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An assessment of current and future vulnerability to coastal inundation due to sea-level extremes in Victoria, southeast Australia

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Abstract

Current climate 1-in-100-year storm tide heights along the coast of Victoria, southeast Australia were estimated by combining probabilities of storm surge and tide heights determined from hydrodynamic modelling. For this return period, levels lie between 1 and 2 m above mean sea level along much of the coastline. Future climate 1-in-100-year storm tide heights were estimated by adding high-end estimates of future sea-level rise from recent literature. The effect of climate change through consistent wind-speed increases was also examined and it was found that, for the late 21st Century, the contribution of wind-speed increase to the increases in extreme storm surge heights is considerably smaller, by a factor of more than 2, than the contribution of sea-level rise.

A computationally inexpensive approach to assessing current and future vulnerability to coastal inundation due to sea-level extremes is then demonstrated for the Victorian coast. A simple inundation algorithm was used with high-resolution terrestrial elevation data from a Light Detection and Ranging (LiDAR) survey of the Victorian coast to evaluate the potential vulnerability of nine coastal regions to inundation by current and future climate 1-in-100-year storm tides. The response of different regions varied from exhibiting proportional increases in inundation to sea-level rise to nonlinear responses, where the exceedance of critical sea-level thresholds led to large stepwise increases in land area or number of land parcels affected by inundation. These responses were a function of both coastal topography and the spatial density of land parcels. The low computational cost of the methodology permits different time horizons and uncertainties in future climate change to be considered using a scenario-based approach and is therefore useful in assessing options for adaptation to climate change. Copyright © 2011 Royal Meteorological Society

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