International Journal of Marine Science, 2017, Vol.7, No.3, 19-30
27
observations was 3.8 m. Total drop of the sea level in the 20th century was 3.2 m. Sea level dropped with an
average intensity of around 4 cm/year. In 1930-1941 and 1970-1977 sea level drop intensity increased to 16
cm/year and 14 cm/year, respectively. After 1978 the sea level started to rise and in 1995 the average annual sea
level rose to -26.52 m. The intensity of the sea level rise in this period in average was around 14 cm/year and in
some years it reached 30 cm. This is most intensive and prolonged sea level rise over the entire period of
instrument-aided observations. The change of the sea level affects the water volume and the area of different parts
of the sea (Table 1). While the total area of the Northern Caspian Sea is 91942 km
2
, the area of its water surface is
90129 km
2
. The Northern Caspian Sea accounts for more than 24.3% of the total sea area. The Middle and the
Southern Caspian Sea have almost the same area. Total area of the Middle Caspian Sea is 137812 km
2
the
Southern Caspian Sea is 148640 km
2
or 25.788 m and 1029 m, respectively, average depth 4.4, 192 and 345.
Table 1 Variation of the area of the Caspian Sea
Sea level (m)
Northern Caspian
(km
2
×1000)
Middle Caspian
(km
2
×1000)
Southern Caspian
(km
2
×1000)
Entire Sea
(km
2
×1000)
-25.97
111.0
138.6
151.4
401.0
-26.97
104.0
138.2
149.9
392.1
-28.0
90.30
137.7
148.5
376.5
-29.0
72.8
137.3
146.9
357.0
-30.0
62.8
137.0
145.3
345.1
2.5 Caspian Sea fluctuation future
The forecasting of Caspian Sea level fluctuation is problematic function and more predictions which have done by
scientists were no precisely correct. But geological clues approved the cyclic fluctuation rhythm as above
mentioned there was 25 meters’ difference in sea level height during Holocene Epoch and 10 meters during past
1500 years ago. Nowadays the global warming impact on Caspian Sea level changing has been accepted and it has
been predicted if the atmosphere temperature arise the Caspian Sea level will be dropped about three meters by
2100 years. So more marginal basin like estuaries, Lagoon, swamp and Bay will be submerged and environment
vulnerability and crisis threaten human societies along the riparian countries. Now there is enough time for hazard
mitigation and crisis management.
2.6 Water temperature
The spatial and temporal variability of Caspian Sea water temperature depends on geographical situation, heat
exchange between atmosphere and water mass, and the thermal energy transfer between sea and rivers. The
distribution of annual mean values of water temperature in long term is considered as the most important thermal
index of Caspian Sea. In fact, this criterion confirms the effect size of seawater heat on climate of its surrounding
lands (Figure 9). The water temperature in offshore and abyssal zone in precaspian adjacent area (North of
Caspian Sea) is 18 degrees centigrade different from the southeast of Caspian Sea. The flow of Volga, Terek, and
Kura rivers and the blow of dominant winds in the region cause in reduction of sea water temperature in the
northern part (Figure 9). In the eastern half, the outflow of cold waters from Caspian Sea bed impacts the annual
temperature distribution and causes in thermal disturbance in the Caspian Sea water temperature. In the western
part of south Caspian, the variance of annual mean temperature is not so high (about one degree centigrade). The
maximum annual temperature variance of Caspian Sea water surface is 20 degrees centigrade, and this amount is
observed in the northern areas and south Caspian coasts (Figure 9). This process is the result of temperature
difference of extreme heat in summer and bitter cold in winter. The least temperature change has been observed in
the south Caspian Sea waters. In the eastern and western coasts of middle Caspian where the upwelling
phenomenon happens, the annual mean temperature variance decreases to 14 to 15 degrees centigrade. In the map
of annual mean temperature distribution on the Caspian Sea surface water, in some seasons the water temperature
is abnormal and this situation is influenced by factors which in short period impact the sea basin as dominant
processes.
