Monitoring the Aral Sea

Situated in central Asia, the Aral Sea was 50 years ago the fourth biggest lake in the world area-wise. Since the 1960s, it has shrunk by a factor of six, as a result of increased irrigation for the development of cotton and rice crops. At the end of the 1980s, it split into two basins, the Little Aral Sea in the north, and the Large Aral Sea to the south. Since then, these two basins have developed in very different ways.

The small sea has more or less stabilised, its level even rising at times due to the building of a dam that retains the spring floods of the river that continues to flow into it, the Syr Darya. On the other hand, the large Aral has continued to shrink inexorably, more or less rapidly depending on the year, and its salinity has increased to values that exceed 100 g/l, thus making it totally hostile to life. In contrast, the salinity of the little Aral has remained fairly low (around 10-15 g/l), and in the past few years fishing has started up again, bringing with it limited but genuine economic recovery.

With regard to the climate, the situation is complex, because the fall in the level of the sea caused by human activity has led to higher temperatures in and around the sea, magnified by global climate change. It is therefore not easy to study and separate the combined effects of these two phenomena, but altimetry satellites and various other instruments, associated with current climate models, will enable us to better understand change in the Aral sea.

Jean-François Crétaux