Pub Date : 2023-02-22DOI: 10.1080/21664250.2023.2170688
E. Jafarzadeh, A. Bohluly, A. Kabiri-Samani, S. Mansourzadeh
ABSTRACT Submerged circular breakwaters are laid to a point at the bottom, simplifying their installation compared to the rigid rectangular ones. In the present study, numerical simulations were performed to evaluate the circular and rectangular submerged breakwaters transmission coefficient, changing different hydraulic/geometric effective parameters. A sensitivity analysis was performed to evaluate the effectiveness of various parameters on the transmission coefficient for different wave heights, water depths, and bed slopes. Numerical simulations were performed using a two-phase free surface flow model. Interface tracking was also performed using the modified fine grid volume tracking-volume of fluid (FGVT-VOF) method. Experimental measurements were employed to verify the numerical results, suggesting that the numerical model accurately predicts the transmission coefficient; thereby, the numerical results are useful for designing submerged breakwaters. An equation was finally derived to determine the transmission coefficient of the circular submerged breakwaters.
{"title":"A study on the performance of circular and rectangular submerged breakwaters using nun-uniform FGVT method","authors":"E. Jafarzadeh, A. Bohluly, A. Kabiri-Samani, S. Mansourzadeh","doi":"10.1080/21664250.2023.2170688","DOIUrl":"https://doi.org/10.1080/21664250.2023.2170688","url":null,"abstract":"ABSTRACT Submerged circular breakwaters are laid to a point at the bottom, simplifying their installation compared to the rigid rectangular ones. In the present study, numerical simulations were performed to evaluate the circular and rectangular submerged breakwaters transmission coefficient, changing different hydraulic/geometric effective parameters. A sensitivity analysis was performed to evaluate the effectiveness of various parameters on the transmission coefficient for different wave heights, water depths, and bed slopes. Numerical simulations were performed using a two-phase free surface flow model. Interface tracking was also performed using the modified fine grid volume tracking-volume of fluid (FGVT-VOF) method. Experimental measurements were employed to verify the numerical results, suggesting that the numerical model accurately predicts the transmission coefficient; thereby, the numerical results are useful for designing submerged breakwaters. An equation was finally derived to determine the transmission coefficient of the circular submerged breakwaters.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"234 - 255"},"PeriodicalIF":2.4,"publicationDate":"2023-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46979573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-08DOI: 10.1080/21664250.2023.2172992
Yesenia Morgado, O. S. Areu-Rangel, Rodolfo Silva, T. Miyashita, N. Mori, T. Tomiczek
ABSTRACT The increase in the magnitude of natural disasters has led to the development of risk assessment methodologies to indicate risk levels in qualitative terms. Among these, the Source-Pathway-Receptor-Consequence (SPRC) methodology assesses the risk from the source of the hazard to the possible consequences. In the present work, an economic evaluation was carried out on the substantial damages directly associated with the floods generated by a 10 m high tsunami off the coast of Zihuatanejo, Mexico. This event was identified as the worst-case scenario of tsunamis associated with a 8.4 Mw earthquake. The method followed was the SPRC, with an economic evaluation, applied to street level in Zihuatanejo. The economic costs were obtained from the results of this work using a criterion to characterize the percentage of damage to various types of housing and goods associated with different levels of flooding. This work is intended as a basis for the better planning of urban development, considering possible economic damage from tsunamis. It also provides a more objective perspective for distributing funds for mitigating natural disasters, allowing aid to be directed to the areas and types of housing with greatest risk from the flooding.
