Christian M. Appendini

Wave Climate and Trends for the Gulf of Mexico: A 30-Yr Wave Hindcast

AbstractThis paper describes wave climate and variability in the Gulf of Mexico based on a 30-yr wave hindcast. The North American Regional Reanalysis wind fields are employed to drive a third-generation spectral wave model with high spatial (0.005°–0.06°) and temporal (3 hourly) resolution from 1979 through 2008. The wave hindcast information is validated using National Data Buoy Center (NDBC) data and altimeter wave information (GlobWave). The model performance is satisfactory (r2 ~ 0.90) in the Gulf of Mexico and to a lesser extent in the Caribbean Sea (r2 ~ 0.87) where only locally generated waves are considered. However, the waves generated by the Caribbean low-level jet (CLLJ) are discussed in this work. Subsequently, the yearly/monthly mean and extreme wave climates are characterized based on the (30 yr) wave hindcast information. The model results show that the mean wave climate is mainly modulated by winter cold fronts (nortes) in the Gulf of Mexico, whereas extreme wave climate is modulated by b...

Longshore Sediment Transport on the Northern Coast of the Yucatan Peninsula

Abstract Appendini, C.M.; Salles, P.; Mendoza, E.T.; López, J., and Torres-Freyermuth, A., 2012. Longshore sediment transport on the northern coast of the Yucatan Peninsula. This paper presents a qualitative assessment of coastal processes along the northern coast of the Yucatan Peninsula based on a method used to estimate the potential longshore sediment transport. Despite the deep-water low-energy wave conditions (Hs  =  1 m) in the study area, erosion is critical in many locations, including the urbanized stretches of coast. The waves were characterized using a 12 y (1997–2009) deep-water wave hindcast data (WAVEWATCH III) as forcing for a spectral wind-wave numerical model (MIKE 21 SW) used to propagate the waves to the coast. Simulated time series of significant wave height, peak period, and direction are compared against in situ measurements at 10 m water depth. Numerical results are further employed for estimation of the nearshore wave climate along the coast. Wave conditions are strongly affected by the wide continental shelf in front of the northern Yucatan Peninsula, with an increase in wave energy at the eastern part of the peninsula where the shelf narrows. The nearshore wave climate is employed for the qualitative assessment of potential longshore sediment transport (LITDRIFT model) in the study area. The sediment transport calculations are consistent with both volume impoundment estimations at a groin and dredging estimates at a harbor (−35,000 m3/y). A net westward potential longshore sediment transport is found along the entire coast, ranging between −20,000 and −80,000 m3/y, except west of Holbox, where longshore transport direction is inverted. Based on sediment transport gradients, potential erosion and deposition areas are identified. Erosion/accretion patterns at nonurbanized areas are consistent with field observations. This dominant westward longshore transport suggests an extremely sensitive shoreline to littoral barriers, as supported by observations in the most urbanized areas. These areas show no gradients on longshore sediment transport, whereas beach erosion is a common feature enhanced by littoral barriers. Shore protection should then be oriented toward sediment management strategies. Resumen En este trabajo se presenta una evaluación cualitativa de los procesos costeros a lo largo de la costa norte de Yucatán, en base a una metodología para la estimación del transporte potencial de sedimentos. A pesar de las condiciones de baja energía de oleaje (Hs  =  1 m) en la zona, los problemas de erosión costera son críticos en varias localidades, incluyendo zonas urbanizadas. Se utilizaron 12 años de datos (1979–2009) de un retroanálisis de oleaje (WAVEWATCH III) como condiciones de frontera para un modelo de oleaje en la zona costera (MIKE 21 SW). Las series de tiempo de altura significante, periodo pico y dirección de oleaje se compararon con mediciones in situ a 10 m de profundidad. Las condiciones de oleaje son muy afectadas por la amplia plataforma continental frente a la costa de Yucatán, mostrando una tendencia a incrementar al acercarnos a la parte este de la península donde la plataforma es reducida. El clima de oleaje determinado a lo largo de la costa fue utilizado para evaluar el transporte potencial de sedimentos (modelo LITDRIFT) en la zona de estudio. Los cálculos de transporte son consistentes con las estimaciones en la zona (−35,000 m3/año). Se determinó una tendencia dominante hacia el oeste para el transporte potencial de sedimentos en prácticamente toda la costa, con valores entre −20,000 y −80,000 m3/año, siendo que únicamente al oeste de Holbox hay una inversión en la dirección del transporte. Los patrones de erosión/acumulación en las zonas no urbanizadas son consistentes con observaciones de campo. La dominancia del transporte de sedimentos con dirección al oeste indica que es una costa muy sensible a las barreras litorales, lo cual es sustentado por las observaciones en las zonas densamente urbanizadas. Estas zonas no muestran gradientes en el transporte de sedimentos, sin embargo la erosión es una característica común como resultado de las barreras litorales. De esta manera, la protección costera deberá orientarse a estrategias de manejo de sedimento.

