by Betsy Murphy
Official enthusiasm for dam projects, especially large-scale hydroelectric dams, has grown tremendously in the last four decades. Governments and lending institutions, eager to build these prestige projects, have been sustained by the pervasive ideological vision of human progress through the control of nature. Large dams have traditionally been viewed as economically and environmentally sensible solutions to energy problems facing societies today. This belief has launched a tremendous dam building frenzy, now numbering over 40,000 large dams worldwide. Over eighty-five percent of these dams have been built within the last four decades, with China alone averaging over 600 large dams built every year in the three decades following the revolution (McCully, 1996). However, the enthusiasm with which dam construction was advocated in the last few decades has waned in recent years. Hydropower projects have been among the most criticized. When independently scrutinized, it has become clear that the expected benefits of hydropower dams are often greatly exaggerated, while the expected costs—economically, socially and environmentally—are often either underestimated or ignored altogether.
Environmental Impacts of Large Scale Dam Construction
The environmental consequences of large dams have been devastating. Reservoirs worldwide have flooded land equal in size to the state of California. (McCully, 1996). This represents not only an immense amount of land lost to dams, but also the loss of some of the earth’s most fertile farmlands and diverse ecosystems. For example, the Three Gorges Dam Project, currently under construction in China, will greatly impact an area that today produces over 40% of the country’s agricultural products (Morrish, 1997). Reservoirs also trap and accumulate a high proportion of a river’s sediment load. This “silting up” of reservoirs is one of the main reasons why dams have a very short live span. Sedimentation has caused Columbia’s Anchicaya Dam to lose over four-fifths of its original five million cubic meter capacity (LePrestre, 1989), and studies of 17 major reservoirs in India show sedimentation up at three times the expected rate (Adams et al, 1985). This build up a river’s sediment load also means that downstream agricultural land loses the influx of nutrient-rich sediments needed for agriculture. Before the Aswan dam was erected on the Nile, the river deposited some 100 million tons of sediment annually on nearly one million hectares of land in the Nile valley. However, farmers along the delta must now use large amounts of artificial fertilizers to maintain the previous level of productivity. According to Egypt’s President Mubarak, “One of the main challenges Egypt now has to face is coping with the effects of the Aswan Dam” (Rao, 1988).
Another ecological problem of large dams is caused by the decomposition of submerged vegetation and soils in the reservoirs. This decomposition process drastically depletes the level of oxygen in the water, often killing much of the aquatic life. The consumption of oxygen by decomposing vegetation in the newly filled reservoir behind Yacyreta Dam on the border between Argentina and Paraguay is believed to have killed more than 120,000 fish, which were found downstream after the first test of the dam’s turbines in August 1994. Moreover, rotting organic matter can lead to releases of large amounts of the greenhouse gases methane and carbon dioxide. The uncleared Balbina reservoir had 26 times more impact on global warming than the emissions from an equivalent coal-fired power station (McCully, 1996). Although this problem could be mitigated by clearing the vegetation from areas to be submerged prior to closing the gates of the dam, this process is rarely done because of the additional costs involved. For example, Brazil's Electronorte cleared less than one-fifth of the 2,250 square kilometers of rainforest inundated by Tucurui and only two percent of the 3,150 square kilometers for the Balbina dam, even despite a legal requirement in Brazil to clear vegetation from all areas to be submerged (McCully, 1996).
Reservoirs are also particularly prone to colonization by aquatic plants, which further decreases hydropower capacity and contributes to new environmental problems. Especially common is the water hyacinth, a weed thrives on decaying vegetation and spreads over the surface of the reservoir, causing up to six times the normal evapotranspiration. This weed can proliferate at an extraordinary rate in eutrophic reservoirs, largely negating efforts to eradicate them by physical removal or by the use of herbicides. Within two years of the completion of Brokopondo Dam in Surinam, over half its reservoir was covered with water hyacinth. Much of the reservoir’s aquatic life died due to the toxicity of the weed; others died because the water hyacinth absorbed the lake’s available nutrients and blocked the sun’s rays from penetrating to the depths of the lake. Despite specially designed filters intended to protect the turbines from such water weeds, many dams like Brokopondo have had to shut down periodically because of clogging (Adams et al, 1985).
