China is building the world's biggest dam. It is that country's most significant public project since the Great Wall. The Three Gorges Dam will stretch a mile across and rise 575 feet above the Yangtze River. Do you know why the dam is being built?
In addition to providing drinking water, dams may be built for flood control, crop irrigation, and the production of energy. China's hydroelectric dam is being built primarily for flood control and energy production.
A hydroelectric dam harnesses water to create electricity. The Three Gorges Dam is expected to create as much electricity as 18 nuclear power plants÷about 18.2 million kilowatts per year. That's up to 1/9 of the electricity currently used per year by this country of approximately 1.4 billion people.
Chinese authorities hope that in addition to providing the country with another energy source, the dam will be able to control the Yangtze's infamous floods. More than 1 million people have died from these floods in the past century alone.
If 18.2 million kilowatts per year equals about 1/9 of China's total electrical usage, how much electricity is used in this country?
These improvements will come with a price. There are many issues involved with proper dam control. For example, earlier this year, the gates at the Kariba Dam in Zambia, Africa, were opened. Heavy rains had been falling along the Zambezi River, and officials worried that the swollen reservoir would break open the dam and cause major flooding. Ironically, the opening of the gates to prevent a potential flood then destroyed many crops farther down the river. Within nine hours, a year's worth of food was destroyed. Now the potential for starvation exists.
Accidental floodings are not the only concern associated with dams. When a new dam is being built, humans are often forced to leave their homes to make way for the reservoir. The 350-mile reservoir created by the Three Gorges Dam is going to "drown" more than 100 towns and displace at least 1.2 million people. Half of these people are farmers and will need either new farmland or urban jobs when they move. Critics of the dam argue that there are not sufficient plans in place to help these citizens.
Archaeologists worry about the nearly 1,300 historic sites that will be drowned when China's Three Gorges Dam is completed.
They are also concerned about third-century treasures that may be flooded in Turkey soon. That country is building the Birecik Dam on the Euphrates River to provide hydroelectric power. The treasures are located in Zeugma, the site of two ancient cities eighteen miles north of Syria. In addition to 14 mosaics, archaeologists have dug up 60,000 ceramic seals and 3,700 silver and bronze coins. The government is delaying the flooding for about 10 days to give archaeologists time to find more relics. More than 30,000 people have left their homes to make way for the dam.
Our Wildlife Friends
Humans are not the only beings facing challenges because of dams. The Yangtze dolphin population is already facing extinction, partly because of dam construction along the Yangtze River. The dolphin population - which 10 years ago was at 300 - has experienced a 2/3 drop.
Based on the statistics above, how many Yangtze River dolphins remain?
View maps and pictures of the
Three Gorges dam site, as well as a photo of a Yangtze River dolphin.
First-time visitors to the Quabbin Reservoir in the western part of Massachusetts may not know that beneath the water's surface are the remainders of four towns. Anglers peering over the sides of their fishing boats can sometimes see the foundations of abandoned homes as well as the stone walls that used to divide people's property.
The villages were located in a valley flooded in 1939 with water from the Swift River. The resulting 412 billion-gallon reservoir now serves as a source of drinking water for the city of Boston, Massachusetts. Planners believe this will be a sufficient water supply for the city until at least 2020.
To make way for the reservoir, homes and factories were bulldozed and many acres of trees were chopped down. Cemeteries were also excavated and all the bodies, except for those of American Indians, were removed.