The prediction of extreme keel depths from sea ice profiles

Abstract The prediction of return periods of extremely deep pressure ridge keels is discussed, using as data a 1400 km submarine profile obtained by U.S.S. “Gurnard” in the Beaufort Sea. Three techniques of predicting return periods at a point are examined: the use of the negative exponential distribution; a depth crossing technique; and a probability plotting technique. The problem of predicting return periods along a line is then examined with reference to ice scouring across seabed pipeline routes. A technique which combines keel statistics and scour depth statistics is used to compute the pipeline burial depth necessary to avoid disturbance by ice for a specified period.