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Cyclic fluctuations in the level
2
of the Caspian Sea
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The Caspian Sea is the largest
closed body of water on the
surface of the Earth. Its com-
plete lack of any natural con-
nection with the oceans makes
it a very special ecosystem, and
as such particularly vulnerable
to external forces, such as cli-
matic conditions or man-made
changes to inflow.
In a century, between 1880 and 1977, the lev-
el of the sea dropped four metres (from –25
metres to –29 metres below mean sea level)
apart from short periods during which it rose
slightly. During this time local people be-
came accustomed to the gradual drop in the
water level, carrying out all sorts of work on
the shores, particularly after the second world
war: port infrastructures, roads and railways,
construction of housing and holiday facilities.
In the Soviet Union the dramatic drying up
of the Azov Sea, a side-basin of the Black Sea,
which occurred at the same time, gave rise to
genuine fears that the Caspian – or at least
its very shallow northern part, which is less
than 25 metres deep – would in turn shrink
significantly. This led to hasty, misguided de-
cisions such as the construction of a dyke in
1983 to close the Kara Bogaz Gulf.
The sudden reversal of the trend after 1977,
with a rise in the water level of about two
metres, took everyone by surprise and
caused widespread problems in several ar-
eas: flooding of urban facilities, destruction
of roads and railways, damage to industrial
The Caspian Sea has been endoreic – inwardly
draining – since the Pliocene epoch (about 5 mil-
lion years ago), prompting some specialists to treat
it as the world’s largest lake. Studies of its geomor-
phology and hydrology have revealed alternating
cycles of rising and falling water levels, raising
many questions, scientific for some, more down-
to-earth for those living on its shores.