Hydrodynamics Sabang Bay and Its Influence on Near Shore Sediment Transport, Weh Island, Indonesia

Sabang Bay is one of the significant areas in Weh Island that becomes a center of marine tourism. Recently, massive urban development in coastal areas impacts on the increase of marine pollution and sedimentation issues within the bay. This study aimed to determine tidal current patterns and their influence on evoking sedimentation within the bay. An Acoustic Doppler Current Profiler (ADCP) was installed within the bay for 30 days, which recorded surface elevation, waves, and sea currents. The numerical hydrodynamic model was developed to figure tidal current features out, validated using field observation data. Sediment transport along the coast was determined by comparing the sediment transport and wave energy component in the form of flux equation. Tidal current speed ranging from 0-0.2 m/s moves predominantly southeastward and northwestward during flood and ebb tides, respectively. Significant wave height (Hs) ranges from 0.18-1 m with a period span of 3.5 seconds propagates toward within the bay, resulting in enhanced sedimentation within the gulf caused by the wave-induced scour and turbulence. Sediment budget transported within the bay reaches 1,586.18 m3/year proving that the sediment movement remarkably occurs within the bay wherein the concentration of suspended sediment ranges from 5-35 mg/L and 2-25 mg/L during the high tidal and low tidal conditions, respectively. Scour and turbulence events induced by internal solitary waves generated from the Andaman Sea result in increased coarse-sized sediment deposition when the flood tide occurs. While, during ebb tide, the widespread distribution of suspended sediment will occur over the bay.