ABSTRACT: Climate-change impacts in the coastal zone: implications for engineering practice.

CGRG Bibliography of Canadian Geomorphology
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Climate change can include warming or cooling trends and changes in climate variability, including extreme events. Coastal impacts of anticipated climate warming in Canada will result from rising sea levels, changes in sea ice and open-water fetch (leading to increased storm wave energy), possible changes in storm tracks and intensity, and effects of warmer temperatures on coastal cliff and slope failure, particularly in northern regions with permafrost and massive ground ice. These changes will increase coastal hazards of engineering concern, including the frequency and magnitude of storm-surge flooding, storm-wave run-up, ice ride-up or pile-up, coastal slope failure, shoreline erosion and impacts on coastal infrastructure, among others.In many parts of Canada, changes are already underway, both in response to recent warming trends and resulting from additional non-climate processes. Relative sea level, RSL, the mean water level observed at a tide gauge, is rising along much of our coast, due in large part to regional crustal subsidence. In other areas, RSL is falling due to crustal uplift at a rate exceeding the regional sea-level rise. Subsidence and uplift arise from the long-term isostatic response to changes in loading at the end of the last glaciation. Thus RSL at Charlottetown, Prince Edward Island, has been rising over the past century at a mean rate of 3.2 mm/a (equivalent to 32 cm over 100 years), while RSL is falling along the Hudson Bay coast of Québec at rates greater than 10 mm/a (>1 m per century) in the south. Falling RSL creates engineering issues including harbour shoaling (as at Churchill, Manitoba) and permafrost development in emergent marine sediments. Rising RSL leads to increased flooding hazards and shoreline erosion. It is important to determine the potential for changing flood probabilities, wave climate, and erosion rates under present rates of sea-level rise as a baseline case for current adaptation requirements. Looking into the future, we then need to assess projected changes in coastal hazards under various climate warming scenarios, including accelerated RSL rise, increased storminess, reduced sea ice, accelerated thaw subsidence, and other factors. Appropriate planning, site selection, design, infrastructure and resource management, hazard mitigation and risk reduction depend on adequate understanding of RSL trends, changes in environmental forcing, long-term shoreline evolution and sediment budget issues, potential thresholds for rapid change, and the moving limits of hazard zones. New technology provides opportunities for improved monitoring and hazard mapping, which are important requirements for planning and adaptation. Adaptation strategies may include a variety of hard and soft engineering, policy and regulatory changes, planning, education, and other components.

Bibliography of Canadian Geomorphology