Et aktivt skredsårs effekt på bunntransport og kornstørrelsestrend i en fjellelv

Abstract

An increased frequency of sediment delivery from hill slops is a leading problem in mountainriver management. And a climate change might lead to an increased frequency of bed load transport and change in grain size trend in mountain river basins. The theme for this master thesis is of importance for the society, because possible effects of a climate change is more frequent flooding and landslide events that might cause the society unexpected stain. This master thesis is based on a comparison of bed load transport and grain size trend between two locations situated upstream - and downstream for a dominating landslide in Vekveselva, Oppdal. The two locations and the dominating landslide are located in a 330 meter study rich which is dominated by a step – pool morphology. Four impact sensors was placed in the rich to measure the bed load transport acceleration from June to July, and pebble counts in eight cross sections were carried out to find the grain size trend in the rich after numerous episodic bed load events, and gradient and step height and step length was measured. The bed load acceleration – and grain size trend study produced interesting data concerning bed load and grain size trend in Mountain Rivers.  The outcomes of the study were discussed in context with current theories concerning bed load acceleration and grain size trend in mountain river basins.