China's Water Shortage Could Shake World Food Security--Part 1
This is the first part of a feature article appearing in
the July/August Issue of World Watch
by Lester R. Brown and Brian Halweil
An unexpectedly abrupt decline in the supply of water for China's farmers poses a rising threat to world food security. China depends on irrigated land to produce 70 percent of the grain for its huge population of 1.2 billion people, but it is drawing more and more of that water to supply the needs of its fast-growing cities and industries. As rivers run dry and aquifers are depleted, the emerging water shortages could sharply raise the country's demand for grain imports, pushing the world's total import needs beyond exportable supplies.
Any major threat to China's food self-sufficiency, if not addressed by strong new measures, would likely push up world grain prices, creating social and political instabilities in Third World cities-as previous WORLD WATCH articles have pointed out (see commentary). New information on the deteriorating water situation has confirmed the imminence of this possibility. The challenge now facing the Chinese government is how to meet the soaring water needs of its swelling urban and industrial sectors without undermining both its own agriculture and the world's food security.
The decline in China's capacity to irrigate its crops-signs of which include the drying-up of rivers and wells all over the northern region of the country-is coming at a time when depleted world grain stocks are near an all-time low. With its booming economy and huge trade surpluses, China can survive its water shortages by simply importing more of its food, because it can afford to pay more for grain. But low-income countries with growing grain deficits may not be able to pay these higher prices. For the 1.3 billion of the world's people who live on $1 a day or less, higher grain prices could quickly become life threatening. The problem is now so clearly linked to global security that the U.S. National Intelligence Council (NIC) the umbrella over all U.S. intelligence agencies, has begun to monitor the situation with the kind of attention it once focused on Soviet military maneuvers.
This deepening concern led the NIC to sponsor a major interdisciplinary assessment of China's food prospect. Headed by Michael McElroy, chairman of Harvard University's Department of Earth and Planetary Sciences, the study used information from intelligence satellites to refine cropland area estimates, and commissioned computer modeling by the Sandia National Laboratory to assess the extent of future water shortages in each of China's river basins. The recently released study concluded that China will need massive grain imports in the decades ahead-a conclusion that meshes with earlier projections published by WORLD WATCH.
Signs of Stress
SINCE MID-CENTURY, the population of China has grown by nearly 700 million-an increase almost equivalent to adding the whole population of the world at the beginning of the Industrial Revolution. Most of that population has concentrated in the region through which several great rivers, including the Yellow and the Yangtze, flow. Those rivers provide the irrigation water needed to grow much of the food for China, as well as the water for its burgeoning cities and industries.
This dependence has placed a growing burden on the region's land and water resources, because the Chinese population has not been able to expand into new land the way the Americans once did with their westward expansion into the Great Plains and California. In China, the western half of the country is mostly desert or mountains. The resulting concentration of Chinese population, industry, and agriculture has been roughly equivalent to squeezing the entire U.S. population into the region east of the Mississippi, then multiplying it by five.
A quarter-century ago, with more and more of its water being pumped out for the country's multiplying needs, the Yellow River began to falter. In 1972, the water level fell so low that for the first time in China's long history it dried up before reaching the sea. It failed on 15 days that year, and intermittently over the next decade or so. Since 1985, it has run dry each year, with the dry period becoming progressively longer. In 1996, it was dry for 133 days. In 1997, a year exacerbated by drought, it failed to reach the sea for 226 days. For long stretches, it did not even reach Shandong Province, the last province it flows through en route to the sea. Shandong, the source of one-fifth of China's corn and one-seventh of its wheat, depends on the Yellow River for half of its irrigation water.
Although it is perhaps the most visible manifestation of water scarcity in China, the drying-up of the Yellow River is only one of many such signs. The Huai, a smaller river situated between the Yellow and Yangtze, was also drained dry in 1997, and failed to reach the sea for 90 days. Satellite photographs show hundreds of lakes disappearing and local streams going dry in recent years, as water tables fall and springs cease to flow. As water tables have fallen, millions of Chinese farmers are finding their wells pumped dry.
