EarthViews is a continuing series in which we share a USGS Image of the Week featuring the USGS/NASA Landsat program. From the artistry of Earth imagery to natural and human-caused land change over time, check back every Friday to finish your week with a visual flourish!

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The EarthView: Three Gorges Dam Brings Power, Concerns to Central China

Description:

The construction of the Three Gorges Dam on the Yangtze River in central China offers an interesting glimpse into the balancing act borne from humanity's changing of the natural landscape.

Images from Landsat 5 in 1993 and Landsat 8 in 2016 show a river transformed after the completion of the largest hydroelectric power plant in the world in 2012. The Yangtze appears light blue in these scenes because of heavy sedimentation in the water as it passes through the Qutang, Wu, and Xiling gorges in this mountainous region. Tributaries with less sediment appear darker blue. Forested areas are red because of Landsat's near-infrared imaging capability.

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Hydropower as an alternative energy source to coal is a valuable output from the dam. Three Gorges' power plant has a generating capacity of 22,500 megawatts, over 3 times that of the Grand Coulee Dam and 20 times that of Hoover Dam. Besides hydropower, the dam has also made river navigation easier, eased flooding, and provided an ample water supply for irrigation.

On the downside, the project forced the relocation of more than 1.2 million people. A 2010 study by the China Earthquake Administration found that Three Gorges Dam had triggered about 3,400 earthquakes from mid-2003 to the end of 2009, as well as numerous landslides, representing a 30-fold increase in seismicity. Environmentalists worry as well that large amounts of silt are congregating in the Three Gorges' region because of a change in the river's flow, that biodiversity in the river downstream from the dam has been lost, and that important archaeological sites and ancient monuments were inundated as the reservoir filled.

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