In recent years, dam builders and operators have been forced to take steps to mitigate environmental impacts of their projects, many of which have been effective in reducing the harmful impacts of dams. The most common mitigation measure, releasing water from the reservoir to benefit fish downstream, can be a beneficial step in minimizing ecological damage. However, it is often carried out with very little consideration to the importance of natural seasonal flow variations, at times causing more harm than good. Occasionally mitigation measures are undertaken in order to give a false impression that the environmental problems caused by a particular dam have been remedied. For example, despite decades of experience showing that rescue missions for animals drowned when a large reservoir is filled are of extremely little benefit, mitigation in the form of highly publicized rescue operations are common. Officials often insist on mounting them, for as a senior World Bank environment employee remarked, “the rescue of individual animals makes for good television” (McCully 1996, 54).
Human Impacts of Large Scale Dam Construction
The human consequences of large-scale dams have been as dramatic as the ecological ones. While dam builders have not bothered to keep count, the number of people flooded off their lands by dams is certainly in the tens of millions. Thirty million is often given as a conservative estimate, although experts would argue for a more ‘realistic’ estimate of 60 million—more than the entire population of the United Kingdom (McCully, 1996). Chinese government records indicate that over 10 million people have been resettled due to dam projects in China alone (Kwai-cheong, 1995). Given China’s high population density and the huge number of dams it has built, however, experts feel a more accurate number is 40 million (Morrish, 1997). Throughout the world, these people have been flooded out of their lands with only minimal compensation—or none at all. Three-fourths of the millions of dam “oustees” in India have been given no replacement land or housing as compensation for their losses. In fact, a recent review of dam projects funded by the World Bank found that over half of the projects had no resettlement plans whatsoever (McCully, 1996). Moreover, estimates of people expected to be evicted by dam projects are often greatly underestimated (see Table 1). Even when compensation is provided for those evicted from their land, rarely are resettled groups able to regain the standard of living they enjoyed prior to their resettlement. For example, the average income of the 6,000 farmers who were moved to make way for Kenya’s Kiambere Hydropower Dam fell by an average of 82 percent. Not only had these farmers lost much of their livestock in the resettlement process, but they also received smaller, less productive lots as compensation for their lost lands (Caufield, 1996). Anthropologists agree that forced resettlement creates tremendous physiological, psychological and sociocultural stress (Weist, 1995). The Gwembe Tonga of Zambia, resettled for the construction of the Kariba Dam, now live in the middle of a tremendous civil war, yet despite the great dangers they face daily, the vast majority of respondents indicated in a recent survey that the most difficult time in the last ten years was the year following their resettlement to the area (at which time there was no communal strife) (Scudder, 1993). Moreover, the pain of displacement is usually the culmination of years, sometimes decades, of the withdrawal of government and private investment. Immediately after a dam is proposed, property prices in the area fall, banks refuse to give loans, and no new schools or health centers are built. The situation is generally worse for dams than for other projects because the planning and construction period is so long, with larger projects taking many decades from conception to completion. For example, although the Three Gorges project in China was first envisaged in 1919 and designs were completed in 1955, construction did not begin until 1993 and final resettlement will not be complete until 2008 (Edmonds, 1992).
However, those displaced by reservoirs are only the most visible victims of large dams. Millions more have lost their land and homes to the roads, power lines, construction housing areas, and industrial development which follow dams. Some of the most serious long-term social effects of dams are suffered by people who live downstream. In Africa, the loss of annual flooding below dams has devastated traditional floodplain farming, fishing, and grazing. While Nigeria’s Kainji Dam directly displaced 44,000 people, the livelihood of hundreds of thousands of Nigerians, who had formerly grazed their livestock and grown crops on land irrigated by the annual flood, was devastated by the dam. A recent survey found that three quarters of the dry-season irrigators in villages affected by Kainji Dam were eventually forced to give up farming altogether (McCully, 1996). Also not reflected in the statistics is the loss of communal lands. Although such lands provide a significant portion of a family’s subsistence, they are compensated. In a 1994 review of World Bank projects involving resettlement, only 1 in 192 projects involved any form of provisions for the loss of common property.
