MODERN THERMAL REGIME OF RIVERS IN RUSSIAN ARCTIC AND PERMAFROST AREAS

Abstract

Thermal regime of rivers plays a great role in rivers ecological state. However, there are a lot of gaps in our knowledge about thermal regime of rivers and about long-term changes of water temperatures and river heat flow due to the scarcity of open-source water temperature data. During the past decade study of thermal regime of rivers has been focused on Arctic Region, primarily on North-East of Russia. Nowadays, we are expanding the spatial coverage of river thermal regime studies to the permafrost areas as regions with the most dynamic climate and landscape changes. Studied area includes territory of Russia North of 60 N, Russian parts of Baikal Lake and Amur River basins, basin of Okhotsk and Japan Seas and Russian part of Caucasus. For all these regions, except the Arctic and Caucasus, our investigations of the thermal regime of rivers are the first ones for the past 5–6 decades. We used monthly average water temperature data from more than 400 gauges on rivers in different landscape conditions for 1961–2022. Annual and monthly heat flux was estimated for data from 200 gauges. Change-point years for all studied characteristics, mean and standard deviations, changes after change-point years and in 1991–2020 in comparison with 1961–1990 were estimated. Moreover, the analysis of air and water temperature relations was carried out. Results are compared for different parts of permafrost zone and compared with Arctic non-permafrost areas. Very low values of the thermal runoff of the North Caucasus are shown. The regions in which local factors play a major role in shaping water temperature compared to climatic ones have been identified, the Baikal basin, for example.