Spatial Variability of Sediment Transport Processes Over Intratidal and Subtidal Timescales Within a Fringing Coral Reef System

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Abstract

Sediment produced on fringing coral reefs that is transported along the bed or in suspension affects ecological reef communities as well as the morphological development of the reef, lagoon, and adjacent shoreline. This study quantified the physical process contribution and relative importance of sea-swell waves, infragravity waves, and mean currents to the spatial and temporal variability of sediment in suspension. Estimates of bed shear stresses demonstrate that sea-swell waves are the key driver of the suspended sediment concentration (SSC) variability spatially (reef flat, lagoon, and channels) but cannot fully describe the SSC variability alone. The comparatively small but statistically significant contribution to the bed shear stress by infragravity waves and currents, along with the spatial availability of sediment of a suitable size and volume, is also important. Although intratidal variability in SSC occurs in the different reef zones, the majority of the variability occurs over longer slowly varying (subtidal) timescales, which is related to the arrival of large swell waves at a reef location. The predominant flow pathway, which can transport suspended sediment, consists of cross-reef flow across the reef flat that diverges in the lagoon and returns offshore through channels. This pathway is primarily due to subtidal variations in wave-driven flows but can also be driven alongshore by wind stresses when the incident waves are small. Higher frequency (intratidal) current variability also occurs due to both tidal flows and variations in the water depth that influence wave transmission across the reef and wave-driven currents.

Original languageEnglish
Pages (from-to)1013-1034
Number of pages22
JournalJournal of Geophysical Research: Earth Surface
Volume123
Issue number5
DOIs
Publication statusPublished - May 2018

Cite this

@article{e02c0d5deced4467b3d78bd3fac2c20c,
title = "Spatial Variability of Sediment Transport Processes Over Intratidal and Subtidal Timescales Within a Fringing Coral Reef System",
abstract = "Sediment produced on fringing coral reefs that is transported along the bed or in suspension affects ecological reef communities as well as the morphological development of the reef, lagoon, and adjacent shoreline. This study quantified the physical process contribution and relative importance of sea-swell waves, infragravity waves, and mean currents to the spatial and temporal variability of sediment in suspension. Estimates of bed shear stresses demonstrate that sea-swell waves are the key driver of the suspended sediment concentration (SSC) variability spatially (reef flat, lagoon, and channels) but cannot fully describe the SSC variability alone. The comparatively small but statistically significant contribution to the bed shear stress by infragravity waves and currents, along with the spatial availability of sediment of a suitable size and volume, is also important. Although intratidal variability in SSC occurs in the different reef zones, the majority of the variability occurs over longer slowly varying (subtidal) timescales, which is related to the arrival of large swell waves at a reef location. The predominant flow pathway, which can transport suspended sediment, consists of cross-reef flow across the reef flat that diverges in the lagoon and returns offshore through channels. This pathway is primarily due to subtidal variations in wave-driven flows but can also be driven alongshore by wind stresses when the incident waves are small. Higher frequency (intratidal) current variability also occurs due to both tidal flows and variations in the water depth that influence wave transmission across the reef and wave-driven currents.",
keywords = "suspended sediment, sediment transport, large roughness, coral reef, fringing reef, hydrodynamics, GREAT-BARRIER-REEF, 2-DIMENSIONAL HORIZONTAL REEF, WAVE-GENERATED FLOW, SUSPENDED-SEDIMENT, SET-UP, LOAD TRANSPORT, DRIVEN FLOW, SAND APRON, ST-CROIX, CURRENTS",
author = "Pomeroy, {Andrew W. M.} and Lowe, {Ryan J.} and Marco Ghisalberti and Gundula Winter and Curt Storlazzi and Michael Cuttler",
year = "2018",
month = "5",
doi = "10.1002/2017JF004468",
language = "English",
volume = "123",
pages = "1013--1034",
journal = "Journal of Geophysical Research: Earth Surface",
issn = "2169-9003",
publisher = "American Geophysical Union",
number = "5",

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TY - JOUR

T1 - Spatial Variability of Sediment Transport Processes Over Intratidal and Subtidal Timescales Within a Fringing Coral Reef System

AU - Pomeroy, Andrew W. M.

