Moving water holds potential for generating electricity, and hydroelectric power currently generates over 16 percent of the world’s electricity.

These Landsat images show the site of the Three Gorges Dam in China, which is the largest hydroelectric dam in the world. The dam is over 2,300 meters (1.4 miles) long and forms the straight line across the river in the second image. The project became fully operational in 2012 and has a power generation capacity of 22,500 megawatts. The reservoir created behind the dam stretches 600 kilometers (373 miles) along the Yangtze River and provides water storage for downstream flood control along with electric power.

The Landsat image from 1993 (left) shows the area one year before construction began. The 2013 image (right) was acquired one year after the power plant became fully operational. The second image shows the reservoir created by the dam and the higher water level that now extends into many side valleys. Also visible in the 2013 image is a lock system that supports shipping traffic, as the increased depth and width of the river now permit larger ships to travel this area.

As hydroelectric power continues to expand around the world, Landsat imagery can help monitor the land surface changes and impacts caused by these projects.