Long-term periods of increased/decreased water and ion discharge of the Northern Dvina in the 19th - 21st centuries
A.G. GEORGIADI1, A.O. DANILENKO2
1Institute of Geography, Russian Academy of Sciences, Moscow, Russia
2Hydrochemical Institute, Rostov-on-Don, Russia
Keywords: arctic rivers, long-term changes, water discharges, hydrological seasons, chemical runoff, mineralization
Abstract
An analysis is made of the long-term data sets on the annual and seasonal water flow and the major ions flux of the Northern Dvina river at the village of Ust’-Pinega where hydrological and hydrometric observations were begun in 1882 and 1947, respectively. Long-term phases of their increased/decreased values were revealed, and their main characteristics were determined. It is established that the difference in the mean annual water flow between the long-term phases of increased and decreased values relative to the values characteristic of the lower flow were 17 % for the annual flow, 16 % for the flood flow, 32 % for the winter flow, and 38 % for the summer-autumn flow. It is concluded that changes in chemical flux during the shift from the phase of increased to decreased water flow was less clearly pronouced. The largest differences in the ion flux in the contrasting phases of water discharge were characteristic for the summer-autumn hydrological season and winter low-water season. During these periods the ion flux increased by 14-17 % and 10-11 %, respectively, whereas during the snow-melt flood period and the whole year, the ion flux was only 5-8 % higher. A relative dynamic constancy of the geochemical load on the White Sea by the Northern Dvina, regardless of its water discharge, is caused by the inverse relationship between water discharge and the concentration of chemicals. In addition, the anthropogenic influence on the ionic composition in the catchment area of the river is insignificant, which makes it possible to maintain established relationships under climate change.
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