The Impact of Storms on a Gravel-dominated Coastline: Cornwallis Island, Canadian Arctic Archipelago

Arctic beaches are noteworthy in that normal wave processes can only operate for a relatively short period of the year due to the presence of sea-ice. The role of low-frequency, high-magnitude storm events in causing rapid and sometimes catastrophic changes to arctic coastal morphology has been recognized by numerous authors since the 1960's. Published accounts of storm effects on arctic gravel beaches are however scarce compared to other types of coastal environment. This paper reports observed changes in beach morphology in relation to sea-ice free storm events along a gravel-dominated stretch of coastline on Cornwallis Island, central Canadian Arctic Archipelago (CAA). The approach consists in linking changes in beach morphology to specific storm events using the closely monitored 2007 storm event (St. Hilaire et al., 2007) as a reference. Methods include multi-temporal analysis and mapping of modern and relict (raised) coastal systems using airphotos, satellite imagery and RTK GPS surveys as well as shallow-water mapping using multibeam sonar, single-beam and side-scan echo-sounders and sub-bottom profiler. Preliminary results suggest that gravel beaches of the central CAA respond to moderate storm activity by morphological changes such as locally constrained erosion and accretion. These beaches however show minimal change when surveys are averaged over a period of several months to several years. This resilience can be attributed to the distinctive dynamic and morphosedimentary characteristics of gravel beaches and to the falling or stable relative sea-level characterizing the area.