{"title":"Using the SPRC methodology to assess tsunami risk in Zihuatanejo, Mexico","authors":"Yesenia Morgado, O. S. Areu-Rangel, Rodolfo Silva, T. Miyashita, N. Mori, T. Tomiczek","doi":"10.1080/21664250.2023.2172992","DOIUrl":"https://doi.org/10.1080/21664250.2023.2172992","url":null,"abstract":"ABSTRACT The increase in the magnitude of natural disasters has led to the development of risk assessment methodologies to indicate risk levels in qualitative terms. Among these, the Source-Pathway-Receptor-Consequence (SPRC) methodology assesses the risk from the source of the hazard to the possible consequences. In the present work, an economic evaluation was carried out on the substantial damages directly associated with the floods generated by a 10 m high tsunami off the coast of Zihuatanejo, Mexico. This event was identified as the worst-case scenario of tsunamis associated with a 8.4 Mw earthquake. The method followed was the SPRC, with an economic evaluation, applied to street level in Zihuatanejo. The economic costs were obtained from the results of this work using a criterion to characterize the percentage of damage to various types of housing and goods associated with different levels of flooding. This work is intended as a basis for the better planning of urban development, considering possible economic damage from tsunamis. It also provides a more objective perspective for distributing funds for mitigating natural disasters, allowing aid to be directed to the areas and types of housing with greatest risk from the flooding.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"256 - 276"},"PeriodicalIF":2.4,"publicationDate":"2023-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42809864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-31DOI: 10.1080/21664250.2023.2167502
Ooki Kurihara, Hidenori Takahashi
ABSTRACT Composite-type breakwaters are reinforced by piling rubble stones and constructing counterweight fillings (known as reinforcing embankments) behind caissons. Important performance requirements for breakwaters include minimal damage and high strength, even when the external forces exceed the design forces. In this study, the failure process and final state of breakwaters with reinforcing embankments are investigated via centrifuge model tests, and the cross-sectional configuration of the reinforcing embankment for improving the tenacity of breakwaters is determined. The results show that, in the overturning mode, when the number of rubble stones decreases, the reinforcing embankment deforms in accordance with the inclination of the caisson; subsequently, the caisson overturns and mounts onto the embankment. When balance is not maintained at that position, the caisson slides down the slope surface, resulting in catastrophic failure. A series of centrifuge model tests qualitatively show that placing more rubble stones adjacent to the caisson is less likely to result in such catastrophic failure. Furthermore, the stability of the breakwaters is evaluated via circular slip analyses, which demonstrate the importance of increasing the volume of the reinforcing embankment adjacent to the caisson in terms of the stability.
{"title":"Backfilling configuration to improve tenacity of composite-type breakwaters","authors":"Ooki Kurihara, Hidenori Takahashi","doi":"10.1080/21664250.2023.2167502","DOIUrl":"https://doi.org/10.1080/21664250.2023.2167502","url":null,"abstract":"ABSTRACT Composite-type breakwaters are reinforced by piling rubble stones and constructing counterweight fillings (known as reinforcing embankments) behind caissons. Important performance requirements for breakwaters include minimal damage and high strength, even when the external forces exceed the design forces. In this study, the failure process and final state of breakwaters with reinforcing embankments are investigated via centrifuge model tests, and the cross-sectional configuration of the reinforcing embankment for improving the tenacity of breakwaters is determined. The results show that, in the overturning mode, when the number of rubble stones decreases, the reinforcing embankment deforms in accordance with the inclination of the caisson; subsequently, the caisson overturns and mounts onto the embankment. When balance is not maintained at that position, the caisson slides down the slope surface, resulting in catastrophic failure. A series of centrifuge model tests qualitatively show that placing more rubble stones adjacent to the caisson is less likely to result in such catastrophic failure. Furthermore, the stability of the breakwaters is evaluated via circular slip analyses, which demonstrate the importance of increasing the volume of the reinforcing embankment adjacent to the caisson in terms of the stability.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"217 - 233"},"PeriodicalIF":2.4,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48401198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-08DOI: 10.1080/21664250.2022.2163844
Chenhao Zhang, Mingliang Zhang
ABSTRACT Wave energy can be reduced by coastal vegetation, which is an important aspect of coastal protection engineering. The effect of vegetation characteristics on solitary wave propagation and attenuation is numerically investigated in this study. A 3D numerical model is established based on the Reynolds Averaged Navier Stokes (RANS) equations combined with k-ω shear stress transport (SST) turbulence model, and the Volume of Fluid (VOF) method is used to capture the free water surface. This model is first validated by a series of physical experimental results with high accuracy. Subsequently, the model is used to simulate the interaction between solitary waves and submerged vegetation with different densities, submergence ratios, and distribution modes. The results indicate that the density and submergence ratios of submerged vegetation significantly affect the propagation and attenuation of solitary waves under uniform distribution modes. Compared with the condition of the uniform distribution mode, the solitary wave dissipates more energy after passing through the vegetation zone under the non-uniform distribution modes. Large differences in velocity fields are found for uniform/non-uniform distribution modes, which contribute to understanding the wave dissipation influenced by vegetation characteristics.
