters living in squalid conditions without sewers into housing blocks.
More than 260 tonnes of rubbish were removed, the area was landscaped, and in 1987, fish returned to the waters.
Worried about pollution, authorities initially kept people away from the waterways.
“We even had warning signs about crocodiles (which had been spotted in the reservoirs) to keep people away,” Madhavan said.
Singapore has since shifted its stance, opening waterfront areas such as Marina Reservoir, where people kayak, bike and fly kites against a backdrop of the city’s highrise skyline.
Holy grail of desalination
Singapore’s “four national taps” supply 400 million gallons each day for 5.4 million people.
The island’s two natural sources are rain and, through an agreement that expires in 2061, up to 250 million gallons per day from Malaysia’s Johor River.
As climate change makes nature’s sources less reliable, Singapore is focusing on its reclaimed and desalinated water taps.
NEWater, introduced in 2003, is the name for used water from the sewerage system, treated and further purified through microfiltration, reverse osmosis and ultraviolet disinfection.
Meeting 30 percent of demand, NEWater is potable but mainly used by industries and during the dry season to top up reservoirs. Singapore aims for NEWater to meet 55 percent of demand by 2060.
The island’s first desalination plant opened in 2005, and desalinated water meets a quarter of demand.
Desalinated water and NEWater are fairly independent of the weather but on the downside, require more energy to produce, Madhavan said.
Conventional reverse osmosis requires 3.5 to 4 kilowatt-hours (kWh) to squeeze seawater through a membrane to make 1,000 litres of freshwater.
Singapore is now building a demonstration plant to scale up tests on electrochemical desalting, which uses an electric field to pull salt out of seawater. Madhavan said PUB hopes to halve energy use.
University researchers are also developing “the holy grail of desalination” – technology that imitates the kidneys, he said.
“This will take some years … They more or less understand how the kidney works to do desalting. But it’s now how to engineer it, how to build it, the enzymes that are key to this process.” More
The world’s largest underground aquifers – a source of fresh water for hundreds of millions of people — are being depleted at alarming rates, according tonew NASA satellite data that provides the most detailed picture yet of vital water reserves hidden under the Earth’s surface.
Twenty-one of the world’s 37 largest aquifers — in locations from India and China to the United States and France — have passed their sustainability tipping points, meaning more water was removed than replaced during the decade-long study period, researchers announced Tuesday. Thirteen aquifers declined at rates that put them into the most troubled category. The researchers said this indicated a long-term problem that’s likely to worsen as reliance on aquifers grows.
Scientists had long suspected that humans were taxing the world’s underground water supply, but the NASA data was the first detailed assessment to demonstrate that major aquifers were indeed struggling to keep pace with demands from agriculture, growing populations, and industries such as mining.
“The situation is quite critical,” said Jay Famiglietti, senior water scientist at NASA’s Jet Propulsion Laboratory in California and principal investigator of the University of California Irvine-led studies.
Underground aquifers supply 35 percent of the water used by humans worldwide. Demand is even greater in times of drought. Rain-starved California is currently tapping aquifers for 60 percent of its water use as its rivers and above-ground reservoirs dry up, a steep increase from the usual 40 percent. Some expect water from aquifers will account for virtually every drop of the state’s fresh water supply by year end
The aquifers under the most stress are in poor, densely populated regions, such as northwest India, Pakistan and North Africa, where alternatives are limited and water shortages could quickly lead to instability.
The researchers used NASA’s GRACE satellites to take precise measurements of the world’s groundwater aquifers. The satellites detected subtle changes in the Earth’s gravitational pull, noting where the heavier weight of water exerted a greater pull on the orbiting spacecraft. Slight changes in aquifer water levels were charted over a decade, from 2003 to 2013.
“This has really been our first chance to see how these large reservoirs change over time,” said Gordon Grant, a research hydrologist at Oregon State University, who was not involved in the studies.
But the NASA satellites could not measure the total capacity of the aquifers. The size of these tucked-away water supplies remains something of a mystery. Still, the satellite data indicated that some aquifers may be much smaller than previously believed, and most estimates of aquifer reserves have “uncertainty ranges across orders of magnitude,” according to the research.
Aquifers can take thousands of years to fill up and only slowly recharge with water from snowmelt and rains. Now, as drilling for water has taken off across the globe, the hidden water reservoirs are being stressed.
“The water table is dropping all over the world,” Famiglietti said. “There’s not an infinite supply of water.”
The health of the world’s aquifers varied widely, mostly dependent on how they were used. In Australia, for example, the Canning Basin in the country’s western end had the third-highest rate of depletion in the world. But the Great Artesian Basin to the east was among the healthiest.
The difference, the studies found, is likely attributable to heavy gold and iron ore mining and oil and gas exploration near the Canning Basin. Those are water-intensive activities.
The world’s most stressed aquifer — defined as suffering rapid depletion with little or no sign of recharging — was the Arabian Aquifer, a water source used by more than 60 million people. That was followed by the Indus Basin in India and Pakistan, then the Murzuk-Djado Basin in Libya and Niger.
California’s Central Valley Aquifer was the most troubled in the United States. It is being drained to irrigate farm fields, where drought has led to an explosion in the number of water wells being drilled. California only last year passed its first extensive groundwater regulations. But the new law could take two decades to take full effect.
Also running a negative balance was the Atlantic and Gulf Coastal Plains Aquifer, which stretches across the southeast coast and Florida. But three other aquifers in the middle of the country appeared to be in relatively good shape.
Some groundwater filters back down to aquifers, such as with field irrigation. But most of it is lost to evaporation or ends up being deposited in oceans, making it harder to use. A 2012 study by Japanese researchers attributed up to 40 percent of the observed sea-level rise in recent decades to groundwater that had been pumped out, used by humans and ended up in the ocean.
Famiglietti said problems with groundwater are exacerbated by global warming, which has caused the regions closest to the equator to get drier and more extreme latitudes to experience wetter and heavier rains. A self-reinforcing cycle begins. People living in mid-range latitudes not only pump more water from aquifers to contend with drier conditions, but that water — once removed from the ground — also then evaporates and gets recirculated to areas far north and south.
The studies were published Tuesday in the Water Resources Research journal.
Famiglietti said he hoped the findings would spur discussion and further research into how much groundwater is left.
“We need to get our heads together on how we manage groundwater,” he said, “because we’re running out of it.” More
Thirsty cities, fields and livestock drink deeply from aquifers, natural sources of groundwater. But a study of three of the most-tapped aquifers in the United States shows that overdrawing from these resources could lead to difficult choices affecting not only domestic food security but also international markets.