AU - Lowe, Ryan J.

AU - Ghisalberti, Marco

AU - Winter, Gundula

AU - Storlazzi, Curt

AU - Cuttler, Michael

PY - 2018/5

Y1 - 2018/5

N2 - Sediment produced on fringing coral reefs that is transported along the bed or in suspension affects ecological reef communities as well as the morphological development of the reef, lagoon, and adjacent shoreline. This study quantified the physical process contribution and relative importance of sea-swell waves, infragravity waves, and mean currents to the spatial and temporal variability of sediment in suspension. Estimates of bed shear stresses demonstrate that sea-swell waves are the key driver of the suspended sediment concentration (SSC) variability spatially (reef flat, lagoon, and channels) but cannot fully describe the SSC variability alone. The comparatively small but statistically significant contribution to the bed shear stress by infragravity waves and currents, along with the spatial availability of sediment of a suitable size and volume, is also important. Although intratidal variability in SSC occurs in the different reef zones, the majority of the variability occurs over longer slowly varying (subtidal) timescales, which is related to the arrival of large swell waves at a reef location. The predominant flow pathway, which can transport suspended sediment, consists of cross-reef flow across the reef flat that diverges in the lagoon and returns offshore through channels. This pathway is primarily due to subtidal variations in wave-driven flows but can also be driven alongshore by wind stresses when the incident waves are small. Higher frequency (intratidal) current variability also occurs due to both tidal flows and variations in the water depth that influence wave transmission across the reef and wave-driven currents.

AB - Sediment produced on fringing coral reefs that is transported along the bed or in suspension affects ecological reef communities as well as the morphological development of the reef, lagoon, and adjacent shoreline. This study quantified the physical process contribution and relative importance of sea-swell waves, infragravity waves, and mean currents to the spatial and temporal variability of sediment in suspension. Estimates of bed shear stresses demonstrate that sea-swell waves are the key driver of the suspended sediment concentration (SSC) variability spatially (reef flat, lagoon, and channels) but cannot fully describe the SSC variability alone. The comparatively small but statistically significant contribution to the bed shear stress by infragravity waves and currents, along with the spatial availability of sediment of a suitable size and volume, is also important. Although intratidal variability in SSC occurs in the different reef zones, the majority of the variability occurs over longer slowly varying (subtidal) timescales, which is related to the arrival of large swell waves at a reef location. The predominant flow pathway, which can transport suspended sediment, consists of cross-reef flow across the reef flat that diverges in the lagoon and returns offshore through channels. This pathway is primarily due to subtidal variations in wave-driven flows but can also be driven alongshore by wind stresses when the incident waves are small. Higher frequency (intratidal) current variability also occurs due to both tidal flows and variations in the water depth that influence wave transmission across the reef and wave-driven currents.

KW - suspended sediment

KW - sediment transport

KW - large roughness

KW - coral reef

KW - fringing reef

KW - hydrodynamics

KW - GREAT-BARRIER-REEF

KW - 2-DIMENSIONAL HORIZONTAL REEF

KW - WAVE-GENERATED FLOW

KW - SUSPENDED-SEDIMENT

KW - SET-UP

KW - LOAD TRANSPORT

KW - DRIVEN FLOW

KW - SAND APRON

KW - ST-CROIX

KW - CURRENTS

U2 - 10.1002/2017JF004468

DO - 10.1002/2017JF004468

M3 - Article

VL - 123

SP - 1013

EP - 1034

JO - Journal of Geophysical Research: Earth Surface

JF - Journal of Geophysical Research: Earth Surface

SN - 2169-9003

IS - 5

ER -