In the geography of water, there are two Chinas. The humid south includes the vast Yangtze River and a population of 700 million. The arid north includes the Yellow, Liao, Hai, and Huai Rivers, and has 550 million. While four-fifths of the water is in the south, two-thirds of the cropland is in the north. As a result, the water per hectare of cropland in the north is only one-eighth that in the south.
Although comprehensive hydrological data are not always available, key pieces of the water puzzle are beginning to emerge from various sources. A recent Chinese survey reported by Professor Liu Yonggong of China Agricultural University in Beijing indicated that the water table beneath much of the North China Plain, a region that produces some 40 percent of China's grain, has fallen an average of 1.5 meters (roughly 5 feet) per year over the last five years. A joint Sino-Japanese analysis of China's agricultural prospect reports that water tables are falling almost everywhere in China that the land is flat.
In the late summer of 1997, many of the irrigation wells in Shandong Province, which was experiencing its worst drought in 25 years, were not pumping. Chinese water analysts report frenzied well-drilling in some provinces as farmers chased the falling water table downward.
Of course, those farmers' ability to provide food enough for their nation is constrained by a range of factors in addition to water-by the construction of roads over once-productive farmland, by erosion of soil, by the diminishing benefits of fertilizer, and by a shrinking backlog of the technology used to raise land productivity. But it is the swelling diversion of irrigation water, combined with heavy losses to aquifer depletion, that has emerged as the most imminent threat to China's food security.
Projected Demand for Water
EVEN AS THE YELLOW RIVER, aquifers, and wells get drier, the amount of water needed continues to swell. Between now and 2030, UN demographers project that China's population will increase from 1.2 billion to 1.5 billion, an increase that exceeds the entire population of the United States. Even if there were no changes in water consumption per person, this would boost the demand for water by one fourth above current levels-but per-person consumption, too, is growing. It is expected to grow in all three of the end use sectors-agricultural, residential, and industrial.
In the agricultural sector, demand for irrigation water, now roughly 400 billion cubic meters or tons per year, is expected to reach 665 billion tons in 2030. As incomes rise, people are consuming more pork, poultry, beef, and eggs, and feedgrain use is growing. For example, to produce one kilogram of pork it takes four kilograms of grain, and one kilogram of chicken takes two kilograms of grain. More grain means more water (see Figure 1). Between 1990 and 1997, consumption of pork climbed by a phenomenal 9 percent per year. Consumption of both beef and poultry, starting from a much smaller base, has climbed at over 20 percent per year. The brewing of beer, which is also made from grain, is growing at 7 percent annually.
In the residential sector, a similar compounding is occurring. At present, some 85 percent of all water withdrawals are for irrigation, but the residential share is increasing as China's population urbanizes and hundreds of millions turn from the village well to indoor plumbing with showers and flush toilets. Combined with projected increases in population, rising individual water use will boost residential water use from 31 billion tons in 1995 to 134 billion tons in 2030, a gain of more than four-fold.
The demand for water by industry is growing even faster. Assuming an economic growth of 5 percent a year from 1995 until 2030 (actual growth in the past decade has been more than twice that rate), industrial water use would increase from 52 billion tons to 269 billion tons (see table). The increase in residential and industrial water use together would total 320 billion tons of water during this 25-year span. If this water were used for irrigation, at 1,000 tons of water required per ton of grain produced, it would yield 320 million tons of grain, an amount approaching China's 1997 grain harvest of 380 million tons.
In other words, non-agricultural uses that are now straining the system by drawing only 15-percent of the supply would multiply nearly five times, while the agricultural needs now taking 85 percent would have increased as well. Obviously, that can't happen. Because consumption can't exceed the sustainable supply for long, China is facing fundamental changes in the way it distributes and uses its water.
