Uncertainty of wave extreme values in Chile

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Abstract

The lack of wave measurements is a reality when making marine engineering designs in Chile. Recent extreme wave events such as 3 July 2013 and 8 August 2015, left considerable structural damage and put into evidence the need for a continuous and long-term wave monitoring programme in order to adequately estimate the frequency of occurrence of these events. Presently, the frequency analysis relies on global wave reanalysis databases of unknown quality for this purpose. This contribution attempts to quantify the uncertainty in the extreme waves frequency analysis. An extreme wave frequency analysis was carried out for different available wave databases. There are differences of the order of hundred years in the significant wave height return values for recent events. The quality of the information of these databases was evaluated by comparing them with the 10% highest values of the significant wave height measured by satellite in 8 areas along Chile. The uncertainty in the 50 year return period spectral significant wave heights tends to increase from north to south, with differences between databases ranging from 2.3 to 6.7 m. The parameters used in the comparison with satellite measurements show, in general, better model skills in the north than in the south except for the R² parameter. Correlations are very low with values of R² near 0 for points in the north. The best correlation is found for IFREMER database in front of Golfo Coronados with R²= 0.66. Biases are generally negative indicating underestimates near 1 m for the highest significant wave heights.

Gallardo, A., Valdivia, J., & Beyá, J. (2017). Uncertainty of wave extreme values in Chile. Latin American Journal of Aquatic Research, 45(4), 649-658. doi:http://dx.doi.org/10.3856/vol45-issue4-fulltext-2

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