The Effect of Waves of Buton Strait Towards the Coastal Abration in Raha City, Southeast Sulawesi

The shoreline change is a continuous process through various processes of both abrasion and accretion caused by sediment movement, longshore current, wave action and land use. This study aimed to determine(1) the characteristics of the waves on the coast of Raha and (2) an effective coastal protection system to protect the beach against abration. The study of wave characteristics was obtained from the secondary data. The calculation of the extreme wave height during certain repetition could be known using the distribution method of Gumbel and forthe fluctuation effect of sea water surface was analyzed using the admirally method. For the coast observation a study was carried out empirically and mathematical model simulation using the Software Surface – Water Model System (SMS) Version 8.1. The research results indicated that the characteristics of the maximum waves came from the southeast with coming angle ofthe waves of 72o with the height and significant period of the waves was 2.19 meters and 8.03 meters second respectively, while the length of the waves was 100.6 meters. Thus, the alternative coastal building was based on the assessment criteria comprising groin, revetment and detached breakwater. Therefore, the result of the research revealed that the effective coastal building is the groin