Raúl Medina

EQUILIBRIUM BEACH PROFILE FOR REFRACTION-DIFFRACTION AREAS

A formulation to determine the equilibrium beach profile for refraction- diffraction areas is proposed. An analytical expression for the wave energy flux for refraction-diffraction areas is derived from the mild slope equation. Assuming uniform wave energy dissipation per unit water volume, it is established that the total shape parameter for the equilibrium beach profile for refraction-diffraction areas is composed of a sediment grain size shape parameter (Deans parameter) and a refraction- diffraction shape parameter (ref-dif shape parameter). An expression to calculate this latter parameter is determined analytically and empirically based on field data. The proposed formulation is used for beaches where the sediment grain size is uniform alongshore and for beaches where the sediment grain size is not uniform alongshore, being observed two different behaviours.

A METHODOLOGY TO STUDY BEACH MORPHODYNAMICS BASED ON SELF-ORGANIZING MAPS AND DIGITAL IMAGES

The use of digital images (DI) to study the beach morphology has become an important tool in recent years, as it is easier to obtain high resolution information for large areas and over longer periods of time. Measuring a large set of DI however is not a simple task. A methodology to classify beach DI based on Self-Organizing Maps has therefore been developed, which required several experiments to find the most adequate variables and metrics for the training process. The methodology has three parts, a preparation of DI, the SOM training and the reconstruction of evolution series. The preparation deals with the effect of tides and variations of light due to the meteorological conditions and time of day. The training of SOM is done using correlation such as metric and the processed DI. The methodology is applied to classify DI from Barceloneta Beach using the coastline position.

LONG TERM BEACH EROSION: MORPHODYNAMIC CASE STUDY IN MONT-ROIG BEACH, SPAIN

Long term coastal erosion in beaches induced by long-shore sediment transport is an important aspect to be taken account in beach behavior. If anthropogenic impacts in coastal stretch (harbor, detached breakwaters, lack of sediments from streams and gullies, and urban pressure) interrupting long-shore currents and transport and decreasing sediment supply, the coastal equilibrium disappears. In this paper a case study is shown in order to analyze long term beach behavior in a coastal stretch affected by erosion. After a brief description of morphological aspects, causes and effects that have incidence on the case study area will be shown. General background and coastal works are detailed. The ideas based on a classical analysis of beach behavior are exposed and results obtained from bathymetric analysis and numerical models are showed. Morphology, wave climate, morphodynamics and sediment budget are evaluated and morphodynamic beach behavior is proposed. A diagnosis is made and mitigation proposal for coastal erosion will be proposed.

Utilisation de l'imagerie vidéo pour la gestion touristique du littoral: Exemple de la plage du « Puntal » (Santander, Espagne)

ABSTRACT The use of video imaging and images processing techniques is increasingly used worldwide to deal with a variety of coastal engineering aspects. The European project COASTVIEW (EVK3-CT-2001-0054) has emphasised various coastal engineering fields for which video systems could be used in support to more traditional procedures of data acquisition and viewed as practical tools for an integrated management. The study presented here specifically deals with the use of video for assessment of the recreational use of beaches and is centred, through the example of the « Puntal » beach at Santander (Spain), on the analysis of the spatial and temporal distribution of the users on the beach.

Morphodynamic Evolution Analysis of Beaches Adjacent to L' Hospitalet Marina after Nourishment Project

Waves and wave induced currents are the main forcings acting on beaches. As a consequence of the interaction of these forcings with coastal geometry and available sediment, long-shore transport and morphological changes appear. These changes generate a constant reshaping of the profile and plan form of beaches that define the beach equilibrium and/or the beach evolution. If human activities introduce a modification in the available sediment or in the coastal geometry the existing coastal equilibrium disappears and the beach evolve to a new state. In this paper a case study is shown where a marina is built in the middle of a coastal stretch and some beach nourishment project are carried out. General background and beach nourishment works are detailed. Results from morphodynamic analysis will be shown and beach behavior will be described.