September 13, 2010 - Aral Sea

Aral Sea

Clear and cloudless skies over Central Asia on September 7, 2010 allowed the Moderate Imaging Resolution Spectroradiometer (MODIS) aboard the Aqua satellite to capture a stunning image of the long-troubled Aral Sea. The country to the north of the boundary line is Kazahkstan, to the south is Uzbekistan, and to the far south lies Turkmenistan.

In this true-color image, the dry steppes are seen as various shades of light tan. The North Aral Sea and the western section of the South Aral Sea are dark emerald-green, while the eastern section of the South Aral Sea appears as bright green and pale teal, with streaks of white. The dark green indicates deeper waters; paler shades indicate shallow areas, while white streaks are most likely salt. The swirls of light green in the darkest water most likely represent a bloom of algae.

The Aral Sea was once the fourth largest inland water body on Earth, with a surface area of 26,000 square miles (67,300 square km) Beginning in the 1960s, diversion of water for irrigation of cropland drained water from the two rivers feeding the Sea - the Amu Darya and the Syr Darya and resulted in desertification. The expanse of the former Sea is colored white in this image a result of salt deposited as water evaporated.

The Syr Darya can be seen as a meandering line of green and tan the east of the Aral. Mottled brown-green patches, indicating vegetation, mark the delta of this river. A similar pattern can be seen at the delta of the Amu Darya, to the south. In 1936, the Amu Darya delta was reported to contain 2,330 square kilometers of lakes; in 1980 this had been reduced to 76.3 square kilometers. In 1936, the Syr Darya delta contained 1490 square km of lakes, with only 400 square kilometers remaining by 1976.

In 2005, Kazakhstan began work on an eight-mile (13 km) dike between the two halves of the Aral Sea, as well as improving irrigation systems on the Syr Darya, with the goal of raising the water level in North Aral. According to National Geographic, the North Aral has since grown by 20 percent, salinity has decreased nearly to the levels of the 1960s, and life is beginning to return. The South Aral, however, continues to shrink.

Image Facts
Satellite: Aqua
Date Acquired: 9/7/2010
Resolutions: 1km ( B), 500m ( B), 250m ( B)
Bands Used: 1,4,3
Image Credit: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC