Transboundary UNECE Water Basins/OULANKA RIVER BASIN
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Finland (upstream country) and the Russian Federation (downstream country) share the basin of the Oulanka River.
The current assessment covers the Oulanka River upstream of Lake Paanajärvi. The river is part of the Koutajoki water system with a total basin area of 18,800 km2 that drains to the White Sea.
Hydrology
| Basin of the Oulanka River upstream of Lake Paanajärvi | |||
| Area | Country | Country's share | |
| 5,566 km2 | Finland | 4,955 km2 | 88% |
| Russian Federation | 651 km2 | 12% |
The Oulanka River, with a total length of 135 km, has its sources in the municipality of Salla (Finland). The westernmost tributaries are the Savinajoki and Aventojoki rivers. Close to the eastern border, the River Kitkajoki flows into it. Just across the Russian border, the Kuusinki River joins it not far from Lake Paanajärvi.
High and steep cliffs flank the upper parts of the river, which mainly flows 100 m below the surroundings. In its lower part, the river meanders slowly. In some places, high sandy banks flank the river. In the course of centuries, the river has eroded the sandy soil; because of this eroding effect there is little or no vegetation in these areas.
At the Oulankajoki station (Finland), the mean annual runoff was 23.9 m3/s (period 1966–1990) and 25.5 m3/s (period 1990–2000), respectively. Spring floods often occur.
During the time period 1966–1990, the statistical maximum and minimum discharge values were as follows: HQ = 462 m3/s, MHQ = 271 m3/s, MNQ = 4.92 m3/s and NQ = 3.10 m3/s. For 1991–2000, these values were: HQ = 404 m3/s, MHQ = 241 m3/s, MNQ = 5.08 m3/s and NQ = 3.37 m3/s.
Pressure factors
There are no significant human activities in the Finnish part of the basin. Sewage discharges from the Oulanka Research Station is the only pressure factor.
The water quality of the Oulanka River has been monitored since 1966; sampling takes place four times a year.
The water quality was classified as excellent (in 2000–2003) as indicated, for example, by the annual mean values for CODMn, suspended solids and oxygen saturation on the Finnish territory of the Oulanka River.
Transboundary impact
There is no significant transboundary impact. In the beginning of the 1990s, the water quality was classified as "good", thereafter as “excellent”.
Trends
There are no water-quality or water-quantity problems at the moment. The river at the border section will remain in the category “in high and good status”.
