Physical and numerical modeling of four different shapes of breakwaters to test the suspended sediment trapping capacity in the Mekong Delta

Nguyet Minh Nguyen; Duong Do Van; Duy Tu Le; Quyen Nguyen; Bang Tran; Thanh Cong Nguyen; David Wright; Ahad Hasan Tanim; Phong Nguyen Thanh; Duong Tran Anh

doi:10.1016/j.ecss.2022.108141

Physical and numerical modeling of four different shapes of breakwaters to test the suspended sediment trapping capacity in the Mekong Delta

Nguyet Minh Nguyen, Duong Do Van, Duy Tu Le, Quyen Nguyen, Bang Tran, Thanh Cong Nguyen, David Wright, Ahad Hasan Tanim, Phong Nguyen Thanh, Duong Tran Anh

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

Extreme coastline erosion has become a major issue in Vietnam's Mekong Delta. Many coastal protection measures have been assessed based on their ability to dissipate incoming waves rather than their ability to facilitate environmental exchange and sedimentation processes. The goal of this study is to evaluate the ability of hollow and porous types of breakwaters to exchange suspended sediment on the deltaic coast. The experiments are set considering the hydrodynamic conditions of the Mekong Delta. We thought of four different types of breakwaters, including pile-rock porous breakwaters (CMD), two-sided perforated hollow breakwaters (TC1 & DRT/VTC), and curtain breakwaters (CWB45). Physical modeling in a wave flume was engaged to investigate the relationship between breakwater shape and sediment-capturing ability. All different breakwaters were placed on the wave flume with identical boundary conditions. Besides the physical modeling in the laboratory, Computational Fluid Dynamics (CFD) techniques using the FLOW3D model were applied. This provided an opportunity to understand the current distribution and the interactions between the fluid and the breakwater, as well as the ability to extract the vertical velocity profile and further additional insights from the interactions of waves and currents with the breakwaters. The wave parameters collected in the lab were further used to evaluate the numerical simulations in FLOW3D, and model validation demonstrated a good agreement with R² = 0.74–0.98 and NSE = 0.74–0.96 for FLOW3D calibration and validation. It was found that fine sand and mud silt deposition on the shoreline of the breakwater alignment were significantly reduced in the case of the perforated hollow breakwaters. Therefore, using these hollow breakwaters for wave energy dissipation and sediment trapping presents a dual purpose in creating an environmentally friendly solution to recover mudflats. Hollow breakwaters also provide numerous advantages for supporting the creation of favorable conditions for the revival of mangrove forests, development of regional biodiversity, and overall improvement of coastal ecosystems on the deltaic coast.

Original language	English
Article number	108141
Journal	Estuarine, Coastal and Shelf Science
Volume	279
DOIs	https://doi.org/10.1016/j.ecss.2022.108141
State	Published - Dec 5 2022
Externally published	Yes

Funding

This work was partially supported by the Ministry of Science and Technology (MOST) Vietnam in a national project (No. ĐTĐL.CN-47/18 ), “Physical model experiment for investigating coastal protection measures of Mekong Delta.” Many thanks to the Southern Institute of Water Resources Research for providing all data, model licenses, and necessary information. The authors greatly appreciate the Editor and sincerely thank the three anonymous reviewers for their constructive comments to improve the manuscript. Many coastal protection measures, including sea dikes, revetments, and offshore breakwaters, as well as soft engineering solutions, have been proposed in response to coastal erosion to stabilize the deltaic coastline (Le Xuan et al., 2020, 2022a; Luom et al., 2021; Albers and Schmitt, 2015; Holger and Peter, 2016; Winterwerp et al., 2020). However, all these measures provide temporary erosion protection for the coastline without supporting sediment flow that provides living shorelines of the LMD region. Some authors argue that the imbalances of fine sediment (i.e., mud and sand) and hydrodynamics at various spatial and temporal scales are the leading causes of severe erosion in the LMD (Tuan, 2021).This work was partially supported by the Ministry of Science and Technology (MOST) Vietnam in a national project (No. ĐTĐL.CN-47/18), “Physical model experiment for investigating coastal protection measures of Mekong Delta.” Many thanks to the Southern Institute of Water Resources Research for providing all data, model licenses, and necessary information. The authors greatly appreciate the Editor and sincerely thank the three anonymous reviewers for their constructive comments to improve the manuscript.

