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Dominique St-Hilaire

Coordinates

Office: SN 2005
Telephone: (709) 864- 6127
Fax: (709) 864- 3119
E-mail: dominique.sthilaire@hotmail.com

Supervisor

Dr. Trevor Bell, Dr. Donald Forbes, Dr. Arthur Dyke and Dr. Bob Taylor

Thesis title

Arctic coastal dynamics under changing relative sea-level and environmental forcing, Canadian Arctic Archipelago.

Research description

The primary goal of my doctoral research is to define Arctic gravel beaches sensitivity and response to changing environmental forcing in the context of anticipated climate change. Two environmental variables that will have a significant impact on the Arctic coastline are relative sea-level (RSL) rise and reduced sea-ice cover (ACIA, 2005). Both can alter the wave energy regime at the coast, causing flooding, enhanced erosion and shoreline retreat, and influencing the morphology and sedimentology of depositional landforms. Such changes represent increased hazard risk for community infrastructure, nearshore benthic habitats, and coastal resources. Projecting the future response of the coastal system to these changes in forcing is a prerequisite for an effective adaptation strategy (Ford et al., 2006).

Two complementary approaches are used in order to achieve this goal: (1) the study of past responses under time-varying conditions as recorded in the geological record and (2) the study of present responses under spatially varying forcing as interpreted from modern processes. Study sites are selected along a longitudinal transect in the Eastern Arctic encompassing gradients of both RSL trends (Tarasov & Peltier, 2004) and coastal exposure and sensitivity to different levels of energy. The westernmost sites are expected to show characteristics of regressive coastal systems in response to postglacial relative sea-level fall (Dyke and Peltier, 2000). Sequences of raised marine landforms encompassing the last few decades to millennia will form the basis of the geological record needed to help understand the dynamics of the past and present coastal system. Evidence of transgressive systems is expected at the easternmost sites where the postglacial RSL lowstand and past shorelines are submerged below present sea level (Andrews, 1989). Candidate sites from west to east are: Lowther Island, Griffith Island, Resolute area, Cape Charles Yorke, Lavoie Point, Bylot Island and Pond Inlet and vicinity.

Onshore research is conducted using the following methods: multi-temporal analysis and mapping of modern and relict (raised) coastal systems using airphotos, satellite imagery, LiDAR and RTK surveys. Land-based work supports temporal studies on the modern coastline using both historical records and ongoing monitoring programs. Surveys of raised marine landforms build on my MSc research and lead to a better understanding of the dynamics of regressive coastal systems (St. Hilaire et al., 2006). Shallow-water mapping of transgressive coastal systems will be carried out using multibeam sonar, single-beam and side-scan echo-sounders, sub-bottom profiler and sediment cores, primarily from the CCGS Amundsen and the CSL Heron during ArcticNet NCE scientific cruises, but local small boat charter and/or ice platforms may also be utilized. Sea-floor imagery and sub-bottom profiles will enable a better understanding of past coastal response to rising RSL and how the offshore topography and sediment composition influence the development of coastal systems under both rising and falling RSL.

The project is consistent with the objectives of Projects 1.2 and 2.4 of the ArcticNet NCE and will form part of a larger integrated regional impact study (IRIS) of climate change in the eastern Arctic. It also contributes to an improved understanding of coastal hazards and climate-change impacts in the coastal zone and will inform decision-making for community and government adaptation strategies to climate change.

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