Hydrologic and biologic consequences of an avalanche striking an ice-covered lake

TitleHydrologic and biologic consequences of an avalanche striking an ice-covered lake
Publication TypeConference Proceedings
Year of Conference1990
AuthorsWilliams, M. W., and Clow D. W.
Conference Name58th Annual Western Snow Conference
Series TitleProceedings of the 58th Annual Western Snow Conference
Date PublishedApril 1990
PublisherWestern Snow Conference
Conference LocationSacramento, California
KeywordsAvalanche, Flood, Lake, Snow, Trout

The hydrological and biological effects of large avalanches striking ice-covered lakes have rarely been documented, due to the extreme weather conditions, remote locations and hazards often associated with these events. Here we report the effects of a large avalanche striking ice-covered Emerald Lake on February 17, 1986. The lake is located at an elevation of 2800 meters, in the southern Sierra Nevada, California. The avalanche, traveling about 20 m/sec, struck the lake with a force of 2.12x10(6) N. About 70% of the unfrozen water (90,000) m(3) in the lake was displaced into the outlet stream. The floodwave in the lake's outflow removed 5.4x10(5) kg of snow from the channel. Scouring of the streambed was observed throughout the exposed reach. The survival rate of embryos and sac fry from the resident brook trout (Salvelinus fortinalis), in the lake's outlet, decreased from close to 90% before the flood to 2.5% after the flood.