NASA: New study: A warming world will further intensify extreme precipitation events

April 4, 2013 According to a newly-published NOAA-led study in Geophysical Research Letters, as the globe warms from rising atmospheric concentrations of greenhouse gases, more moisture in a warmer atmosphere will make the most extreme precipitation events more intense.

The study, conducted by a team of researchers from the North Carolina State University’s Cooperative Institute for Climate and Satellites-North Carolina (CICS-NC), NOAA’s National Climatic Data Center (NCDC), the Desert Research Institute, University of Wisconsin-Madison, and ERT, Inc., reports that the extra moisture due to a warmer atmosphere dominates all other factors and leads to notable increases in the most intense precipitation rates.

The study also shows a 20-30 percent expected increase in the maximum precipitation possible over large portions of the Northern Hemisphere by the end of the 21st century if greenhouse gases continue to rise at a high emissions rate.

“We have high confidence that the most extreme rainfalls will become even more intense, as it is virtually certain that the atmosphere will provide more water to fuel these events,” said Kenneth Kunkel, Ph.D., senior research professor at CICS-NC and lead author of the paper.

The paper looked at three factors that go into the maximum precipitation value possible in any given location: moisture in the atmosphere, upward motion of air in the atmosphere, and horizontal winds. The team examined climate model data to understand how a continued course of high greenhouse gas emissions would influence the potential maximum precipitation. While greenhouse gas increases did not substantially change the maximum upward motion of the atmosphere or horizontal winds, the models did show a 20-30 percent increase in maximum moisture in the atmosphere, which led to a corresponding increase in the maximum precipitation value.

The findings of this report could inform “design values,” or precipitation amounts, used by water resource managers, insurance and building sectors in modeling the risk due to catastrophic precipitation amounts. Engineers use design values to determine the design of water impoundments and runoff control structures, such as dams, culverts, and detention ponds.

“Our next challenge is to translate this research into local and regional new design values that can be used for identifying risks and mitigating potential disasters. Findings of this study, and others like it, could lead to new information for engineers and developers that will save lives and major infrastructure investments,” said Thomas R. Karl, L.H.D., director of NOAA’s NCDC in Asheville, N.C., and co-author on the paper.

The study, Probable Maximum Precipitation (PMP) and Climate Change, can be viewed online. More

 

 

Ancient aqueducts [karez] give Iraq a trickle of hope

A millennia-old labyrinth of underground canals may help solve the Middle East's water crisis, say experts.

The ancient karez in Kunaflusa

In the windswept plateaus of northern Iraq, unseen aqueducts which have channelled water to arid settlements for centuries are running dry. Experts say the wide-scale demise of these ancient water systems is an ominous sign of how scarce water in the region will soon become, and the humanitarian disasters that could follow.

For villagers here, tragic consequences have already arrived.

Farez Abdulrahman Ali strides across a muddy field and sweeps a burly arm towards the mountains that loom over Shekh Mamudian village in the wilds of Iraq’s semi-autonomous Kurdistan region. This is the rugged terrain of thepeshmerga, the Kurdish military whose name means "those who face death".

Ali explains that a subterranean canal - known in Iraq as a karez - once brought water to the village, where it gushed from a rock-lined tunnel into a pool just below the entrance to the local mosque. From there, it was channelled to nearby fields of okra, eggplant, onion and tobacco.

"Farmers would use the water," said Ali. "On hot days, children would play in the water. In the evenings, people would gather at the karez to talk about village things."

"The karez dates back to the time when karez were dug," he added, matter-of-factly. "Nobody in the village knows when it was dug. Even my grandfather doesn't know. It is probably 800 or 900 or 1,000 years old."

"There is now not enough water for farming. If the karez runs dry,

we will be forced to leave the village." - Fadel Salah, Kunaflusa villager

Dry county

In autumn 2011, for the first time in the village's collective memory, the karez in Shekh Mamudian went dry. As the village chief, or mukhtar, Ali sees the loss of the karez as catastrophic for the livestock and crops the village depends on for its hard won self-sufficiency. Unless it is restored, he fears for the end of a community that withstood assaults by Saddam Hussein’s army in the 1980s, and survived as a bloody no-man's land in the Kurdish civil war of the mid-1990s.

"The karez was the source of life," Ali said. "The village now feels like a family that has lost its father."

