Answer: Aral; irrigation
Step-by-step explanation:
The waters of the Aral sea have been reduced due to overuse for irrigation purposes.
Once one of the largest lakes in the world - fourth largest - the Aral sea is now about 10% of its original size as its waters were reduced massively when its source rivers were diverted for irrigation by the Soviet Union.
With little water to feed it, the lake kept shrinking till it got to its current size. Environmentalists call it one of the worst disasters to ever affect the environment.