Hadewych Verhaeghe

The international database on wave overtopping

One of the main objectives within the EU-project CLASH (www.clash-eu.org) was to create a generic prediction method for wave overtopping at coastal structures by means of the Neural Network technique. An extensive and homogeneous database on wave overtopping was set up within CLASH, mainly with the aim to be used for the training process of the Neural Network (NN). A total number of 10,532 tests from 163 independent test series were screened and included in the database. The final database consists of far more information than needed for the training of the NN: 31 parameters are included to describe each overtopping test of which only 17 are used for the NN development. This explains the possible use of the overtopping database on its own. Plotting various parameters of the database together in graphs gives a clear view on the contents of the database. Also the ranges covered by the parameters can be detected in this way. The creation of the database, the analysis of the database, and the possible use of the database on its own are described in this paper.

Wave energy on the Belgian Continental Shelf

The inexhaustible wave energy resource is at the basis of the increasing research on wave energy exploitation. Till now the resource is studied in detail for regions with a high wave energy density. As the problems to guarantee the survivability of wave energy converters (WECs) in a severe and energetic wave climate are not solved yet, the possibilities of wave power conversion in a less aggressive wave climate should be investigated. This paper describes the wave climate and correspondent wave power resource in a rather sheltered area i.e., the Belgian Continental Shelf (southern part of the North Sea). The available wave power is studied on six buoy locations. Furthermore characteristic sea states and design conditions are derived for the most suitable locations for wave energy production. The available wave power is compared with other sites in the North Sea. Near shore (< 30 km off the coast) less than 10 kW/m is available.

Wave Overtopping Database as the Starting Point for a Neural Network Prediction Method

The European Union (EU) CLASH project stands for “Crash Level Assessment of coastal Structures by full scale monitoring, neural network prediction and Hazard analysis on permissible wave overtopping. One of the objectives of CLASH is to produce a generally applicable prediction method for wave overtopping at coastal structures based on permissible wave overtopping and hazard analysis. The set up of a homogeneous database on wave overtopping is one of the main tasks within the framework of CLASH and it is the main subject of this paper. On the one had, the database gives a detailed inventory of overtopping tests which have been performed and on the other hand, the database serves as the starting point for a neural network prediction method. At this moment, the overtopping database consists of more than 6500 overtopping tests. This paper gives a complete overview of the contents of the database and discusses the methodology.

Prototype wave measurements on the beach of Ostend

The city of Ostend (Oostende) is situated centrally along the Belgian North Sea coast. The low-lying city centre is located very close to the shore. The shoreline consists of a sandy beach and a smooth impermeable sea dike. In 2002-2003 it was concluded that the risk of flooding of Ostend was critically high. As provisional solution, the beach was nourished in April 2004. The wave propagation on the beach is monitored with 3 different wave measurement devices placed into the sea / on the beach. This paper presents the results of the prototype measurements performed on the beach of Ostend. Further the prototype wave characteristics are compared with results of scale model tests performed at the Department of Civil Engineering of the University of Ghent.