Assessment of the Impact of Climate Change on the Hydrological Regime of the Amur River in the Lower Reaches

The transformations of the water, channel, and ice regimes of the Amur River, caused by global climate warming in the region, have been considered. Based on an analysis of air temperature trends in the Amur lower reaches at meteorological stations with long series of observations, the rates of their changes are estimated based on an analysis of air temperature trends in the Institute of Water and Environmental Problems, Far East Branch, Russian Academy of Sciences. The air temperature in the Khabarovsk region has increased by 1.1 degrees C over 100 years and by 0.56 degrees C since the 1980s. It was revealed that, for more than a century of observation of the water regime of the Amur, there has been a clearly pronounced alternation of periods of high and low water content of the river, each of which has a duration of 12-17 years. It has been established that the probability of catastrophic floods related to dangerous hydrological phenomena during the period of high water content of the Amur is much higher than during the low water period. There is a steady upward trend in the amplitude of fluctuations in extreme water levels and an increase in the scale of floods in recent decades. The activation of channel processes and redistribution of water runoff between arms in the branched sections of the Amur River channel, the intensity of which is due to frequent large floods during periods of high water content, have been revealed. It has been shown that the impact of climate change is most clearly manifested in the ice regime in the lower reaches of the Amur. For all hydrological stations of the river, this section shows a later onset of fall ice phenomena and an earlier spring ice drift. The reduction in the duration of freeze-up for the period of 1991-2018 compared with the earlier period was 3-5 days.