A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering of the Asian Institute of Technology, Bangkok, Thailand

Thesis (M.Eng.) - Asian Institute of Technology, 1979

When breakwaters are constructed offshore in sedimentary coastal area, shoreline will undergo a modification in shape, giving rise to protuberance in front of the breakwaters. Ultimately a shape is reached which is in equilibrium. This occurs when incoming waves break simultaneously around t he periphery, diminishing the longshore drift. The eventual development of such an equilibrium shaped shoreline under oblique wave attack was studied by means of a model in which wave length, periods and breakwater length were the sole variables. Thus the water depth, beach slope, wave direction, sedimentary material, gap between breakwaters and distance from shoreline to breakwater were maintained same throughout. The beach was first brought into equilibrium by running without breakwaters. Subsequently breakwaters were placed and chronological development of shoreline up· to equilibrium was measured. In addition current magnitudes and bottom topography were recorded. This whole procedure was repeated for different wave characteristics and different breakwater lengths. It was found that deposition increases with increasing wave energy. Further it was observed that shoreline indentation is heavily influenced by varying lengths of breakwaters.