A STUDY ON THE NEARSHORE CURRENT USING NONLINEAR PARABOLIC MILD SLOPE AND QUASI-3D EQUATION

Abstract

The nearshore regions are very important places where are closely related with human civilization. In particular, Korea, the peninsula country, is close to the ocean so the nearshore regions have been used as distribution facilities such as harbors connecting rand and ocean transportation. Recently, due to the increase in the peoples' leisure time, the importance of nearshore regions adjacent to recreation areas and tourist attractions has been increasing. Thus, preservations and maintenances of nearshore regions have been issued. In nearshore regions, the causes of sediment transport and shoreline erosion are waves, nearshore currents, the tide, wind, and the outflow of rivers. The most important cause among these has known as nearshore current. When the water circulation system is changed by constructing artificial construction at the nearshore region, the balance in the sediment system will then be broken. Consequently, the shoreline and cross-profile may be damaged seriously. In fact, many problems such as erosion and accumulation by sediment transport occurred. Therefore, studies on the nearshore current are necessary to effectively use the nearshore area. In this study, by using nonlinear parabolic mild slope and Quasi-3d equations, the circulation phenomena are simulated. When the numerical analysis is carried out, the numerical result of the wave model is calculated by the circulation model after input wave data are computed by the wave model. Through the above simultaneous process, the water circulation phenomena are analyzed, for the nearshore current is generated by wave-current interaction. The numerical models used in this study are compared with observational result and numerical result of previous literature so proprieties of the numerical models are verified. The verification models are circulation phenomenon of the nearshore current in the coast established detached breakwater and inclined coast, and good agreements are obtained. Circulation tendencies of the nearshore current using the numerical model in this study are computed. Study areas are Gangjeong Waters, Jeju and Haeundae Waters, Busan, respectively. The numerical analysises at Gangjeong, Jeju are performed to examine variations of the nearshore current caused by constructing artificial constructions, and those at Haeundae, Busan are performed to see effects of the wind stresses. As a result, the understanding of the water circulation system within nearshore area is improved, and it is therefore considered that it can be applied to developing and utilizing the nearshore regions effectively.