Water and ise regime of the mayma river (the altay mauntains) in the context of the current climate change

The paper considers changes in the annual and seasonal runoff, as well as the ice regime of the Mayma River in response to changing climatic conditions in the catchment area during the period of 1940–2016. Significant positive trends, especially occurring during the winter months, have been identified in the long-term course of annual and seasonal air temperatures. A significant decrease in precipitation rate is observed in the cold period of the year. According to the analysis of the hydrological characteristics for the periods of 1940–1975 (the background period) and of 1976–2016 (the period of contemporary climate change), the annual runoff for the Mayma River basin shows a downward trend against the background of the observed climatic changes. The decrease in annual flow is the result of a decrease in the flood flow. Thus, with the observed winter warming and a decrease in the amount of solid precipitation, the average maximum discharge for the wettest month (April) decreased by 35 % in the period of 1976–2016 with respect to the background level of the 1940–1976 period. Winter warming contributes to less soil freezing and replenishment of groundwater during periods of winter thaw and intensive snowmelt, which lead to an increase in runoff in the last winter months and the first months of summer-autumn low-flow periods. Winter warming manifested itself in the ice mode of the river Mayma. Since the beginning of the period of the current climate change (1976) there has been an observed decrease in the duration of ice freeze-up and a shift towards later freezing dates and earlier break-up dates.