The ice regime of the Russian Arctic rivers and its hazardous manifestations under current climate conditions are characterized. The ice phenomena in rivers in the region determine the conditions of navigation, water supply, hydropower station (HPS) operation, and the construction of temporary ice bridges and roads. Data of more than 100 hydrological gages over period from 1936 to 2016 were used to compile various cartographic materials and to analyze the spatial variations of the dates of ice phenomena, the duration of ice-free and ice cover periods, and the maximal ice thickness. Special attention is paid to the characteristics of level regime in periods with ice phenomena. Data on the frequency of floodplain inundation during spring ice run, the hazard of ice jams, and the seasonal features of the passage of maximal annual water level are generalized.The observed changes in ice regime characteristics and ice hazard are analyzed. The years of the start of statistically significant shift of the periods of ice phenomena, caused by both climate changes and anthropogenic impact, are identified. The increase in the duration of the ice-free period was found to be not greater than 3–4 days for East Siberian rivers, 5–6 days for the Middle and West Siberian rivers, and up to 10–12 days for the rivers in the European part. A decrease in the maximal ice thickness is most pronounced in the rivers of the Northern European Russia, where it is 10–15 cm. The frequency of floodplain inundation during spring ice run remains constant.

Compound (II) is used as starting material for a series of reactions yielding different kinds of pyrazole derivatives.

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