The importance of communication routes in modern international relations is rapidly increasing, and they are becoming an integral part of the global and regional political and economic agenda. Communication routes become particularly complex and acquire a multi-layered structure, including rail, sea, and air networks, often combining them in a multimodal logic. These infrastructure projects have a political context and become an arena of perpetual strategic competition between large and small states. 



The uninterrupted operation of communication routes is vital not only for beneficiary countries but also for distant continents, supranational international organizations, and the business community. Almost all states are making every effort to join one or another communication network, build alternative routes, and push rival states from their sphere of influence. For thousands of years, transit routes have always been at the center of the main contradictions of human civilization, becoming the subject of conflicts, geopolitical confrontations and wars.

In addition to regional and geopolitical shocks, communication routes are vulnerable to natural and man-made disasters that, over time, can destroy logistics systems formed and developed over decades. These threats include climate change and global warming, of which the situation in the Caspian Sea basin is a vivid example. Environmental changes and anthropogenic interference have led to a decline in water levels in the Caspian Sea, which, in addition to climatic threats, creates difficulties for two important communication routes: the Trans-Caspian International Transport Route (TITR) and the International North-South Transport Corridor (INSTC).  

Water level fluctuations in the Caspian Sea are not a new phenomenon and have been recorded as far back as the last century. The Caspian Sea level was 25.8 meters below sea level at the beginning of the 20th century, before relatively stabilizing in the 1950s. However, in the 1970s, there was a sharp decline in water levels, bringing them down to a historically low level of approximately 29 meters. The opposite trend was observed until the second half of the 1990s, when water levels rose again, but then a new phase of decline began. Since the mid-2000s, the level of the Caspian Sea has been declining by approximately 20 centimeters annually. Over the last 5 years, the rate of decline has further increased, exceeding the previously recorded minimum. International scientific and environmental organizations note that the situation could worsen during the 21st century. However, forecasts remain varied and often contradictory: according to some models, the Caspian Sea level could fall by 9-18 meters by the end of the century. At the same time, there are more moderate estimates that suggest continued fluctuations without a catastrophic downturn.  

The northern and northeastern parts of the Caspian Sea are shallow waters with an average depth of only 4 meters. The depth in the central part is 100-140 meters, which is a significant factor for large vessels. In the southern part, where the depth approaches one kilometer, the threat to immediate navigability is less. However, even here, there are risks associated with coastal infrastructures (ports, terminals) due to changes in water levels.  

The decline in water levels in the Caspian Sea is a regional phenomenon, but its impact on the five coastal states is uneven. Kazakhstan is in the most vulnerable position, bearing the main environmental and economic burden. Since 2006, the area of Kazakhstan’s coastal waters has decreased by about 30,000 km².

The reasons for the decline in water levels in the Caspian Sea vary. Still, researchers point to a combination of two factors: a decrease in the volume of the Volga River’s flow and a temperature rise, which causes more water to evaporate than fills the lake. More than a hundred rivers flow into the Caspian Sea, several of which provide the majority of its water balance. The largest of them is the Volga, which provides about 84% of its water balance. The role of other rivers feeding the lake basin, such as the Kura and the Ural (about 6% and 3%) as well as rivers flowing from Iran, is relatively small. These rivers have a minor impact on the volume of water in the Caspian Sea basin. 

The water flow in the Volga River also decreased. Numerous dams and reservoirs built on the river during the Soviet years created a large hydra technical system for solving many important issues: power generation, centralized water supply, agricultural irrigation, cooling of power and industrial facilities. In recent years, the volume of the Volga River flow has decreased by 30-40 km², which according to some experts, significantly affects the level of the Caspian Sea. Due to the functioning of transit corridors and ports, Kazakhstan has to make diplomatic efforts and regularly discuss with the Russian Federation the issue of regulating the flow and capacity of the Volga River. 

The decline in water levels in the Caspian Sea developed into an operational crisis directly threatening the stable operation of the Middle Corridor.  Cargoes from China, Kazakhstan and other countries arrive by rail at the Kazakh ports of Aktau and Kuryk, then are loaded onto ferries and transported by water to the Azerbaijani ports of Baku and Eilat. Here, the cargo is reloaded into wagons and transported by the Baku-Tbilisi-Kars railway to Turkey or to the Black Sea ports of Georgia.  

Another option for organizing trans-Caspian logistics is based on the use of ferry crossings. Thanks to this technology, railway wagons can be completely loaded onto special ships without unloading, which significantly reduces loading/unloading times. 