Hurricane-induced waves and storm surge modeling for the Mexican coast

This paper describes the application of a third-generation wave model and a hydrodynamic model to determine extreme waves and water levels associated to the incidence of tropical cyclones along the Mexican coast. In addition to historical records and to overcome the limitation associated to data scarcity in Mexico, we employ information from 3100 synthetic events generated from a statistical/deterministic hurricane model. This enables the generation of a more robust database for the characterization of extreme water levels along the Mexican coast. The procedure incorporates a storm track modeling approach where, for each hurricane (historic and synthetic), the entire track is numerically reproduced as it crosses the ocean and makes landfall. Extreme values for both, waves and storm surge, are determined through an extreme value analysis at each mesh element, allowing for the identification of their spatial variability. Results for the Gulf of Mexico show that highest waves are expected along both the Caribbean Sea and the northern coast of the Gulf of Mexico, while extreme water levels due to storm surge are identified in the northern part of the Yucatan Peninsula. On the other hand, along the Pacific coast, extreme values for waves are identified at the central mainland Mexico while storm surge is minimal. The methodology is proved to be a good alternative in the reproduction of continuously varying tropical cyclone climatology along the Mexican coastline, and it provides a rational approach for assessing the hurricane-induced risk in coastal areas.

Storm characterization and coastal hazards in the Yucatan Peninsula

ABSTRACT Mendoza, E.T., Trejo-Rangel., M. A., Salles, P., Appendini, C.M., Lopez-Gonzalez, J. and Torres-Freyermuth, A., 2013. Storm characterization and coastal vulnerability in the Yucatan Peninsula A preliminary coastal hazard potential assessment due to storm impacts in terms of erosion and flooding for the Yucatan coast is presented. Firstly, a 30-year wave hindcast is employed in order to characterize the coastal storms by creating a 5-class storm scale in terms of wave information. Subsequently, the storm classification is converted to one based on the consequences over 26 beach profile sections located along the Yucatan coast. The storm consequences were classified according to their flood and erosion potential by means of parametric and numerical model results which are correlated with key beach characteristics such as beach width and maximum beach height. According to the obtained results, the storms were characterized in five different categories and it was found that the Yucatan coast presents higher threat to flood than to erosion during the impact of storms.

On the Role of Climate Change on Wind Waves Generated by Tropical Cyclones in the Gulf of Mexico

To generate projections of wave climate associated to tropical cyclones is a challenge due to their short historical record of events, their low occurrence, and the poor wind field resolution in General Circulation Models. Hence, synthetic tropical cyclones provide an alternative to overcome such limitations, improving robust statistics under both present and future climates. We use synthetic events to characterize present and future wave climate associated with tropical cyclones in the Gulf of Mexico. The NCEP/NCAR atmospheric reanalysis and the Coupled Model Intercomparison Project Phase 5 models NOAA/GFDL CM3 and UK Met Office HADGEM2-ES, were used to derive present and future wave climate under RCPs 4.5 and 8.5 scenarios. The GFDL model shows less bias in the present climate with respect to NCEP/NCAR results. Furthermore, the numerical results suggest an increase in wave activity for the future climate in the Caribbean Sea and Northern Gulf of Mexico, whereas some areas are expected to decrease the wave energy, as the stretch of the Gulf of Mexico between Yucatan and Southern Texas. The results have practical implications on the design of offshore structures. The 100-year design wave based on the present climate might result in under/over design of structures, owing to the lifespan of a structure that is within the future wave climate period.

Storm surge at a western Gulf of Mexico site: variations on Tropical Storm Arlene

ABSTRACT Storm surge was calculated based on 23 different scenarios of a tropical cyclone (TC) trajectory, intensity and translation speed making landfall over a radius of 100 km of the Pánuco River at Tampico, Mexico. At the coast, the highest water levels resulted when the landfall was directly over the study area. When the landfall was 50 km south the high water levels remained for the longest time and highest levels occurred upstream. Also, high water levels were sustained longer when the TC had a slow translational speed (∼2 m/s) relative to fast-moving storms (∼4 m/s). Negative water levels resulted for events making landfall north of the study area, which may increase flushing of the river discharge and mitigate flooding from river overflown. The implications of the different scenarios are discussed in relation to management and implementation of contingency plans.