One of the most devastating consequences of large dams to human life is the increase in the contraction of diseases that dams inevitably bring in their wake. Dams and irrigation systems spread diseases because they create ideal habitats in which the mosquitoes, snails, and other animals that serve as vectors for water-borne disease parasites can thrive. Increases in the contraction of schistosomiasis, malaria, Rift Valley fever, yellow fever, and dengue fever are all common near reservoirs and have taken an inestimable human toll. For example, in central Ghana, after the construction of Akosombo Dam, the rate of infection with schistosomiasis in regions surrounding the dam grew from 5 percent to 80 percent within a few years of the filling of the reservoir. Within 10 years of the construction of the dam, over 100,000 people were afflicted with river blindness, with over 70% of them were completely blind (Caufield, 1996).
Assessing the benefits of large-scale hydropower dams
These ‘victims of development’ are often dismissed by dam proponents as the unfortunate ‘losers’ of an enterprise that will bring a better life for a vastly greater number of ‘winners.’ However, this belief that hydropower projects provide local peasants in the rural areas surrounding the dam with much need electricity is often unfounded. Many hydroelectric dams are never intended to benefit local residents, but are instead constructed to be used in industrial production (often to supply First World markets.) For example, Laos is considering building up to 60 new dams, primarily for export electricity (Usher, 1996; Wilkes, 1996). Likewise, the recently completed hydroelectric plant on Tibet’s third largest lake (projected to drain the lake in 50 years time) was built not to benefit the local Tibetan communities, but to increase industrial output China. (Wilkes, 1996)
When dam builders are faced with the negative social and environmental consequences of their projects, these problems are claimed to be regrettable side effects to projects which are, in their entirety, ‘proven’ to be overwhelmingly beneficial. Yet this argument assumes that dams fulfill the many promises that are attributed to them. While the drawbacks of dam projects are consistently belittled, the benefits that they provide are regularly exaggerated. What is often downplayed is the inherent conflict between the different uses of a dam. For example, maximizing power production requires a reservoir to maintain a high water level, while preventing the likelihood of flooding requires keeping the water level low. Although a dam cannot simultaneously maintain both functions, many are classified as multipurpose to intensify public support for dam projects. Central to the tremendous increase in hydropower dam construction is the belief that hydro projects are a clean, cheap, and renewable alternative to other forms of energy production. The unquestioning acceptance of this idea overlooks a great deal of evidence to suggest that hydropower dams are not as economically and environmentally benign as has been traditionally thought.
For example, is hydropower clean? While the pollution that is caused by large-scale dams may be less obvious than the dirty columns of smoke belching from coal-burning plants, dams do cause pollution. Among the many negative ecological consequences, damming rivers leads to seriously contaminated water in reservoirs and often releases high levels of the greenhouse gasses due to the rotting of submerged vegetation and soil. Brazil’s Balbina Reservoir emits a tremendous 23,750,000 tonnes of carbon dioxide and 140,000 tons of methane, making its impact on global warming 26 times that of an equivalent coal-fired power station (McCully, 1996). While all dams are not this lethal, table 2 (see appendix) illustrates that hydropower is far from being as ‘climate-friendly’ as its proponents allege. Moreover, the Three Gorges scheme has been defended on the grounds that it will generate clean energy, reducing pollution from thermal power stations. Yet by 2010, it is predicted that more than three quarters of the country’s energy will still be supplied by coal, oil, and gas—the same proportions as today (Morrish, 1997). Hence, an increase in hydroelectric projects does not necessarily guarantee a cleaner environment, for often dams are constructed as simply another means of keeping pace with an energy-hungry world.
