Daniel González-Marco

Best practice for the estimation of extremes: A review

Task 2: Estimation of Extremes of the European Union research project FLOODsite was dedicated to analysing single and joint probability extremes in river, coastal and estuarine environments. It considers the sources of risk, such as river flow and level, wave height, period and direction, and sea level. Herein the work done within Task 2 is reviewed. Several statistical models and various fitting techniques are described. Planning an appropriate extremes analysis involves an understanding of the problem to be addressed, selection and preparation of source data, selection of methods for analysis and parameter fitting, and use of the derived extremes to address the problem. The applications described illustrate some of the pitfalls and difficulties associated with extreme predictions, particularly for the case of more than one variable. Understanding the assumptions and interpreting the obtained results are important for extreme analysis.

Extreme values for coastal, estuarine, and riverine environments

The increasing pressures associated to the development of coastal zones and near river courses have enhanced the sensitivity of these areas to natural processes such as flooding or erosion. The characterization of the associated drivers and responses, particularly under extreme conditions, has become an acute need for managing those areas and the risks for uses and resources there located. This paper summarizes the work done within Task 2 of the EU Integrated Research Project FLOODsite in the extreme distribution functions related to flood and erosion hazards. A wide range of models, parameters and fitting techniques were applied to a variety of geographic and climatic environments. The emphasis focused on selecting models and techniques based on a parsimony principle, to propose robust extrapolations of characteristic variables for a reliable flood hazard assessment.

Implications of nearshore processes on the significant wave height probability distribution

This paper analyzes the effect of hydrodynamic processes associated with the beach morphology on the long-term distribution of waves. This is made using the three parameter Weibull Probability Distribution Function for the significant wave height. The analysis shows the evolution of the Weibull position (A), scale (B) and shape (C) parameters at the three main scales of interest for engineering and coastal management applications. These are the plan (offshore) scale, the profile (surf) scale, and the swash (beach face) scale. Implications regarding processes, morphology, and numerical modeling were also analyzed and discussed. This paper illustrates how the probability distribution function of waves in the near shore zone is controlled by hydro-morphodynamic processes. The results lead to different probabilities and therefore risks for erosion or flooding, which have significant implications for coastal management decisions.

COASTAL DYNAMICS AROUND A SUBMERGED BARRIER

Submerged barriers are one of the most promising kind of shoreline protecting structures. The advantages offered vs. the conventional emerged structures are somehow off set because they are much more difficult to project. This decreases their use and limits their application potential. The paper presents some results, obtained by using numerical models on the hydro-morphodynamic behaviour of such structural concept. They illustrate the observed interactions between the freeboard of the structure, its distance to the coast and the resulting wave field, induced circulation and sediment transport patterns.

Short communication: Numerical model for wave overtopping and transmission through permeable coastal structures

In this paper, an energetic wave propagation model that reproduces shoaling, refraction, diffraction, wave-current interaction, bottom friction and wave breaking is modified to simulate also the processes of overtopping and wave transmission over and through permeable coastal structures. This enhances the capabilities of the model and allows to obtain, at a low computational cost, a better reproduction of the wave field (and as a consequence currents and beach response) behind a coastal structure, especially if it is permeable and/or low crested. Model results are compared with laboratory data, showing a good agreement and the suitability of the followed approach.

Numerical simulations and observations for offshore wind farms in a NW Mediterranean shelf

ABSTRACT Sánchez-Arcilla, A., González-Marco, D., Sospedra, J., Palomares, A., Sierra, J.P., Schuon, F., Espino. M., Grifoll, M., Pallarés, E., Jiménez, P.A. and Navarro, J. 2013. Meteo-oceanographic simulations and observations to assess the potential of offshore wind farm in a NW Mediterranean shelf. Renewable marine energy is important in squeezed Mediterranean coastal zones. Wind turbines deployed over the narrow Catalan continental shelf require accurate wind/wave/current fields for a reliable design, operation and maintenance. This paper presents the large (comparative to other open sea areas) errors in meteo-oceanographic predictions for semi enclosed domains such as the coastal sea off the Ebro Delta coast. The emphasis is on the sequence of high resolution coupled and nested models and the role of in situ collocated measurements for calibration and validation.