Large dams, defined by the World Commission on Dams as more than 15 meters high or with reservoirs holding more than 3 million cubic meters of water, are making a fast-growing contribution to electricity production in developing countries, especially in Asia. China alone accounts for nearly half the world's big dams, yet authorities there say that more than four-fifths of the country's hydroelectric potential remains unexploited. Accordingly, whether or how to build more dams there and elsewhere, and how to deal with the side-effects of dams already built or under construction, are big issues with regional and global implications.
In the next decades, countries like India and China that are enormously dependent on coal will be able to cut their greenhouse gas emissions only by burning less coal or burning it more efficiently. Dams have a role to play in accomplishing that. Granted, the electricity they produce is not necessarily, contrary to popular opinion, completely emissions-free, because decomposing organic matter in the reservoirs behind dams generates methane, a potent greenhouse gas. But it is generally safe to assume that electricity generated by a dam will have significantly less impact on climate than the same amount of electricity from a coal-fired plant.
In recent years, China has been adding hydro capacity at a rate close to 5 GW a year. Its total installed hydro capacity now is near 75 GW, about a fifth of the nation's whole electricity supply. By 2005, capacity is expected to approach 100 GW, to account for close to a quarter of total electricity, according to the Natural Re -sources Defense Council in Washington, D.C. That growing reliance on hydroelectricity will help constrain increases in greenhouse gas emissions. In fact, it may already have been an element in China's success in recent years in cutting those emissions, even as its economy has grown at near-double-digit annual rates.
Yet, despite their evident benefits, big dams are regarded with great suspicion by environmentalists and human rights activists. Because of an ever-shriller debate worldwide about their merits and defects, international lending agencies are increasingly loathe to support them.
The reasons are manifold. Inevitably dams displace thousands or even tens or hundreds of thousands of people, who are uprooted from ancestral lands and then must be resettled, often among land-hungry or poorly employed populations who do not greet them with open arms. Ecosystems and habitats, both upstream and downstream from dams, are disrupted and often permanently destroyed.
Often, too, instead of the dams improving flood control, unexpected patterns of sedimentation and changes in water flow lead to less frequent but even more catastrophic floods. Instead of yielding an agricultural paradise, vaunted irrigation schemes may waterlog the land and saturate it with salt. The benefits of irrigation, to the extent they materialize as advertised, end up being appropriated by the richer landowners who wield the most power locally. The construction process itself, and the huge sums of money distributed to deal with the effects of the dam being built, are invitations to corruption.
Even in China, plans for big dams have prompted some otherwise unparalleled open debate. Its two great rivers, the Yellow (Huang) and the Yangzi (Changjiang), are the cradles of its civilization and still its greatest resources. So the question of how those rivers should be put to best use has been too important to keep behind closed doors, even in the country's tightly controlled one-party system. China's decision at the end of the 1980s to build the biggest of all big dams, at Three Gorges on the upper Yangzi, failed to obtain the unanimous support of its normally rubber-stamp legislature [see IEEE Spectrum, January 1998, pp. 6771].
Another immense project, the smaller but still very large Xiaolangdi Dam on the Yellow River, is in some ways a show-opener for Three Gorges. It is the main focus of this article. Critics have charged that already, barely a year in operation, Xiaolangdi is silting excessively, cannot produce electricity at the expected capacity of 1800 MW (the equivalent of several coal-fired plants or a large nuclear reactor complex), and has left people homeless, workless, and vulnerable to disease.
Debates like these are raging in every part of the world where big dams are being built or reconsidered, and among the governmental and international organizations that fund them. To bring the contending parties to a single table and to narrow differences, a World Commission on Dams was established in 1997 under the auspices of the World Bank and conservation organizations. It issued a report last November in which it concluded that disagreements over dams have little to do with their technical features and everything to do with the complicated cost-benefit analysis done to justify them.
In an effort to better understand what goes into that kind of cost-benefit analysis, Spectrum visited the Xiaolangdi Dam earlier this year, mainly to get a sense of the human and environmental costs associated with its construction and operation. Several days spent exploring the dam and areas around it left the impression, admittedly guarded, that its disadvantages have been exaggerated, though, of course, there was much that could not be seen in that short time. Most of all, the visit brought home the fact that every big dam is unique, must be closely evaluated on its own merits, and cannot sensibly be lionized or rejected just because it is a big dam.
