Drought Led to Demise of Ancient City of Angkor

The ancient city of Angkor is best known for its ruined temple of Angkor Wat.
CREDIT: Mary Beth Day, University of Cambridge

02 January 2012
Charles Choi, LiveScience Contributor

"Angkor can be an example of how technology isn't always sufficient to prevent major collapse during times of severe instability," Day told LiveScience. "Angkor had a highly sophisticated water management infrastructure, but this technologic advantage was not enough to prevent its collapse in the face of extreme environmental conditions."

The ancient city of Angkor — the most famous monument of which is the breathtaking ruined temple of Angkor Wat — might have collapsed due to valiant but ultimately failed efforts to battle drought, scientists find.

The great city of Angkor in Cambodia, first established in the ninth century, was the capital of the Khmer Empire, the major player in southeast Asia for nearly five centuries. It stretched over more than 385 square miles (1,000 square kilometers), making it the most extensive urban complex of the preindustrial world. In comparison, Philadelphia covers 135 square miles (350 sq. km), while Phoenix sprawls across more than 500 square miles (1,300 sq. km), not including the huge suburbs.

Ancient Capital Wilted When Water Ran Low

Angkor Wat in 1866

January 2, 2012
By HENRY FOUNTAIN
The New York Times

Angkor, the ancient city in Cambodia that was the seat of the Khmer empire, flourished from the 9th to the 15th century. Today, tourists still appreciate the remnants of its architecture and sophisticated hydro-engineering systems, composed of canals, moats and large reservoirs known as barays.

Researchers now studying sediments from one of the reservoirs report that prolonged droughts and overuse of the soil may have interfered with Angkor’s water management system and led to the empire’s decline.

“When Angkor collapsed, there was a drop in water levels,” said Mary Beth Day, an earth scientist at the University of Cambridge in England. “And much less sediment was delivered to the baray at the time.”

Will water scarcity increase tensions across Asia?

Mon, Dec 26, 2011
By: Sundeep Waslekar/ Forbes India

Governments across the underdeveloped regions of the world are already facing the threat of water wars. We believe 2012 will be the year the world starts looking for solutions to its aqua problems.

Water will be one of the defining issues of the next half century. It’s a critical issue and this realisation will start from 2012.

There are a number of reasons why water will be so critical. Let’s start from Southeast Asia and go all the way to Africa. Vietnam, Cambodia, Thailand, Laos; then there’s China, Bangladesh, Nepal, India, Pakistan, Afghanistan, Iran, Iraq, Syria, Turkey; then we go south to Israel, Palestine, Egypt and all the way to Tanzania. It’s a mega arc of hydro insecurity.

If water supply drops by 5 percent in 20-25 years in China and India, food production here will also drop, while demand would have gone up substantially. Already there are food crises. The world noticed that in 2008 when prices went up for the first time. Right now, India and China are not in the market in a big way. In another 25 years you have a possibility of these countries entering the food market as buyers. This will wreak huge havoc.

Water shortage looms large [in Vietnam], say experts

12/11/2010

VietNamNet Bridge – Despite its huge water resources, Vietnam will face a critical shortage of water for economic development in the years to come due to uncontrolled tapping, pollution and local and regional constructions of dams, experts said on Wednesday.

The lack of water has in fact existed, as the country’s current water usage per capita is between 2,800 and 3,500 cubic meters per year only, said an official of the Ministry of Natural Resources and Environment.

Le Huu Thuan, deputy general director of the ministry’s Department of Water Resources Management, told reporters that if the water amount per capita of a nation was under 4,000 cubic meters a year, then that nation was considered in a lack of water. He was speaking at a seminar titled “Vietnam’s Water Resources and Challenges.”

Thuan told the Daily on the sidelines of the seminar that at the moment, Vietnam is annually exploiting a total of over 80 billion cubic meters of surface water plus over four billion cubic meters of underground water.

But the demand will rise by 50% in the next ten years for economic development, he said.

“The required water volume for all industries since 2020 is estimated to rise up to 120 billion cubic meters, an increase of 48% compared to the present demand,” he said. He projected that water for farming would increase by 30%, for industrial use by 190%, urban consumption by 150% and aquaculture by 90% in the next ten years.

Although the water demand is projected to increase sharply, the surface water resources in many waterways, lakes and rivers has been heavily polluted, hindering exploitation and supply in the future, he said.

“If we have no drastic measures for effective management and usage of our water resources right now, then the country will face a severe shortage of water for economic development in the years to come,” he said.

“Therefore, we have to consider a water security program like the food or energy security programs,” he stressed.

