Abstracts Biological Sciences

The relationship between extreme weather events and slide events in Norway

by Magdalena Natalia Krzystyniak

Norway is a country that is frequently exposed to extreme weather events (EWEs).Norway experienced EWEs every year. The characteristic of extreme weather events is that they occur infrequently and normally result in inexperienced consequences. They can further be the trigger for geohazards such as floods, landslides and avalanches. Landslides and snow avalanches are complex processes whose climatic triggering factors are not completely understood. In order to predict such events there is obviously a need for understanding the triggering factors among others are certain extreme weather events. Norwegian landslide and snow avalanche events have been frequent and had fatal consequences in historical times in Norway making Norway important area of study. The aim of this study was to understand the relationship between EWEs and geohazards in Norway. The analysis is based on EWEs that caused slide and snow avalanche events in Norway the last 15 years. This study is connected with the InfraRisk project that is concerned with the impacts of EWEs on the transport infrastructure in Norway. The goal was to check if there is a correlation between EWEs and slide events and if EWEs could be a good indicator for slide events. The EWEs data was provided by The Norwegian Meteorological Institute (met.no) and the slide data by NGU – Norges Geologiske Undersøkelse. From the slide database rockfalls, debris flows and snow avalanches were extracted for the analysis. The method was to locate EWEs and to indentify the number of slides that were triggered by EWEs, as well as selecting a representative meteorological station for detailed analysis of weather conditions such as wind, precipitation and temperatures around slide events. The best correlation between EWEs and slide events could be found for debris flows. Debris flows usually occur at the day of EWEs. The relations with rockfalls and snow avalanches were found to be not fully understood.Often the relation between rockfalls/snow avalanches and EWEs is disturbed by a time lag. EWEs worked quite good as an indicator for snow avalanche events, while for rockfalls EWEs were found to be a poor indicator. The method used has shown difficulties in establishing the relationship between EWEs and slide events. The disadvantage of this method was that the definitions of EWEs were based only on the wind velocities. Moreover, the information about locations of areas affected by EWEs was too general. The locations were too large to choose a good representative meteorological station for the analysis of detailed weather conditions. Such data are necessary when trying to find a better correlation. Information from only one station that represents a large area was not sufficient to achieve conclusive results.Therefore the method and the data should be improved.