How did the Greater Sea divide into eastern and western lobes?

The division of the Aral Sea into eastern and western lobes was a direct consequence of the dramatic shrinkage of the lake, which began in the second half of the 20th century due to the diversion of the Amu Darya and Syr Darya rivers for large-scale irrigation projects.12

As the water level dropped, the lake receded into separate bodies of water. By 1989, the sea had split into the "Lesser Sea" in the north and the "Greater Sea" in the south. Continued water loss caused the Greater Sea to further recede, and by 2001, it had divided into a long, narrow western lobe and a larger, broader eastern lobe. This process was driven by the evaporation of unreplenished waters, as the rivers that once maintained the lake's stable water level were largely diverted before reaching the basin.21