Thuan said the Ministry of Natural Resources and Environment is mapping out some projects for building capacity of assessing and managing the water resources in Vietnam with the technical assistance from several international organizations and other countries.

Figures from the seminar show that Vietnam is endowed with a dense waterway system of some 2,370 rivers in the country. Water resources are estimated at 640 billion cubic meters of rainwater a year, 830 billion cubic meters from the system of rivers and canals, and 64 billion cubic meters of underground water.

However, the problem is that the huge water resources are not evenly allocated, with the Mekong Delta region along accounting for 57% compared to some 40% for the rest of the country.

The Dong Nai River basin, for example, accounts for only 4.2% of the country’s total water reserve, while this region makes up 28% of the nation’s gross domestic product.

Furthermore, nearly two-thirds of the surface water volume flows from outside the country like China, Thailand, Laos, and Cambodia, so the construction of hydropower dams upstream will also pose huge risks.

Martin Junker, an expert of the Belgian-funded CAPAS project to assist Vietnam in water resources management, told the Daily at the seminar that given the country’s economic growth of some 7.5% a year and the increasing rural-to-urban migration, the water supply scenario is changing for the worse.

Therefore, it is high time to look for far-reaching solutions to remedy the overexploitation of river basins, he said.

Water shortage among the poor in Kampong Thom province0

Kampong Chhnang farmers face water shortage still

Report and video by Uon Chhin, Radio Free Asia

Asia’s Water Crisis

August 30, 2010
Mong Palatino
The New Nation (Bangladesh)

As the contradictions of Asia's water challenges have been laid bare this summer-with millions affected by flooding while others are hit by droughts-one thing has been made clearer: the coming water crisis could exacerbate already simmering domestic and regional tensions.

Heavy monsoon rains have produced the worst flooding in Pakistan's history, with more than three weeks of flooding leaving at least 1,500 dead and more than 4 million homeless. Millions of Pakistanis already require humanitarian assistance, yet the likelihood that many more could be added to this list has grown with the announcement that 200,000 have been evacuated as flood waters continue to rise in Singh Province in the country's south.

Meanwhile, flash floods and mudslides have submerged some villages in China's Gansu Province, killing hundreds and leaving more than a thousand missing. Today, Chinese state media announced 250,000 had been evacuated in the north of the country after the Yalu River burst its banks.

But while attention has been focused on disasters in Pakistan in China, South-east Asia has been hit by its own torrential downpours. Last month, Singapore suffered three major floods-an unprecedented number for the prosperous city state-with even the shopping and financial districts hit in the first serious flooding disaster in the city since 1978.

Vietnam has also been affected, with many parts of Hanoi under water last month after a major storm struck the country. What added insult to injury in Vietnam's case is that the flooding came after a nine-month dry spell that disrupted the country's power supply (about a third of Vietnam's power source comes from hydroelectric power plants whose operations have been adversely affected by falling water levels in the Mekong River).

And Vietnam hasn't been the only country in the region to face the twin curse of droughts and flooding. The Philippines (recently ranked by the Belgium-based Center for Research and Epidemiology Disasters as the most disaster-prone area in the world) was last year hit by 14 meteorological and 9 hydrological disasters, the most devastating of which was last September's typhoon, which unleashed the worst flooding in Metro Manila in 40 years.

This year, although floods have been a regular occurrence in Manila since the start of the wet season, the June-July rainfall was insufficient to increase water levels at the Angat Dam-the principal source of fresh water in the country's capital. The result has been both tragic and somehow comic: Residential homes are flooded, but there's no water in the faucets.

To top all this, Thailand is also this year experiencing a longer than usual dry season and was forced to postpone the rice planting season for a month, which will have knock-on effects around the region as Thailand, like Vietnam, is among the world's top rice exporters.

It's an alarming pattern-both flooding and dry spells across Asia are becoming more intense, and occurring more frequently, each year.

So how should Asian governments respond? For a start, they can do better than simply blaming God or Nature, arguments rolled out by one Singaporean minister to explain the massive flooding there.

Flash floods, landslides, and other symptoms of climate change are also in part man-made disasters. In the case of Singapore, for example, some experts blame excessive property development in the city for rising floodwaters, while the Gansu landslide in China has been linked to massive deforestation, mining activities and the construction of several hydropower plants in the area.

Inadequate government planning is also a major reason for the rising human casualties. The Philippines drafted comprehensive flood control measures as early as 1976 but failed to implement the proposed engineering solutions to minimize the harmful impact of the annual floods. Water rationing is now being undertaken in Manila precisely because previous governments have failed to develop or tap other sources of clean water. If Malaysia doesn't learn from the mistakes of the Philippines, it's estimated that it too could encounter a water crisis in 2014.

