ИСТИНА

Arctic rivers of Russia transport a huge amount of water, sediment, dissolved substances and heat. It provides an important role of river flux in hydrological regime and climate of Russian Arctic seas, river lower reaches and mouths. Since the 1970s and especially since the late 1980s, fluctuations of annual and seasonal river runoff do not correspond to pattern of long-term variability of past decades. The relative increase in water resources is 5.8%, the range varies from 0.5 to 20%. It is explained by the increasing in runoff of all hydrological seasons, especially during winter low-period, and is mainly accompanied by decreasing in maximum discharges. Several rivers and territories are an exception. Suspended sediment yield and its intra-annual regime have changed even more. Statistically significant disturbances were found for rivers located in the permafrost zone. Here, distinct increase of sediment concentration and yield is accompanied by a change in the form of relationship between water and suspended sediment discharges, intensification of channel and delta processes. The observation data reveal an increase in water temperature and heat flux. The main cause is climate changes. Water intake does not affect Arctic river runoff in their lower reaches and mouths. Mining violates the regime of sediment load, but only in several basins. The main anthropogenic factor is the creation of reservoirs. These and other problems are studied for large and moderate-size rivers flowing into the Russia Arctic seas. Data of 420 posts were used. This study was supported by RSF grant No.14-37-00038.