River discharge and runoff 641 River discharge data

The most comprehensive network of discharge gauging stations in the terrestrial Arctic drainage is represented by R-ArcticNET, which was compiled from original national sources by investigators at the University of New Hampshire, Durham. Version 2.0 of R-ArcticNET holds data from 3754 sites. Figure 6.12 gives the location of the subset of gauges for basins of at least 104 km2. Also shown is a digital river network at 30 min x 30 min resolution (longitude x latitude) (known as STN-30p) developed by

Figure 6.12 River system for the Arctic terrestrial drainage based on the STN-30 digital network and location of discharge gauging stations for basins with areas greater than 10 000 km2. The lines over the Arctic Ocean indicate sea basins into which different river systems drain (from Lammers et al., 2001, by permission of AGU).

Figure 6.12 River system for the Arctic terrestrial drainage based on the STN-30 digital network and location of discharge gauging stations for basins with areas greater than 10 000 km2. The lines over the Arctic Ocean indicate sea basins into which different river systems drain (from Lammers et al., 2001, by permission of AGU).

Vorosmarty et al. (2000). The river network does not include the Greenland ice cap, but does include the non ice-covered portions of Greenland. Within the confines of the terrestrial Arctic drainage at this resolution there are 1967 individual drainage systems discharging to the ocean, encompassing a land area of 22.4 x 106 km2. As summarized by Lammers et al. (2001), typical errors for measured discharge are within the range of ±2 to 5% for non-ice conditions in river cross sections without floodplains and ±5 to 12% for rivers with floodplains. Maximum errors are in mountain rivers and can be as high as 25%. When temperatures are low, the discharge estimates are more uncertain due to anchor ice, frazil ice and backwater conditions, as well as floodplain icings (aufeis).

At present, about 70% of the total Arctic terrestrial drainage is monitored. In turn, over 70% of the Eurasian drainage area has been monitored by at least one gauge

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Figure 6.13 Number of gauges in the R-ArcticNET data base through time and the percentage of the drainage area monitored. Data are shown for North America, Eurasia and the Arctic drainage as a whole. Only gauges monitoring an area greater than 10 000 km2 are used for the percentage of area monitored (adapted from Lammers et al., 2001, by permission of AGU).

a 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990

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Figure 6.13 Number of gauges in the R-ArcticNET data base through time and the percentage of the drainage area monitored. Data are shown for North America, Eurasia and the Arctic drainage as a whole. Only gauges monitoring an area greater than 10 000 km2 are used for the percentage of area monitored (adapted from Lammers et al., 2001, by permission of AGU).

since 1936 (Figure 6.13). However, in the North American part of the drainage, the total gauged area did not surpass 50% until 1964. Since 1985, there has been a large decrease in the number of gauges over Eurasia. Fortunately, this has not significantly reduced the total monitored area as the gauges no longer in operation are usually not the most downstream gauges.

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