Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Coastal Processes and Climate Change along the Canadian Beaufort Sea
Steven Solomon1, Gavin Manson2
1Geological Survey of Canada, Natural Resources Canada, PO Box 1006, Dartmouth, NS, B2Y 4A2, Canada, Phone 902-426-8911, Fax 902-426-4104, ssolomon@nrcan.gc.ca
2Geological Survey of Canada (Atlantic), PO Box 1006, Dartmouth, Canada, Phone 902-426-3144 , Fax 902-426-4104, gmanson@nrcan.gc.ca
Coastal processes occur at the interface between ocean, atmosphere and land. Oceanographic forcing in the form of waves, currents and water levels interact with seabed and terrestrial materials, modifying coastal morphology. Winds drive the waves and water levels, whereas air temperatures affect the cryological conditions both on land and in the sea. Coastal processes occurring at high latitudes differ fundamentally from those at temperate latitudes because of the presence of ice (both ground ice and sea ice) and permafrost. Sea ice mediates the interaction between atmosphere and ocean, affecting wave generation and storm surges and impacts nearshore sediment transport and coastal permafrost stability. The presence of ground ice and permafrost control the initial strength of coastal materials and ice content affects the nearshore sediment budget and local morphological conditions.
Over the past 10 years, coastal research in the Canadian Beaufort Sea has focused on improving our understanding of the relations between the unique aspects of high latitude environmental forcing and coastal impacts. Coastal processes in the region tend to be storm-dominated and occur during the short open-water season. Analysis of coastal meteorological and sea ice records have identified a high degree of interannual variability, but no apparent trends in storminess or open water season sea ice extent. However, there is an indication that open water extent just prior to freeze up is increasing. Tide gauge records indicate that relative sea level is rising at rates of up to 3.5 mm per year as a result of the combination of subsidence and eustatic sea level rise. The relative importance of the former is critical in order to estimate impacts resulting from predicted acceleration of the latter. Co-located tide gauges and global positioning systems have been installed in several locations in the Canadian Arctic in order to determine absolute rates of sea level change, by direct measurement of vertical motion and relative sea level.
Coastal change rates have been measured using a combination of ground surveys, marine surveys and remote sensing methods. Mechanisms of subaerial coastal change (e.g. retrogressive thaw failure and thermal notching) affect retreat rate measurements by causing lag effects between storm events and removal of erosion products. The coastal change rates show a high degree of both temporal and spatial variability with differences of more than an order of magnitude in successive years and between adjacent coastal reaches. To date, no trends in rates of change have been observed. It is noteworthy that rates of coastal change do not appear to be substantially affected by sea ice conditions. This is because wind-generated waves and storm surges are limited as much or more by local morphological conditions (e.g. water depth and coastline shape and exposure) than by fetch limitations imposed by sea ice. Therefore, predicted changes in sea ice extent are likely to be less important than changes in the length of the open water season. Extension of the open water season into the fall will increase the probability of occurrence of high magnitude storm events when the coast is vulnerable. Ground ice content is a locally important determinant of coastal change rates, especially where sediment supplies are already limited and ground ice is close to or below mean sea level.
Abstract Categories: Coastal Processes
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