Slushflow hazard — where, why and when? 25 years of experience with slushflow consulting and research

Abstract

ABSTRACT. Slushflows -Oowing mixtures of water and snow -are a major natural hazard in Norway. Knowl edge gathered by the Norwegian Geotechnical Institute during 25 years of slushOow consulting and research is presented. The variation in regional occurrence is described and related to climatic premises and ground conditions. The principal ideas about slushf10w relea e, down-slope propagation and run-out are outlined. They are closely related to the rate and duration of water supply, snowpack properties and geomorphic factors. Slushf10w release is caused by basal shear failure aided by water pressure to cause loss of basal support and finally tensile failure through the snowpack. Our methods of hazard evaluation and acute-hazard prediction and warning are summarized, including the estimation of water supply based on meteorological data. The results of a worldwide questionnaire on slushflows, literature studies and scientific contacts, indicate that slushf10ws occur in all countries having a seasonal snow cover and that the results of our studies in Norway have a general validity.

The European mountain cryosphere: A review of past, current and future issues

“…Until recently, for example, slush-flows -mixtures of water and loose snow (Hestnes, 1998) -were mostly documented in Scandinavian mountains during a rather short spring period only (Schlyter et al, 1993). Local testimonies, however, now report such events over larger areas and longer time periods.…”

Slushflows at El Port del Comte, northeast Spain

“…A sharp rise in water level in dra in age courses is critica l to slush flow r elease (Hestnes, 1998). Th e water su ppl y gene rated by the rech a rge of th e aquifers, a nd th e fact tha t th e sp oradic springs became operational probably some hours aftcr th e saturation of th e base of the snow cove r, led to a sudden rise in the local water tabl e. As a res ult, the slushflows, ori ginating in the springs, were released.…”

“…Slushflows, or rapid m ass m ovements of wa ter-saturated snow (H estnes and others, 1994), are cha rac teristic of high latitudes, th ough they can occ ur whereve r snow cover is seasona l (H estnes, 1985;On esti and Hestnes, 1989;Hestnes, 1998). Slushfl ows had never been reported in the Iberian Peninsul a until they occ urred at the ski reso rt o f El Port del Comte (Fig.…”

Influence of snow cover properties on avalanche dynamics

“…Also slushflows [Onesti, 1987], a flowing mixture of water and snow, cause damage every year to man and property in arctic and mountainous regions [Jaedicke et al, 2008]. According to historical documentation, slushflows and snow avalanches are almost equally responsible for both damage and economic losses [Hestnes, 1998]. …”