Search

Abstract: The Gold Coast, Australia is a coastal resort city whose urban environment has evolved through a series of human interventions on the natural shoreline. Such cities rely on a perceived high quality environment which in turn is reliant on continuing maintenance (e.g. beach nourishment, inlet dredging, drainage). Climate change consequently holds particular challenges for coastal resort cities. Sea-level rise impacts are likely to be manifest in increased frequency of flooding and beach erosion episodes. Here we consider adaptation options for the city under various future sea-level rise (SLR) scenarios at the high end of current predictions for the next century (+1 m, +2 m and +5 m) with the proviso that the beach and waterways must be preserved to enable the city to continue to exist as a resort. We conclude that pre-planned adaptation would probably enable the city to survive SLR of 1m. An unplanned response to the same SLR would likely be characterised by periodic crises, growing uncertainty and public unease and would have marginal chances of success. For a 2m SLR we contend that even with an adaptation plan in place, the scale of measures required would severely stretch the city''s resources. Under a 5m SLR over the next century we do not believe that any amount of planning would enable the city to survive as a coastal resort. Any adaptation to SLR would involve increased cost to maintain the artificial coastal environment. Adaptation options are particularly constrained by the widespread development around the waterways of the back-barrier area. Unlike other coastal cities, resorts depend on a public perception of a high quality environment. Maintaining this perception under SLR imposes particular adaptation constraints on resort cities. [Copyright &y& Elsevier]

Abstract: The concept of beach morphodynamic states has achieved widespread acceptance in the coastal geological literature since its inception in the mid-1980s and expansion in the 1990s. Much of the pioneering work was undertaken in Australia under a range of environmental conditions in microtidal environments and a close empirical relationship between beach 3-dimensional morphology and the Dean''s parameter (H b/W s T) was established. Subsequently, the Relative Tidal Range parameter (H b/TR) was extended to beaches of all tidal ranges. In this paper, observations are presented from 25 beaches around the north coast of Ireland. These beaches exist on an environmental gradient that encompasses marked tidal and wave energy variability (micro to macrotidal and low to high wave energy). Each beach was visually categorised into one of several established beach states described in the literature, on the basis of field observations. For each beach, the RTR and Dean''s parameter were calculated for the immediately antecedent period and used to predict the beach state using published relationships. Observed and predicted beach states were then compared. Comparison of observed and predicted beach states showed that while beaches with observed dissipative morphology typically matched the expected criteria, most other beach states did not. Lack of agreement between predicted and observed beach states has been reported elsewhere and attributed to failings in the RTR and Dean''s parameter. In addition, this study identifies geological factors as important constraints on actual beach state. In the majority of beaches studied, inherited geological factors appear to be more important determinants of beach morphology than contemporary dynamics. [Copyright &y& Elsevier]

Pilkey, O.H. and Cooper, J.A.G., 2007. Lifting up the flap or why quantitative beach behaviour predictive modelling can't work. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 585 – 587. Gold Coast, Australia, ISSN 0749.0208 Quantitative mathematical modelling of beach behaviour with sufficient accuracy for engineering purposes is not possible. Success in "prediction" by hindcasting does not indicate a model works. Probabilistic modelling of beach processes is not possible either because accurate determinations of error bars is impossible. One measure of the problem with quantitative modelling is the nature of model simplifications. In qualitative models where the how, why and what if answers sought are directional, or order of magnitude, simplifications are often quite useful and valid. But a quantitative model can have no simplifications of important processes. All important processes along with their interactions and feedbacks must be represented in the models. Even if all parameters in the models are perfectly understood, one never knows their intensity, frequency, direction or duration. Some widely used models such as the Bruun Rule use virtually none of the critical processes in the model (except sea level rise) that cause shoreline retreat. The CERC equation and its many variants uses only a few of what are likely to be the important parameters effecting sand transport. [ABSTRACT FROM AUTHOR]