'Military report on Tehran and adjacent Provinces of North-West Persia (including the Caspian Littoral)' [‎222r] (448/610)

409
A.—Water.
The Caspian is divided by a line of submarine hills between
Baku and Krasnovodsk into two basins, the Southern being the
deeper with a maximum depth of 517 fathoms near the South
West corner where the Elburz approach close to the sea. It
is shallowest along the desert on the East.
Great variations of climate are experienced. In the
Northern basin the winter is arctic, and North of a line drawn
from Chechan island to Alexandrovsk, i.e., the Northern
quarter, the sea is frozen from the latter part of December
to mid-April. Thin ice reaches Petrovsk and Krasnovodsk
and snow falls at Baku.
In the Southern basin the winter is mild, very IPile snow
falls on the coast of Gilan and on the coast of Mazandaran any
snow at all is abnormal.
The prevailing winds in the open sea are North and South
and gales are most prevalent in winter and spring, but even in
fair weather storms rise and fall with great suddenness, and the
sea, from being as calm as a mill pond, within a few hours
becomes very rough and as quickly subsides. These sudden
winds are probably caused by the heating and cooling of the
desert. At Baku in summer a strong wind off the shore blows
from 1 or 2 to 5 days at a time and drives clouds of dust which
hide the land.
There is no tidal rise or fall, but a strong wind makes a dif
ference of some inches at Baku and of some feet near the mouths
of the Volga, where the sea is very shallow. In the Northern
basin, especially, there appears to be a circular anticlockwise
current which is lessened or increased by heavy winds.
In this basin heavy atmospherics are very prevalent in
spring and summer and interfere with wireless. Fogs are very
prevalent near Baku and may be due to a current of cold water
from the North being forced up to the surface by the submerged
ridge between Baku and Krasnovodsk. Similarly during April
and May, when the ice is breal ing, the cold water coming
South causes thick fogs in the Northern Caspian.
. Salinity steadily increases from North to outh Forty
miles from the mouths of the Volga ships pump Pesh drinking
water and at Chechan Island. 100 miles from the Volga, the
wa er is sti 1 s table for washing purposes. In the ‘ outh-
em basin ships draw their fresh water from the Kura river.
The treaty of Turkomanchai imposed by Russia on Persia
in 1828, stipulated that the Persian flag should not be flown by
2 D
Natural
Features
of Caspian Sea.
Russian
activities on the
Caspian.