But swiftly addressing these problems is about more than the immediate goal of saving lives in individual countries-doing so can also help prevent regional disputes. For example, the construction of several dams in China along the Mekong River has been pinpointed as one reason for the drop in water levels along the river, which is vital for servicing the water needs of Thailand, Laos, Cambodia, and Vietnam (though of course China resents any suggestion that its damming activities are causing environmental problems for its neighbours).

There's potential for such disputes to turn into conflict. For countries like Singapore confronted with scarce water supplies, it's crucial that sustainable water agreements are inked with adjacent countries. Singapore has a water agreement with Malaysia, but the deal comes to an end next year. Former Malaysian Prime Minister Mahathir Mohamad pondered in a blog entry whether it's time to charge Singapore for the water it buys from Malaysia at adjusted market prices. This comes at a time when Malaysia is blaming Singapore's land reclamation project for flooding in the Sungai Johor area. Could Malaysia and Singapore end up battling over clean water next year?

This isn't, of course, the only potential flashpoint over water in Asia-India and Pakistan have already been widely cited as two countries at risk of conflict over Himalayan water sources.

But it's still unclear whether there's any urgency to take a more broad-based approach to tackling these problems.

Regional governments find plenty of time to meet and discuss trade imbalances, poverty and terrorism. But recent crises have demonstrated that it's time they also stopped seeing problems such as the floods in Pakistan as simply national, internal issues and started taking a regional perspective instead. Failure to do so may well prove nothing short of disastrous.

China's dams on the Brahmaputra

• India and China have no water-sharing agreements
• Pressure should be put on China to respect international regulations

May 25, 2010
Rediff News

For many months the fact that China was building a dam in Zangmu was known and photographs were circulating on the Internet. Why did India take up the matter with China so warily? Claude Arpi on the dangers of China's dams on the Brahmaputra in Tibet.

In October 2003, I wrote an article Diverting the Brahmaputra: a Declaration of War. At the time, I was told that it was a cheap journalistic gimmick; there was no 'scientific' proof!

My question then was: "What is the rationale for the project?" My answer was that the two most acute problems faced by China were food and water.

Seven years later, these issues are more acute than ever: Water is a rarer commodity in China and agriculture needs more water to sustain the increasing requirements of a wealthier population.

Twenty years ago, this led Chinese experts to look around for water. The answer was not far: Tibet is the water tower of Asia. About 90 per cent of the Tibetan rivers runoff flows downstream to China, India, Bangladesh, Nepal, Pakistan, Thailand, Burma, Laos, Cambodia and Vietnam.

Thus the idea to use Tibet's waters for Northern China was born.

One of the possibilities was to divert waters from the Great Bend of the Yarlung Tsangpo, north of the McMahon Line, by building a mega structure. There are different versions of the project, but the Shuotian Canal is the most elaborated. It is the brainchild of an engineer, Guo Kai, whose life mission is to save China with Tibet's waters.

Guo not only worked closely with experts from the Chinese ministry of water resources and the academy of sciences, but he also made several on-the-spot investigations and surveys, before coming up with the details of his pharaonic scheme.

From the start the Chinese military have shown a lot of interest in Guo's Great Western Route scheme. In November 2005, the Great Western Route project got a boost with the publication of a book entitled Save China Through Water From Tibet, written by a Li Ling; the writer used Guo's theme and arguments.

In November 2006, Chinese Minister for Water Resources Wang Shucheng categorically stated that the proposal was 'unnecessary, unfeasible and unscientific.' He, however, admitted: 'There may be some retired officials that support the plan, but they are not the experts advising the government.' It was not a point blank denial as he admitted that the project existed. As we know, governments change, so do their advisors.

Mekong River to be thirsty for fresh water

Farmers in the Mekong River Delta are facing the encroachment of salt water. Photo: Farmers in Tien Giang province cut down paddy trees which are dried by salt water as food for cattle.

27/05/2009
VietNamNet/TT

VietNamNet Bridge – China’s construction of big hydro-power dams on the Mekong River will be a great threat to the future of the river, a significant water source for Southeast Asia, a United Nations report said. Senior experts analysed the impacts on Vietnam’s Mekong River Delta.

According to AP, China has built eight dams on the upper Mekong River in Yunnan province. It recently finished the construction of the 292m Xiaowant Dam, the world’s highest arch dam. The UN report released on May 21 said that this dam’s capacity is equivalent to the entire capacity of all reservoirs in Southeast Asia.

