Global warming affects the state of water resources in Siberia. An increase in air temperature causes the annual thawing of permafrost, which contributes to an increase in the flow of Siberian rivers. The results of the study are published in the journal Geography and Natural Resources.

Global warming is more pronounced in the northern latitudes of our planet. This problem is especially relevant for Siberia since most part of this region is located in the permafrost zone.

Researchers of the Federal Research Center "KSC SB RAS" determined the relationship between the air temperature and the volume of the river flows. They showed that the volume of the river runoff is determined not only by the amount of precipitation but also by the air temperature. An increase in the air temperature, on the one hand, contributes to the thawing of frozen soils and to an increase in the hydrological regime of northern rivers, and on the other hand, it leads to an increase in evaporation in the river basin, which reduces the moisture inflow into water bodies.

The scientists analyzed the dynamics of the annual runoff of nine rivers located in the forest-tundra, northern and middle taiga, as well as the average monthly and average annual air temperatures and precipitation over the last 50 years. The analysis included both small and fairly large rivers, for example, the Podkamennaya Tunguska, one of the main tributaries of the Yenisei.

The results showed that the annual and minimum winter runoffs tend to increase, despite declining precipitation trends. The data on the river runoff and precipitation indicate an additional source of moisture entering water bodies. With an increase in the continentality of the climate from the southwest to the northeast, this trend is more pronounced, indicating a large role of the thawing of permafrost soils in the increase in river flows in the northern regions.

“We tried to explain the significant increase in river water recorded in recent decades, which could not be caused by an increase in precipitation in the region. The average annual surface air temperatures in the area under study have increased by 0.26-0.36°C every 10 years since the middle of the last century. This affects the hydrological regime of rivers. An increase in an annual runoff with an increase in temperature from July to September indirectly indicates that the inflow of water into these rivers is affected by moisture from periodically thawing upper soil horizons. At the same time, the spring decrease in the runoff of the Graviika, Turukhan, Erachimo, and Podkamennaya Tunguska rivers with an increase in temperature in May may be due to higher evaporation from the snow surface and to the absence of precipitation during this period. This confirms that the dynamics of climatic conditions change the state of the water resources in the Region. Melting permafrost is an additional source of groundwater and surface water? which disrupts the established hydrological cycle in the river basins and water-salt balance in the Arctic Ocean since almost all Siberian rivers flow into it,” said Tamara Burenina, Candidate of Agricultural Sciences, Senior Researcher at the V. N. Sukachev  Institute of Forest FRC KSC SB RAS.