The probabilistic model is applied at data rich Narrabeen beach, Australia. Kriebel and Dean (1993) and SBeach are used ¡®on-line¡¯ in the probabilistic simulations, while XBeach is used with an innovative off-line tabulation approach to facilitate reasonable computational times. SBeach is calibrated for a mid-range erosion event while XBeach is validated for the same single erosion event as well as for all measured storm erosion volumes during the 30 year study period. The Kriebel and Dean (1993) model is used with recommended parameter settings and therefore does not require calibration.
When both SBeach and XBeach are calibrated against the single erosion event, SBeach provides the most accurate and robust probabilistic estimates of storm erosion. However, when XBeach is calibrated using the entire erosion volume data series, the results improve significantly raising the accuracy and robustness of the probabilistic estimates of storm erosion volumes obtained with XBeach to be on par with those obtained with SBeach. However, only XBeach predicts storm erosion volumes with the physically more plausible behaviour of a downward concave tail shape when plotted as cross-shore beach-erosion volume on a vertical linear axis against return period on a horizontal logarithmic axis.
The simulation time (on a standard single processor) when using the simple Kriebel and Dean (1993) model is about 1 day, whereas for SBeach (on-line) and XBeach (tabulation), the simulation time is about 1000 h. However, the physically more plausible and the more accurate and robust results that can be obtained with SBeach or XBeach justifies the additional computational cost.
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