University of Illinois professors of civil and environmental engineering Ximing Cai and Megan Konar, along with graduate student Landon Marston and Lehigh University professor Tara Troy, studied groundwater consumption from three main systems. Reliance on these aquifers intensified so much from 2000 to 2008 that it accounted for 93 percent of groundwater depletion in the U.S. They published their findings in the Proceedings of the National Academy of Sciences.
The U.S. Geological Survey identifies the Central Valley aquifer in California, the High Plains aquifer in the Great Plains states, and the Mississippi Embayment aquifer in the lower Midwest as being managed unsustainably, which means that is being extracted from the aquifer faster than it is replenishing.
"Deep groundwater is like natural gas. If you use it, it takes a while to recharge," Cai said. "Unsustainable usage means the water table is lowered, which makes it more difficult and more expensive to pump water since we have to keep going deeper. It also affects ecosystems associated with the water table, such as streams and wetlands."
The researchers tracked water consumption from the aquifers to see where the water was going, both in terms of geography and usage. For example, when water was used to irrigate a crop, the researchers tracked where those crops were shipped.
"When we think of water, we think of direct water, the water that comes out of our faucets. But we actually use a lot of embodied water in our everyday lives – the water footprint to produce a product," Konar said. "We looked at the water implicitly being transferred between states and countries in the products."
The researchers found that the vast majority – 91 percent – of embodied groundwater from these three aquifers stayed within the U.S. The remaining 9 percent was exported internationally. They identified the states most heavily reliant on each aquifer, and the breakdown of what was produced using water from each aquifer. For example, the largest percentage of water from the High Plains aquifer irrigated grains, while the largest contribution from the Central Valley aquifer in California went to producing meat. See the infographic for the detailed findings.
The researchers hope that having detailed information on how aquifer water is used, and the complex economic and environmental implications of that use, can help policy makers in their decisions about water resource management.
"The issue here is the tradeoffs. That's the difficulty for the decision makers," Cai said. "There is a tradeoff between the environment and economic profit, and there is a trade-off between the current use and future use. The environment is affected, the food markets are affected, the resources for fisheries are affected. That helps the decision makers understand the issue. I think this information is also important for the public to understand the issue."
The researchers feel that the study is also important for international leaders, as any decisions will affect global food production and prices. Although the international exports represented a small percent of the overall water consumption, the exported goods account for a large market share in the countries that import them, the study found.
Next, the researchers plan to study major watersheds in the U.S. to gain a more comprehensive picture of natural water resources in the United States. They are interested in detailing water use under variable conditions, both in terms of economic and environmental impact.
"Managing water resources for the future is especially important because future rainfall patterns are going to be more variable, with more droughts predicted," Konar said. "As we're seeing in California, they were really lucky to have aquifers to rely on during a drought. We don't want to deplete these aquifer supplies, so that when we get into these drought situations, we have some emergency backup." More
More information: "Virtual groundwater transfers from overexploited aquifers in the United States" PNAS 2015 ; published ahead of print June 29, 2015, DOI: 10.1073/pnas.1500457112
At the launch of A New Climate for Peace, a new report on climate-fragility risks produced for the G7 by a consortium of international partners including the Wilson Center, USAID Deputy Assistant Administrator Christian Holmes called water a common denominator for climate risk.
“How you manage your water programs…has a huge amount to do with how you mitigate the prospect for increased fragility,” he said. “Sometimes it’s the obvious that’s so easy to miss, and I think that the obvious on water as it relates to economic development is, essentially, the question of sustainable water supply.”
One of the most striking infographics from A New Climate for Peace touches on that question of supply. Using data from Oregon State University’s Transboundary Freshwater Dispute Database and adapted from a graphic that originally appeared in Popular Sciencelast year, the map shows the world’s most active – and tension-filled – international water basins.
Water is a common denominator for climate risk
The Transboundary Freshwater Dispute Database measures not only the frequency of hostile events in a basin, but cooperative ones as well, each on a sliding scale. Hostile events range from declarations of war (zero recorded from 1990 to 2008, the period of time encompassed by the graphic) to leaders using “language of discord.” Cooperative events range from “mild verbal support” to “voluntary unification into a single country.”
The total number of events is indicated by shades of blue – the darker the blue, the more transboundary events, both positive and negative. This is essentially the “hot list” of international water basins – which regions have the most official and unofficial chatter over water.
Circles superimposed on the basins represent the total number of hostile events. As the description text points out, however, “circle size does not automatically translate into conflict danger.” In some places, transboundary institutions and diplomatic frameworks allow different actors to work through their differences. Cooperative hostility, if you will. In the Danube River Basin, for example, the high number of “hostile” events is mitigated by strong cooperative incentives associated with European integration. Likewise in North America, where Canada, the United States, and Mexico share several basins with a high number of hostile events, there is little chance of violent conflict.
Water basins in South Asia, the Middle East, and East Africa are major hotspots with a high number of hostile events and weaker institutional frameworks to mitigate them. The Indus, Ganges-Brahmaputra-Meghna, Salween, Tigris-Euphrates, and Jordan basins witness a very high number of interactions, suggesting at least that continued dialogue could be a way forward to mitigate the risk of violent conflict or fragility. The Nile Basin has less activity reflecting the stalled negotiations between the basin’s 10 member states to replace colonial-era water agreements. The Mekong Basin, where the largest member, China, does not participate as a full member of the Mekong River Commission, shows less activity as well.
The map does a great job illustrating why it can be difficult to answer the question, where is the highest risk of water-related violence? Tensions between states and other freshwater basin actors isn’t necessarily a sign of impending violence if there’s a framework to resolve them. Likewise, lack of communication over a major natural resource can be a bad sign for cooperation when the resource in question is the Nile. More
More infographics from ‘A New Climate for Peace: Taking Action on Climate and Fragility Risks’ are available on NewClimateforPeace.org.
Lake Mead Drops Below Rationing Line For First Time in Its History.
1075 feet. That’s the water level Lake Mead must stay above before mandatory multi-state water rationing goes into effect. A level just 25 feet above the highest intake pipe used to supply cities across the Desert Southwest. Last night water levels at the key national water storage facility fell below that hard line to 1074.99 feet — a record low never before seen in all of its history.
If water levels remain below the 1075 foot mark through January of 2016, then a multi-state rationing will go into effect (with most acute impacts for Arizona and Nevada). A rationing that will have serious consequences for desert cities across the Southwest, cities like Las Vegas which rely on Lake Mead for so much of their water.
Despite Lake Mead hitting the 1075 hard line, it appears that rationing may be forestalled through 2016. It’s a silver lining of all the severe summer storms that have rolled through the Colorado River Basin this spring and summer — pumping up water flows to Lake Mead and Lake Powell. A flush of much needed moisture that will, hopefully, prevent water rationing from going into effect during 2016. But prospects for the future, despite this temporary respite, are starting to look a bit grim.
