Probabilistic characterization of single and concurrent metocean variables of mexican coasts with seasonal variability using extreme value theory, with application to reliability of coastal structures
- Autores: Felícitas Calderón Vega
- Directores de la Tesis: Adrián David García Soto (dir. tes.), Cesar Mösso Aranda (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2021
- Idioma: español
- Materias:
- Texto completo no disponible (Saber más ...)
- Resumen
This thesis encompasses a set of different subjects related to metocean variables but studied from different perspectives. The metocean variables are mainly significant wave heights and wind velocities and, to a lesser extent, wave periods. The extreme value theory is used to probabilistically characterized the metocean variables by means of the generalized extreme value distribution (GEV). The effect of seasonality is included by considering monthly maxima and using harmonic and subharmonic functions (i.e., time dependency in the GEV model is incorporated). Although Mexican information was not available to this study, the studies are considered applicable to Mexican coasts in the Gulf of Mexico and the Pacific, since available public information from U.S. buoys located in the Atlantic and Pacific oceans relatively close to the Mexican coasts is employed. For the Pacific region, the GEV model accounting for seasonality is applied to data from a buoy (this is reported in an article in the appendix and summarized as a book chapter in the compendium of publications) and comparisons are carried out versus analogous results for buoys in the Gulf of Mexico obtained in a previous study (included also in the appendix). In other part of the thesis (another book chapter in the compendium), but also for the buoy in the Pacific Ocean, a study is carried out to assess the impact of including or excluding an atypical wave height in the seasonality and in future projections (i.e., wave heights associated with given return periods), since an atypically large significant wave heigh was observed for the considered buoy. One more study (an article in the compendium) introduces the wind velocity as a Metocean variable to be characterized with the time-dependent GEV model from data of a buoy in the Gulf of Mexico. This wind velocity is not for monthly maxima, but for the recorded wind velocity which simultaneously occurred with the maximum significant wave heights. This allowed to propose a simplified approach to determined concurrent significant wave heights and associated wind velocities for given return periods, while accounting for seasonality and quantitatively establishing the uncertainty in the correlated metocean variables in question. This proposal can be potentially used for design and engineering purposes, if the metocean are considered as hazards which imposed demands on coastal (and structural) engineering systems. Additionally, the effect of varying the considered time window for the extreme projections is explored. In a final study (also an article in the compendium), an introduction to the reliability of coastal (and also structural) engineering systems is presented; a breakwater is used as case-study. The coastal structure is subjected to the action of wave heights with different wave periods, for which the joint Longuet-Higgins distribution is used, and the overtopping probability of failure is computed by using classical and revisited reliability approaches. Future studies could combine the characterization of metocean variables as time-dependent GEV models and the used reliability approaches to further investigate the reliability of coastal and offshore systems.
