Water Productivity In Irrigation example essay topic

Emerging Water Shortages Threaten Food Supplies, Regional Peace Spreading water shortages threaten to reduce the global food supply by more than 10 percent. Left unaddressed, these shortages could lead to hunger, civil unrest, and even wars over water, reports a new book from the Worldwatch Institute. Irrigation accounts for two thirds of global water use, but less than half that water reaches the roots of plants. 'Without increasing water productivity in irrigation, major food-producing regions will not have enough water to sustain crop production,' said Sandra Postel, author of Pillar of Sand: Can the Irrigation Miracle Last? The book was funded by the Wallace Genetic Foundation and by the Pew Fellows Program of the Pew Charitable Trusts. 'Some 40 percent of the world's food comes from irrigated cropland,' said Postel, 'and we " re betting on that share to increase to feed a growing population.

' But the productivity of irrigation is in jeopardy from the over pumping of groundwater, the growing diversion of irrigation water to cities, and the buildup of salts in the soil. 'Our civilization is not the first to be faced with the challenge of sustaining its irrigation base,' said Postel, director of the Global Water Policy Project in Amherst, Massachusetts, and a senior fellow at the Worldwatch Institute. 'A key lesson from history is that most irrigation-based civilizations fail. As we enter the third millennium A.D., the question is: will ours be any different?' Today, irrigation problems are widespread in the grain-growing regions of central and northern China, northwest and southern India, parts of Pakistan, much of the western United States, North Africa, the Middle East, and the Arabian Peninsula.

Water tables are dropping steadily in several major food-producing regions as groundwater is pumped faster than nature replenishes it. The world's farmers are racking up an annual water deficit of some 160 billion cubic meters-the amount used to produce nearly 10 percent of the world's grain. The over pumping of groundwater cannot continue indefinitely. Eventually the wells run dry, or it becomes too expensive to pump from greater depths. Meanwhile, the amount of irrigated land per person is shrinking. It has dropped 5 percent since its peak in 1978, and will continue to fall.

At the same time, one in five hectares of irrigated land is damaged by salt-the silent scourge that played a role in the decline of ancient Mesopotamian societies. So much water is being diverted for irrigation and other human uses that many major rivers now run dry for large portions of the year-including the Yellow in China, the Indus in Pakistan, the Ganges in South Asia, and the Colorado in the American Southwest. The Yellow River, the cradle of Chinese civilization, ran dry for a record period in 1997, failing to reach the sea for 226 days. With population growing rapidly in many of the most water-short regions, water problems are bound to worsen. The number of people living in water-stressed countries is projected to climb from 470 million to 3 billion by 2025, the study notes.

Already many countries do not have enough water to meet domestic demands for food, creating a source of potential political instability. Water-short countries are increasingly turning to the world grain market. In the swathe of countries from Morocco across North Africa and the Middle East to Iran, virtually every nation is facing water shortages as rising populations draw against a limited supply and as irrigation water is diverted to satisfy growing urban demand. To meet their food needs, these countries are importing grain.

(Importing a ton of wheat is the equivalent of importing 1,000 tons of water.) Last year, the water required to produce the grain and other farm products imported into the region was equal to the annual flow of the Nile River. And this deficit is growing year after year. Jordan is importing some 91 percent of its grain, Israel 87 percent, Libya 85 percent, Saudi Arabia 50 percent, and Egypt 40 percent. 'As water shortages continue to mount, it is dangerous to presume, as many officials do, that there will be enough exportable grain to meet the import needs of all water-short countries at a price they can afford,' said Postel.

'Most of the growth in water-stressed populations will be in South Asia and sub-Saharan Africa, where the majority of the world's poor and malnourished are today. ' In five of the world's hot spots of water dispute-the Aral Sea region, the Ganges, the Jordan, the Nile, and the Tigris-Euphrates-the population of the nations within each basin is projected to climb between 44 and 75 percent by 2025. Some 260 rivers flow through two or more countries, but in most cases there is no treaty among all the parties that sets out how that river water should be shared. In the absence of water-sharing agreements, tensions are bound to rise. Irrigation's heavy water demands are also damaging the health of the aquatic environment-shrinking wetlands, reducing fish populations, and pushing species toward extinction.

'Using water as inefficiently as we do today, meeting the food demands of the projected 8 billion people in 2030 would result in costly losses of ecological services that the economy depends upon,' Postel said. To meet the challenges of a water-short world, Postel proposes a 'Blue Revolution' to dramatically boost water productivity. 'Most farmers today irrigate the way their predecessors did hundreds of years ago,' said Postel. 'Just as raising land productivity helped meet food needs during the last half of this century, boosting water productivity will be the agricultural frontier during the next century.

The challenge today is to substitute technology and better management for water. ' Postel describes a diverse and creative mix of 'Blue Revolution's trategies: . Farmers in India, Israel, Jordan, Spain and the United States have shown that drip irrigation systems that deliver water directly to crop roots can cut water use by 30 to 70 percent and raise crop yields by 20 to 90 percent... In the Texas High Plains, farmers using highly efficient sprinklers raised their water efficiency to more than 90 percent while simultaneously increasing corn yields by 10 percent and cotton yields by 15 percent...

Rice farmers in an area of Malaysia saw a 45 percent increase in their water productivity through a combination of better scheduling their irrigation's, shoring up canals, and sowing seeds directly in the field rather than transplanting seedlings... Farmers in California's Imperial Valley are lining canals, recycling farm runoff and selling the saved water to southern California cities... Israel is now reusing 65 percent of its domestic wastewater for crop production, freeing up additional freshwater for households and industries. Postel shows that a special effort is needed to lift the water productivity of millions of very poor farmers who cannot afford some of the more advanced technological solutions.

'Helping small-scale farm families raise their incomes and improve their food security can be a powerful engine of economic growth in the world's poorest regions,' Postel said. In Bangladesh, farmers have purchased 1.2 million treadle pumps, a human-powered device that allows users to pump previously inaccessible groundwater. These pumps, which to an affluent Westerner look remarkably like a Stairmaster exercise machine, cost $35 but typically return more than $100 in the first year of operation. In Kenya, Chad, Zambia and India, farmers are combining indigenous water-management techniques with inexpensive new technologies like low-cost sprinklers, bucket-drip systems, small-scale pumps, and check dams. For the 'Blue Revolution' to succeed, Postel says, it is up to governments and water authorities to adopt new rules of the game for irrigation. Government subsidies totaling at least $33 billion a year make it cheaper to waste water than to conserve it.

Legal barriers often make it difficult for farmers to sell any water they save through conservation practices. And the failure to regulate groundwater over pumping leaves the world vulnerable to sudden cutbacks in food production as water tables drop to greater and greater depths. FOR MORE INFORMATION CONTACT: Worldwatch Institute 1776 Massachusetts Ave NW Washington, DC 20036 telephone: 202 452-1999 fax: 202 296-7365 e-mail or visit our website web.