Risk of Future Megadrought
The trend set in place by a human-forced warming of the Desert Southwest has resulted in an increasing number of dry years. The added heat forces water to evaporate more rapidly. So even when it does rain an average amount, moisture levels still fall. The result is not only an increase in single year droughts, but an increased risk of decadal droughts (called megadroughts).
As the years progress and more of the impacts of human-forced global warming become apparent, the drought impacts and severe drought risks are only expected to rise. For according to a recent Cornell University report (2014) the chance of a 10 year drought for the US Southwest under a moderate warming scenario (RCP 4.5) is 50% this century (greater for states like Texas, Oklahoma, New Mexico, Arizona, and Nevada — see graphic below). The chances of a 30 year drought range from 20-50 percent depending on the severity of the human greenhouse gas emission. More
The worst drought in five years is creeping across the Caribbean, prompting officials around the region to brace for a bone dry summer.
From Puerto Rico to Cuba to the eastern Caribbean island of St. Lucia, crops are withering, reservoirs are drying up and cattle are dying while forecasters worry that the situation could only grow worse in the coming months.
Thanks to El Nino, a warming of the tropical Pacific that affects global weather, and a quieter-than-normal hurricane season that began in June, forecasters expect a shorter wet season. That means less rain to help refill Puerto Rico's thirsty Carraizo and La Plata reservoirs as well as the La Plata river in the central island community of Naranjito. A tropical disturbance that hit the U.S. territory on Monday did not fill up those reservoirs as officials had anticipated.
Puerto Rico is among the Caribbean islands worst-hit by the , with more than 1.5 million people affected by the drought so far, according to the U.S. National Drought Mitigation Center.
Tens of thousands of people receive water only every third day under strict rationing recently imposed by the island government. Puerto Rico last week also activated National Guard troops to help distribute water and approved a resolution to impose fines on people and businesses for improper water use.
The Caribbean's last severe drought was in 2010. The current one could grow worse if the hurricane season ending in November produces scant rainfall and the region enters the dry season with parched reservoirs, said Cedric Van Meerbeeck, a climatologist with the Caribbean Institute for Meteorology and Hydrology.
"We might have serious water shortages ... for irrigation of crops, firefighting, domestic consumption or consumption by the hotel sector," he said.
The Caribbean isn't the only area in the Western Hemisphere dealing with extreme water shortages. Brazil has been struggling with its own severe drought that has drained reservoirs serving the metropolis of Sao Paulo.
In the Caribbean, the farm sector has lost more than $1 million in crops as well as tens of thousands of dollars in livestock, said Norman Gibson, scientific officer at the Trinidad-based Caribbean Agricultural Research and Development Institute.
On St. Lucia, which has been especially hard hit, farmers say crops including coconuts, cashews and oranges are withering.
"The outlook is very, very bad," said Anthony Herman, who oversees a local farm cooperative. "The trees are dying, the plants are dying ... It's stripping the very life of rivers."
Officials in Cuba say 75 percent of the island is enduring a drought that has killed cattle and destroyed thousands of hectares (acres) of crops including plantains, citrus, rice and beans. Recent heavy rains in some areas have alleviated the problem some, but all 200 government-run reservoirs are far below capacity.
In the nearby Dominican Republic, water shortages have been reported in hundreds of communities, said Martin Melendez, a civil engineer and hydrology expert who has worked as a government consultant. "We were 30 days away from the entire water system collapsing," he said.
The tourism sector has also been affected.
Most large hotels in Puerto Rico have big water tanks and some recycle wastewater to irrigate green areas, but many have curtailed water use, said Frank Comito, CEO of the Florida-based Caribbean Hotel & Tourism Association.
Other hotels have cut back on sprinkler time by up to 50 percent, said Carlos Martinez of Puerto Rico's Association of Hotels. "Everybody here is worried," he said. "They are selling water tanks like hot cakes ... and begging God for rain."
Guests at Puerto Rico's El Canario by the Lagoon hotel get a note with their room keys asking them to keep their showers short amid the water shortage. "We need your cooperation to avoid waste," says the message distributed at the front desk of the hotel in the popular Condado district.
At the Casa del Vega guesthouse in St. Lucia, tourists sometimes find the in their rooms turned off for the day, preventing them from taking a shower. "Even though we have a drought guests are not sympathetic to that," hotel manager Merlyn Compton said. More
It turns out that the steady dripping of water deep underground can reveal a surprising amount of information about the constantly changing cycles of heat and cold, precipitation and drought in the turbulent atmosphere above. The analysis of a stalagmite from a cave in north east India can detect the link between El Nino conditions in the Pacific Ocean and the Indian monsoon, a new study has found.
When the conversation turns to the weather and the climate, most people’s thoughts naturally drift upward toward the clouds, but Jessica Oster’s sink down into the subterranean world of stalactites and stalagmites.
That is because the assistant professor of earth and environmental sciences at Vanderbilt University is a member of a small group of earth scientists who are pioneering in the use of mineral cave deposits, collectively known as speleothems, as proxies for the prehistoric climate.
It turns out that the steady dripping of water deep underground can reveal a surprising amount of information about the constantly changing cycles of heat and cold, precipitation and drought in the turbulent atmosphere above.
As water seeps down through the ground it picks up minerals, most commonly calcium carbonate. When this mineral-rich water drips into caves, it leaves mineral deposits behind that form layers which grow during wet periods and form dusty skins when the water dries up.
Today, scientists can date these layers with extreme precision based on the radioactive decay of uranium into its daughter product thorium. Variations in the thickness of the layers is determined by a combination of the amount of water seeping into the cave and the concentration of carbon dioxide in the cave’s atmosphere so, when conditions are right, they can provide a measure of how the amount of precipitation above the cave varies over time. By analyzing the ratios of heavy to light isotopes of oxygen present in the layers, the researchers can track changes in the temperature at which the water originally condensed into droplets in the atmosphere changes and whether the rainfall’s point of origin was local or if traveled a long way before falling to the ground.
The value of this information is illustrated by the results of a study published May 19 in the journal Geophysical Research Letters by Oster’s group, working with colleagues from the Berkeley Geochronology Center, the Smithsonian Institution National Museum of Natural History and the University of Cambridge titled “Northeast Indian stalagmite records Pacific decadal climate change: Implications for moisture transport and drought in India.”
In the study, Oster and her team made a detailed record of the last 50 years of growth of a stalagmite that formed in Mawmluh Cave in the East Khasi Hills district in the northeastern Indian state of Meghalaya, an area credited as the rainiest place on Earth.