At the same time, Laos has begun to build 23 dams on the lower Mekong River and its estuaries. This work is scheduled to finish in 2010.

The UN report stated that only the Xiaowant Dam can change the water volume and the running speed of water, creating a reduction of water quality and biodiversity in the Mekong River, which runs through six countries.

Young Woo Park, the UN Environment Programme director, warned the six governments to pay attention to the Mekong River, otherwise the future water resources of these countries may be threatened.

Ky Quang Vinh, director of the HCM City-based Centre for Observation of Natural Resources and the Environment, analysed the impacts of Chinese dams on the lower section of the Mekong River, particularly the Mekong River Delta of Vietnam.

He said: Dams of 15m height are quite big. It is unimaginable that the Xiaowant Dam is 292m. This dam may help draw water to serve some dry regions in China or to produce hydro-power. However, a vast area will be submerged, which will cause changes in the eco-system in this region. Some flora and fauna species may disappear, including rare ones.

The Mekong River is being cut into pieces, not only by the Xiaowant Dam in China, but dams in other countries like Laos, Thailand and Cambodia. These Southeast Asian countries plan to build 11 hydro-power dams on the main branch of the Mekong River. These dams will prevent flows of fish and cause disorder in the river, threatening the lives of millions of people who live along the river.

China’s dams on the upper Mekong River have caused serious environmental problems for the lower section like in Myanmar, northern Thailand and northern Laos. The decline of fish reserves and the change of the water level will make the lives of local people harder.

The Mekong River ranks behind only the Amazon in diversity of aquatic animals. It is one of the richest baskets of fresh-water fish in the world, which supports over 60 million people. It is estimated that the river yields income of more than $3 billion a year.

The construction of dams on the main stem of the river will threaten the extinction of rare animals, for example the Irrawaddy dolphin, Mekong giant catfish and others. Eco-regression will be a global disaster.

In Vietnam, there will be eco-changes. A huge volume of fish often moves to the Cuu Long River (the section of Mekong River in Vietnam) during the flood season. Dams prevent the flow of fish to Vietnam. In addition, ecological balance will shift. Perhaps the Mekong River Delta will not have a flood season anymore because there will not be enough water.

More dangerously, the river will be seriously short of fresh water. It happened in the recent dry season and will be more serious in the coming years. The water volume has also decreased. Measurements conducted last October showed that the flow was 28,000 cu.m per second while it was 40,000 cu.m in the past.

In the 2009 winter-spring crop, the flow of the Tien and Hau Rivers was only 1,600 cu.m per second, 100 cu.m per second less than required. In some areas in the lower section of the Cuu Long River, farmers lacked fresh water for irrigation. In coastal areas of Tien Giang, Ben Tre, Tra Vinh, Soc Trang, Bac Lieu and Ca Mau, salt water encroached 70km into the mainland.

In Vi Thanh town, Tien Giang province, for the first time the local people had to use salt water for 3-4 days continuously because tap water providers didn’t know that their sources of water were contaminated with salt water.

Prof. Ngo Dinh Tuan, chairman of the Institute for Southeast Asian Water Resources and Environment’s Scientific Council, said:

In the 1950s, China announced its strategy to move water from the south to the north. Since then they have constructed many dams on the Mekong River. These dams initially serve hydro-power production but according to many experts, they will serve to transfer water from the Mekong River to the Yangzi Jiang River and then to the dry northern region of China.

Other countries like Laos, Cambodia and Thailand are also building dams on the river. It is estimated that around 20 dams will be built on the river and these dams will greatly influence Vietnam, at the lower section of the Mekong River.

If China builds dams to serve power production, the first impact would be a remarkable reduction of aquatic resources and the volume of alluvium in the Mekong River Delta, resulting in landslides to balance the alluvial volume. It would be very dangerous for people who live in the lower section.

If China builds dams to transfer water from the Mekong River to the northern region, it would be very dangerous because the water volume going down to the lower section would be reduced considerably.

Some institutions were established to deal with these problems, for example the Mekong River Committee of Vietnam and the International Mekong River Committee, which groups up Vietnam, Laos, Cambodia and Thailand. However, the role of these institutions is modest.

Anyways, the Mekong River Committee of Vietnam partly contributes to prevent adverse impacts on the lower section of the Mekong River. We have to take initiative in joining voices with the world in preventing countries on the upper part of the river from overexploiting water resources. We have to accept the construction of dams to produce hydroelectricity but we have to protest the transfer of water from the river to other regions, otherwise the impacts would be very serious, especially when Vietnam has to suffer from impacts of climate changes.

