Why does the level of the Caspian sea and Aral Sea drops each year?

Question

Some sources say it's a matter of evaporation, yet we know that other lakes situated in hotter places on Earth don't suffer such a regression. And is it true that wise men once considered either of these two ponds as the "navel of the earth" and "the fountain of youth" (holy grail for christians)?

Answer 1

The Caspian Sea has no natural outflow, so it loses water through evaporation. It rises and falls depending largely on the volume of water coming in from the Volga River. The total water from the Volga dependson rainfall in the large catchment basin. Rain and snow in the basin are related to weather cycles in the North Atlantic. For this reason, the Caspian is said to be a good place to study the causes and effects of global climate change.
The land-locked Aral Sea loses water to evaporation, but "since the 1960s the Aral Sea has been shrinking, as the rivers that feed it (the Amu Darya and the Syr Darya) were diverted by the Soviet Union for irrigation. "

Answer 2

I am not sure if these 2 lakes have some other source of drainage or not. To the best of my knowledge, they are land locked and lose water by virtue of evaporation. This is the same mechanism for water loss by various lakes in what is known as the Great Basin area of California and Nevada. Other lakes in other regions most likely have other water sources to keep them full, so long as that flow is available. It really is wrong to assume that what causes one lake to rise or fall is based on the mechanisms of another lake in another part of the world. Using your faulty premise, all of the lakes in Northern California, or Nevada should never fall below their full water level. Water should be able to climb up through the high passes to keep these lakes full, based on your premise of other lakes in warmer regions.