Studies of historical records in India suggest that reduced monsoon rainfall in central India has occurred when the sea surface temperatures in specific regions of the Pacific Ocean were warmer than normal. These naturally recurring sea surface temperature “anomalies” are known as the El Niño Modoki, which occurs in the central Pacific, and the Pacific Decadal Oscillation, which takes place in the northern Pacific. (By contrast, the historical record indicates that the traditional El Niño, which occurs in the eastern Pacific, has little effect on rainfall levels in the subcontinent.)
When the researchers analyzed the Mawmluh stalagmite record, the results were consistent with the historical record. Specifically, they found that during El Niño Modoki events, when drought was occurring in central India, the mineral chemistry suggested more localized storm events occurred above the cave, while during the non-El Niño periods, the water that seeped into the cave had traveled much farther before it fell, which is the typical monsoon pattern.
“Now that we have shown that the Mawmluh cave record agrees with the instrumental record for the last 50 years, we hope to use it to investigate relationships between the Indian monsoon and El Niño during prehistoric times such as the Holocene,” said Oster.
The Holocene Climate Optimum was a period of global climate warming that occurred between six to nine thousand years ago. At that time, the global average temperatures were somewhere between four to six degrees Celsius higher than they are today. That is the range of warming that climatologists are predicting due to the build-up of greenhouse gases in the atmosphere from human activity. So information about the behavior of the monsoon during the Holocene could provide clues to how it is likely to behave in the future. This knowledge could be very important for the 600 million people living on the Indian subcontinent who rely on the monsoon, which provides the area with 75 percent of its annual rainfall.
“The study actually grew out of an accidental discovery,” said Oster. Vanderbilt graduate student Chris Myers visited the cave, which co-author Sebastian Breitenbach from Cambridge has been studying for several years, to see if it contained enough broken speleothems so they could use them to date major prehistoric earthquakes in the area.
Myers found a number of columns that appear to have broken off in the magnitude 8.6 earthquake that hit Assam, Tibet in 1950. But he also discovered a number of new stalagmites that had begun growing on the broken bases. When he examined these in detail he found that they had very thick layers and high concentrates of uranium, which made them perfect for analysis.
Because of the large amount of water running into the cave, the stalagmite they choose to analyze had grown about 2.5 centimeters in 50 years. (If that seems slow, compare it with growth rates of a few millimeters in a thousand years found in caves in arid regions like the Sierra Nevada.) As a result, the annual layers averaged about 0.4 millimeters thick — wide enough for the researchers to get seven to eight samples per layer, which is slightly better than one measurement every two months. The amount of information about the climate that scientists can extract from the stalagmites and stalactites in a cave is amazing. But the value of this approach increases substantially as the number of caves that can act as climate proxies increases.
It is not a simple task. Because each cave is unique, the scientists have to study it for several years before they understand it well enough to use it as a proxy. For example, they must establish how long it takes water to move from the surface down to the cave, a factor that can vary from days to months.
Efforts to use the mineral deposits in caves as climate proxies began in the 1990’s. Currently, there are only a few dozen scientists who are pursuing this line of research and they have analyzed the mineral deposits from 100 to 200 caves in this fashion.
Story Source:
The above story is based on materials provided by Vanderbilt University. The original article was written by David Salisbury. Note: Materials may be edited for content and length.
Journal Reference:
Christopher G. Myers, Jessica L. Oster, Warren D. Sharp, Ralf Bennartz, Neil P. Kelley, Aaron K. Covey, Sebastian F.M. Breitenbach. Northeast Indian stalagmite records Pacific decadal climate change: Implications for moisture transport and drought in India. Geophysical Research Letters, 2015; DOI: 10.1002/2015GL063826
The American engineers who traveled to rural India two years ago believed they were going to help poor villagers get rid of microbes in their drinking water. But soon after their arrival, they began hearing about a different problem: salt.
“People kept talking about the salt in the water,” recalled Natasha Wright, a doctoral candidate who was part of the team from Massachusetts Institute of Technology that made the journey in 2013. “The groundwater beneath the villages was brackish.”
Those complaints inspired new technology that could some day supply water to thirsty villages and drought-stricken farms in other parts of the world. The MIT team developed a solar-powered water desalination system that uses the sun’s energy to turn brackish liquid into contaminant-free water safe for drinking and for crops.
While there are dozens of different desalination systems in use around the world, MIT’s is uniquely designed to be small, relatively cheap and 100-percent solar-powered, making it suitable for remote areas where the electricity supply is unreliable or non-existent, Wright said.
The panel of judges last month deemed the machine’s potential so impressive that they gave the inventors the $140,000 “Desal Prize,” an award sponsored by Securing Water for Food, a joint project of the U.S. Agency for International Development and the governments of Sweden and the Netherlands. Some 68 engineering teams from 29 countries competed in the contest, hosted by the Interior Department’s Bureau of Reclamation in Alamogordo, N.M.
“Providing a sustainable water supply is important for the West, the country and the world,” Esteva Lopez, the department’s reclamation commissioner, said after the top prize was awarded to MIT and its research partner, Jain Irrigation Systems.
Wright said she and fellow engineers from MIT’s Global Engineering and Research Laboratory became aware the extent of saltwater intrusion in northern and central Indian aquifers during visits to investigate solutions for widespread water contamination in India. In addition to problems with bacterial contamination, the groundwater in much of rural India is brackish, having a salt content lower than seawater but still high enough to cause problems. In some of the villages visited by the MIT researchers, locals were trying unsuccessfully to remove the salt using filters and chemicals.
“People complained about the salty taste,” Wright said, “and the salt ruined their cooking pots.”
Traditional desalination systems are expensive and require substantial amounts of electricity to operate, making them impractical for India’s remote farming communities. Instead, the MIT researchers designed a system that removes salt through a process called electrodialysis, using a series of electrodes and membranes to remove the salt. They added solar panels and batteries to run the pumps and charge the electrodes. Then, in a final step, they installed ultraviolet light arrays to kill any microbes remaining in the water.
The finished prototype is small enough to fit in a tractor-trailer and includes photovoltaic cells to supply the electricity. The system, when fully operational, can supply the basic water needs of a village of between 2,000 and 5,000 people, MIT officials said. Although the prototype was more expensive, Wright said the team is hopes to lower the costs of a village-sized unit to about $11,000.
Such a lower-power system is useful mainly for treating brackish water and not seawater, which contains far more salt. But the prototype now being tested could handle water that contains salt concentrations of up to 4,000 parts per million, meaning it would work in about 90 percent of India’s wells, Wright said. Seawater’s salt concentration averages about 35,000 parts per million.
