Photo: Process drying of Aral sea (Interactive map from wikimedia.org)
Millions of years ago, the northwestern part of Uzbekistan and western Kazakhstan were covered by a massive inland sea. When the waters receded, they left a remnant sea known as the Aral.
The Aral as an inland salt-water sea has no outlet being fed by the Amu Darya and Syr Darya Rivers. The fresh water from these two rivers once held the Aral's water and salt levels in balance. However after the 50ies and 60ies when a series of major irrigation schemes were undertaken on the two rivers by Soviet Engineers the water started to recede.
The schemes were based on constructing a series of dams on both two rivers to create reservoirs from which eventially 40.000 km of canals would be dug to divert water to field crops. Afterwards however there was little or no water left in the riverbeds to flow to the Aral Sea. Consequently the water level in the last 50 years in the Aral has dropped by 16 metres (60%) and the volume has been reduced by 75 percent.
Whilst triggering what is considered one of the 20th Centuries greatest ecological disasters; these schemes will not be reversed as irrigated crops are the main source of income and food for millions of people living in the region. The fall in the Aral Sea appears to have slowed, the most recent Google Earth images showed only small changes since ca. 2003.
Photos: NASA satellite images the Aral Sea and part of the lowland section of the Aral basin.