We need a national strategy on this issue. I think we have to build doors at the estuaries of nine branches of the Mekong River in Vietnam to prevent the encroachment of salt water. We also have to build reservoirs to stock up on water for the dry season.

This is a big issue that the government should address soon. It is not only a problem for the Cuu Long River, but the Red River as well, because China has also built dams on the upper Red River.

UN study advises caution over dams

Thursday, May 21, 2009
By MICHAEL CASEY

BANGKOK (AP) — A dam-building spree in China poses the greatest threat to the future of the already beleaguered Mekong, one of the world's major rivers and a key source of water for the region, a U.N. report said Thursday.

China is constructing a series of eight dams on the upper half of the Mekong as it passes through high gorges of Yunnan Province, including the recently completed Xiowan Dam, which — at 958 feet (292 meters) high — is the world's tallest. Its storage capacity is equal to all the Southeast Asia reservoirs combined, the U.N. report said.

Laos, meanwhile, has started construction on 23 dams expected to be finished by 2010 on the Mekong and its tributaries, the U.N. said, as a means to spur development and lift the country from poverty. Cambodia and Vietnam also have ambitious dam-building plans.

"China's extremely ambitious plan to build a massive cascade of eight dams on the upper half of the Mekong River, as it tumbles through the high gorges of Yunnan Province, may pose the single greatest threat to the river," the report said.

The report went onto to say that the impacts of the proposed dam development include "changes in river flow volume and timing, water quality deterioration and loss of biodiversity."

China's Foreign Ministry spokesman Ma Zhaoxu said in a regular briefing the government pays equal attention to the development of the Mekong and its protection. The Mekong is known as the Lancang river in China.

"I would like to point out that the Chinese government attaches great importance to the exploration and the protection of cross-border rivers and conducts the policy of equal attention to development and protection," Ma said.

The proposed dams would add further pressure to the Mekong, which runs through China, Myanmar, Laos, Thailand, Cambodia and Vietnam. The 307,000-square-mile (795,000-square-kilometer) river network is home to dozens of rare bird and marine species, including the Mekong giant catfish, and is a source of food and jobs for the 65 million people who live in the river basin.

The river and its vast tributary network already face threats from pollution, climate change and the effects of earlier dams that were built in China and have caused water levels to drop sharply on the upper Mekong.

Still, the U.N. report said for the time being, the Mekong's pollution levels were not at "alarming levels" while water shortages and conflicts over water on the Mekong have so far not emerged.

"The Mekong is in good condition at this time and can take more pressure such as irrigation development or industrial development," said Mukand S. Babel, one of the reports' authors.

The report, however, found several river basins in the Mekong that are under threat, including the Tonle Sap in Cambodia, Nam Khan in Laos and Sekong-Sesan Srepok in Vietnam and Cambodia due to increasing development and demand for water.

It called for countries bordering the Mekong to work more closely together to ensure that the region's growing population and expected economic development doesn't further strain the capacity of the delta.

"The time to tackle these challenges is now, otherwise the projected growth and development may impact on the basin's ability to meet future water needs," said Young-Woo Park, a U.N. regional director.

Asia may see more conflicts over water: Report

• 1 in 5 Asians lack access to safe drinking water
• Problem worsened by population growth, climate change

By Claudia Parsons

NEW YORK, April 17 (Reuters) - Asia may see more conflicts over scarce water resources in the coming years as climate change and population growth threaten access to the most basic natural resource, a report warned on Friday.

Water problems in Asia are already severe, with one in five people, or 700 million, not having access to safe drinking water and half the region's population lacking access to basic sanitation, according to the report produced by the Asia Society, a New York-based think tank.

Population growth, rapid urbanization and climate change are expected to worsen the situation, according to the report, "Asia's Next Challenge: Securing the Region's Water Future."

It noted water disputes between hostile neighbors India and Pakistan and the complex relations governing the vast Mekong River, which is shared by China and its southern neighbors, Myanmar, Laos, Thailand, Cambodia and Vietnam.

The report said while water issues have more often generated cooperation than conflict between nations in the past, demographic pressures and water scarcity would be unprecedented in the coming decades.

"The potential for conflicts sparked by the direct and indirect impacts of an increasingly volatile water supply should not be underestimated, particularly in the light of rising concerns about climate change," it said.

"No matter how we approach water resources -- whether it is on the basis of quality and quantity, or as the most potent manifestation of extreme climatic events -- hydropolitics is likely to be a growing force in Asian security," it said.

While Asia is home to more than half the world's population, it has less fresh water per person than any other populated continent, the report said. Asia's population is expected to rise by nearly 500 million within 10 years.

