THE EFFECT OF ARTIFICIAL SEAWEED IN PROMOTING THE BUILD-UP OF BEACHES

Abstract

The paper describes tests carried out m the laboratory and in the field in an attempt to discover whether a field of artificial seaweed placed offshore can promote an onshore transport of bed material and hence a build-up of beach levels. Tests in a wave tank showed that beach levels could be built up in this way - the effect of the seaweed being to increase the net drift of bed water m the direction of wave propagation i.e. towards the shore. The field trials were not as conclusive as was hoped, but nevertheless some build-up of beach levels did take place at a time when erosion of the beach due to many storms might have been anticipated. A simple hydrodynamic model is proposed to represent the effect of artificial seaweed on gravity waves. The model predicts increased wave attenuation and increased shoreward mass-transport consistent with the experimental results.