The decline in water levels limits ferry capacity, resulting in increased crossing times and additional costs. Kazakh tankers carrying oil from fields in the north-eastern part of the Caspian Sea also face this problem. Additionally, the shallow water makes it difficult for ferries to approach ports.

The only solution to the problem at the moment is probably the deepening of the Caspian Sea bed initiated by the government of Kazakhstan. This complex and expensive work can only be carried out by specialized dredging vessels. Early last year, Kazakhstan’s Prime Minister announced that the government had allocated $84,5 million to the dredging work at the port of Aktau by 1.5-2 meters. This work should be carried out by the Belgian specialized company Jan de Nul, which has international experience in dredging ports and waterways. 

Similar dredging works also started in December 2025 at the port of Kuryk, another important transit point in Kazakhstan. Work is scheduled to be completed in the first half of 2026, with plans to deepen the seabed by 5 meters and remove around 1 million km² of soil.  

Besides Kazakhstan, declining water resources are of concern in other countries in the Caspian Sea basin. On November 18, 2025, the heads of 12 provinces of 5 countries bordering the Caspian Sea met in Rasht city, Gilan province, Iran. Economic cooperation and tourism issues were discussed. Ambassadors and Iranian Foreign Minister Abbas Araghchi also attended the event. During the meeting, the environmental problems of the Caspian Sea were also touched upon. 

Azerbaijan has also repeatedly stated its intention to prevent an environmental catastrophe threatening the Caspian Sea. The problem of water depletion is also regularly discussed by the leaders of coastal countries, but no significant initiatives or changes have been noticed so far. Statements are made at meetings representing the economic and environmental importance of the world’s largest lake, but the decline has yet to be halted.  

For Iran, water scarcity is certainly a serious problem, but the nature of the problem is somewhat different. Although the northern and north-eastern parts of the Caspian Sea are the shallowest, the deepest part of the lake is located on the Iranian side, which does not pose significant difficulties for shipping and tankers. Declining water levels and coastal expansion are making it increasingly difficult for ships to approach ports. Besides the social hardships of coastal residents, the main problem is the general water shortage, which is affecting the already water-stressed northern and northeastern regions of Iran. 

Declining water supplies also pose challenges to Iran’s energy system. In particular, thermal power plants located near the Caspian Sea, which constantly require water for cooling, must consider repairing pumping stations and deepening and widening the lake bed. This problem is relevant for the Shahid Salimi (Neka) thermal power plant in the Mazandaran province. In the spring of 2025, the deputy director of the thermal power plant noted that they had to deepen the bottom of the lake that cools the plant,  so that the 8 pumping stations can run smoothly. Otherwise, they will have to cut back on power generation to avoid overheating and accidents.    

Iranian scientists’ assessments of the scale of the environmental disaster in the Caspian Sea also differ. They believe, that climate change, global warming and wind direction, rather than dams built on the Volga, are the main reasons for the water decrease. Due to falling water levels, several ports in Iran (and not only in Iran) are also forced to dredge. According to official statements, the deepening of Iran’s Amirabad, Noshahr, and Anzali ports will require the excavation and removal of approximately 6 million m³ of soil. 

The decline in the level of the Caspian Sea has a negative impact on Iran’s infrastructure: the construction of a new Ro-Ro berth for direct loading of cars and trains onto ferries has been suspended at the port of Amirabad. This system allows trains to be loaded onto the large ferries without unloading and transported by sea to other ports. For large vessels to safely approach the berths, they have to be built at a considerable distance from the shore. Thus,  according to Iranian experts’ estimates, the new Amirabad port should now be more than 2000 meters from the shore.    

The possible opposite process, rising water levels, is of equal concern: history shows that the lake level fluctuated significantly twice during the 20th century. While experts agree that, at least by 2050, water levels will drop, the negative consequences will be just as severe if they rise. In the early 1990s, sea level rise caused billions of dollars in damage to coastal states.   

Declining water levels in the Caspian Sea represent a major challenge for the region, with severe infrastructural, social and environmental consequences. 

It should be noted, however, that despite the growing challenges, trade across the Caspian Sea is increasing rapidly. Moreover, due to geopolitical developments, the importance of the Middle Corridor is increasing day by day for the countries in the region, as well as for Europe and the United States. Over the past two years, Western investments in the Middle Corridor countries have increased significantly, with some specifically aimed at solving the logistical problems of the Caspian Sea. It can be said with certainty that the decline in water resources will not have a significant impact on major infrastructure projects and transport routes in the coming years.