Secondly, is hydropower cheap? This claim, based on the idea that water is ‘free’, quickly dissipates when the tremendous costs of construction are factored in. While the operating costs of hydropower dams are low in comparison to other forms of electricity production, the incredible costs of construction (which generally overrun original estimates by 30 percent) often make hydropower generation more costly per kilowatt than both natural gas and coal-fired power generation (McCully, 1996). Environmental degradation can also incur tremendous costs. The Vietnamese government estimates that the new Pa Mong Dam will require $80 million in additional investments because of the unexpected rate of erosion along the river’s banks (Lohmann, 1990). Health and social problems, as well as lower than estimated plant productivity, must also be factored into the final cost-benefit analyses of hydropower dams (see Table 3 in appendix). In a recent review, India found that some of the nation’s dams would have never been built had all the costs been included in the original analysis. In fact, in one of the reexamined projects, the costs of the dam turned out to be nearly twice its benefits (Adams et al, 1985). Clearly, hydropower dams are not always an economically sensible form of power generation.
Lastly, is hydropower renewable? If a government is willing to carry out the costly and repetitive process of removing sediment build-up in a dam’s reservoir, then hydropower dams can be considered a renewable resource. As sediment removal is key to maintaining a dam’s generating capacity, the schedule with which sediment is extracted from the reservoir will determine the long-term success of the dam as a means of power generation. However, due to the tremendous environmental degradation which follow these projects, hydropower dams cannot be classified as sustainable, for they compromise the ability of future generations to meet their own needs. Therefore, hydropower dams should be more accurately classified as an “unsustainable, potentially renewable resource” (Adams et al, 1985).
Grassroots efforts to stop the construction of large scale dams
Dam critics and grassroots organizations have used this knowledge to show that the actual realized benefits of large dam projects appear, in the majority of documented cases, to be much lower than those claimed. Over the last decade citizen protests against dams have grown and become better organized and able to fight projects on the local, national and international scales. In March 1997, the first ever international gathering of dam-affected people met in Curitiba, Brazil. With representatives from 20 countries, the group issued a call for an international moratorium on the building of large dams and also demanded reparations for the millions of people whose livelihoods have suffered because of dam construction (Wilkes, 1997). First World environmental organizations have also joined in the protest, accusing western engineering firms of “environmental dumping.” Dams such as the Bakun Hydroelectric Project in Sarawak, overseen by a Swiss engineering company, would not be permitted in most Western countries (Bawe, 1996). Working together, these organizations have forced an international debate on the negative impacts of large-scale dams.
The successes of many grassroots groups around the world have given strength to the movement. Groups protesting the poor compensation received by those resettled by the Riam Kana hydroelectric dam in Indonesia took the local authorities to court and won the case (Aditjondro et al, 1994). Additionally, protest groups, like the Chipko movement, are sharing information and using ecological analyses from diverse sources worldwide in strengthening a widespread popular position in favor of using sustainable uses of water resources (Bandyopadhyay, 1992a). Unfortunately, not all campaigns have been victorious. Groups opposed to the Sardar Sarovar Dam and the Tehri Dam in India were successful in convincing the World Bank to pull its funding of the project, but were not able to halt the construction altogether (Bandyopadhyay, 1992b). The Indian government contends that whatever the pros and cons, too much money has already been spent to cancel the projects altogether (Pearce, 1991; Wood, 1993). Unfortunately, civil protests have at times erupted into violence. Almost four hundred Maya Achi Indians were massacred in Guatemala in 1982 while protesting the construction of the Chixoy Dam (McCully, 1992). Luckily there have not been many situations of such severe repression, yet the memory of this event has served as a reminder of the importance of working toward an equitable solution in a timely manner.
The future for large-scale dam construction
The solutions provided by dam critics vary widely. Some critics are simply calling for more environmental assessments to be performed prior to the construction of dams. Other critics feel that they only way to correct this problem is to tear down large-scale dams and allow the rivers to run their course (McCully, 1996). What all critics do agree on is the need to further develop solar and wind power generation technologies, in the hope that these processes can someday replace the environmentally destructive methods used today.
