River input

The pan-Arctic watershed contains many rivers with several of Earth’s largest rivers. These rivers exert a disproportionate influence on the Arctic ocean as they transport more than 10% of global river discharge into the Arctic Ocean, which contains only ~1% of global ocean volume. In order to understand the dynamics of the Arctic ocean it is crucial to be able to quantify the discharge and nutrient fluxes originating from the rivers from this pan-Arctic watershed into the Arctic ocean. There are six Arctic rivers in this pan-Arctic watershed that have basin area’s exceeding 500 000km2 (the Ob’, Yenisey, Lena, Mackenzie, Yukon and Kolyma). Combined these “Big 6” cover 67% of the pan-Arctic watershed and 63% of the total discharge into the Arctic ocean. The next eight largest rivers and their watersheds together only cover an additional 11% of this area and 16% of the discharge, with 22% of the area and 21% of the discharge left for the remaining ‘smaller rivers’ of the Arctic.

map pan-Arctic watershed

Figure 1 Map of the pan-Arctic watershed, showing its major rivers with the six largest in dark grey and the next eight largest in light grey. The dark grey line indicates the boundary of the pan-Arctic watershed (Holmes et al., 2013)

The objective for the River Challenge of the Sea Basin Checkpoint Arctic project is to provide time series of the annual input into the Arctic Ocean of:

Data Availability
The data availability is very different for the requested parameters. Most data is available for the volume of water discharge. For some large Russian rivers time series are quite long, more than 70 years, up to more than 100 years. But many time series are relatively short, a few decades in many cases, and often incomplete. It is worrying that stations have been closed and data are delayed.

The data availability for the other parameters is much worse. Water quality monitoring is expensive, especially at remote sites. Therefore measurements are erratic, time series are short and measurement protocols differ between sites.

Bring and Destouni (2009) have also studied the status of the Arctic monitoring effort. They conclude that especially the water quality monitoring is fragmented and this restricts environmental modelers, policy makers and the public in their ability to integrate accessible data and accurately assess bio- geochemical changes in the Arctic environment. They note that the recent PARTNERS project (now continued as the Arctic-GRO) improves the situation, but large areas remain unmonitored. Bring and Destouni (2009) show that there is a significant difference between the characteristics of the monitored and unmonitored areas which limits the possibilities to generalize hydrological and hydrochemical impact assessments based on monitoring data. Even if the quality monitoring were at a level comparable to the quantity monitoring, the short time series still poses an significant problem.

An overview of available data sets can be found here.

Bring, A., & Destouni, G. (2009). Hydrological and hydrochemical observation status in the pan-Arctic drainage basin. Polar Research, 28(3), 327–338. http://doi.org/10.1111/j.1751-8369.2009.00126.x