The research on the effect of coastal facilities for protecting an estuary from channel blockage and a coast from beach erosion by waves demands to understand wave propagation, a nearshore current and sediment transportation. The purpose of this research is to evaluate the effect of jetties to the Chumphon estuary coast in Chumphon province, Thailand, and propose measures for erosion protecting in this coast. The long term prediction by a one-line model indicates the heavy erosion of around 1000 m northward from the jetties, the erosion around 250 m and 650 m southward from the jetties. As for the erosion of around 250 m southward, measures were examined in the last inter-national conference of ISOPE. As for the erosion of around 650 m southward, since there is no property which should be protected, it is ignored here. Therefore, about the heavy erosion of around 1000 m northward, measures are examined. In this study, since almost of all sand must be transported to jetties, sand nourishment is not a good measure. Detached breakwaters, artificial reefs, and non-measures are examined with the costs on the construction or the compensation, and the prevention effect of wave overtopping, short term erosion, and deterioration of a view. It makes clear that the most effective measure is non-measures (in other words, it is "set back").
At present, the coast of Thailand suffers from severe coastal erosion, resulting in loss of property of the people and the government spoil the scenery which affect to the tourism business and also causes damage to coastal resources.
Coastal erosion in many areas is likely to be more frequent and intensify. Therefore, it is necessary to have plan for prevent and resolve the problem properly. Chumphon estuary is a fishing port and a major economic center of the province. There are many fishing boats of thefishery communities and this is one of the most important fishing area of the country and also a good place for the commercial of sea food products in Chumphon province, there are beautiful sandy beaches where are suitable for tourism and relaxation. There are also boat trips to islandsand ocean to see the beauty of nature on land and under the sea.