Assessment of Methane Emissions from the Surface of the Volgograd Reservoir and the Associated Impact on the Environment

The article presents the results of a study of hydroecological characteristics (water temperature, dissolved oxygen, methane content and emissions) in the Volgograd Reservoir in the autumn of 2021–2022. A classification of external effects (externalities) associated with the design and operation of the reservoir is given, and negative and positive externalities associated with methane emissions are identified. It is shown that with relatively small specific methane flows, annual emissions from the entire area of the reservoir lead to annual damage of 99 807 tons of CO₂-eq. This value takes into account the positive external effect of the reservoir (service) in reducing the specific methane flow relative to the river that forms it and can serve as a basis for determining annual payments to make the reservoir carbon neutral.