1. Three Gorges Project, China Three Gorges Project, China This hydroelectric dam is the world’s biggest dam, producing 22,500MWh of earth-friendly electricity. However the 39.3km 3 dam has also been mired in controversy from the outset, causing the displacement of over 1.2 million people and untold environmental damage. Experts have also warned that the Three Gorges dam’s position on a series of seismic faults could also trigger a catastrophic earthquake. However, the Three Gorges dam will also remove some 100 million tonnes of CO 2 and 2 million tonnes of SO 2 that would otherwise have been generated by coal-fired power stations.

2. 3 Gorges Dam

6. Three Gorges Dam video clip

7. Hoover Dam Facts 726.4 feet high -- 1,244 feet across at the top -- 660 feet thick at the base -- 45 feet thick at the top -- weighs 6.6 million tons -- the surface area of Lake Mead is 146,000 acres... -- the maximum water surface elevation of Lake Mead is 1229 FT -- the maximum depth of Lake Mead is 590 FT -- the length of Lake Mead is 115 miles... -- has a power generating capacity of 2.8 million kilowatts... Located near Las Vegas, Nevada, spans the Colorado River

8. Hoover Dam Constructed in the 1930s, the concrete arch- gravity structure was intended to prevent flooding as well as provide much-needed irrigation and hydroelectric power to arid regions of states like California and Arizona. Building Hoover Dam required more than 5 million barrels of concrete. The finished dam contains enough concrete (4.5 million cubic yards) to build a two-lane highway from Seattle, Washington to Miami, Florida.

9. Hoover Dam

11. Construction on the Hoover Dam began September 30, 1930. The last concrete was poured in 1935. Hoover Dam is part of a system which provides water to over 25 million people in the southwest United States. About 16,000 men and women worked on the project. Video on Hoover DamVideo on Hoover Dam (show first 11-12 minutes and then last 8 or so)

12. Aswan Dam in Egypt The old Aswan Dam was built between 1898 and 1902. It was a very big hydrological project undertaken by the British to increase irrigation and hydro- electric energy.

13. Buford Dam An earthen dam

14. Dams Most dams are earthen dams. They are the least expensive to build Most massive structures. The core is made of an impervious material such as clay or concrete. Buford dam is an earthen dam.

15. . The idea of a lake and dam north of Atlanta traced to Atlanta Mayor William Hartsfield (third from left in photo), who was interested in controlling downstream flooding, a reliable source of drinking water, hydroelectric power, and a lake for recreation purposes. (1950)