Panagiota GALİATSATOU, Panayotis PRİNOS, Nikolay VALCHEV, Ekaterina TRİFONOVA

Analysis of Extreme Marine Events Causing Flooding in Varna Region

In the present paper extreme wave height, wave period and storm surge events in the marine area of the Varna region are analyzed using Extreme Value Theory (EVT) to estimate return levels of the aforementioned variables corresponding to selected return periods. Both univariate and multivariate techniques are utilized. The GEV (Generalized Extreme Value) distribution is implemented to extrapolate the marine variables to levels more extreme than those observed. Joint probability analysis is also conducted. A bivariate extreme value model is used to produce estimates of joint probabilities of extreme wave heights and storm surges. For wave period extremes, a conditional distribution on extreme wave height is utilized. Joint estimates of wave height, storm surge and wave period are compared to the respective estimates of the univariate analysis, for selected return periods.

PDF

___

Athanassoulis, G.A., Skarsoulis, E.K. and Belibassakis, K.A. 1994. Bivariate distributions with given marginals with an application to wave climate description, Applied Ocean Research, 16: 1-17.

Coles, S. 2001. An introduction to statistical modeling of extreme values, Springer Series in Statistics, 1st Edition., London, 210 pp.

Coles, S., Heffernan, J. and Tawn, J. 1999. Dependence measures of extreme value analysis, Extremes, 2(4): 339-365.

Coles, S., Pericchi, L.R. and Sisson, S. 2003. A fully probabilistic approach to extreme rainfall modeling, Journal of Hydrology, 273: 35-50

Coles, S.G. and Casson, E.A. 1999. Spatial regression models for extremes, Extremes, 1: 449-468.

Coles, S.G. and Tawn, J.A. 1991. Modelling extreme multivariate events, Journal of the Royal Statistical Society B, 53: 377-392.

Coles, S.G. and Tawn, J.A. 1994. Statistical methods for multivariate extremes: an application to structural design, Applied Statistics, 43: 1-48.

Coles, S.G. and Tawn, J.A. 1996. Modeling extremes of the areal rainfall process, Journal of the Royal Statistical Society B, 58: 329-347.

Davison, A.C. and Smith, R.L. 1990. Models for exceedances over high thresholds, Journal of the Royal Statistical Society B, 52: 393-442.

De Haan, L. and De Ronde, J. 1998. Sea and wind: Multivariate extremes at work, Extremes, 1: 7-45.

Ferreira, J.A. and Soares, C.G. 2002. Modelling bivariate distributions of significant wave height and mean period, Applied Ocean Research, 24: 31-45.

Galiatsatou, P. 2007. Joint exceedance probabilities of extreme waves and storm surges, XXXIII Congress of IAHR, JFK Competition, Venice, Italy, 780 pp (abstract).

Galiatsatou, P. and Prinos, P. 2006. Analysis of extreme rainfall events using a Poisson process, Proc. of the 10th Hellenic Conference by Hellenic Hydrotechnical Association, Kalithea/Chalkidiki, Greece: 47-54

Galiatsatou, P. and Prinos, P. 2008. Bivariate analysis and joint exceedance probabilities of extreme wave heights and periods, Coastal Engineering 2008, Proc. of the 31st International Conference, Hamburg, Germany: 4121-4133.

Galiatsatou, P., Prinos, P. and Sánchez-Arcilla, A. 2008. Estimation of extremes. Conventional versus Bayesian techniques, Journal of Hydraulic Research, 46(2): 211-223.

Goda, Y. 2000. Random seas and Design of Maritime Structures, In: Liu, P.L.-F. (Ed.), Advanced Series on Ocean Engineering, World Scientific, Singapore, 443 pp.

Günther, H., Hasselmann, S. and Janssen, P.A.E.M. 1992. Wave model Cycle 4, Technical Report No.4, Deutsches Klima Rechen Zentrum, Germany.

Hawkes, P.J., Gouldby, B.P., Tawn, J.A. and Owen, M.W. 2002. The joint probability of waves and water levels in coastal engineering design, Journal of Hydraulic Research, 40(3): 241-251.

Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K.C., Ropelewski, C., Wang, J., Leetmaa, A., Reynolds, R., Jenne, R. and Joseph, D. 1996. The NCEP/NCAR reanalysis project, Buletin of the American Meteorological Society, 77: 437-471.

Keremedchiev, S., Trifonova, E., Eftimova, P. and Nikolova, A. 2008. Assessment of the geodynamic vulnerabilityof risk coastal areas along Varna coast, Proc. of the 5th International Conference, Global changes Vulnerability, Mitigation and Adaptation. 17- 18 April, St. Kilent Ohridski" University Press., Sofia, Bulgaria: 138-144.

Lavrenov, I. 1998. Numerical modeling of wind waves in spatially heterogeneous ocean, Gidrometeoizdat, St. Petersburg, 449 pp. (in Russian).

Morton, I.D. and Bowers, J. 1996. Extreme value analysis in a multivariate offshore environment, Applied Ocean Research, 8: 303-317.

Repko, A., van Gelder, P.H.A.J.M., Voortman, H.G. and Vrijling, J.K. 2004. Bivariate description of offshore wave conditions with physics-based extreme value statistics, Applied Ocean Research, 26: 162-170.

Schlather, M. and Tawn, J.A. 2003. A dependence measure for multivariate and spatial extreme values: Properties and inference, Biometrika, 90(1): 139-156.

Tawn, J.A. 1988. Bivariate extreme value theory: Models and estimation, Biometrika, 75: 397-415.

Tawn, J.A. 1992. Estimating probabilities of extreme sea levels, Applied Statistics, 41: 77-93.

The SWAN Team, 2006. SWAN User Manual, Delft University of Technology, the Netherlands

Valchev, N., Davidan, I., Belberov, Z., Palazov, A. and Valcheva, N. 2008. Estimation of wind wave climate of the Western Black Sea during the last 50 years, Proc. of 9th Int. Conf., Marine Sciences and Technologies - Black Sea'2008, Varna, Bulgaria: 231- 239.

van Gelder, P.H.A.J.M. 2000. Statistical Methods for the Risk-based design of civil structures, PhD thesis. Delft: University of Technology, The Netherlands.

Walshaw, D. 1994. Getting the most from your extreme wind data: a step by step guide, Journal of Research of the National Institute of Standards and Technology, 99: 399-411.

Walshaw, D. and Anderson, C.W. 2000. A model for extreme wind gusts, Applied Statistics, 49: 499-508.

Zachary, S., Feld, G., Ward, G. and Wolfram, J. 1998. Multivariate environment, Applied Ocean Research, 20: 273-295. in the offshore