The biggest in operation
By some measures the Xiaolangdi Dam is the largest one currently operating in China. It is located roughly halfway between the ancient capitals of Xi-an and Kaifeng and near Luoyang, in northwest China. Hardly a household name outside China, Louyang also is one of the country's ancient capitals and the place where paper is said to have been invented. Today, by Chinese standards, it is a mid-sized city, with about twice as many people as Chicago.
Xiaolangdi is a multipurpose dam built mainly to trap the Eurasian loess that is constantly being deposited in the giant valley and plateau upriver on the Yellow. That sediment is to be released by the dam in controlled fashion, so as to economize on construction of dike systems downriver, where the bed otherwise rises at a rate of meters per decade.
Still not quite finished, Xiaolangdi displaced about 175 000 people, has cost upward of US $4 billion to build, and is the biggest single project ever supported by the World Bank in China. The reservoir behind the dam stretches 103 km upriver to another dam, the Sanmenxia, built in the 1970s. It reputedly silted up so badly almost immediately that it threatened to cause flooding further upriver in Xi-an. It eventually had to be rebuilt, at enormous embarrassment and expense.
From these experiences, the Chinese believe they have learned their lessons. According to the Environmental Impact Statement for Xiaolangdi, "The reservoir is designed to be operated in a...way believed to be unique in worldwide major dam history....To optimize sediment deposition in the reservoir, the water level will be regulated initially at the minimum head for effective power production and then increased at a rate of 3 meters per year. This will trap most of the coarse sand, while most of the fine silt will be discharged. After about 30 years of operation, the design sediment storage capacity will be filled. The water level will then be dropped to flush out accumulated sediments, and thereby regain the reservoir storage and regulation capacity."
Observations at Xiaolangdi
Traveling on a tourist visa, this writer was accompanied by two friends. One was Tim Connor, a photographer, whose day job is with a leading expert-driven environmental organization in New York City. The other was Jerry Epstein, an economist at the University of Massachusetts, Amherst, who had picked up enough Chinese during a one-year sabbatical to serve as guide and interpreter. We were determined to avoid any kind of official gloss on the project. Our strategy was to look first, ask questions later.
Before we started our journey, we were prepared for some difficulty. The person at a leading anti-dam organization who had provided us with the environmental impact statement and resettlement plan for the dam told us there was little chance we would get anywhere near it. She predicted we would be stopped by the police, and seemed to imply that we should carry enough cash to bribe ourselves out of any trouble we got into. Complaints prepared by her organization and submitted to the World Bank had forecast, among other things, that the dam would cause a regional epidemic of hemorrhagic fever, carried by rats driven out by the rising waters. So we went wearing heavy boots and carrying plenty of petty cash, on a war-correspondent footing.
As it turned out, our actual experiences were almost hilariously at variance with expectations. Coming in from Xi-an to the west, upriver of the dam, we traveled on a well-appointed train through hundreds of kilometers of dramatically dry country, characterized by layered loess bluffs. For millennia, the indigenous Han people have burrowed out "cave" dwellings in the soft loess, hundreds of meters deep--a custom they continue to this day. It was easy to see where all the sediment in the Yellow River was coming from.
Along the way, we passed two brand-new coal-fired plants, which brought home vividly that while big dams might help reduce reliance on coal, coal plants continue to be stamped out as if from a single template, even in an area where a very large dam has just been built. What impressed us even more, however, was just the dryness; it was our first glimpse of a drought that has been ravaging this part of China.
Upon arrival at our hotel in Luoyang, we discovered picture postcards of the dam on sale in the gift shop, and learned that, far from being off limits, the dam could be visited on buses sponsored by various tourism organizations. Those we shunned, for fear of being saddled with a propaganda-spewing guide or a police agent, and of being shown nothing but Potemkin villages, the fake showcase villages a Russian prime minister once had built to impress the czar. Instead, we simply walked outside, hailed the first cab we saw, and readily talked the driver into driving us the 35 km northwest to the dam. In the course of the day exploring the dam and its environs, the driver proved only too happy to show us anything we wanted, and often pointed out resettlement villages and other items of interest at his own initiative.
Arriving at Xiaolangdi, we immediately established that much of what we had heard about the dam was false or exaggerated. True, the reservoir was low, reflecting drought conditions, and we already knew from news reports that power production had been curtailed or stopped altogether because water had to be preserved for irrigation upriver.
