Record Russian river discharge in 2007 and the limits of analysis

Abstract

The Arctic water cycle has experienced an unprecedented degree of change which may have planetary-scale impacts. The year 2007 in particular not only was unique in terms of minimum sea ice extent in the Arctic Ocean but also was a record breaking year for Eurasian river inflow to the Arctic Ocean. Over the observational period from 1936 to 2006, the mean annual river discharge for the six largest Russian rivers was 1796 km 3 y −1 , with the previous record high being 2080 km 3 y −1 , in 2002. The year 2007 showed a massive flux of fresh water from these six drainage basins of 2254 km 3 y −1 . We investigated the hydroclimatological conditions for such extreme river discharge and found that while that year's flow was unusually high, the overall spatial patterns were consistent with the hydroclimatic trends since 1980, indicating that 2007 was not an aberration but a part of the general trend.We wanted to extend our hydroclimatological analysis of river discharge anomalies to seasonal and monthly time steps; however, there were limits to such analyses due to the direct human impact on the river systems. Using reconstructions of the naturalized hydrographs over the Yenisey basin we defined the limits to analysis due to the effect of reservoirs on river discharge. For annual time steps the trends are less impacted by dam construction, whereas for seasonal and monthly time steps these data are confounded by the two sources of change, and the climate change signals were overwhelmed by the human-induced river impoundments. We offer two solutions to this problem; first, we recommend wider use of algorithms to 'naturalize' the river discharge data and, second, we suggest the identification of a network of existing and stable river monitoring sites to be used for climate change analysis.

Extreme Sea Ice Loss over the Arctic: An Analysis Based on Anomalous Moisture Transport

“…Gimeno et al [49] have previously demonstrated the relation between intensification of this moisture source and increased moisture contribution over the Eurasian river basins. This finding is especially relevant because the Atlantic Ocean was previously found to be one of the most important sources for the Eurasian river basins [50]. In agreement with our result, Zhang et al [32] observed an increased moisture transport into the Eurasian river basins, and Shiklomanov and Lammers [50] described a peak river discharge in 2007.…”

Relevance of Hydro-Climatic Change Projection and Monitoring for Assessment of Water Cycle Changes in the Arctic

“…A general picture of increasing runoff trends in the panArctic drainage basin has been established in recent years (Peterson et al 2002Dyurgerov and Carter 2004;McClelland et al 2006;Shiklomanov and Lammers 2009). Dyurgerov et al (2010) have further reported that river runoff to the Arctic Ocean has increased independently of, but with similar magnitude as the increase in freshwater input from glacier melting.…”

“…Local anthropogenic water-use changes, for instance the construction and use of dams, may also influence the runoff and complicate the assessment of precipitation-runoff relations (Shibuo et al 2007;Adam et al 2007;Rawlins et al 2009b;Shiklomanov and Lammers 2009), although the effect of dams on annual discharge in the Arctic is generally small over longer time periods . In the Churchill basin, however, large-scale diversions of water out of the basin have strongly influenced the river flow (Déry et al 2005), yielding a considerably greater decrease in runoff than in precipitation over the studied period.…”

“…For all basins, only years with complete runoff data for all months of the year were included. We have not corrected for the influence of dams in our analysis, as their effect on annual discharge trends over longer time periods has been shown to be relatively insignificant Adam et al 2007;Shiklomanov and Lammers 2009). …”

Climate-Induced Extreme Hydrologic Events in the Arctic

“…Our results also showed increasing positive trends in both precipitation amount and air temperature (Figures 2a and 3b). According to Shiklomanov and Lammers [6], river discharge from the large Russian basins (e.g., Yenisey, Ob and Lena) into the Arctic Ocean peaked in 2007 due to the increase in precipitation across the northern parts of the basins and intensive permafrost thawing. Consequently, the economic costs associated with the implementation of flood countermeasures in 2007 reached approximately 2% of the revenue of the Sakha Republic of the Russian Federation [8].…”