Extreme Wave Analysis Using Satellite Data

JERICHO is an interdisciplinary research project (within the BNSC LINK programme) which has investigated the application of the wave measurements from satellites, with shallow water wave models, to the strategic planning of coastal defences. JERICHO has been primarily a scientific project, but was directed by the practical strategic requirements of the Environment Agency (EA), who were a full participant in the project. The design of sea defences, such as sea walls, groynes and revetments, to provide protection to the livelihood of people living close to the coast, requires a good knowledge of local wave, tide and beach conditions. Of these factors, it is the local inshore wave conditions that have, perhaps, the most uncertainty. Long term wave recordings are scarce and so offshore conditions are often determined from the output of numerical wave prediction models using predicted wind fields from numerical forecast models. However, good quality in situ wave measurements covering extended periods of more than a month are extremely scarce. Moreover, making such measurements can be an extremely expensive undertaking. The search for alternative sources of wave information has prompted the use of: observations from ships; output of wave prediction models and latterly, satellite-derived measurements. These sources usually provide information about waves in deep water some distance away from the site of interest. In order to make use of such information it is necessary to be able to transform the offshore wave climate to the shore. There are a number of methods available for wave transformation. Here, a wave refraction model is used as the site of interest, Holderness, is on open coast with an evenly shoaling seabed. The same approach has also been used in a study to investigate the use of synthetic wave data from a global operational wave model for flood warning. Establishing the accuracy of using deep-water waves (whether measured or simulated) and a wave transformation model instead of in situ measurements is important from two perspectives. Firstly, if the transformation of deep-water conditions is sufficiently accurate it provides an economic and accessible means of determining inshore wave conditions. Secondly, it provides the scope for including the effects of climate change, such as increased wave heights or storminess, into the design and management of coastal schemes.