How did river diversion for irrigation contribute to the shrinking of the Aral Sea?

The shrinking of the Aral Sea was primarily caused by the Soviet Union’s economic policies, which diverted the waters of its two main inflowing rivers—the Syr Darya in the north and the Amu Darya in the south—for large-scale agricultural irrigation projects.123

Historically, the water balance of the Aral Sea was maintained by the inflow from these rivers, which roughly equaled the amount of water lost to evaporation. Beginning in the 1960s, the government converted vast areas of pasture and untilled land into irrigated farmlands, particularly for cotton cultivation. As these rivers were diverted to supply water to these arid regions, the volume of water reaching the sea dropped drastically.134

By the 1980s, the rivers often dried up entirely before reaching the lake, causing the sea to shrink rapidly due to unreplenished evaporation. This ecological disaster led to a significant loss of surface area and volume, increased salinity, the collapse of the local fishing industry, and severe environmental and health consequences for the surrounding populations.315