Indonesia Conference Directory

Rip currents are hydrodynamic events that vary alongshore and important to be well-understood for its uniqueness and safety issues on recreational beaches. In this study, bathymetrically-controlled rips are the main focus as this type is commonly found on Indonesia-s coastal areas, particularly in the south coast of West Java. This unique hydrodynamics feature affects sediment characteristic, particularly at the rip channel as the lower part tends to have coarser sediment due to larger friction. Such complex interactions need thorough investigation, therefore, a study was conducted in Pangandaran which well-known for its rip currents. Field observation was made to collect sediment sample on a cross-shore direction which shows finer sediment on upper rip channel and coarser sediment on the lower part with a diameter size of 0.35 mm and 0.37 mm, respectively. In addition, simple simulations were also made to illustrate rip current movement on a channel. The result shows that in the strongest current area with over than 3.0 m/s current speed, i.e. on the lower part of the rip channel, bed shear stress is found to be the strongest. It is been noticed as well that the bed shear stress forms a pattern which delineates overall movement of a rip current. Furthermore, the variation of bed shear stress is revealed as the main cause of sediment distribution along the cross-shore direction. Therefore, this simple approach qualitatively illustrates the dynamics of a rip current phenomenon.