Abstract:
The coastline of Lower Gulf of Thailand has experienced with the severe problems of shoreline recession for more than 80 years. As an open sea connected to the South China Sea, the Lower Gulf of Thailand is rather rough by waves travelling directly from the south China sea. The study aims at evaluating coastal erosion along coastline of the Lower Gulf of Thailand in Narathiwat from the mouth of Golok River to Tanyong Mountain whose distance of about 35 km. The detached breakwater is assumed to be a headland which makes the shoreline stable and can trap a fraction of sediment. The thesis also summarized the past researches on equilibrium bay, headland structures, and coastline protection works. The design procedure for detached breakwater which was employed in this study, bases largely on those researches. With a breakwater of 50 m. long located at 50 m. from the shoreline and 200 m. apart each other, the coastal erosion was expected as much as 45 m. from the headland. For the coastline at river mouth each breakwaters was located at 50 m. apart to protect the shore from the force of current in Golok River. The erosion was found as much as 25 m. The tombolo was found along the shore, immediately adjacent to the toe of breakwaters.