Iceberg Grounding and Scouring Frequency, Labrador Sea

Iceberg scouring presents a major problem in the placement of pipelines and other seabed installations at producing wells in the iceberg-rich waters of the eastern Canadian continental shelf. Over fifty grounded and scouring icebergs have been identified from iceberg observations made at twelve exploratory wellsites on the Labrador and northeast Newfoundland shelf areas. From these data sets, icebergs which remained stationary for twelve hours or more, were considered to be grounded. Bergs which moved into shallower water from the grounding sites were interpreted to be scouring. We found that icebergs can scour both up and downslope; one berg scoured over a vertical interval of 45 m. Many scour tracks exceeded lengths of 20 km and some exceeded 50 km. The grounding frequency varied greatly between years and wellsites; the average, however, ranges between 5 groundings per 100 bergs at N and 3.4 per 100 at N.