"The majority of Asia's water problems are not attributable to an actual shortage, but rather are the result of poor water governance," it said. "They are solvable through more effective governance and better management practices."

The report makes 10 recommendations to governments in Asia, including greater regional cooperation and ensuring that water management organizations work directly with those responsible for defense and diplomacy.

It also urged more investment, both public and private, in efficient water management and infrastructure.

(Editing by Ellen Wulfhorst and Eric Beech)

Cambodia faces immediate threats from climate change

PHNOM PENH, Nov. 29 (Xinhua) -- Cambodia faces immediate threats to its agricultural production and food security from climate change in rainfall, temperatures and availability of water, said the UNDP Human Development Report (HDR) 2007 released here on Thursday.

For most Cambodians live in rural areas and are reliant on agriculture, long-term risks associated with climate change include water insecurity, increased sea level, cyclones and disruption or collapse of Cambodia's critical ecosystems, said the United Nations Development Program (UNDP) in the report.

Climate change may increase occurrence of drought and flood while increasing the vulnerability of Cambodia's poor people to their effects, it said.

Increase of disease with climate change may have an adverse impact on people's health, particularly the most vulnerable poor, it said.

However, it said, climate change presents Cambodia many opportunities.

For example, it said, Cambodia can seek technical assistance and financial resources to promote climate change mitigation and adaptation, and mobilize private sector partnerships to transfer appropriate technologies to promote renewable energy in order to support the development of other sectors such as health, education, and transport.

With 0.2 percent of world's population, Cambodia accounts for a negligible percentage of global emissions, it said.

The country has signed and ratified the Kyoto Protocol and as a developing country, Cambodia has no obligation to reduce its greenhouse gas emissions, but can contribute to emission reduction on a voluntary basis, including through the Clean Development Mechanism (CDM), it said.

Cambodia ranks 131 out of 177 countries in the Human Development Index (HDI) with its HDI value moving up from 0.543 to0.598 in the last five years, according to the report.

Falling water tables threatens grain harvests [The Damming of the Mekong River]

08 Aug 2007
By Lester R.Brown
President of the Washington-based Earth Policy Institute
Posted at PeopleandPlanet.net

As China's farmers sink their pumps ever lower and aquifers begin to run dry grain harvests could be in serious trouble says Lester Brown in this wide-ranging report on the problem.

As the world's demand for water has tripled over the last half-century and as the demand for hydroelectric power has grown even faster, dams and diversions of river water have drained many rivers dry. As water tables fall, the springs that feed rivers go dry, reducing river flows.

Scores of countries are overpumping aquifers as they struggle to satisfy their growing water needs, including each of the big three grain producers - China, India, and the United States. More than half the world's people live in countries where water tables are falling.

There are two types of aquifers: replenishable and nonreplenishable (or fossil) aquifers. Most of the aquifers in India and the shallow aquifer under the North China Plain are replenishable. When these are depleted, the maximum rate of pumping is automatically reduced to the rate of recharge.

For fossil aquifers, such as the vast US Ogallala aquifer, the deep aquifer under the North China Plain, or the Saudi aquifer, depletion brings pumping to an end. Farmers who lose their irrigation water have the option of returning to lower-yield dryland farming if rainfall permits. In more arid regions, however, such as in the southwestern United States or the Middle East, the loss of irrigation water means the end of agriculture.

1000-feet pumps

The US embassy in Beijing reports that Chinese wheat farmers in some areas are now pumping from a depth of 300 metres, or nearly 1,000 feet. Pumping water from this far down raises pumping costs so high that farmers are often forced to abandon irrigation and return to less productive dryland farming. A World Bank study indicates that China is overpumping three river basins in the north - the Hai, which flows through Beijing and Tianjin; the Yellow; and the Huai, the next river south of the Yellow. Since it takes 1,000 tons of water to produce one ton of grain, the shortfall in the Hai basin of nearly 40 billion tons of water per year (1 ton equals 1 cubic metre) means that when the aquifer is depleted, the grain harvest will drop by 40 million tons -enough to feed 120 million Chinese.

In India, water shortages are particularly serious simply because the margin between actual food consumption and survival is so precarious. In a survey of India's water situation, Fred Pearce reported in New Scientist that the 21 million wells drilled are lowering water tables in most of the country. In North Gujarat, the water table is falling by 6 meters (20 feet) per year. In Tamil Nadu, a state with more than 62 million people in southern India, wells are going dry almost everywhere and falling water tables have dried up 95 percent of the wells owned by small farmers, reducing the irrigated area in the state by half over the last decade.

