Soviet dike alters Caspian Sea dynamics

In 1980, the USSR built a dike to address rising Caspian Sea levels by cutting off the Kara-Bogaz-Gol gulf, a shallow bay on Turkmenistan’s coast. The gulf was intended to function as a natural valve, drawing water from the sea and returning it to the atmosphere through evaporation, thus reducing the sea’s level.

Unexpected drying of the gulf

The dike was expected to take about 25 years to dry the gulf, but it happened in just three years, creating a salt desert covering 18,000 km². This was due to the Caspian Sea’s level having already risen for three years before the gulf was sealed, altering the expected hydrological balance.

Environmental consequences of the dike

The rapid drying of the gulf led to severe environmental effects, including salt storms that spread fine particles over large areas, degrading soil quality and affecting crops. By 1992, after the USSR collapsed and Turkmenistan gained independence, the dike was destroyed to restore the gulf’s connection to the Caspian Sea and mitigate the damage.

Caspian Sea continues to shrink

Since 1996, the Caspian Sea has been losing surface area, with over 23,000 km² lost, according to a study in the journal Earth's Future. This decline is mainly due to reduced river inflows, especially from the Volga River, with evaporation playing a smaller role.

Future projections and lessons learned

Projections in Nature suggest the Caspian Sea’s level could drop by up to 18 meters by 2100, potentially drying the Kara-Bogaz-Gol gulf permanently and exposing submerged plateaus. Scientists emphasize the importance of understanding complex hydrological systems, using the dike as a cautionary example of unintended environmental consequences from large-scale human interventions.