HYDRORECESSION: A Matlab toolbox for streamflow recession analysis

Abstract Streamflow recession analysis from observed hydrographs allows to extract information about the storage-discharge relationship of a catchment and some of their groundwater hydraulic properties. The HYDRORECESSION toolbox, presented in this paper, is a graphical user interface for Matlab and it was developed to analyse streamflow recession curves with the support of different tools. The software extracts hydrograph recessions segments with three different methods (Vogel, Brutsaert and Aksoy) that are later analysed with four of the most common models to simulate recession curves (Maillet, Boussinesq, Coutagne and Wittenberg) and it includes four parameter-fitting techniques (linear regression, lower envelope, data binning and mean squared error). HYDRORECESSION offers tools to parameterize linear and nonlinear storage-outflow relationships and it is useful for regionalization purposes, catchment classification, baseflow separation, hydrological modeling and low flows prediction. HYDRORECESSION is freely available for non-commercial and academic purposes and is available at Matlab File Exchange ( http://www.mathworks.com/matlabcentral/fileexchange/51332-hydroecession ).

Effect of climate change on wind waves generated by anticyclonic cold front intrusions in the Gulf of Mexico

Anticyclonic cold surges entering the Gulf of Mexico (Nortes) generate ocean waves that disrupt maritime activities. Norte derived waves are less energetic than the devastating waves from tropical cyclones, but more frequent (~ 22 events/year) and with larger spatial influence. Despite their importance, few studies characterize Nortes derived waves and assess the effects of climate change on their occurrence. This study presents a method to identify and characterize Nortes with relation to their derived waves in the Gulf of Mexico. We based the identification of Nortes on synoptic measurements of pressure differences between Yucatan and Texas and wind speed at different buoy locations in the Gulf of Mexico. Subsequently, we identified the events in the CFSR reanalysis (present climate) and the CNRM-M5 model for the present climate and the RCP 8.5 scenario. We then forced a wave model to characterize the wave power generated by each event, followed by a principal component analysis and classification by k-means clustering analysis. Five different Nortes types were identified, each one representing a characteristic intensity and area of influence of the Norte driven waves. Finally, we estimated the occurrence of each Norte type for the present and future climates, where the CNRM-M5 results indicate that the high-intensity events will be less frequent in a warming climate, while mild events will become more frequent. The consequences of such changes may provide relief for maritime and coastal operations because of reduced downtimes. This result is particularly relevant for the operational design of coastal and marine facilities.

An Engineering Approach for Modeling Hurricane Extreme Waves Using Analytical and Numerical Tools

This work aims to evaluate the ocean wave statistics (i.e., significant height, peak period, mean wave direction, and spectral form) under hurricane events, at any geographical point and coastal location by employing two different approaches. First, by the use of classical fast and mid-accurate analytical engineering tools comparing three classical set of equations (Bretschneider 1990; Young 1988; and the Shore Protection Manual SPM 1984) and their further validation against instrumental data provided by the National Data Buoy Centre (NDBC). On the other hand, by using a high-accurate numerical approach is proposed, using the unstructured-mesh SWAN spectral wave model (Zijlema et al. 2010), comparing the results between the stationary and non stationary approach, and validating the nearshore ocean wave characteristics with measured data at different water depth locations. Both approaches are forced with accurate pressure and wind speed fields obtained with classical and well-known parametric equations (i.e., Holland 1980; Hydromet-Rankin Vortex 1980; and Bretschneider 1990), integrated with the NCEP/NCAP wind fields. Hurricane waves for both approaches are validated with instrumental data from the NDBC measured for hurricanes: Katrina (2005); Gilbert (1998); Mitch (1998); Wilma (2005); and Ike (2008). Comparisons between both approaches have been made. Additionally, user recommendations and a sensitivity analysis about the optimization and design of the numerical mesh are presented, taking into account an efficient design of the numerical finite element mesh of the model, and the optimal spatial distribution of the nodes and elements along the hurricane track. The present study provides an efficient and easy engineering-mathematical tool to evaluate the hurricane induced waves, identifying its application limits and derived recommendations. Moreover, an accurate numeric methodology is here described, which allows to obtain the historical ocean wave data for all the historic events and tracks for North Atlantic and Pacific hurricanes, registered since mid-50’s (lat-lon tracks, and central pressures provided by NOAA and the National Hurricane Centre), by improving the hurricane wind fields of any reanalysis database. Finally providing improved knowledge for coastal and harbor design considerations / construction purposes.

Storm-wave trends in Mexican waters of the Gulf of Mexico and Caribbean Sea

Thirty-year time series of hindcast wave data were analysed for 10 coastal locations along the eastern Mexican coast to obtain information about storm events occurring in the region, with the goal of examining the possible presence of interannual trends in the number of storm-wave events and their main features (wave height, duration and energy content). The storms were defined according to their significant wave height and duration, and the events were classified as related to either tropical cyclones or Norte events. The occurrence and characteristics of both types of events were analysed independently. There is no statistically significant change in the number of storm-wave events related to Nortes or their characteristics during the study period. However, there is a subtle increase in the number of events related to tropical cyclones in the western Caribbean region and a more evident increase in wave height and energy content of these events.