The Aral Sea is an outflowless lake in Central Asia that is fed by the Amu Darya and Syr Darya rivers. An ecological catastrophe has occurred in the region around the lake, the area of which has been shrinking for decades. The causes are human interference in the ecosystem to obtain irrigation areas for cotton cultivation. In these interventions, the complex relationships between all components of the ecosystem were not sufficiently taken into account, which had catastrophic consequences.
The Aral Sea is an inland lake with no outflow in the Turan lowlands between the CIS countries Kazakhstan and Uzbekistan (Fig. 1).
It is fed by the Amu Darya and Syr Darya rivers. Their source rivers arise in the glacier regions of the Central Asian high mountains Pamir, Hindu Kush and Tienschan. On their way to the Aral Sea, the currents flow through the Karakum (black sand) and Kysylkum (red sand) deserts.
An ecological catastrophe that threatens nature and humans is taking place at the Aral Sea. It is an example of how short-sighted human interference in nature can endanger entire habitats:
Since the 1960’s, the Aral Sea has “shrunk” from the fourth largest inland lake in the world with an area of 68,000 km² to almost half of its area and is also divided into a large and a small Aral Sea (Fig. 2).
The water level sank by 13 m from the original average of 17 m to 4 m. The coastline receded between 70 and 80 kilometers. In front of the gates of the former port cities of Aralsk and Muynak there are desert-like salt plains.
The amount of water in the lake decreased by 60%. Its salinity, on the other hand, almost tripled and is already above that of the Dead Sea. The lake and riparian zones are therefore biologically as good as dead. The region’s economy based on fishing and fish processing has collapsed.
Karakum and Kyzylkum have had a rapidly growing sister, the “Akkum” (White Desert) disaster zone around the lake.
Violent storms sweep over the former lake floor, blowing around 100 million tons of a sand-dust mixture every year to the edge of the Pamir. This mixture is mixed with fertilizers and pesticides that were previously brought onto the arable land in an uncontrolled manner and washed into the lake. This has led to an epidemic-like spread of diseases in the population.
Amu Darya and Syr Darya are drying up in the expanses of the Central Asian deserts and only reach the lake in extremely wet years.
… and its causes
This catastrophic development, which threatens the existence of more than 3 million Kazakhs and Uzbeks, goes back to government decisions in the former Soviet Union.
In order to make the country independent of foreign imports, it was decided in the 1950’s to significantly expand cotton cultivation in the steppe and desert regions of Central Asia.
The water necessary for growing cotton had to be obtained from the rivers. On Amu Darya and Syr Darya a huge system of irrigation canals arose. The irrigation areas along the rivers and the Karakum Canal tripled between 1950 and 1990. 90% of the Soviet cotton was produced on them in quantities that made the country independent of imports.
With this the goal of the government, which initially brought the people a certain prosperity, was achieved. But it was bought at a high price:
not only new irrigation areas, but also the rapidly growing population of cities and new industries required huge amounts of water.
There was also a large amount of wasted water. It has been calculated that around 84 billion cubic meters of water were used for irrigation in 10 years. However, 100 billion cubic meters trickled through the walls and joints of defective sewers, seeped into marshy depressions or evaporated in lakes without drainage.
The amounts of water removed from the rivers soon exceeded the “replenishment” from the mountains and from the already low rainfall in this region.
This ultimately led to the catastrophic consequences for nature and people described above.
These consequences show that the complex interrelationships in the geosphere have to be carefully considered and considered if human intervention is not to outweigh the disadvantages in the long term.