Keywords

Mekong Delta
Physical experiments
Porous/hollow breakwaters
Suspended sediment exchange

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.ecss.2022.108141

Cite this

Nguyen, N. M., Van, D. D., Le, D. T., Nguyen, Q., Tran, B., Nguyen, T. C., Wright, D., Tanim, A. H., Thanh, P. N., & Anh, D. T. (2022). Physical and numerical modeling of four different shapes of breakwaters to test the suspended sediment trapping capacity in the Mekong Delta. Estuarine, Coastal and Shelf Science, 279, Article 108141. https://doi.org/10.1016/j.ecss.2022.108141

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title = "Physical and numerical modeling of four different shapes of breakwaters to test the suspended sediment trapping capacity in the Mekong Delta",

abstract = "Extreme coastline erosion has become a major issue in Vietnam's Mekong Delta. Many coastal protection measures have been assessed based on their ability to dissipate incoming waves rather than their ability to facilitate environmental exchange and sedimentation processes. The goal of this study is to evaluate the ability of hollow and porous types of breakwaters to exchange suspended sediment on the deltaic coast. The experiments are set considering the hydrodynamic conditions of the Mekong Delta. We thought of four different types of breakwaters, including pile-rock porous breakwaters (CMD), two-sided perforated hollow breakwaters (TC1 & DRT/VTC), and curtain breakwaters (CWB45). Physical modeling in a wave flume was engaged to investigate the relationship between breakwater shape and sediment-capturing ability. All different breakwaters were placed on the wave flume with identical boundary conditions. Besides the physical modeling in the laboratory, Computational Fluid Dynamics (CFD) techniques using the FLOW3D model were applied. This provided an opportunity to understand the current distribution and the interactions between the fluid and the breakwater, as well as the ability to extract the vertical velocity profile and further additional insights from the interactions of waves and currents with the breakwaters. The wave parameters collected in the lab were further used to evaluate the numerical simulations in FLOW3D, and model validation demonstrated a good agreement with R2 = 0.74–0.98 and NSE = 0.74–0.96 for FLOW3D calibration and validation. It was found that fine sand and mud silt deposition on the shoreline of the breakwater alignment were significantly reduced in the case of the perforated hollow breakwaters. Therefore, using these hollow breakwaters for wave energy dissipation and sediment trapping presents a dual purpose in creating an environmentally friendly solution to recover mudflats. Hollow breakwaters also provide numerous advantages for supporting the creation of favorable conditions for the revival of mangrove forests, development of regional biodiversity, and overall improvement of coastal ecosystems on the deltaic coast.",

keywords = "Mekong Delta, Physical experiments, Porous/hollow breakwaters, Suspended sediment exchange",

author = "Nguyen, {Nguyet Minh} and Van, {Duong Do} and Le, {Duy Tu} and Quyen Nguyen and Bang Tran and Nguyen, {Thanh Cong} and David Wright and Tanim, {Ahad Hasan} and Thanh, {Phong Nguyen} and Anh, {Duong Tran}",

