The dam is built along the Yangtze River, the third largest in the world, stretching more than 3,900 miles across China before reaching its mouth near Shanghai. Historically, the river has been prone to massive flooding, overflowing its banks about once every ten years. During the 20th century alone, Chinese authorities estimate that some 300,000 people were killed from Yangtze River floods. The dam is designed to greatly improve flood control on the river and protect the 15 million people and 3.7 million acres of farmland in the lower Yangtze flood plains.

Observations from the NASA-built Landsat satellites provide an overview of the dam's construction. The earliest data set, from 1987, shows the region prior to start of construction. By 2000, construction along each riverbank was underway, but sediment-filled water still flowed through a narrow channel near the river's south bank. The 2004 data shows development of the main wall and the partial filling of the reservoir, including numerous side canyons. By mid-2006, construction of the main wall was completed and a reservoir more than 2 miles (3 kilometers) across had filled just upstream of the dam.

To read more about the Three Gorges Dam, please click here.

This animation was designed in three parts:

Part 1: The first part of this animation zooms in to the Three Gorges Dam and travels backward and forward through time emphasizing the dam construction and filling of the reservoir. This animation then continues seemlessly into Part 2.

Part 2: Starting where Part 1 leaves off, the camera flies up the 2006 data showing the high water levels that have already filled the multiple gorges upstream.

Part 3: Identical to Part 2, except showing the 1987 data prior to the dam construction.