World Savvy Monitor

For a long time, building dams has been an effective way to harness water for human use.  Recently, however, it has become clear that the consequences of our reliance on dams are mixed.  A good example is the controversial Three Gorges Dam on the Yangtze River in China.    

• Background
• The Three Gorges Dam

Background

For much of the 20th Century, dam projects were seen as cost-effective ways to increase energy availability, harness and provide clean water, and control flooding, while also providing jobs and economic growth.  Dams were the preferred way to:

• Manage seasonal variability in rainfall and water supplies;
• Regulate water flows in order to prevent floods;
• Create hydroelectric power;
• Entice vendors and consumers of lake recreation and tourism; and
• Display national pride and know-how in giant infrastructure construction.

Today new dams no longer seem so appealing.

• Most easily diverted major waterways are already dammed, especially in the developed world. 
• The human cost of dams in terms of people displaced by construction and resulting pollution is becoming more apparent and less tolerable.
• The environmental costs are becoming evident in terms of destroyed ecosystems and damage to animal and plant species.
• Large reservoirs combined with global warming are leading to high evaporation rates that result in decreased water yields from dams. 
• Major accidents from leaky or breached dams have the potential to kill large numbers of people, especially as populations around them become denser.
• Soil erosion along diverted waterways can lead to deadly landslides, while the buildup of silt in other parts of the system impedes water flows and electricity generation.

There are currently 50,000 plus large dams in the world.  It is unlikely that many more will be built, since in the 21st Century the logistical, human, and ecological costs would in all probability outweigh the benefits.

The Three Gorges Dam

In no place has the concern over dam projects generated more publicity than in China, home to many of the world’s medium and large-sized dams.  Included on China’s list is the recently completed Three Gorges Dam, the world’s largest hydroelectric project.  The Three Gorges Dam is part of a concerted effort by the Chinese to tap into the many rivers draining out of the Tibetan high plateau to meet the country’s ever growing energy needs.

While initially the Chinese government proudly emphasized the engineering marvel that was represented by the dam, it has become increasingly evident that the dam has taken a staggering social and cultural toll.  It is estimated that 1.3 million people were forced into resettlement during construction, with up to 4 million more anticipated to be relocated in the next 15 years due to environmental damage (primarily landslides) and pollution from the project.  Entire communities, ways of life, and ancestral archives have been flooded and/or destroyed.  Fears are rising that a natural disaster, such as an earthquake, could cause immense damage to the dam, and potentially kill millions in a resulting flood. 

The environmental toll has been no less significant; the litany of effects described above for dams has occurred on an unprecedented scale.  Ecosystem destruction and pollution has occurred not only at the site of the dam, but also in communities where large populations have had to relocate and further stress natural balances in regions already suffering from overpopulation.  As farmers retreat to higher ground and attempt to build farms on the hillsides, massive erosion and landslides are occurring.  Geologists believe that the threat of earthquakes, already a risk in this region, is increased by the pressure from the water in the dam’s growing reservoir.  Silt accumulation in the reservoir is developing rapidly, and is expected to cause flooding upstream. 

The problems created by the Three Gorges Dam have clearly demonstrated that large dam projects are not the solution they were once thought to be.  Alternative methods of energy generation more suited to modern life and environmental realities must be developed; these will undoubtedly be more technologically creative, more local, and less environmentally destructive.  

See:

New York Times' "Chinese Dam Projects Criticized for Their Human Costs"

BBC News' "In Pictures:  Three Gorges Dam"

BBC News' "Three Gorges Dam Reaches for the Sky"

BBC News' "Deep Concern Over Three Gorges Dam"

Next:  Water, Politics, and Conflict