As water tables fall, well drillers are using modified oil-drilling technology to reach water, going as deep as 1,000 meters in some locations. In communities where underground water sources have dried up entirely, all agriculture is rain-fed and drinking water is trucked in. Tushaar Shah, who heads the International Water Management Institute's groundwater station in Gujarat, says of India's water situation, "When the balloon bursts, untold anarchy will be the lot of rural India."

In the United States, the U.S. Department of Agriculture reports that in parts of Texas, Oklahoma, and Kansas--three leading grain-producing states--the underground water table has dropped by more than 30 meters (100 feet). As a result, wells have gone dry on thousands of farms in the southern Great Plains. Although this mining of underground water is taking a toll on U.S. grain production, irrigated land accounts for only one fifth of the U.S. grain harvest, compared with close to three fifths of the harvest in India and four fifths in China.

Pakistan, a country with 158 million people that is growing by 3 million per year, is also mining its underground water. In the Pakistani part of the fertile Punjab plain, the drop in water tables appears to be similar to that in India. Observation wells near the twin cities of Islamabad and Rawalpindi show a fall in the water table between 1982 and 2000 that ranges from 1 to nearly 2 meters a year.

In the province of Baluchistan, water tables around the capital, Quetta, are falling by 3.5 meters per year. Richard Garstang, a water expert with the World Wildlife Fund and a participant in a study of Pakistan's water situation, said in 2001 that "within 15 years Quetta will run out of water if the current consumption rate continues."

Iran villages abandoned

Iran, a country of 70 million people, is overpumping its aquifers by an average of 5 billion tons of water per year, the water equivalent of one third of its annual grain harvest. Under the small but agriculturally rich Chenaran Plain in northeastern Iran, the water table was falling by 2.8 meters a year in the late 1990s. New wells being drilled both for irrigation and to supply the nearby city of Mashad are responsible. Villages in eastern Iran are being abandoned as wells go dry, generating a flow of "water refugees."

Saudi Arabia, a country of 25 million people, is as water-poor as it is oil-rich. Relying heavily on subsidies, it developed an extensive irrigated agriculture based largely on its deep fossil aquifer. After several years of using oil money to support wheat prices at five times the world market level, the government was forced to face fiscal reality and cut the subsidies. Its wheat harvest dropped from a high of 4 million tons in 1992 to some 2 million tons in 2005. Some Saudi farmers are now pumping water from wells that are 1,200 meters deep (nearly four fifths of a mile).

In neighboring Yemen, a nation of 21 million, the water table under most of the country is falling by roughly 2 meters a year as water use outstrips the sustainable yield of aquifers. In western Yemen's Sana'a Basin, the estimated annual water extraction of 224 million tons exceeds the annual recharge of 42 million tons by a factor of five, dropping the water table 6 meters per year. World Bank projections indicate the Sana'a Basin--site of the national capital, Sana'a, and home to 2 million people--will be pumped dry by 2010.

In the search for water, the Yemeni government has drilled test wells in the basin that are 2 kilometres (1.2 miles) deep - depths normally associated with the oil industry - but they have failed to find water. Yemen must soon decide whether to bring water to Sana'a, possibly by pipeline from coastal desalting plants, if it can afford it, or to relocate the capital. Either alternative will be costly and potentially traumatic.

Israel's growing population

Israel, even though it is a pioneer in raising irrigation water productivity, is depleting both of its principal aquifers--the coastal aquifer and the mountain aquifer that it shares with Palestinians. Israel's population, whose growth is fueled by both natural increase and immigration, is outgrowing its water supply. Conflicts between Israelis and Palestinians over the allocation of water in the latter area are ongoing. Because of severe water shortages, Israel has banned the irrigation of wheat.

In Mexico - home to a population of 107 million that is projected to reach 140 million by 2050 -the demand for water is outstripping supply. Mexico City's water problems are well known. Rural areas are also suffering. For example, in the agricultural state of Guanajuato, the water table is falling by 2 metres or more a year. At the national level, 51 per cent of all the water extracted from underground is from aquifers that are being overpumped.

Since the overpumping of aquifers is occurring in many countries more or less simultaneously, the depletion of aquifers and the resulting harvest cutbacks could come at roughly the same time. And the accelerating depletion of aquifers means this day may come soon, creating potentially unmanageable food scarcity.

Disappearing rivers

While falling water tables are largely hidden, rivers that are drained dry before they reach the sea are highly visible. Two rivers where this phenomenon can be seen are the Colorado, the major river in the southwestern United States, and the Yellow, the largest river in northern China. Other large rivers that either run dry or are reduced to a mere trickle during the dry season are the Nile, the lifeline of Egypt; the Indus, which supplies most of Pakistan's irrigation water; and the Ganges in India's densely populated Gangetic basin. Many smaller rivers have disappeared entirely.