“There are places where this kind of system won’t work, but the advantage is, it uses half the energy of other systems,” said Wright. And, thanks to solar cells, “you can be fully off the grid.” More
So says a protester walking though the streets of Sao Paul as water service is being drastically cut due to a relentless drought in Brazils most populous state. The 20 million people that live in Sao Paulo, Brazil have run out of water and things are starting to get ugly really fast.
Secretly recorded, Paulo Massato, the metropolitan director of the São Paulo state-run water utility, said that people might have to flee the city. "There's not enough water, there won't be water to bathe, to clean," says Massato. Fears of what comes next has begun and thousands took to the streets recently walking from the poor neighborhoods and marching past wealthy residential towers most of which have their own water tanks, to the Bandeirantes Palace in Morumbi, where the official residence of the governor (State of Sao Paolo Geraldo Alckmin) is located.
A demonstrator holds up a bucket with a sign reading "Water, Yes," in reference to water rationing in Sao Paulo January 29, 2015. Residents of Brazil's largest city, Sao Paulo, could soon only have running water two days a week. (REUTERS/Nacho Doce)
São Paulo, along with 93 smaller localities around Brazil, is facing drastic water shortages that could mean up to five days a week without running water starting in April. The mega-city’s largest reservoir, which supplies about 30 percent of the 20 million people living in the metropolitan region, is currently at only 5.1 percent of its capacity. It’s all the result of a severe drought that has extended throughout Brazil’s Southeastern region, and could soon lead to water rationing for as much as 40 percent of the population.
Aside from practical residential concerns, the shortage has affected industry and agriculture across the region, including the production of hydroelectricity, a key component of Brazil’s power grid. Even the carnaval is threatened—celebrations have been cancelled in some dry municipalities and the Río samba groups are altering their choreography to eliminate traditionally prominent water us.
The latest must-have item in the city is a rainwater cistern. A local group created in October, Cisterna Já, teaches city residents how to make their own mini-cisterns, allowing them to cut back on increasingly expensive and scarce public water supplies.
Consumption in the metropolitan region has already been reduced by a quarter, according to the president of Sabesp, the city’s water utility. Yet the main water loss culprit isn’t long showers, but rather leaky pipes. In order to address the problem, he explained in a recent op-ed, about 64,000 kilometers of buried pipes would have to be replaced.
Experts say they are concerned there is little practical preparation for upcoming shortages and argue that few relevant policy measures are being put into place.
The roots of the water shortage can be traced back to deforestation and industrialization across the region, according to Marcos Sorrentino, a professor of education and environmental policy at the University of São Paulo. A lack of political will to address the problem has led São Paulo to maintain a system of wasteful water distribution and consumption, and the city has missed opportunities to implement water saving and reuse technologies, Sorrentino says.
Residential water use only accounts for an estimated 6 percent of water usage in the region, which means that even if Paulistas stopped bathing altogether they won’t be able to resolve the “crisis de agua,” as it’s called locally. “Agriculture and industry, the biggest consumers, are only now being mobilized to commit to reducing consumption,” says Sorrentino.
A recent study found that 95 percent of businesses, industries, hospitals and hotels in the state of São Paulo don’t have a water supply contingency plan. “Lack of water will certainly compromise the operations of places that depend on the public water system,” says Rodnei Domingues, the study’s coordinator.
Sorrentino is particularly concerned about the drought’s impact on food prices, and notes that there have already been several water shortage-related protests. “The discontent of the population of the cities in which rationing has started is very large and it is not difficult to predict effects on public health and the expansion of urban violence,” he says.
The drought began last austral summer (December to February), when São Paulo state received about one-third to half of its usual amount of rain during what should have been its wettest season. In the seven months since, rainfall has been about 40 percent of normal. Across southeastern Brazil, production of key crops like coffee and sugar are in steep decline, and citizens are facing periodic outages in the water supply—even as news agencies report that local water authorities have not instituted conservation measures.
“The climate of the region is seasonal, with a rainy summer and a dry winter, and the drought has extended through the current dry season and the past rainy season,” noted Marcos Heil Costa, climate scientist at the Universidade Federal de Viçosa. “To make things worse, the onset of the rainy season—which usually happens in late September or early October—has not happened yet.”
“For the last rainy season, the pattern [of reduced rainfall] has been observed in the past, though the intensity was unprecedented this year,” Costa added. “For the dry season, coincidence or not, it looks exactly like what has been predicted by IPCC for a warmer climate. And it is now clear that our policies on management of water resources are unsustainable. No city in southeast Brazil seems prepared to handle a drought like this one. It is a mix of a lack of preparation for low levels of rain and a lack of environmental education in the population. Most people continue to use water as if we were in a normal year.” More
Organiser: UN-Water Decade Programmeon Advocacy and Communication (UNW-DPAC)
Achieving the Water for Life Decade’s goals has needed sustained commitment, engagement, cooperation and investment from all. As the Decade is officially drawing to a close in 2015, the UN-Water Decade Programme on Advocacy and Communication (UNW-DPAC)wants to show how people’s efforts have contributed to its success. To this end, the Water for Life Voices campaign has gathered the voices of those whose life has changed over the last 10 years due to water and sanitation. Selected contributions from the campaign will form the exhibition at the UN Headquarters from 9 March to 14 April 2015. It is hoped that the exhibition will bring the voices of beneficiaries of water programmes over the Decade and highlight the human aspect of water programmes, and thus help support the inclusion of such considerations into the Sustainable Development Goals (SDG). As Josefina Maestu, Director of the Office to support the Water for Life Decade, explains: "This exhibit brings the lives and voices of the beneficiaries of water programmes right into the halls of the UN General Assembly. It serves as a reminder to the UN’s top decision makers of just how much impact their work has had on people over the last Decade. It should also show visitors how much has been done, and how much there is yet to do to ensure continued development and progress for all the world’s peoples."
Climate change was a key driver of the Syrian uprising, according to research which warns that global warming is likely to unleash more wars in the coming decades, with Eastern Mediterranean countries such as Jordan and Lebanon particularly at risk.
Experts have long predicted that climate change will be a major source of conflict as drought and rising temperatures hurt agriculture, putting a further strain on resources in already unstable regimes.
But the Syria conflict is the first war that scientists have explicitly linked to climate change. Researchers say that global warming intensified the region’s worst-ever drought, pushing the country into civil war by destroying agriculture and forcing an exodus to cities already straining from poverty, an influx of refugees from war-torn Iraq next door and poor government, the report finds.
“Added to all the other stressors, climate change helped kick things over the threshold into open conflict,” said report co-author Richard Seager, of Columbia University in New York.
“I think this is scary and it’s only just beginning. It’s going to continue through the current century as part of the general drying of the Eastern Mediterranean – I don’t see how things are going to survive there,” Professor Seager added.
