Big dams are plain bad. They flood people out of their homes and off their lands; wipe out endangered habitats and species; spread water-borne diseases; deprive flood plains of the water and sediments of life-giving floods (while increasing the damage floods cause to people); ruin beautiful landscapes and submerge places of great cultural or spiritual importance. And that’s just a partial charge sheet.
Big dams even cause earthquakes (because of the weight of water in reservoirs), release greenhouse gases (because of the rotting of flooded vegetation), destroy marine fisheries (because they disrupt river-borne flows of freshwater and nutrients into oceans) and lead to coastal erosion (because the sediments that eventually fill reservoirs would previously have flowed out through estuaries and then been washed back by waves to protect the shoreline). Occasionally, they collapse and drown people. In the world’s worst dam disaster – a mega-catastrophe that struck central China in 1975 when two large dams burst – as many as 230,000 people died.
The world’s baddest big dam has to be the gargantuan Three Gorges project in China. It will cause all of the problems above – on a mind-bending scale. More than half a million people are scheduled to be moved from their homes along the Yangtze by June 2003 when the first stage of filling the Three Gorges reservoir begins. By the start of the final phase of reservoir-filling in 2008 – just in time for the Beijing Olympics – a further 700,000 people (according to government statistics) will have been evicted. Chinese critics claim the final number will reach nearly two million. For their trouble, these critics have been beaten up, imprisoned and had their books and articles banned.
Human-rights abuses regularly accompany big dams – not just in China. In the 1980s more than 440 Guatemalans, mainly women and children, were murdered by paramilitaries because of their refusal to accept the resettlement package offered by the World Bank-funded electricity utility building the Chixoy dam.
Today, almost everywhere that a big dam is being proposed or built there is a community or a group of activists organizing against it. In southern Mexico, indigenous communities are fighting to win reparations for dams built 50 years ago.
While not every big dam causes huge damage, cumulatively the world’s over 45,000 large dams have done major harm. The World Commission on Dams, a World Bank-sponsored initiative backed by both dam supporters and critics, estimated that 40 to 80 million people have been displaced by dams. Sixty per cent of the length of the world’s large river systems are at least moderately or severely fragmented by dams and related withdrawals of water for irrigation.
This massive replumbing of the world’s rivers is a major reason for the rapid loss of freshwater species. Around a third of freshwater fish species are classified as extinct, endangered or vulnerable. A significant but unknown share of shellfish, amphibians, plants and birds that depend on freshwater habitats are also extinct or at risk.
But aren’t dams, like dentists’ drills and taxes, just a necessary evil that we must grudgingly accept for our greater good? Don’t we need to store water to keep us and our crops alive through dry seasons and dry years? Don’t we need to block floods? Don’t we need hydroelectricity?
We do need to store water. In large parts of the world rain falls only during one or two wet seasons, and within those seasons almost all the rain might fall in just one or two storms. And global warming is going to make rainfall even less dependable.
But the best form of water storage is in the ground, not in huge surface reservoirs created by damming rivers. Storage in the form of groundwater does not flood homes or habitats, and does not evaporate as does water in reservoirs.
Aren’t dams, like dentists’ drills and taxes, just a necessary evil that we must grudgingly accept for our greater good?
Groundwater is the primary source of drinking water for roughly a third of the world’s people and the great majority of rural dwellers. Land irrigated with groundwater tends to be far more productive than that watered from huge dam-and-canal irrigation projects. The difference is mainly because a farmer can control when they use water from their own well – with big dam irrigation schemes the quantity and timing of water supplied is at the mercy of an often inefficient and corrupt bureaucracy.
A growing movement, especially in India, but also in many other parts of the world, is now seeking to revive and update the age-old practice of augmenting the natural recharge of groundwater by trapping rainfall behind small embankments and dams long enough for it to soak through into the ground. In Alwar and neighbouring districts of northeast Rajasthan state alone, around 700,000 people benefit from the improved access to groundwater for household use, farm animals and crops. Not a single family has been displaced in order to achieve this. Rainwater harvesting also works in urban areas, where rain can be caught on rooftops and channelled into tanks.
Another benefit of water harvesting is that by slowing run-off from storms it reduces flood peaks downstream. Particularly in the US and Europe there has been a sea-change in attitudes towards floods in recent years. The old and failed approach of attempting to ‘control’ floods through building dams and embankments has now given way to a realization that it is much more effective to ‘manage’ floods.
Flood management means recognizing that floods are going to happen but trying to minimize the damage they cause. This can be done through better watershed management (including rainwater harvesting, halting deforestation and restoring wetlands) and urban planning, and early-warning systems to get people out of harm’s way.
While there is no alternative to life-giving water, there are many alternatives to hydroelectricity. The first is just to use electricity more efficiently. In India, as much as half the electricity generated is lost before it gets to consumers. The second is to explore new renewable sources of energy that can go a long way towards meeting needs.
So why have way too many dams have been built on the world’s rivers? There has never been a fair playing field when dams have been compared with their alternatives. Corruption and the power of the big-dam lobby, both in government and corporations, has meant that feasibility studies for new dams have regularly underestimated their costs and exaggerated their benefits. If assessments of options for water and energy needs were made comprehensive, transparent and participatory, very few large dams would make the grade. This is no doubt a major factor in the dam industry’s squeals of protest over the recommendations of the World Commission on Dams, which include just such assessments.
History shows that trying to dam our way out of our water problems will just make them worse. It also shows that a better water world is possible.
The big dam top 10 and Big dams by region
Indian author Arundhati Roy’s comment on the World Commission on Dams’ estimate that big dams contribute less than 10 per cent to India’s grain production:
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