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

Abstract

Sabang Bay is one of areas of significance 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 hydrodynamic characteristics and its influence on evoking sedimentation within the bay. Acoustic Doppler Current Profiler (ADCP) was installed within the bay for 30 days, which recorded surface elevation, waves, and sea currents. Sediment transport along the coast was determined by comparing the sediment transport and waves 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 the period span of 3.5 seconds propagates toward within the bay, resulting in enhanced sedimentation within the bay caused by the wave-induced scour and turbulence. Sediment budget transported within the bay reaches 1586.18 m3/year. This proves that the sediment movement extremely 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 are strongly induced by internal solitary waves generated from the Andaman Sea that results in increased coarse-sized sediment deposition when the flood tide takes place. While, during ebb tide, the widespread distribution of suspended sediment will occur over the bay.