Photogrammetric Analysis of a Slush Torrent in the Kärkevagge, Northern Sweden

Abstract

Slushflows have been investigated in various regions of the Earth for more than forty years. Most of the observed events occurred in mountainous drainage basins at high latitudes, so relatively few observations and measurements are presented in the scientific literature. This particularly holds for slush torrents which are major slushflow events reaching supercritical flow velocities. Thus, information on dynamical features of slush torrents are rather limited, and most results are based on qualitative observations. On June 3,1995, during a field campaign in the Kärkevagge, a drainage basin in Swedish Lapland, a slush torrent could be observed and documented by a time series of photographs and by video recordings. Quantitative results from a photogrammetric analysis of the photographs show that the first wave front of that slush torrent reached peak velocities of more than 40 ms−1. A second wave front was able to reach even higher velocities due to the fact that the first wave had almost completely removed all snow from the transport path. Consequently, the viscosity of the flow was significantly reduced. To the author's best knowledge, these results are the first quantitative measurements of a slush torrent during its movement.