Turkey, Lebananon, Israel, Jordan, Iraq and Afghanistan are among those most at risk from drought because of the intensity of the drying and the history of conflict in the region, he says. Israel is much better equipped to withstand climate change than its neighbours because it is wealthy, politically stable and imports much of its food. Drought-ravaged East African countries such as Somalia and Sudan are also vulnerable along with parts of Central America – especially Mexico, which is afflicted by crime, is politically unstable, short of water and reliant on agriculture, Prof Seager said.
The conflict in Syria began in spring 2011 and has evolved into a complex multinational war that has killed at least 200,000 people and displaced millions more, according to the Columbia study, which appears in the journal Proceedings of the National Academy of Sciences. It was preceded by a record drought that ravaged Syria between 2006 and 2010.The paper says the timing is unlikely to be a coincidence, citing a recent interview with a 38-year old farmer in Mohasen, an agricultural village in the north east of Syria.
Asked if the conflict was about the drought, Faten – a female farmer who did not want to give her last name – said: “Of course. The drought and unemployment were important in pushing people towards revolution. When the drought happened, we could handle it for two years, and then we said, ‘It’s enough’,” the report said.
The study combined climate, social and economic data relating to the so-called Fertile Crescent, spanning parts of Turkey and much of Syria and Iraq, where agriculture and herding are thought to have started 12,000 years ago and continue to be crucial.
The region has warmed by between 1 and 1.2C since 1900, reducing rainfall in the wet season by an average of 10 per cent. In addition to the warming – which has found to be caused by human greenhouse gas emissions – Syria has had to contend with rapid population growth, from 4 million in the 1950s to 22 million now.
The ruling al-Assad family encouraged water-intensive export crops such as cotton, while illegal drilling of irrigation wells dramatically depleted groundwater that might have provided valuable reserves, the report said. The drought’s effects were immediate. Agriculture production, which typically makes up a quarter of Syria’s economy, plummeted by a third.
In the hard-hit northeast, livestock herds were practically obliterated, cereal prices doubled and nutrition-related diseases among children increased dramatically. As many as 1.5m people fled from the country to the city.
“Whether it was a primary or substantial factor is impossible to know, but drought can lead to devastating consequences when coupled with pre-existing acute vulnerability,” said lead author Colin Kelley, who did the work at Columbia but is now the University of California, Santa Barbara.
The pressure exerted by climate change is even more dangerous because it comes against a backdrop of rising populations and growing scarcity of resources, experts say.
With demand for basic commodities such as wheat and copper set to soar over the next two decades, relatively small shocks to supply risk causing sudden price rises and triggering “overreactions or even militarised responses”, the Chatham House think-tank has warned.
Furthermore, while the effects of rising population and global warming may be felt hardest among the poorer countries most affected by climate change, the impact will be felt worldwide.
Global trade is so interconnected that no importer of resources is insulated from the problems of key exporters – a fact of concern to the UK, which imports 40 per cent of its food and a high proportion of fossil fuels and metals, the think-tank warns. More
LAS VEGAS – The patroller stopped his water district truck and grabbed his camcorde "Here we go," he said, sliding from the cab and pointing his lens at the fine spray of water and rainbow rising from pop-up sprinklers on the lawn of a low-slung ranch home.
Central Arizona Project Canal
"Thursday," he spoke, recording the day as evidence. No watering allowed on Thursdays.
Welcome to the future, where every drop of Colorado River water is guarded and squeezed. Only here, in the city that gets 90 percent of its water from the fickle and fading river, the future is now.
The vast and highly urbanized Southwest, built on the promise of a bountiful river propped up by monumental dams, is up against its limits. Already tapped beyond its supply, the river is now threatened by a warming climate that shrinks its alpine source.
To support fast-growing urban populations in a time of dwindling supply, the Southwest is due for rapid and revolutionary changes.
A region that uses two-thirds of its water outdoors, and mostly for agriculture, will have to find ways of sharing and boosting efficiency — a shift that many experts believe will mean city dwellers paying to upgrade rural irrigation systems.
Cities such as Phoenix and Las Vegas, which have reduced their per-person water usage through better landscaping and appliances, will have to do better. They lag behind Los Angeles, whose growing population, by necessity, uses no more water than it did 40 years ago.
Water suppliers from Denver to San Diego will spend billions of dollars to squeeze more out of each drop, and to clean and use wastewater and salt water. It means a future of higher water bills, further promoting conservation.
Problem can't be deferred
"We're in a drought," water patroller Robert Kern said after hanging a warning notice on the home's doorknob. Two more violations and the water district will fine the owner $80.
"Everyone has to do their part."
Residents in this part of town — known as Zone C to the Las Vegas Valley Water District — may only water on Monday, Wednesday and Friday from fall through spring. They're freer to soak their grass at will in summer, when the withering heat demands it.
The cooler months are for austerity, to give the plummeting water levels behind Hoover Dam a break. The river's massive storage tub, Lake Mead, is draining.
The Colorado isn't all that we thought it would be when we divvied up the rights in the Roaring '20s. Most years, it gives less than it once did, and there are more users taking from it.
A 2012 government study of supply and demand predicted a 2060 annual shortfall of nearly a trillion gallons — enough to cover the sprawling city of Phoenix 9 feet deep or to supply 6 million Southwestern households for a year.
How the Southwest's leaders, farmers and lawn waterers respond will help decide how many millions of people this drying corner of the continent can sustain in the next century.
Throughout this year, The Arizona Republic will examine the twin stresses of climate change and population growth, and ways to ensure reliable water for the next generation of Southwesterners.
"This is not one of the problems you can defer and let your grandkids deal with," said Doug Kenney, a University of Colorado law professor.
Last year, the Arizona Department of Water Resources published a "strategic vision" for the coming century. The department stopped short of calling the state's current situation a "crisis," but said Arizona is at a "crossroads" and needs to decide on actions to secure new water.
Many potentially costly steps for metro Phoenix were included: conservation, treated water recycling, watershed forest thinning, cloud seeding and seawater desalination among them.
Kenney chairs the newly formed Colorado River Research Group, an independent group of 10 river and climate experts from regional universities. This winter, they made a simple recommendation that would have sounded outlandish in the past century.
Use no more water.
Cities will have to grow within their means, through conservation and by paying farmers to save and transfer water, he said. When the river already falls short of supplying everyone who has a legal right to it, there's no sensible way of taking more from it.
"If everyone takes what they're legally entitled to," Kenney said, "the system crashes."
That's true even if the wetter 20th century hydrology repeats. But that's not what the big water suppliers are expecting.