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AU - Nguyen, Nguyet Minh

AU - Van, Duong Do

AU - Le, Duy Tu

AU - Nguyen, Quyen

AU - Tran, Bang

AU - Nguyen, Thanh Cong

AU - Wright, David

AU - Tanim, Ahad Hasan

AU - Thanh, Phong Nguyen

AU - Anh, Duong Tran

PY - 2022/12/5

Y1 - 2022/12/5

N2 - Extreme coastline erosion has become a major issue in Vietnam's Mekong Delta. Many coastal protection measures have been assessed based on their ability to dissipate incoming waves rather than their ability to facilitate environmental exchange and sedimentation processes. The goal of this study is to evaluate the ability of hollow and porous types of breakwaters to exchange suspended sediment on the deltaic coast. The experiments are set considering the hydrodynamic conditions of the Mekong Delta. We thought of four different types of breakwaters, including pile-rock porous breakwaters (CMD), two-sided perforated hollow breakwaters (TC1 & DRT/VTC), and curtain breakwaters (CWB45). Physical modeling in a wave flume was engaged to investigate the relationship between breakwater shape and sediment-capturing ability. All different breakwaters were placed on the wave flume with identical boundary conditions. Besides the physical modeling in the laboratory, Computational Fluid Dynamics (CFD) techniques using the FLOW3D model were applied. This provided an opportunity to understand the current distribution and the interactions between the fluid and the breakwater, as well as the ability to extract the vertical velocity profile and further additional insights from the interactions of waves and currents with the breakwaters. The wave parameters collected in the lab were further used to evaluate the numerical simulations in FLOW3D, and model validation demonstrated a good agreement with R2 = 0.74–0.98 and NSE = 0.74–0.96 for FLOW3D calibration and validation. It was found that fine sand and mud silt deposition on the shoreline of the breakwater alignment were significantly reduced in the case of the perforated hollow breakwaters. Therefore, using these hollow breakwaters for wave energy dissipation and sediment trapping presents a dual purpose in creating an environmentally friendly solution to recover mudflats. Hollow breakwaters also provide numerous advantages for supporting the creation of favorable conditions for the revival of mangrove forests, development of regional biodiversity, and overall improvement of coastal ecosystems on the deltaic coast.

AB - Extreme coastline erosion has become a major issue in Vietnam's Mekong Delta. Many coastal protection measures have been assessed based on their ability to dissipate incoming waves rather than their ability to facilitate environmental exchange and sedimentation processes. The goal of this study is to evaluate the ability of hollow and porous types of breakwaters to exchange suspended sediment on the deltaic coast. The experiments are set considering the hydrodynamic conditions of the Mekong Delta. We thought of four different types of breakwaters, including pile-rock porous breakwaters (CMD), two-sided perforated hollow breakwaters (TC1 & DRT/VTC), and curtain breakwaters (CWB45). Physical modeling in a wave flume was engaged to investigate the relationship between breakwater shape and sediment-capturing ability. All different breakwaters were placed on the wave flume with identical boundary conditions. Besides the physical modeling in the laboratory, Computational Fluid Dynamics (CFD) techniques using the FLOW3D model were applied. This provided an opportunity to understand the current distribution and the interactions between the fluid and the breakwater, as well as the ability to extract the vertical velocity profile and further additional insights from the interactions of waves and currents with the breakwaters. The wave parameters collected in the lab were further used to evaluate the numerical simulations in FLOW3D, and model validation demonstrated a good agreement with R2 = 0.74–0.98 and NSE = 0.74–0.96 for FLOW3D calibration and validation. It was found that fine sand and mud silt deposition on the shoreline of the breakwater alignment were significantly reduced in the case of the perforated hollow breakwaters. Therefore, using these hollow breakwaters for wave energy dissipation and sediment trapping presents a dual purpose in creating an environmentally friendly solution to recover mudflats. Hollow breakwaters also provide numerous advantages for supporting the creation of favorable conditions for the revival of mangrove forests, development of regional biodiversity, and overall improvement of coastal ecosystems on the deltaic coast.

KW - Mekong Delta

KW - Physical experiments

KW - Porous/hollow breakwaters

KW - Suspended sediment exchange

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M3 - Article

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SN - 0272-7714

VL - 279

JO - Estuarine, Coastal and Shelf Science

JF - Estuarine, Coastal and Shelf Science

M1 - 108141

ER -

Physical and numerical modeling of four different shapes of breakwaters to test the suspended sediment trapping capacity in the Mekong Delta

Abstract

Funding

Keywords

UN SDGs

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