At the site we found ourselves among hundreds of Chinese tourists who had come to admire the dam for the day and to inspect an area that, along with the area around Three Gorges on the Yangzi, the authorities planned to develop as a resort for camping, swimming, boating, and fishing. This was a benefit that had not occurred to us--the endowment of China's increasingly prosperous but vacation-starved people with a retreat from grimy, crowded metropolises.
Exploring the wider area around the dam, admittedly a very tiny part of the region affected by it, we saw no sign of rats, contagion, human dislocation, or popular discontent. As best one could tell from the driver's attitude and the outward signs of life, most people seemed content to accept official assurances that all would be well, though older people surely take the loss of ancestral homes much harder, and must bear with the inundation and permanent loss of grave sites where ancestors have been buried for centuries.
The three villages near the dam that the driver pointed out as having been built or expanded to accommodate refugees from the reservoir ranged from desolate and uniform to suspiciously nice. In fact, one looked so much like a pleasant first-world suburb, I wondered whether a rural middle class was re-emerging from the ashes of the Chinese revolution, and appropriating the benefits of the dam at the expense of the less fortunate (a pattern critics have found at many other large dams). Seeming to sense what I was driving at, despite our limited ability to communicate, the driver said the houses would accommodate more than one family each.
In what seemed the most typical of the villages, we found ourselves looking down a long street with newly built, somewhat ramshackle, homes, not too great but not to awful, facing a huge new statue of Chairman Mao. After spending most of our time previously in urban China, where Mao typically is paid the barest lip service and the late reformist leader Deng Xiaoping is the true hero, this was a reminder that here in rural China the Great Helmsman is still venerated.
On the way back to Luoyang that evening, we encountered an old coal-fired plant that had been decommissioned, its electricity replaced perhaps by hydropower from Xiaolangdi. Yet the next day, exploring a wider swathe of territory downriver, we came upon a brand-new plant, similar to those we had seen upriver during our train ride to the dam area.
Implications for Three Gorges
One conspicuous problem with big multipurpose dams is that the uses are not always consistent, so that one must be sacrificed to another. "It's like the conundrum of trying to ford a river with a fox, a chicken, and a bag of grain," observed the Indian writer Arundhati Roy, a shrill critic of a big dam project on the Indian subcontinent.
But juggling those varied purposes can have some operational advantages if alternative resources can be brought into play as needed, sources in China reminded Spectrum. "Last year and this, due to the severe drought in North China, the operation of Xiaolangdi has been adjusted to meet water needs, producing substantial social and economic benefits," Li Xiaokai, project director for the dam with the World Bank's Beijing office, said in an e-mail reply to questions.
What's more, added Zhou Xiaoxin, chief of simulation engineering at the Electric Power Research Institute in Beijing, in a similar communication, while "the output of power stations in Northwest China has been affected by the drought, the Xiaolangdi reservoir is big enough [at 12.65 billion cubic meters] to withstand [adverse conditions] to some extent. And also we have the [country's] largest coal reserves in this area [so that coal generation can be substituted as needed]....Most important is that we have a long-term plan for the interconnection of our regional power grids." That, he said, will effectively solve the problem of occasional inadequate rainfall and guarantee better use of hydro.
But what happens when the scale of operations is magnified by a factor of 10, as at Three Gorges? From a power perspective, the huge dam being built on the upper Yangzi is ideally situated to provide a huge amount of electricity to Chongqing, a vast sprawling city with a regional population of about 30 million, as well as to industries concentrated in the central and eastern part of the country. But if Three Gorges does not produce expected electricity, those load centers would be vulnerable to huge disruptions.
Even normal weather changes might affect the electricity supplied. An electrical engineer who visited Three Gorges earlier this year as part of an engineering party did some back-of-the-envelope calculations based on data provided by his hosts and concluded that the dam's electrical output may be hostage to the regular variations of nature. Teradyne cofounder Nick de Wolf found that, despite the enormous size of the dam and reservoir being built, if there were not enough new water entering the reservoir during the driest part of the year, in February, the dam's generators would have to be shut down entirely after 12 days. De Wolf said he subsequently checked his calculation with a Canadian expert on the dam, who confirmed it.
Perhaps that dependence on weather and climate is one reason China's power officials have been lukewarm about Three Gorges. Yet, the dam, like Xiaolangdi, promises other substantial benefits besides electricity generation. It is intended to control often catastrophic flooding downriver, and to provide--through an unprecedented system of locks and ship elevators--passage for ocean-going freighters all the way to Chongqing, making the inland city in effect a coastal harbor.