{"title":"Numerical investigation of solitary wave attenuation and mitigation caused by vegetation using OpenFOAM","authors":"Chenhao Zhang, Mingliang Zhang","doi":"10.1080/21664250.2022.2163844","DOIUrl":"https://doi.org/10.1080/21664250.2022.2163844","url":null,"abstract":"ABSTRACT Wave energy can be reduced by coastal vegetation, which is an important aspect of coastal protection engineering. The effect of vegetation characteristics on solitary wave propagation and attenuation is numerically investigated in this study. A 3D numerical model is established based on the Reynolds Averaged Navier Stokes (RANS) equations combined with k-ω shear stress transport (SST) turbulence model, and the Volume of Fluid (VOF) method is used to capture the free water surface. This model is first validated by a series of physical experimental results with high accuracy. Subsequently, the model is used to simulate the interaction between solitary waves and submerged vegetation with different densities, submergence ratios, and distribution modes. The results indicate that the density and submergence ratios of submerged vegetation significantly affect the propagation and attenuation of solitary waves under uniform distribution modes. Compared with the condition of the uniform distribution mode, the solitary wave dissipates more energy after passing through the vegetation zone under the non-uniform distribution modes. Large differences in velocity fields are found for uniform/non-uniform distribution modes, which contribute to understanding the wave dissipation influenced by vegetation characteristics.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"198 - 216"},"PeriodicalIF":2.4,"publicationDate":"2023-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42152509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-02DOI: 10.1080/21664250.2023.2178122
H. Takagi, M. Heidarzadeh
With 60% of the world’s population, low-lying deltas, numerous islands, long coastlines, rapid population growth, and economic development, the Asian coast is the most vulnerable area in the world to disasters. No other part of the world has such a large number of subduction plate boundaries and warm ocean basins, resulting in massive tsunamis, tropical cyclones, and storm surges (Figure 1). In reality, the six worst coastal disasters of the 21st century in terms of number of casualties all occurred in Asia: the Indian Ocean Tsunami (2004), Cyclone Sidr (Bangladesh, 2007), Cyclone Nargis (Myanmar, 2008), the Great East Japan Earthquake and Tsunami (Japan, 2011), Typhoon Haiyan (the Philippines, 2013), and the Sulawesi (Palu) Earthquake, Landslide and Tsunami (Indonesia, 2018). These six disasters have claimed more than 400,000 victims. Natural and anthropogenic environmental degradation, such as coastal erosion, land subsidence, and mangrove deforestation, have also been remarkably increasing the risk of disasters in Asia (Hao and Takewaka 2022; Sreeranga et al. 2022). Locallyintensified tsunamis due to a combination of earthquakes, volcanic eruptions, subaerial and submarine landslides (Heidarzadeh and Mulia 2022; Sabeti and Heidarzadeh 2022) and risks associated with the uncertainty of large thrust earthquakes also need to be further studied and clarified (Momeni et al. 2022). Where major disasters occurred in Asia, recovery has immediately begun with international support, but the midand long-term successes of such recovery efforts are not straightforward (Iuchi et al. 2023). In countries with sufficient financial resources, the immediate recovery steps will be to strengthen through, for example, coastal dikes and embankments. However, not many areas in Asia can take into action appropriate hard countermeasures such as construction of coastal dikes due to financial constraints (Takagi et al., 2022). Asia has countless examples of disasters, which, on the other hand, means that there is ample evidence on the ground that can be used to enhance scientific understanding (Valdez et al. 2022; Heidarzadeh and Mulia 2022). Limited funds and resources also mean that there are opportunities for innovation in various disaster mitigation measures (Pringgana, Cunningham, and Rogers 2023). In fact, several Asian countries have successfully implemented mass evacuations of
亚洲海岸拥有世界上60%的人口、低洼的三角洲、众多的岛屿、漫长的海岸线、快速的人口增长和经济发展，是世界上最容易受到灾害影响的地区。世界上没有任何其他地区有如此多的俯冲板块边界和温暖的海洋盆地，导致了大规模的海啸、热带气旋和风暴潮(图1)。实际上，21世纪伤亡人数最多的六大沿海灾害都发生在亚洲:印度洋海啸(2004年)、锡德飓风(孟加拉国，2007年)、纳尔吉斯飓风(缅甸，2008年)、东日本大地震和海啸(日本，2011年)、台风海燕(菲律宾，2013年)和苏拉威西岛(帕卢)地震、山体滑坡和海啸(印度尼西亚，2018年)。这六场灾难造成40多万人死亡。自然和人为的环境退化，如海岸侵蚀、地面沉降和红树林砍伐，也显著增加了亚洲发生灾害的风险(Hao和Takewaka 2022;Sreeranga et al. 2022)。由于地震、火山爆发、地面和海底滑坡的共同作用，局部加剧的海啸(Heidarzadeh和Mulia 2022;Sabeti和Heidarzadeh 2022)以及与大逆冲地震的不确定性相关的风险也需要进一步研究和澄清(Momeni et al. 2022)。在亚洲发生重大灾害的地方，在国际支持下立即开始了恢复工作，但这种恢复工作的中长期成功并不容易(Iuchi et al. 2023)。在财政资源充足的国家，立即采取的恢复措施将是加强沿海堤防和堤防等。然而，由于资金限制，亚洲没有多少地区可以采取适当的硬对策，如建设沿海堤坝(Takagi等人，2022)。亚洲有无数灾难的例子，另一方面，这意味着有充足的实地证据可用于加强科学理解(Valdez等人，2022;Heidarzadeh and Mulia 2022)。有限的资金和资源也意味着在各种减灾措施方面存在创新的机会(Pringgana, Cunningham, and Rogers, 2023)。事实上，一些亚洲国家已经成功地实施了大规模人员撤离
