Climate change will bring recurring winter floods to Finland

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As a result of climate change, temperatures in Finland are predicted to rise and rainfall to increase.
      Last weekend the warm weather, heavy rains, and melting snow raised the water level of Finnish rivers to exceptional heights - normally experienced only in the spring - in Southern and Southwestern Finland as well as in Ostrobothnia. In many places the flow rate of waters reached annual records.
      "This is exactly what we can expect in the future, and we will just have to get used to this. In the winter snow melts, it rains and water levels rise", notes hydrologist Bertel Vehviläinen from the Finnish Environment Institute (SYKE).
      "At present, winter still comes to Southern Finland, while in the future, when there are no winters any more, the large central lakes will have more water in the winter than during spring floods", predicts Vehviläinen.
     
The measuring station in Helsinki’s Kaisaniemi district recorded some 25 per cent more rain during the first days of December than usually during the entire month of December on average, according to researcher Ari Venäläinen from the Finnish Meteorological Institute.
      "The impacts of climate change have been predicted to be like this. Especially winter precipitation will become heavier, with the proportion of rains becoming bigger than ever before", notes Ari Venäläinen.
      "According to forecasts, the amount of precipitation in December will increase by around 30 per cent by the end of the current century", Venäläinen reports.
      He notes further that winter floods may even out the flood peaks of the spring in the future, while the flow rate of rivers will be strong through the winter.
     
Across Southern Finland, the water surfaces of lakes are currently higher than average, and the water is still rising as a result of last week’s precipitation.
      In rivers, the flow rates are declining and the flood peak is over for the time being. According to weather forecasts, precipitation will decrease and the weather will get chillier at least temporarily.
     
In the River Vantaa and in its tributaries in the province of Uusimaa the water surfaces peaked on Sunday. In the River Vantaa at Oulunkylä, the water level was 7.6 metres at its highest, which is the same as the flood level.
      According to Kari Rantakokko, who is in charge of flood protection at the Uusimaa Regional Environment Centre, water rose onto the yards of the cottages in the Oulunkylä allotment gardens. At the weekend, dozens of hectares of fields were under water along the shores of the rivers Lepsämäjoki and Kytäjoki.
      "This autumn has been exceptional. High flow rates have been experienced many times. The flow rate of the River Vantaa has now been as high as the readings normally taken in the spring, which is extremely uncommon", noted Rantakokko.
     
In Ostrobothnia, the rivers have also reached spring flood levels, as a result of heavy precipitation, while in the lowest parts of the River Lapua the water is already washing against the fields flanking the river banks.
      In Lapland the flow rate of the River Simojoki was on Monday eight times the rate regarded as normal at this time of the year.


Previously in HS International Edition:
  New mission for Jorma Ollila: fighting climate change (30.1.2007)

Links:
  Climate Change (Wikipedia)
  Finnish Environment Institute (SYKE)

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