World Sea Day is celebrated annually on September 29. The goal is to draw the attention of the international community to the problems of the seas and oceans, such as pollution, poaching, climate change, the newspaper ”Caspian” writes.
One of the main problems of the Caspian Sea in recent years is shallowing, and we talked about this with the head of the Iglim company engaged in environmental research, Doctor of Philosophy in Geographical Sciences Mirzakhan Mansimov.
– Let’s talk about the reasons for the shallowing of the Caspian Sea.
– The main reason is the change in the elements of the water balance. 80-82% of our reservoir is fed by the Volga, but due to the fact that recent years have been arid, there is less water inflow from there. Evaporation in the catchment basin and from the surface of the Caspian Sea itself is also increasing.
– Is global warming to blame for this process?
– Of course, global warming contributes to the climate. But in the 90s, warming was already observed, but the level of the Caspian Sea rose, not decreased. Now the situation is reversed. The climate is changeable: somewhere the moisture content of the territory increases, somewhere it decreases. When the Gulf Stream moved towards the Arctic Ocean in the 90s, humidity increased in our region (Eastern European Sector). The Volga became high–water, which affected the level of the Caspian Sea – it increased by 2.5 m in 1979-96. During this period, cyclonic activity prevailed over the catchment area of the sea. In the last 20 years, an anticyclone has taken over, and this has caused the formation of an arid climate. Precipitation is less, water runoff in rivers has decreased, and evaporation has increased. Therefore, the water level in the sea has decreased.
The lowering of the Caspian Sea level is not the first time, it was observed until the mid-70s. Then the sea dropped to the level of 29 meters below the level of the world ocean. Archaeological data show that the level of the Caspian Sea has been below this mark. This is evidenced, in particular, by the ruins of the Sabail fortress. To the south of Alyat is the sunken settlement of Pirsagat – once there was a city that went under water.
In general, the level of the Caspian Sea obeys a certain periodicity, but the cycles are large – 200-300 years. Lowering and raising the level of the Caspian Sea is a natural process. There was the same excitement when its level noticeably increased – compared to 1979 by 2.5 meters and lasted at this level until 1995. Then it stabilized, and after 1998 there was a gradual decline.
– Recently, a forecast was announced according to which, by the end of this century, the Caspian Sea may become very shallow – by 9 and even 18 meters. The reservoir will lose 34% of the area…
– The Caspian is perhaps the most well-studied body of water in the world. But in my opinion, it is impossible to give an accurate forecast of what will happen to the Caspian Sea before the end of the century. One can only imagine a possible scenario. If we consider that the total volume of the Caspian Sea is 78,000 cubic meters. km, one third will be approximately 26,000 cubic km of water. Even taking into account the absence of tributaries, it will take at least 70 years for such an amount of water to disappear. And while the Volga flows into the Caspian, this will never happen.
As for the foreseeable future, it can be expected that the decline in sea level will gradually stop. There is a limit to evaporation, reduction of water resources. According to forecasts, in the near future (about 20 years), the rate of decline in the level will slow down and gradually the level will stabilize around the mark of 29 meters. That is, about another 0.8-1 meter. This sea level was already observed in 1977. But there will be no reduction of 18 meters in our century.
– How will the shallowing affect the countries of the region and the biodiversity of the Caspian Sea?
– The countries of the Caspian region, of course, need to adapt to the realities. The shallowing will have a negative impact on the infrastructure, since the channels and ports are designed for a different water level. So some damage is possible. It is much worse when the water level rises sharply – the economy can be significantly damaged. But for the ecology of the sea, the level rise is more favorable. Shallowing has a negative effect on marine life. Fish spawn in shallow water, in swampy areas, and the fact that the Caspian Sea is getting shallow will affect the population. Another negative factor for the fauna is an increase in mineralization, that is, the salinity of water.
– Is it necessary to take any measures at the level of the states of the region in connection with the shallowing of the Caspian Sea?
– In the 70s, when the level of the Caspian Sea was falling, as it is now, it was decided to block the Karabogaz Bay, located on the territory of Turkmenistan. In fact, it is an evaporator, where 17-18 billion cubic meters, or 5 cm of water from the Caspian Sea goes annually, and completely disappears there. Two years after the closure of the gulf, the level of the Caspian Sea rose, and so much so that in 1992 it was necessary to destroy the dam. The lesson from this, I think, has been learned. But what really needs to be done is to achieve the rational use of water resources by the Caspian states. First of all, we are talking about the Volga. Now there is a very large loss on all rivers where many reservoirs have been built – more water evaporates there. If there were no reservoirs, the water level in the Caspian Sea would be 2-3 meters higher than the current one. On the other hand, countries need water for irrigation and water supply, electricity production. That is, these are unavoidable factors.
I would like to emphasize that despite the constant interest of scientific organizations of the Caspian countries in the problem of the Caspian Sea, in particular, changes in its level, research is still fragmented, uncoordinated, which does not allow us to present a complete picture of the processes taking place in its basin. In this regard, there is no doubt that only coordination and unification of the efforts of all the Caspian countries will allow us to obtain complete and objective information about the hydrometeorological and environmental processes taking place in the Volga-Caspian basin, and above all, related to long–period fluctuations in the level of the Caspian Sea.