The Inflow of River Water into Russian Arctic Seas: Its Amount, Long-term and Intraannual Changes

On the basis of the data of runoff observations at 73 gauging stations on the rivers flowing into Russian Arctic seas, long-term series (for 1936–2022) of the annual inflow of river water into the Arctic seas were obtained, and the total annual runoff was estimated at 2775 km3. The runoff from individual areas of the sea coasts, at the outlets, and in the mouths of the main rivers was determined. It was found that the average annual runoff to the seas increased by 238 km3 per year, or by 8.9% as compared to 1936–1988, and 1989 should be considered as a general turning point. The proven increase is provided by the same trends in annual runoff for almost all the rivers in the catchments of Arctic seas, except for the rivers in the northeast of Russia, and by mainly positive trends in seasonal runoff. The statistical structure of long-term fluctuations in annual runoff was studied. It was shown that water management activities almost did not affect the long-term dynamics of annual runoff (except for the Yenisei River), but changed the water regime of many rivers regulated by reservoirs, including the largest ones.