Snow compaction method for the analysis of runoff from rain on snow

TitleSnow compaction method for the analysis of runoff from rain on snow
Publication TypeConference Proceedings
Year of Conference1965
AuthorsBertle, F. A.
Conference Name33rd Annual Western Snow Conference
Series TitleProceedings of the 33rd Annual Western Snow Conference
Date PublishedApril 1965
PublisherWestern Snow Conference
Conference LocationColorado Springs, Colorado
KeywordsAnalysis, Floods, Runoff, Snowmelt, Snowpack

A description of a water budget method used in inflow design flood studies to account for the effect of a fresh snowpack on the runoff from rain and snowmelt in the mountainous areas of the western U.S. is presented. The parameters used in the method were derived from a laboratory experiment and were checked by analysis of a large flood in California. The unique feature of the method is the evaluation of the amount of compaction (or shrinkage) in a fresh snowpack that results form the metamorphosis of the snow crystals when water is added. The snow crystals in a fresh snowpack undergo changes, as free water is added, that results in a shrinkage (or compaction) of the snowpack. Free water is retained in the snowpack until the threshold density is attained. Subsequent melting releases this free water. The procedure described, which uses a water budget based on the concept of snow compaction and a threshold density, has been a valuable aid in our design flood studies to estimate runoff from a design condition of warm rain on a relatively fresh snowpack.