Why did the Caspian Sea water level rise after 1978?

The rise in the Caspian Sea water level after 1978 was primarily driven by climate change, which altered the balance between water gains and losses.1

Specifically, the increase in water level resulted from the following factors:

• Increased River Inflow: There was a significant rise in the inflow from the Volga River, which in some years was considerably higher than the historical average.1
• Precipitation and Evaporation: An increase in precipitation directly over the sea, combined with a decrease in evaporation, contributed to the rising levels.1
• Human Intervention: In 1980, Soviet hydrologists constructed sand barricades to block the outflow of water into the Kara-Bogaz-Gol, further helping to retain water within the sea.1

These factors reversed the trend of the preceding decades, during which the sea level had declined due to increased evaporation, reduced river influx, and the construction of reservoirs for irrigation and industry.12