Ocean-shelf exchange through the Berau barrier reef, Indonesia
The present study aims to investigate the ocean-shelf exchange through a barrier reef at the shelf edge of the Berau Continental Shelf, Indonesia. Moored and shipboard measurements on currents and turbulence were taken as part of the multidisciplinary East Kalimantan Research Program. These measurements, and collected data on sea levels, meteorology and bathymetry, were used to setup and calibrate a threedimensional hydrodynamic model in the ECOMSED environment, which is derived from the Princeton Ocean Model. The data and model results were first used to study the tidal propagation and mean circulation patterns on the entire Berau Shelf. The diurnal and semidiurnal tides propagate across the isobaths towards the coast, where amplitudes increase. Tide-induced mean currents dominate over monsoon-driven currents, and feature a southward transport pattern close to the coast and a northward transport patterns at 10 to 20 meters depth. Next, the river plume behaviour is studied. Key factors controlling the river plume behavior include advection of stratified waters by the subtidal motion and mixing, which inhibits the stratified region to extend beyond the reef region. The tides drive freshwater in northeastern direction, towards the reef area. The model is subsequently refined and used to study the exchange of water via the reef gaps and over the reef flats in detail. Moored ADCP data reveal extremely large roughness heights in the reef passages and reef flats. These limit the exchange of tidal energy to some degree, acting as a control on sea level gradients over the reefs. Shipboard ADCP measurements across the reef passages show that the spatial structure of velocity data exhibits features of a classical plane jet generated by strong tidal flows. There is a persistent asymmetry between the ebb and flood flow structures. The flow in the center of the reef passage is often opposed to the flow near the reef boundaries. Both data and model results averaged over a tidal period suggest a net flow from ocean to shelf at the shallow reef flats and from shelf to ocean through a deep reef gap
| Main Authors: | , , |
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| Format: | Article in monograph or in proceedings biblioteca |
| Language: | English |
| Published: |
PECS
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| Subjects: | Life Science, |
| Online Access: | https://research.wur.nl/en/publications/ocean-shelf-exchange-through-the-berau-barrier-reef-indonesia |
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| Summary: | The present study aims to investigate the ocean-shelf exchange through a barrier reef at the shelf edge of the Berau Continental Shelf, Indonesia. Moored and shipboard measurements on currents and turbulence were taken as part of the multidisciplinary East Kalimantan Research Program. These measurements, and collected data on sea levels, meteorology and bathymetry, were used to setup and calibrate a threedimensional hydrodynamic model in the ECOMSED environment, which is derived from the Princeton Ocean Model. The data and model results were first used to study the tidal propagation and mean circulation patterns on the entire Berau Shelf. The diurnal and semidiurnal tides propagate across the isobaths towards the coast, where amplitudes increase. Tide-induced mean currents dominate over monsoon-driven currents, and feature a southward transport pattern close to the coast and a northward transport patterns at 10 to 20 meters depth. Next, the river plume behaviour is studied. Key factors controlling the river plume behavior include advection of stratified waters by the subtidal motion and mixing, which inhibits the stratified region to extend beyond the reef region. The tides drive freshwater in northeastern direction, towards the reef area. The model is subsequently refined and used to study the exchange of water via the reef gaps and over the reef flats in detail. Moored ADCP data reveal extremely large roughness heights in the reef passages and reef flats. These limit the exchange of tidal energy to some degree, acting as a control on sea level gradients over the reefs. Shipboard ADCP measurements across the reef passages show that the spatial structure of velocity data exhibits features of a classical plane jet generated by strong tidal flows. There is a persistent asymmetry between the ebb and flood flow structures. The flow in the center of the reef passage is often opposed to the flow near the reef boundaries. Both data and model results averaged over a tidal period suggest a net flow from ocean to shelf at the shallow reef flats and from shelf to ocean through a deep reef gap |
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