Since 1950, the number of large dams, those over 15 meters high, has increased from 5,000 to 45,000. Each dam deprives a river of some of its flow. Engineers like to say that dams built to generate electricity do not take water from the river, only its energy, but this is not entirely true since reservoirs increase evaporation. The annual loss of water from a reservoir in arid or semiarid regions, where evaporation rates are high, is typically equal to 10 percent of its storage capacity.

The Colorado River now rarely makes it to the sea. With the states of Colorado, Utah, Arizona, Nevada, and, most important, California depending heavily on the Colorado's water, the river is simply drained dry before it reaches the Gulf of California. This excessive demand for water is destroying the river's ecosystem, including its fisheries.

A similar situation exists in Central Asia. The Amu Darya--which, along with the Syr Darya, feeds the Aral Sea--is diverted to irrigate the cotton fields of Central Asia. In the late 1980s, water levels dropped so low that the sea split in two. While recent efforts to revitalize the North Aral Sea have raised the water level somewhat, the South Aral Sea will likely never recover.

China's Yellow River, which flows some 4,000 kilometers through five provinces before it reaches the Yellow Sea, has been under mounting pressure for several decades. It first ran dry in 1972. Since 1985 it has often failed to reach the sea, although better management and greater reservoir capacity have facilitated year-round flow in recent years.

The Nile, site of another ancient civilization, now barely makes it to the sea. Water analyst Sandra Postel, in Pillar of Sand, notes that before the Aswan Dam was built, some 32 billion cubic meters of water reached the Mediterranean each year. After the dam was completed, however, increasing irrigation, evaporation, and other demands reduced its discharge to less than 2 billion cubic meters.

Pakistan, like Egypt, is essentially a river-based civilization, heavily dependent on the Indus. This river, originating in the Himalayas and flowing westward to the Indian Ocean, not only provides surface water, it also recharges aquifers that supply the irrigation wells dotting the Pakistani countryside. In the face of growing water demand, it too is starting to run dry in its lower reaches. Pakistan, with a population projected to reach 305 million by 2050, is in trouble.

Damming the Mekong

In Southeast Asia, the flow of the Mekong is being reduced by the dams being built on its upper reaches by the Chinese. The downstream countries, including Cambodia, Laos, Thailand, and Viet Nam--countries with 168 million people--complain about the reduced flow of the Mekong, but this has done little to curb China's efforts to exploit the power and the water in the river.

The same problem exists with the Tigris and Euphrates Rivers, which originate in Turkey and flow through Syria and Iraq en route to the Persian Gulf. This river system, the site of Sumer and other early civilizations, is being overused. Large dams erected in Turkey and Iraq have reduced water flow to the once "fertile crescent," helping to destroy more than 90 percent of the formerly vast wetlands that enriched the delta region.

In the river systems just mentioned, virtually all the water in the basin is being used. Inevitably, if people upstream use more water, those downstream will get less. As demands continue to grow, balancing water demand and supply is imperative. Failure to do so means that water tables will continue to fall, more rivers will run dry, and more lakes and wetlands will disappear.

Lester R.Brown is President of the Washington-based Earth Policy Institute.

This article is adapted from Chapter 3, "Emerging Water Shortages" in Lester R. Brown, Plan B 2.0: Rescuing a Planet Under Stress and a Civilization in Trouble (New York: W.W. Norton & Company, 2006), available free of charge on-line at
www.earthpolicy.org

Drought in Kompong Thom worries farmers

Provincial Drought Worries Farmers

Suon Kanika, VOA Khmer
Original report from Kampong Thom Province
20/06/2007

Drought in Kampong Thom province has farmers in the area worried over impending hardship.

Rainfall has been short, and farmers who rely on Cambodia's monsoon season fret they won't produce enough food for their families and income. "Right now I am worried," said Stoung town farmer Buth Chorn, who has six children. "This year I am a victim to this extended drought…. Next year, I will definitely be needy again, meaning I will starve."

Preah Damrey Commune Chief Mith Salang, from the opposition Sam Rainsy Party, told VOA Khmer farmers from more than 1,200 families in his commune could only plant one season of rice due to lack of water.

In normal years, farmers can plant two seasons of the staple.

"The town has no capacity" to help drought-stricken farmers, Ang Ky, chief of Stoung town, said.

Local representatives were being sent to assess villagers' needs, he said.

"Whatever the villagers lost because of the drought, like seeds, then the town will help intervene and contact the provincial agricultural authorities and other institutions," he said.