The Long-Term Changes in Water and Ions Flux of Northern Dvina and Pechora

Abstract

The long-term data sets of the annual and seasonal water flows and the major ions fluxes of the Northern Dvina River at the village of Ust-Pinega and Pechora River at the village of Ust-Tsilma were analyzed. Long-term phases of increased and decreased values of water runoff were identified, the duration of which ranged from 9 to 50 years, and their main characteristics were determined. The sequence and boundaries of the change in the contrasting phases of the annual water flow, the snowmelt flood flow and the summer-autumn flow on the Northern Dvina River and the annual water flow and snowmelt flood flow on the Pechora River practically coincided. The difference between the average annual and seasonal water flow in the phases of its increased and decreased values ranged from 11 to 41%, and the ion fluxes were in the range of 5–36%. The ion flux of contrast phases, as a rule, differs less than the water flow. This is due to the inverse nature of the dependence of the concentration of ions on the daily water discharges, because of which a kind of negative feedback is formed, stabilizing the intensity of chemical denudation in the wa- tersheds of these rivers and the flux of the main ions into the seas, even with noticeable fluctuations in water flow. Keywords: the Northern Dvina River, the Pechora River, water flow, ion flux, long-term phases of changes, cumulative deviation curves.