While the debates are still highly polarized, critics have been successful in introducing the drawbacks of large scale dams into the international planning arena, so that today projects are no longer automatically approved by governments and funding agencies as have been in the last few centuries. However, it is still far too early to write the epitaph of the large dam. Although the rate of building has sharply declined, many large dams are still being built each year. As long as the environmental and social issues remain undervalued and understudied, large dams will continue to remind us that it is not possible to both dominate something and live in harmony with it.
*This paper was prepared for
a California State University Fullerton Graduate Seminar on Cultural Ecology.
|Adams, P. and Solomon, L. 1985. In the Name of Progress. Toronto: Doubleday.|
|Aditjondro, G. and Kowalewski, D. 1994. Damning the Dams in Indonesia. Asian Survey|
|Bawe, L. 1996. Private Profit at Public Expense: The Bakun Hydroelectric Project. The|
|Ecologist 26: 229-233.|
|Bandyopadhyay, J. 1992a. From Environmental Conflicts to Sustainable Mountain Transformation:|
|Ecological Action in the Garhwal Himalaya. In Grassroots Environmental Action: People’s|
|participation in sustainable development, ed. D. Ghai and J. M. Vivian, pp. 259-280.|
|Bandyopadhyay, J. 1992b. Sustainability and Survival in the Mountain Context. Ambio 21: 297-302.|
|Caufield, C. 1996. Masters of Illusion: The World Bank and the Poverty of Nations. New York:|
|Henry Holt and Company.|
|Edmonds, R. L. 1992. The Sanxia (Three Gorges) Project: the environmental argument surrounding|
|China’s super dam. Global Ecology and Biogeography Letters 2: 105-125.|
|Esteva, G. and Prakash, M. S. 1992. Grassroots Resistance to Sustainable Development: Lessons|
|from the Banks of the Narmada. The Ecologist 22: 45-51.|
|Kwai-cheong, C. 1995. The Three Gorges Project of China: Resettlement Prospects and Problems.|
|Ambio 24: 99-102.|
|Le Prestre, P. 1989. The World Bank and the Environmental Challenge. London: Associated|
|Lohmann, Larry. 1990. Remaking the Mekong. The Ecologist 20: 61-66.|
|McDonald, M. D. 1993. Dams, Displacement, and Development: A Resistance Movement in|
|Southern Brazil. In In Defense of Livelihood: Comparative Studies on Environmental|
|Action, ed. J. Friedmann and H. Rangan, pp. 79-104.|
|McCully, P. 1996. Silenced Rivers: The Ecology and Politics of Large Dams. London: Zed Books.|
|Morrish, M. 1997. The Living Geography of China. Geography 82: 3-16.|
|Pearce, F. 1991. Building a Disaster: The Monumental Folly of India’s Tehri Dam. The Ecologist|
|Rao, R. 1988. What Price Tehri Dam? Ambio 17: 246-247.|
|Scudder, T. 1993. Development-induced Relocation and Refugee Studies: 37 Years of Change|
|and Continuity among Zambia’s Gwembe Tonga. Journal of Refugee Studies 6: 123-152.|
|Usher, A. D. 1996. Damming the Theun River: Nordic Companies in Laos. The Ecologist|
|Weist, K. M. 1995. Development Refugees: Africans, Indians and Big Dams. Journal of Refugee|
|Studies 8: 163-184.|
|Wilkes, A. 1997. Dam-affected people call for end to large dams. The Ecologist 27: c2.|
|Wilkes, A. 1996. More Evictions at Nam Theun 2 in Laos. The Ecologist 26: c4.|
|Wilkes, A. 1996. Another Dam on the Bio-Bio. The Ecologist 26: c4.|
|Wilkes, A. 1996. Tibetans Oppose Hydroelectric Dam. The Ecologist 26: c4.|
|Wood, J. 1993. India’s Narmada River Dams. Asian Survey 33: 968-984.|