Since we tend to take water for granted, it is almost always a bad sign when it is in the news; and lately there has been all too much water-related news from some of Asia’s most populous nations.footnote^＊ The stories have ranged from the distressingly familiar—suicides of drought-hit Indian farmers—to the surprising: evidence that pressure from water in the reservoir behind the new Zipingpu dam may have triggered the massive Sichuan earthquake in May 2008, for example.footnote¹ Meanwhile glaciers, which almost never used to make the news, are now generating plenty of worrisome headlines.

For almost half the world’s population, water-related dreams and fears intersect in the Himalayas and on the Tibetan plateau. Other regions have their share of conflicting claims over water issues: Turkey, Syria and Iraq over the headwaters of the Tigris; Israel and its neighbours around the Jordan basin; the us and Mexico over the Colorado River; the riparian states of the Paraguay, the Parana or the Nile. But none combine the same scale of population, scarcity of rainfall, dependence on agriculture, scope for mega-dam projects and vulnerability to climate change as those at stake within the greater Himalayan region. Here, glaciers and annual snowmelts feed rivers serving just under half of the world’s population, while the unequalled heights from which their waters descend could provide vast amounts of hydro-power. At the same time, both India and China face the grim reality that their economic and social achievements since the late 1940s—both ‘planned’ and ‘market-based’—have depended on unsustainable rates of groundwater extraction; hundreds of millions of people now face devastating shortages.

In response, plans are moving forward to harness Himalayan waters through the largest series of construction projects in human history. Looked at individually, some of these carry enormous risks and, even if they work as planned, will hurt large numbers of people while helping others. Looked at collectively—as overlapping, sometimes contradictory demands on environments that will also feel some of the sharpest effects of global warming over the next several decades—their interactions will be extraordinarily complex and their possible implications are devastating. Since many of the agencies responsible for these projects are far from transparent, it is very difficult to keep track of the rapidly multiplying future scenarios. But some basic outlines do emerge if we start from China—for various reasons, the most dynamic actor in the story—and then survey the broad belt of lands that border it to the south.

Water has always been a problem in China, and effective control of it has been associated with both personal heroism and legitimate sovereignty for as far back as our records go—or perhaps even further, since the mythological sage-king Yu proved his right to rule by controlling floods. But water scarcity has perhaps been an even greater problem than excess, especially in the modern period. Surface and near-surface water per capita in China today is roughly a quarter of the global average, and worse yet, it is distributed very unevenly. The north and northwest, with about 380 million people, almost 30 per cent of the population, and over half the country’s arable land, have about 7 per cent of its surface water, so per capita resources there are roughly 20–25 per cent of the average for China as a whole, and less than 6 per cent of the global average.footnote² Northern waters also carry heavier sediment loads: most readings on southern rivers fall within eu maxima for drinking water, while some on the Wei, Yongding and the middle and lower Yellow Rivers are 25 to 50 times that level; water shortages are such that northern rivers also carry far more industrial pollutants per cubic meter, even though the South has far more industry.footnote³ Northern China has unusually violent seasonal fluctuations in water supply, too; both rainfall and river levels change much more over the course of the year than in Europe or the Americas. North China’s year-to-year rainfall fluctuations are also well above average, although not as severe as those in north and northwest India. While the most famous of China’s roughly 90,000 large and medium-sized dams are associated with hydro-power—about which more below—a great many exist mostly to store water during the peak flow of rivers for use at other times.

The People’s Republic has made enormous efforts to address these problems and achieved impressive short-term successes, which are now extremely vulnerable. Irrigated acreage has more than tripled since 1950, mostly during the Maoist period, with the vast majority of those gains coming in the north and northwest. It was this, more than anything else, that turned the notorious ‘land of famine’ of the 1850–1950 period into a crucial grain-surplus area, and contributed mightily to improving per capita food supplies for a national population that has more than doubled since 1949. Irrigation made it possible for much of northern China to grow two crops a year for the first time in history, often by adding winter wheat, which needs a lot of water; and plentiful, reliable supplies of water were necessary to allow the use of new seed varieties and chemical fertilizers, which can otherwise burn the soil. And, of course, irrigation greatly reduced the problem of rain coming at the wrong time of year, or not at all. During the previous two centuries, farming in northern China had become steadily more precarious, in part because population growth had lowered the water table—early 20th-century maps show much smaller lakes than 150 years before, and there are many reports of wells needing to be re-drilled at great expense—and in part because the safety net the Qing had once provided fell apart. But beginning in the 1950s and—after the setbacks of the Great Leap Forward—especially in the 1960s, things turned around very impressively.

Much of that turnaround, however, relied on very widespread use of deep wells, employing gasoline or electrical power to bring up underground water from unprecedented depths.footnote⁴ Large-scale exploitation of China’s northern groundwater began in the 1960s and peaked in the 1970s, at roughly ten times the annual extraction rates that prevailed during 1949–61; it has remained steady since about 1980 at roughly four times the 1949–61 level.footnote⁵ But this amount of water withdrawal is unsustainable. The North China water table has been dropping by roughly 4–6 feet per year for quite some time now, and by over 10 feet per year in many places; if this rate of extraction is maintained, the aquifers beneath the plain will be completely gone in 30–40 years, according to some estimates.footnote⁶ This is by no means a unique situation. In the United States, for instance, the Ogallala Aquifer—which lies beneath portions of western South Dakota, Nebraska, Kansas, Oklahoma and Texas, and eastern Wyoming, Colorado and New Mexico—is being depleted at roughly the same rate. Serious excess withdrawals began there in the 1950s, and as in China, turned areas previously marginal for farming—the land of the 1930s Dust Bowl—into a bread-basket. But while the 175,000 square miles served by the Ogallala Aquifer are home to less than 2 million people, the 125,000 square miles of the North China Plain are home to over 214 million, 80 per cent of them rural.footnote⁷ The 2008 North China drought—the worst since the late 1950s drought that exacerbated the Great Leap famines—focused global attention on the problem for a brief moment, but chronic water shortages, both in cities and in the countryside, have been a fact of life for years, and conflicts over scarce or polluted water have become common events.footnote⁸ So, what is to be done?

One hears periodically about inefficient water use in the cities: the Chinese steel industry, for instance, consumes about twice as much water per ton produced as steel-makers in the most technologically advanced countries (though the Indian steel industry is considerably worse than China’s on this score).footnote⁹ Leaky pipes and other infrastructure problems create considerable waste. But relatively speaking, industrial and urban residential losses are small potatoes; agriculture still uses at least 65 per cent of all water in China—though less, even in absolute terms, than 20 years ago—and has far worse efficiency rates.footnote¹⁰ The cities are certainly not the site of the greatest wastage in commercial terms: according to one estimate, a gallon of water sent from the countryside to Tianjin yields 60 times as much income in its new urban locale as it did in the countryside.footnote¹¹ The best hope of moderating overall water demand is probably to keep per capita urban use from growing too much, and improve use-efficiency, even as the urban population expands. Certainly price increases—unless they are intolerably large—are unlikely to cause city dwellers to cut back much. Any significant reductions will have to come from the countryside. That process has begun, but it is unclear how far it can go without devastating social consequences.