As at Xiaolangdi, as best as outside observers can tell, the people most directly affected by the dam seem to largely accept that benefits will outweigh the personal sacrifices they may have to make.
The price China pays
Peter Hessler, a writer from the United States who taught English for two years in Fuling, a small city on the Yangzi that will be almost entirely flooded by the Three Gorges reservoir, said in a book published earlier this year that he seldom met anybody who was seriously upset about being uprooted by the dam or, indeed, at all inclined to question official claims. "In the two years I lived there, I never heard a single resident complain about the Three Gorges Project, and I heard gripes about virtually every other sensitive subject," he wrote.
Speaking just for himself, there were days when Hessler felt sad looking down on the river from his apartment in Fuling, thinking of all that would disappear. But on other days he could not see the river at all, because of all the coal pollution in the air.
Hessler, now Beijing correspondent for The New Yorker, found he could not get terribly sentimental about "untouched nature" with all that humans have done, over thousands of years, to every nook and cranny of the river's valley. "With all of this history, it was impossible to say that the new dam was an entirely new sort of violation."
Still, he said, "to have [the Yangzi] simply stop--to turn the river into a lake--for some reason that bothered me more than anything else. In a selfish way, I didn't mind so much the lost temples or the scenery's lessened magnificence, or even the displaced people. The part that bothered me the most was all that stagnant water."
That kind of sentiment about taming wild rivers is perhaps not widely shared among hydroelectric engineers, but it is not unusual among people who are affected by dams and concerned about them. It is a kind of spiritual viewpoint that has deep roots in China itself, where so much of the country's history has been bound up with the domestication of its great waterways.
Writer Simon Winchester, in a study of the Yangzi River, found that all of 2500 years ago--still prehistoric times in much of the world--two contending philosophies about river control were already well articulated, with reference to the lower reaches of the Yellow River: "Taoists, followers of what we might call a bohemian way of life, supported the building of only very low levees besides rivers and, generally speaking, letting them devise their own courses to the sea. Confucianists, who took a much more rigid approach to governance and life in general...believed that massive dikes should be built to corral the waterways along man-made courses and that the extra land thus freed should be intensively used for agriculture."
In other words, what those of the Taoist spirit experience as a violation of nature is part of the price a country pays to build big dams, to obtain the benefits so admired by Confucians.
The losses associated with permanently changing a great landscape or with flooding ancestral graves [photos], probably cannot be monetized and incorporated into any meaningful cost-benefit analysis. Yet even items that can be readily assigned cash value are not always easy to allocate to the cost or benefit side of the ledger.
Engineers visiting Three Gorges earlier this year noticed that once the Yangzi is dammed, all the municipalities upstream, covering a distance about two-thirds the length of California, will no longer be able to just dump their raw sewage into the river, to see it swept away to the sea. Proper waste treatment plants will have to be built, at an aggregate cost that could rival the expense of the dam itself.
Should those waste treatment plants have been considered part of the cost of building Three Gorges? Or are they in some sense a benefit of the dam, as they might not have been built any time soon without the incentive the dam gives? It, like so many of the issues arising with very big dams, is a Solomonic question.
This much bears repeating: the construction of big dams in China, besides helping more or less as advertised with flood control and electricity production, stands to make a substantial contribution to reduction of its greenhouse gas emissions. Whether or not one approves of that strategy, it must be acknowledged that China is paying a substantial price not only monetarily, but also in terms of social and environmental costs and risks, to achieve a goal the whole world has been promoting.
To Probe Further
Arundhati Roy's anti-dam polemic, "The Greater Common Good," is the first of two essays in The Cost of Living (Modern Library, New York, 1999). A critique of Three Gorges is The Dragon Has Come: The Three Gorges Dam and the Fate of China's Yangtze River and Its Peopls, 15 essays compiled by the dam's leading critic, Dai Qing (M.E. Sharpe, Armonk, N.Y., 1998).
A copy of the Environmental Impact Statement for the Xiaolangdi Yellow River Multipurpose Economic-cum-Environmental Improvement Project (June 1993) is available from William Sweet at IEEE Spectrum, as is a copy of the Yellow River Conservation Commission's program plan submitted to the World Bank under the title "China--Xiaolangdi Resettlement Project."
The Natural Resources Defense Council's "China Is Aggressively Reducing Its Carbon Dioxide Emissions" is available on http://www.nrdc.org.