Shifting discharge peaks in arctic rivers, 1977–2007

Abstract.

The Arctic regions are undergoing rapid warming, at rates that are significantly faster than the global average and its hydrological system is responding to this change. Rivers may be seen as integrators of changes in the hydrological cycle. Changes in the freshwater fluxes have immediate impact on Arctic Ocean dynamics, and are teleconnected to the global ocean‐atmosphere.

Here, the most recent observational records are analyzed for 19 large rivers encompassing the entire Arctic region over the period 1977 to 2007. Trends in total annual water discharge, melt month and peak month discharge are calculated for individual systems based on records with monthly time resolution.

We found consistent increase in annual discharge over the entire region (+9.8%) over the last 30 years. Combined change in water outflux is significantly higher than previous reconstructions for the Canadian Arctic (+2% over 1964–2000) and Eurasia (+7% over 1936–1999). Individual river systems show strong acceleration of change.

Melt month discharge increases considerably (+66%), whereas peak month discharge is reduced (–6.8%). Our records mostly span the post‐dam establishment period, when dam management is considered relatively stable. Consequently we attribute the considerable change in the melt month to a shift in snowmelt in the drainage basin.

Key words:

• Arctic rivers
• hydrology
• global change
• seasonality
• floods