Actual flow of Colorado River versus water promised for Southwest
Agreements have promised 16.5 million acre-feet of water annually to come out of the Colorado River for use by Western states and Mexico. But in many years, the actual flow of the Colorado has been lower than what’s promised, which is marked by the solid line. The 110 year average is shown by the dotted line.
"In my opinion, the future of the Colorado Basin is a future where we have less water than we have right now," said John Entsminger, general manager of the Southern Nevada Water Authority.
"The future of the Colorado Basin also has less grass."
But it won't be just the urban lawns that attract scrutiny. Farmers from Wyoming to Mexico — by far the biggest users of the river — will have to back off on hay production
They'll also have to embrace expensive but efficient drip irrigation, Entsminger said. Urban water users will help pay for that through higher rates.
"Everybody's going to have to figure out how to do the same or more with less water."
Robert Kern, a Waster Water Investigator for the Las Vegas Valley Water District, documents a watering restriction violation in a west-central Las Vegas neighborhood. Las Vegas residents are only allowed to water on assigned days, Kern issued a warning to the homeowner.
At Lake Mead, America's most voluminous water impoundment when it was full and a lifeline to everyone from Phoenix to San Diego, the crisis has already arrived.
Lake Mead Water Level
Desiccated palm trees flap over the cracked and peeling shell of a resort hotel at Echo Bay Marina at the northern end of the lake, the tattered banners of a man-made oasis now drained and vacant. Dormant boat docks lie stacked against each other.
To nearby innkeeper Chris Wiggins, it's a sign of government mismanagement.
"Climate change?" he scoffed. "That's the biggest joke."
You don't have to believe in a climate connection to recognize the risks in doling out on paper more water than a river can give.
"In the lower basin, we use more water than in a normal year we receive," said Chuck Cullom, Colorado River program manager for the Central Arizona Project, whose canal pumps water to Phoenix and Tucson.
"Even absent the drought we would still be facing a declining Lake Mead."
A sustained regional drought that started in the late 20th century shrank the reservoir to its record low by last summer. Federal officials say there's a 1-in-4 chance it will sink low enough — to 1,075 feet above sea level — by next year that Arizona will have to cut back substantially on what it takes from the river.
After that, the government projects, the odds are better than even — about 60 percent — for a declared shortage and restrictions in 2017.
The reservoir has fallen by more than 100 feet since 2000. Its stored water, paired with upriver sister reservoir Lake Powell, is at about half-capacity.
The water's retreat is a slow-blooming crisis that many have seen coming for years. Some communities have used the time to curb their thirst.
Los Angeles residents use 129 gallons a day each. That's stingier than the 160-gallon average in Phoenix, whose use rate has nonetheless plummeted in recent years.
Now, though, even conservation-minded Los Angeles is following the unlikely lead of a gaudy, electrified billboard for sustainability. Still ridiculed in some corners as a wasteful and whimsical boomtown in the desert, metro Las Vegas has nonetheless turned its precarious relationship with the river into a powerful incentive to cut back.
Southern Nevadans use 212 gallons a day, which is more than their counterparts in either Los Angeles or Phoenix. But they also return almost 40 percent of that to the river as treated and reusable wastewater, making their net usage rate 124 gallons.
They have slashed usage steeply and deeply, by more than 100 gallons in about a decade.
Las Vegas has cut use of the river by nearly a third in a 12-year period that saw its metro population grow by 25 percent.
Vegas did it by regulating outdoor watering, and by paying $205 million — up to $2 a square foot — to entice people to remove lawns and "embrace living in the Mojave Desert," Entsminger said.
That was crucial, because in 2002, Nevada was using more than its legal entitlement to the river.
Now Los Angeles is following, paying homeowners even more money to strip lawns.
For decades, the Colorado River hasn't typically flowed as high as it did about a century ago, when Congress authorized impounding it at what would become Hoover Dam.
Climate scientists say there's a strong chance it never — or rarely — will again. Yet unlike in those pioneering days of last century, more than 30 million people and several billion dollars in farm production are now counting on a river that is so tapped that in most years it no longer reaches the sea.
What's left after the U.S. uses most of the water is diverted to farmers in Mexico.
"The Colorado River Compact appears to have been negotiated during an unusually wet period," said Connie Woodhouse, a University of Arizona geosciences professor who has studied historic flows on the river. "I don't think anyone would argue with that."
The 1922 agreement split the river's flow between upper- and lower-basin states, with the divide just upstream of Grand Canyon, at Lees Ferry. In the first few decades of the 20th century, an average approaching 17 million acre-feet — each acre-foot gushing 326,000 gallons, 51/2 trillion gallons in all — flowed past Lees Ferry every year.
For most of the past 90 years, though, the average flows have sagged below even the 15 million acre-feet that the states legally share, let alone the 1.5 million owed to Mexico by treaty.
The enormous but shrinking reservoirs at Lake Mead and Lake Powell, capturing spikes in runoff during occasional wet years, have forestalled shortages. The flow was 20 million acre-feet in 2011, and just half that in 2013.
That Colorado, Wyoming and Utah weren't using their full shares also postponed a reckoning.
Until now.
The drought that started in 2000 and sent the reservoir holdings plunging is a preview of expected dry spells unprecedented in recent centuries, Woodhouse said. Temperatures are higher than those of the last century's droughts, compounding the intensity.
"The (rising) temperatures are only going to exacerbate conditions that we would normally expect under natural conditions," she said.
There are lots of reasons to think the droughts of coming decades will be worse than anything we've ever experienced — regardless of whether there's any change in precipitation.
The first is that as the region warms, the trees and plants using the snowmelt will need and tap more of it before it ever reaches the river or pipes.
The next and arguably bigger threat is that the warmth will melt snow faster or even make it fall instead as rain. Either change will lead to more evaporation and less seepage into the soils that, in turn, release water to streams feeding the river.
Four years ago, the U.S. Bureau of Reclamation — the Southwest's federal water managers — crunched all of the climate model projections for the Colorado River watershed and determined the average outlook was for a river pumping 9 percent less water through the region by 2050.
There is always a chance that monstrous snowstorms and winter rains will bring enough new winter precipitation to offset the warming's worst effects, said Jeff Lukas, climate scientist with the University of Colorado's Western Water Assessment team.
"Increasing flow isn't precluded," he added. "It just appears to be less likely."
Past warm spells, etched as living history in the West's tree rings and lake beds, indicate that where there's heat there's often stinging drought, according to Woodhouse's work.
She co-authored a 2010 study using regional tree rings from an unusually long and hot medieval drought to project that each increase of a degree Celsius results in a decrease in Colorado River flows of between 2 percent and 8 percent.