Diversion, Depletion, and Pollution
THOUGH 70-PERCENT OF THE GRAIN produced in China comes from irrigated land, the country is seeing its irrigation supply depleted on three fronts: the diversion of water from rivers and reservoirs to cities; the depletion of underground supplies in aquifers; and the increasing pollution caused by rapid industrialization. Politically, it is difficult for any government to deny people water for their showers and toilets, if they can afford to buy it-and China's urbanizing population increasingly can. And economically, farms can't compete with factories for water. As competition among farms, homes, and industries intensifies, farms inevitably lose out.
Of China's 617 cities, 300 are already facing water shortages. In those areas of north China where all available water is being used, these shortfalls can be filled only by diverting water from agriculture. In the spring of 1994, farmers in the region surrounding Beijing were denied access to reservoirs, their traditional source of irrigation water, because all the water was needed to satisfy the city's burgeoning demand. That established a pattern for water-stressed cities all over the north North China Plain
As for the demand from industry, agriculture simply cannot compete in China or anywhere else. A thousand tons of water produces one ton of wheat, which has a market value of $200, whereas the same amount of water used in industry yields an estimated $14,000 of output-70 times as much. Moreover, that economic advantage is reinforced by a political one: the need to provide jobs for some 14 million new entrants into the labor force each year. And, as China's old state-run corporations are cut back, massive layoffs are leaving millions of people unemployed. As it happens, water used in industry can also create a disproportionately large number of jobs. Since incomes are much higher in industry than in agriculture, the number of jobs a given amount of water can bring to industry versus agriculture is somewhat less than the 70 to 1 just mentioned, but the bottom line still is that shifting irrigation water to industry creates many more jobs.
While farmers are losing out to cities and industries politically, they are also losing ground hydrologically. As the demand for underground water increases over time, the pumping eventually surpasses the natural recharge of the aquifer, which comes from precipitation in the upstream portion of the watershed. After this "sustainable yield threshold" is passed, the water table starts to fall. If demand continues to climb, the excess of pumping over the sustainable yield of the aquifer widens each year. As a result, the distance the water table falls increases each year.
Once the aquifer is depleted, the amount of water pumped is limited to the rate of recharge. It cannot be otherwise. If the pumping has been taking place at double the recharge when depletion occurs, then the pumping will be cut by half. If pumping has been five times the recharge, it will be cut by four fifths. Under the North China Plain, if the water table is falling 1.5 meters per year, then the pumping could easily be occurring at double the recharge rate. And if it is, the time will come when the amount of water pumped in this wheat and corn belt will be necessarily cut by half.
When farmers lose irrigation water, they either revert to rainfed farming if rainfall is sufficient or they abandon the land if it is not. For China, most of the land will simply revert to rainfed agriculture. The yield will then decline by about one-half to two-thirds.
Unfortunately, even this stark arithmetic fails to fully convey the extent to which China's grainland irrigation water is being lost, because it doesn't account for losses to pollution. There are 50,000 kilometers of major rivers in China, and, according to the UN Food and Agriculture Organization, 80 percent of them are so degraded they no longer support fish. As a result of toxic discharge from cities and upstream enterprises, which include such highly polluting industries as paper mills, tanneries, oil-refineries and chemical plants, the Yellow River water is now loaded with heavy metals and other toxins that make it unfit even for irrigation, much less for human consumption, along much of its route.
Water pollution horror stories abound throughout China as farmers-for want of a cleaner source-irrigate with heavily polluted water. In Shanxi province, in the Yellow River watershed, rice has been found to contain excessive levels of chromium and lead, and the cabbage is laced with cadmium. Along the length of the Yellow River, abnormally high rates of mental retardation, stunting and developmental diseases are linked to elevated concentrations of arsenic and lead in the water and food.
As industrialization outpaces pollution control, more and more river water is rendered unsuitable for irrigation. In the heavily industrialized, heavily populated Yangtze valley, it may not be the diversion of water to industry that most threatens agriculture, but the pollution of water by industry, which renders it unsuitable for irrigation to begin with.
continues - Part 2
This Feature Article appears in the July/August 1998 issue of World Watch magazine.
Copyright © 1998 Worldwatch Institute