Echoes of Ali’s lament are being heard throughout the arid mountains and plains of Kurdistan, where the widespread demise of karez is becoming a humanitarian nightmare.

Last year, an inventory of karez systems in Kurdistan - believed to be the first such compiled in modern times - found that decades of war and years of grinding drought, combined with neglect and over-pumping from nearby mechanised wells, had brought these vital water lifelines to the edge of extinction.

According to a UNESCO report, just 116 of the 683 karez networks located in northern Iraq were still supplying water as of August 2009. As many as 40 per cent of the region's karez have dried up in the past four years alone.

Since 2005, more than 100,000 people have been forced to abandon their homes because their karez stopped flowing, and a further 36,000 are at immediate risk of evacuating their villages, according to the UN agency.

Parched land

In Kunaflusa, a rocky 90-minute drive north of Erbil, the village karez was last year producing only a trickle. Village mukhtar Fadel Abdullah Salah said families were allotted one-hour time slots to fill up enough water jugs to last a week.

"There is not enough water now for farming," said Salah. "If the karez runs dry, we will be forced to leave the village."

Water brought in tanker trucks by the Kurdistan Regional Government has helped the people of Kunaflusa. But experts say quick fixes such as hauling in water or drilling new, gas-fuelled wells are expensive band-aids that will ultimately prove unsustainable.

Salah said the village had some 200 houses in 1984, but today only 13 remain occupied. The UN report found that, on average, 70 per cent of residents moved away from their villages after the local karez went dry. More

 

World Water Day 2012 official video

World Water Day 2012 official video, focusing on the theme of the campaign "Water and Food Security".

Produced by kf@kantfish.com and featuring a soundtrack by DDG Project. Animations by antiestatico.com
Download your animation on: http://www.unwater.org/worldwaterday

5 Sobering Realities About Global Water Security

Some people say that water is the oil of the 21st Century. If only water were that simple.

Water is very complicated. It’s affected by large-scale issues like climate change and globalization. International commerce moves virtual water (the water it takes to grow or produce a product) from farms in Brazil to grocery stores in China and Egypt.

But water is also inherently local, impacted by site-specific weather, geography, and other environmental and land use conditions. Managing and using water, then, requires understanding it in its full geographic context.

Today, WRI is launching its new Aqueduct mapping tool to do just that. Aqueduct provides businesses, governments, and other decision makers with the highest-resolution, most up-to-date data on water risk across the globe. Armed with this information, these decision-makers can better understand how water risk impacts them—and hopefully, take actions to improve water security.

5 Findings about Water

So, what are these global maps telling us? Here are five immediate conclusions:

• Water risk has many dimensions. WRI’s Aqueduct tool offers a new way of combining and mapping multiple indicators of water stress. Factors like inter-annual variability, floods, droughts, and groundwater depletion are added to baseline water stress, revealing a richer picture of water stress across the globe. Other important factors related to water quality and reputational risk are also included to help companies and governments understand the full breadth of water risks associated with a particular region or water basin. Not only do these layers enrich the overall picture, they can help inform strategies for improving water security.

• Water stress is growing worldwide. Our new global Aqueduct maps use the most recent 2010 data (previous maps used data from 2000). The picture that emerges shows that water stress is both more prevalent and more severe than estimated in 2000. The new maps reveal areas of higher water stress on every continent, particularlyin China, South and Central Asia, and Africa.

• Water stress isn’t just in arid regions anymore. One of the striking things about Aqueduct’s new maps is that many parts of Europe and the U.S. East Coast and upper Midwest now show medium to high levels of water risk. These regions are not arid, yet they still face significant water stress as demand increases and supply is affected by climate change and other factors.

• High competition and annual variability make for a bad combination. In some areas with elevated water stress—including the U.S. West, Australia, northern China, northwest India, and parts of Pakistan—there is also high variability in available water supply from year to year. In places where demand for water is high relative to the available supply, a greater likelihood of low-water years makes the situation even riskier.

• Increasing risks to food security. Most of the world’s water is used for agriculture, which accounts for approximately 70 percent of all freshwater withdrawals. Overlaying the world’s major irrigated crop regions on Aqueduct maps reveals that many of these areas already face significant water stress. The situation may become more severe in the future—water stress is likely to grow due to climate change and increased demand for food and water. More