Variation of Seasonal Monsoon Wave-Driven Circulation Pattern in the Lee of Groyne in Kuala Nerus beach

Abstract

Terengganu coast tend to dual monsoonal as presenting Northeast Monsoon (NEM) as a storm season and Southwest Monsoon (SWM) as a calm season. The area of interest is a groyne in Kuala Nerus, Terengganu on east part of Peninsular Malaysia. The use of numerical model was performed on the dual monsoon seasons with MIKE 21 modules (Spectral Wave FM and Flow Model Hydrodynamic FM modules). Two numerical model were set up according to the two season. The resulting model indicates, the current circulation pattern consisted of persistent eddy re-circulation in the lee of the groyne during both season. As the longshore current directed into the groyne, it deflected offshore resulting in rip current along the groyne. The rip current and incoming wave converge at the tip of the groyne and flow parallel to coastline before being projected onshore performing a re-circulation cell. During NEM, the model shows a clockwise re-circulation cell and counter-clockwise formation during SWM. The formation of the rip current and eddy circulation is associated with erosion event as the sediment transported offshore causing sediment shortage on the adjacent shore. The importance of this study can be a reference to any development of coastal defense monsoon dominated environment.