Most of the region already has warmed by more than a degree on average in the past quarter-century, according to last year's U.S. National Climate Assessment. Further warming of at least a couple of degrees in a few decades and up to 5 degrees by 2100 is expected even if global carbon emissions are substantially reduced.
The medieval drought, in its worst decade, baked the river down to about two-thirds of what the U.S. and Mexico draw out of it today.
The drought lasted 60 years, but it was not as hot as today. So it seems the next time there's a repeat of whatever natural phenomena conspired back then to produce such a long, dry spell, the river will be even drier.
Since Woodhouse's study, a team of 14 university and government researchers has conducted what Woodhouse calls the "best synthesis" of existing climate and flow models — with jaw-dropping, if imprecise, predictions.
The river's flow probably will drop between 5 percent and 35 percent in response to warming by midcentury, according to that team, which published a January 2014 report in the Bulletin of the American Meteorological Society.
Lukas' University of Colorado colleague, snow researcher Jeffrey Deems, said there's reason to believe the bureau's predicted 9 percent reduction in flow is optimistic.
Already, the Rocky Mountain snowpack is melting three to six weeks earlier than before American settlement of the region, Deems' studies have found, because dust drifting up from grazing lands and other disturbances collects solar heat on the snow's surface. Today's snowmelt is measured by direct observation and compared with computer models of older trends.
Without emissions curbs, Deems said, his modeling and others project flows slashed by about a fifth on average by midcentury.
"Even if it's only 9 percent," he said, in a nod to the Bureau of Reclamation study, "that's a huge shock to any overallocated system."
A 9 percent reduction would roughly equal the 1.5 million acre-feet that Arizona is allowed to pump through CAP's 336-mile canal every year.
But that's a midcentury outlook with lots of climate variables. What about the near-term effects of the existing drought?
If the government declares a Lake Mead shortage because the water drops below the mandated trigger elevation of 1,075 feet — the 58 percent probability that managers have projected by 2017 — then Arizona would lose 320,000 acre-feet every year that the water is so low.
An acre-foot of water is about the amount two Southwest families use each year. So the loss would be about three times the potable water that Tucson Water pumps to customers each year. But it's not the cities and their residents who will suffer first or most.
CAP was built largely to fuel growth in metropolitan areas of Arizona. The farmers who have used what until now was excess water have the lowest legal priority. Some of them will voluntarily cut back on watering hay and other crops this year, in an effort to help keep Lake Mead from falling.
In December, CAP signed an agreement with the Bureau of Reclamation and water providers for Southern California and Nevada to save 740,000 acre-feet over the next three years, and to keep it in Lake Mead. Each of those organizations would sacrifice water or improve efficiency.
Arizona, with the most to lose from a shortage, is responsible for the largest share: 345,000 acre-feet.
Of that, the deepest cuts — nearly half — will come out of farm irrigation districts. But CAP will pay those farmers $5 million.
"It could actually protect us (from shortage) for a couple of years, and that would more than repay our efforts." said Cullom, CAP's Colorado River program manager.
But in the same agreement, the states predicted that these savings might be only half the job of restoring reliable water by 2019. So they also will join Denver Water in sponsoring $11 million in pilot programs that other customers can use to suppress their needs — some of it perhaps for farm upgrades such as drip irrigation or laser field leveling.
If Lake Mead drops another 25 feet after the first shortage, central Arizona would lose nearly a third of what it draws off the Colorado. Farmers there would get nothing from the river, and cities such as Phoenix, Mesa and Scottsdale could start to lose some of the canal water they're now leasing from Indian tribes.
Best to act now, Cullom said, and reload Lake Mead.
"It's like a scene from 'Jaws,' when one of the characters says, 'We need a bigger boat,' " he said. "We're trying to find ways to get a bigger boat."
Some water managers and politicians have mused about importing the solution, from the Great Lakes or the Mississippi River Basin by pipe, or even from Alaska by ship. But the U.S. Interior Department effectively called those schemes pipe dreams, in a study of options for the Southwest.
For one thing, other states may guard their resources as jealously as Arizona would covet them in a water-strapped future. The Great Lakes states even have a compact prohibiting export, and it is being invoked to prevent a Wisconsin county that touches on the drainage from piping water over the line.
Also, the costs, both environmental and financial, caused the Obama administration to reject the idea. Pumping water from the Missouri River to Denver would cost 21/2 times the predicted price to conserve the same amount within the Southwest.
Conservation probably can provide only a third of the new water needed in 50 years.
Environmentalists generally have recommended starting there, though, and then adding treatment plants to clean salt from used irrigation water and return it to the river. Utility managers are also looking to add costlier, more energy-intensive seawater desalination, which could reduce coastal cities' reliance on the river.
An old car on the Baker Ranch near Baker, Nev.
The biggest sponge out there, though, is agriculture. Its use of two-thirds of the Colorado's bounty offers future urban residents a tantalizing buffer for growth — or a water grab — if it can be reallocated.
About a third of the Colorado River's annual flow goes just to alfalfa, pasture and other forage for livestock, according to a 2013 analysis of farming in the 256,000-square-mile watershed, conducted by the Pacific Institute.
Much of that grass is flood-irrigated, putting to work water that farmers earned through settlement claims under a "use it or lose it" system that predates the West's urban population explosion.
The institute modeled other options for ranchers — modern irrigation equipment and a more judicious schedule for watering — and projected a potential savings of 1 million acre-feet a year.
Farmers won't give up water if they think it means losing their rights to it, and to the income it can bring them, said Kenney, the University of Colorado law professor. But states are free to change the laws, to ditch "use it or lose it." They can ensure that farmers and rural areas are compensated.
Kenney expects change to come, and city dwellers to pay up, as the Central Arizona Groundwater Replenishment District is doing in an experimental program that gives 33 farmers $750 per acre per year for three years to cut and fallow some citrus orchards.
"Scarcity drives innovation," he said.
Back in Las Vegas, water patroller Robert Kern spotted a wet sidewalk near the first violator he nabbed. It wasn't a sprinkler, though. What grass the lawn had was yellowed and crisp.
"I had to mow her lawn the other day because I was afraid there'd be a fire," said a neighbor, Danny Hinchcliffe, standing on his own dewy grass.
Kern climbed from the truck, knelt to find moss growing in a slight but steady stream of water flowing from a broken underground pipe. He attached another warning to her doorknob.
Hinchcliffe said his own yard used to be rock, but he switched to grass because it helped cool his home and keep down the electric bill.
Reminded that his grass blades shouldn't be glistening with water on a day when sprinkling is banned, he said his landscaper likely hadn't had a chance to adjust his timer for the season.
But he didn't get a citation.
Kern can't issue a warning or a ticket unless he actually sees the water spraying.
"Our biggest thing is education," he said. "Without the water, we're not going to be here.
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