Autumn 1994 (2.3)
Pages 48, 76
Fluctuating Levels of the Caspian Sea
by Mirzakhan Mansimov and Amir Aliyev
Photo: Caspian Sea rising at living quarters at Oily Rocks. 1994.
The Caspian is of exceptional interest to scientists because of its history of fluctuations in both area and depth, which offer clues to the complex geological and climatic evolution of the region.
Approximately 5 million years ago, the Caspian Sea separated from the Black Sea as a result of tectonic and climatic processes and formed its own independent basin. Today it is the world's largest lake. More than 80% of its shoreline falls within area that used to be part of the Soviet territory, and which now includes four Republics - Azerbaijan, Turkmenistan, Kazakhstan and Russia. The Caspian also borders Iran.
Its elongated shape sprawls for nearly 750 miles (1,200 km) from north to south and its average width is about 200 miles (320 km). It currently covers an area of about 143,000 square miles (371,000 km2) an area larger than the land mass of Japan. The Caspian not only is an economical source but also a climatic regulator of the area.
During these many years there have been considerable fluctuations of the sea level. Short-term wind-induced fluctuations can cause rises up to seven feet, though the average is about two feet. Barometric pressure changes can cause similar fluctuations. Tidal variations are but a few inches. And the seasonal rises induced by high spring water in the rivers are not much more.
One of the more fascinating aspects of the study of the Caspian, however, is the reconstruction of long-term fluctuations over the centuries gathered from archaeological, geographical, and historical evidence.
Fluctuations over the Centuries
Levels were fairly even from the 5th to 8th century but rose during the 12-13th, and again in the17-19th centuries only to plunge in the 14th and 20th. Gauge readings extend back to 1830 and suggest a relationship of high lake levels with cool, rainy summers over the Volga drainage basin in central Russia; the lake level fell almost steadily between 1929-1945 partly due to the removal or retention of Volga waters for irrigation and hydroelectric projects.
Between 1930-1977, the sea level fell dramatically-more than 3 meters (10 feet). By 1977, it was minus 29 meters below sea level, the lowest level ever recorded in the previous five centuries. However since 1978, the situation has reversed itself and the Caspian is rising at the rate of 15-25 cm per year. In the last 15 years, it has risen more than 2.5 meters (8 ft.).
Reasons for Sea Fluctuations
Scientists are baffled as there are so many contributing factors that could effect the rise such as runoff inflow, precipitation over the sea itself and evaporation from the sea surface. The water balance of the Caspian depends directly on climate changes, taking place on all territory of the Caspian Sea's basin which, in turn, is greatly influenced by the Volga which provides more than 80% of the lake's volume.
Some scientists have suggested that the sea level variations are due to tectonic processes taking place in the region of the Caspian. But a study of geomorphologic processes for the last 200 years shows that the tectonic activity in the region is very weak. Some have even suggested that there is a relation between the Caspian Sea's rise and the Aral Sea's (Kazakhstan) dramatic fall even suggesting there might be an underground canal, linking the two seas. But such ideas don't have scientific basis. The Aral Sea is caused by the diversion of water resources of Amu-Darya and Sir-Darya rivers to agriculture.
Predicting the Future
One of the most important, yet at the same time, most complicated, problems relates to the elaborate process of predicting long-term variations in the sea level. Many scientists confirm that contemporary science does not have the capability to forecast beyond 5-10 years. Even in countries which are highly equipped with modern calculation technology, forecasts are usually not made beyond 3-6 years.
Will the Caspian Continue to Rise?
It's very difficult to know. The Caspian Sea level variations are determined by atmospheric circulation and their change in the Northern Hemisphere, which are related to such geophysical processes as movement in the oceans and continents, change of radiation, solar activity and solar-terrestrial relations.
Forecasting based on the change of types of atmosphere circulation and anthropogenetic climate changes shows that the Caspian's level will rise another 1-1.5 meters until about 2020. Then for the next 40-50 years there should be stabilization in the sea, leveling off at about minus 26 meters.
Consequences of the Rise
The most serious problem relates to the coastal territories. From 1978 to 1993 more than 40,000 square kms. of coastal zones have been flooded, 800 km2 of which lies in the territory of Azerbaijan where there are about 50 settlements, including such large cities as Baku, Sumgayit, Lankoran, 250 industrial facilities, and 20 kms of railway which are now exposed to flooding.
Oil fields adjacent to the Caspian sea are beginning to be flooded. The level of ground water also is rising which leads to swamping and salinity of lowland territories on the southern sea coast. In connection with the rise in sea level, there has been an increase in the effect of winds which have inflicted the greatest damage on the northern and southern shores.
Regional Problems Require Regional Solutions
The problems of the Caspian are not restricted to Azerbaijan-all five countries share these problems and as such, no single country can provide the solutions. They require regional economic and environmental decisions, legislation, and enforcement. Since the breakup of the Soviet Union, there has been no mechanism to promote the joint use of bioproductivity and industrial potential.
Therefore, all five countries must be involved in the decisions which directly affect each of them. A Joint Body of all five States needs to be formed, probably best worked out under the umbrella of the United Nations. The Caspian is an international treasure which must be maintained for all the world.
Mirzakhan Mansimov is Vice Chairman of the State Committee for Hydrometeorology in Azerbaijan and Amir Aliyev is Chief of the Hydrometeorological Center, "The Caspian."
Translated from Russian by Alia Abassova and Farida Husseinova.
From Azerbaijan International (2.3) Autumn 1994.
© Azerbaijan International 1994. All rights reserved.