By the Iranian Transportation Think Tank
The steady decline in the Caspian Sea’s water level is becoming an operational constraint for the Middle Corridor. This issue is particularly significant as countries along this strategic route, especially Kazakhstan and Azerbaijan, continue to invest in expanding its capacity and capturing a larger share of China–Europe trade.
The most immediate impact of falling water levels is the reduction in permissible vessel drafts, which limits the amount of cargo ships can carry. According to Azerbaijan Caspian Shipping Company (ASCO), some vessels are currently able to operate at only around 80% of their full cargo capacity.
Other reports also indicate that the loading capacity of certain Caspian Sea vessels has fallen to approximately 75–80% of their maximum capacity. According to the company, the Caspian Sea’s water level declines by around 15–20 centimeters annually. If this trend continues, existing restrictions on vessel drafts and access to ports could become more severe in the coming years.
This development has significant economic implications. When each vessel carries less cargo, more voyages are required to transport the same volume of goods. As a result, fuel consumption, crew expenses, port operating costs, and transportation times increase, while the effective freight capacity of the corridor’s maritime fleet declines.
Kazakhstan Invests in Port Dredging to Maintain Freight Capacity
To preserve access to its ports and enable vessels to operate at their maximum capacity, particularly at Aktau and Kuryk, Kazakhstan has undertaken dredging projects and improvements to port infrastructure.
At the Port of Kuryk, more than 1.7 million cubic meters of sediment have been removed from the port’s waters, turning basin, and access channel. This work has increased the port’s operational depth to approximately 8.5 meters. The project aims to restore vessels’ ability to load cargo at full capacity.
At Aktau, a dredging project worth approximately $39.8 million is underway, alongside plans to rehabilitate and expand several berths. The combined cost of dredging projects at Kuryk and Aktau is estimated at approximately $96.6 million.
The declining water level of the Caspian Sea is therefore more than an environmental concern; it is generating direct costs for maintaining existing transportation capacity. Investments that could otherwise be allocated to expanding the corridor’s capacity are increasingly being redirected toward preserving its current operational capabilities.
Rising Freight Demand Intensifies Pressure on the Middle Corridor
The significance of this challenge becomes even clearer as freight volumes and demand along the Middle Corridor continue to grow alongside the decline in water levels.
In recent years, the Middle Corridor has experienced substantial growth in freight traffic amid the limited capacity of alternative routes passing through Iran. Cargo volumes along the route reached approximately 4.12 million tonnes in 2025, around eight times the level recorded in 2021.
The corridor aims to increase its annual freight capacity to 10 million tonnes by 2027. However, this expansion target now coincides with mounting restrictions on vessel loading capacity in the Caspian Sea.
Without a coordinated approach among the countries that depend on the route, addressing environmental challenges, dredging requirements, access-channel maintenance, and the adaptation of port berths to changing water levels could become increasingly difficult.
As climate-related pressures intensify, the absence of coordinated measures could create more serious obstacles to the movement of goods along the Middle Corridor, undermining efforts to expand its capacity and strengthen its position in China–Europe trade.
The Caspian Sea’s declining water level thus presents a strategic challenge for the Middle Corridor: the route must expand its freight capacity at a time when the maritime infrastructure connecting its key transit countries is becoming increasingly constrained.
