Populations outrunning water supply as world hits 6 billion
As world population approaches 6 billion on October 12, water tables are falling on every continent, major rivers are drained dry before they reach the sea and millions of people lack enough water to satisfy basic needs, according to the Worldwatch Institute.
Water tables are now falling in China, India, and the United States, which together produce half the world’s food. Historically, irrigated farming has been plagued with waterlogging, salting, and silting, but now, with the advent of powerful diesel and electrically powered pumps, it is also threatened by aquifer depletion, says Worldwatch president, Lester Brown.
In China, water tables are falling almost everywhere that the land is flat. Under the North China Plain, the country’s breadbasket, water tables are falling by 1.5 metres per year. Where wells have gone dry, farmers have been forced either to drill deeper, if they can afford it, or to abandon irrigated agriculture, converting back to lower-yield rain-fed farming.
In India, a country whose population hit 1 billion on August 15, the pumping of underground water is now estimated to be double the rate of aquifer recharge from rainfall. The International Water Management Institute, the world’s premier water research group, estimates that India’s grain harvest could be reduced by up to one fourth as a result of aquifer depletion.
In the southern Great Plains of the United States, depletion of the Ogallala aquifer has already led to irrigation cutbacks. Texas, Oklahoma, Kansas, and Colorado have been losing irrigated land over the last two decades. Texas, for example, has lost irrigated land at roughly one percent per year since 1980.
Hydrologists estimate that when the amount of fresh water per person in a country drops below 1,700 cubic meters per year the country is facing water stress. In her new book, Pillar of Sand: Can the Irrigation Miracle Last, Worldwatch senior fellow Sandra Postel reports that the number of people living in countries experiencing water stress will increase from 467 million in 1995 to over 3 billion by 2025 as population continues to grow. In effect, these people will not have enough water to produce food and satisfy residential and other needs.
As water becomes scarce, the competition for water between cities and countryside intensifies. In this competition, farmers almost always lose. In North Africa and the Middle East, the region ranging from Morocco in the west to
Iran in the east, virtually every country is experiencing water shortages. As cities grow, countries take water from agriculture to satisfy expanding urban water needs. The countries then import grain to offset the water losses.
Given that importing one ton of grain is equal to importing 1,000 tons of water, this is the most efficient way for water-short countries to import water. Last year the water required to produce the grain and other farm products imported into this region was roughly equal to the annual flow of the Nile River. With more and more countries looking to the world market for food, says Postel, spreading water scarcity may soon translate into world food scarcity.
It is often said that the competition for water among countries may take the form of military conflict. But now, Postel suggests, it seems more likely that the competition for water will take place in world grain markets.