<P> By 1960 , between 20 and 60 km ( 4.8 and 14.4 cu mi ) of water each year was going to the land instead of the sea . Most of the sea 's water supply had been diverted , and in the 1960s , the Aral Sea began to shrink . From 1961 to 1970 , the Aral 's level fell at an average of 20 cm ( 7.9 in ) a year ; in the 1970s , the average rate nearly tripled to 50 -- 60 cm ( 20 -- 24 in ) per year , and by the 1980s , it continued to drop , now with a mean of 80 -- 90 cm ( 31 -- 35 in ) each year . The rate of water use for irrigation continued to increase ; the amount of water taken from the rivers doubled between 1960 and 2000 , and cotton production nearly doubled in the same period . </P>
what caused the dramatic reduction to the aral sea in former soviet union
between 20 and 60 km ( 4.8 and 14.4 cu mi ) of water each year was going to the land instead of the sea