Water levels high and rivers in full spate after October rains

Flood risk on Lake Saimaa kept in check by increasing run-off to Ladoga

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The heavy rain experienced in October and also in recent weeks has not gone unnoticed by the public, or by the natural surroundings.
      Water levels are higher than average almost all over the country, and flows in rivers are above normal everywhere except in some parts of Lapland.
     
In order to reduce the risk of flooding, outflow from the Saimaa lake basin has been increased to Lake Ladoga. The intention is to lower the levels in the lake by around five centimetres by the end of the year.
      On Monday, Saimaa was around 40 cm higher than average for this time of year, and the level was still rising.
      When the normal outflow from the lake basin is around 720 cubic metres of water a second, the current flow has been raised to 800 cubic metres a second.
      This amount of water can be run through power station turbines without having to bypass the hydropower systems.
     
Hydrologist Noora Veijalainen of the Finnish Environment Institute says that under normal circumstances the water level should be falling at this time of year, rather than rising. One reason for increasing the outflow rate is to pre-empt the anticipated rise in levels that will come with the snowmelt of next spring.
     
As everyone here is well aware, it has rained exceptionally much over the past six weeks or so.
      October was above the long-term average in both temperature and precipitation. According to the Finnish Meteorological Institute in places the rainfall amounts were double the long-term norm.
      Water levels in Lake Päijänne are around 35 cm above normal for the time of year, and here, too, outflow is high, keeping the flow in the Kymi River at a brisk pace.
     
In Lapland, the situation has normalised, since winter has arrived to slow things down, but further south the overabundance of water has already led to local flooding - in Huittinen at the end of last week, a 400-hectare lake formed when the Kokemäki River overflowed its banks.
      Quite modest rivers in the south of the country are in full spate, as if it were spring melt times.
     


Links:
  Finnish Environment Institute - Water Resources Management
  Finnish Meterological Institute - Precipitation

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