Natural variability in extreme weather events and climatic change effects on avalanche and flood hazard

Participants: Lars Harald Blikra, Kari Sletten, Øyvind Nordli, Svein Olav Dahl og Atle Nesje

Extreme weather events as major storms, heavy rain and snowfall have large impact and consequences on the environment. Such events often triggers different types of avalanches and leads to major floods which often threats people, buildings and communication. The occurrence of extreme weather today have by some been interpreted as an effect of a human-induced changing climate. However, this will only be speculation if we do not know the natural variability of such events. One goal in this project is to assess the impact of climatic changes on avalanche and flood activity in the future.

The record of avalanche activity and floods are probably the best indicator or source for extreme weather information during the last 10.000 years. Snow avalanche-dominated deposits are thought to give information of the occurrence of major winter storms, or in general the winter climatic conditions. Debris flows and floods seem to occur in connection with major rainfall events, or in combination with intense snowmelt. There have been developed fairly good records from western Norway, and this project will be more concentrated on eastern and northern Norway. The data will also be important for evaluation of avalanche hazard.