The extreme weather “Hans” has angry siblings who will hit Norway in the years to come. In recent weeks, several scientists have pooled their strength to find out how we should prepare for the next bouts of angry weather. “Hans” hit southern Norway at the beginning of August and caused extensive damage, especially in the Buskerud area and Innlandet, which were hit by floods, landslides and floods. On Thursday, Niva (Norwegian Institute for Water Research) and the Meteorological Institute gave a lecture on preliminary research in the wake of “Hans”. The enormous amounts of water have affected the environment in lakes, rivers and the fjord. Abnormal time Håkon Mjelstad from the Meteorological Institute says that “Hans” behaved in a very special way. – It was an unusually strong low pressure, considering that it came from the southeast. And then it was unusually strong for the time of year. We have rare measurements, in some places they have never occurred before. “His” was a rare and special weather event, says Mjelstad. After hitting Norway, “Hans” stuck in the mountain ranges in the west. – We have never before measured so much rain over such large areas in Eastern Norway. And these are areas that are not used to so much rain, and then the consequences will be much greater, he says. Brown water Thus, the storm affected areas in a different way than before, even though both the Drammensvassdraget and Glomma have also experienced great forces in the past. Usually it is the spring flood that dominates and it is more unusual to have large floods in the summer. This is some of what researcher Øyvind Kaste and his colleagues in Niva have found through continuous investigations in Glomma and Drammenselva: There is ten times as much phosphorus and “suspended particles”, small parts of a substance/material that are not dissolved in the water, as before the flood. There is 25 per cent more organic material such as soil, plants and trees in Glomma and 50 per cent more in Drammenselva. When so much more fresh water comes from the rivers to the sea, it has major consequences, says Niva researcher Anette Engesmo. The fjord becomes browner. The fjord gets fresher. Conditions are facilitated for algal blooms, but algal blooms can also be inhibited by the dark colour. There will be a competition for the light. – The light only manages to penetrate one to two metres. It does not look appetizing, nor does it provide good living conditions for the communities that live there. We have seen the immediate effects, but we do not know how this will affect the fjord in the longer term, says Engesmo. The Norwegian Institute for Water Research believes that in the future we need more wetlands and fewer parking spaces in flood-prone areas. Photo: Frida Synnøve Høyås / news Must park differently The researchers believe we must live and build differently. – To reduce rather than increase the risk, we probably need to have more wetlands and fewer parking spaces in flood-prone areas, says Niva’s deputy managing director Thorjørn Larssen. Because even though “Hans” was most powerful locally, the consequences can also be large in larger areas. – “Hans” hit the two largest waterways in Norway, and thus also many large lakes and rivers. Both end in the Oslofjord. The water turned really brown, with rubbish and sewage from the waterways, says Niva researcher Sigrid Haande. Wetter and wilder – We have been monitoring the environmental status of Norwegian waters for a long time. Everyone saw the immediate effect as round bales and caravans floated in the river. But there is also a long-term effect here, when materials are added from land to water, says Thorjørn Larssen. Things that don’t belong end up at the bottom and stay. In the worst case, the ecosystem and diversity will be reduced. – The long-term environmental consequences will come after the flood peak is over. August was the fourth wettest recorded in Norway since measurements began in 1900. It was doomed to be wet and wild around the waterways. – What we see now, we will probably be able to experience more of. This is an effect of climate change. Wilder and wetter weather in Norway, Prime Minister Jonas Gahr Støre said on the first day, when preparedness was stepped up. The researchers say the same thing: It will happen again. – How can we limit such consequences in the future? – We have to use the lessons from “Hans” and perhaps we have to consider where to start construction and what to rebuild. It is also important to set aside area and space for flooding and use nature as part of the solution, says Thorjørn Larssen.
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Long-term consequences can be big – news Oslo og Viken – Local news, TV and radio