{"title":"Coastal disasters in Asia: Forecasting, Uncovering, Recovering, and Mitigation","authors":"H. Takagi, M. Heidarzadeh","doi":"10.1080/21664250.2023.2178122","DOIUrl":"https://doi.org/10.1080/21664250.2023.2178122","url":null,"abstract":"With 60% of the world’s population, low-lying deltas, numerous islands, long coastlines, rapid population growth, and economic development, the Asian coast is the most vulnerable area in the world to disasters. No other part of the world has such a large number of subduction plate boundaries and warm ocean basins, resulting in massive tsunamis, tropical cyclones, and storm surges (Figure 1). In reality, the six worst coastal disasters of the 21st century in terms of number of casualties all occurred in Asia: the Indian Ocean Tsunami (2004), Cyclone Sidr (Bangladesh, 2007), Cyclone Nargis (Myanmar, 2008), the Great East Japan Earthquake and Tsunami (Japan, 2011), Typhoon Haiyan (the Philippines, 2013), and the Sulawesi (Palu) Earthquake, Landslide and Tsunami (Indonesia, 2018). These six disasters have claimed more than 400,000 victims. Natural and anthropogenic environmental degradation, such as coastal erosion, land subsidence, and mangrove deforestation, have also been remarkably increasing the risk of disasters in Asia (Hao and Takewaka 2022; Sreeranga et al. 2022). Locallyintensified tsunamis due to a combination of earthquakes, volcanic eruptions, subaerial and submarine landslides (Heidarzadeh and Mulia 2022; Sabeti and Heidarzadeh 2022) and risks associated with the uncertainty of large thrust earthquakes also need to be further studied and clarified (Momeni et al. 2022). Where major disasters occurred in Asia, recovery has immediately begun with international support, but the midand long-term successes of such recovery efforts are not straightforward (Iuchi et al. 2023). In countries with sufficient financial resources, the immediate recovery steps will be to strengthen through, for example, coastal dikes and embankments. However, not many areas in Asia can take into action appropriate hard countermeasures such as construction of coastal dikes due to financial constraints (Takagi et al., 2022). Asia has countless examples of disasters, which, on the other hand, means that there is ample evidence on the ground that can be used to enhance scientific understanding (Valdez et al. 2022; Heidarzadeh and Mulia 2022). Limited funds and resources also mean that there are opportunities for innovation in various disaster mitigation measures (Pringgana, Cunningham, and Rogers 2023). In fact, several Asian countries have successfully implemented mass evacuations of","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"1 - 2"},"PeriodicalIF":2.4,"publicationDate":"2023-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42612104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-02DOI: 10.1080/21664250.2023.2170690
G. Pringgana, L. Cunningham, B. Rogers
ABSTRACT This study investigates the effectiveness of a new discrete V-shaped coastal barrier (V-wall) to reduce multiple tsunami-bore impacts on a group of idealized coastal structures. The performance comparison has been made between a baseline model (BM), continuous straight wall models (SW), and V-wall (VW) models. A number of key parameters including the barrier height and length along with the arrangement of the landward structures are investigated numerically using the 3-D smoothed particle hydrodynamics (SPH) approach. From the SPH models output the bore velocity, maximum force, total impulse, and pressure distribution on the structures are examined. The results indicate that the V-walls can provide a similar level of protection to continuous seawalls of the same height and hence can be considered as an economic alternative to protection in tsunami prone regions. However, in order to gain the greatest benefit from the V-walls, strategic planning of the position and orientation of landward structures and the walls themselves are needed to avoid bore flow focusing and reflection effects.
{"title":"Mitigating tsunami effects on buildings via novel use of discrete onshore protection systems","authors":"G. Pringgana, L. Cunningham, B. Rogers","doi":"10.1080/21664250.2023.2170690","DOIUrl":"https://doi.org/10.1080/21664250.2023.2170690","url":null,"abstract":"ABSTRACT This study investigates the effectiveness of a new discrete V-shaped coastal barrier (V-wall) to reduce multiple tsunami-bore impacts on a group of idealized coastal structures. The performance comparison has been made between a baseline model (BM), continuous straight wall models (SW), and V-wall (VW) models. A number of key parameters including the barrier height and length along with the arrangement of the landward structures are investigated numerically using the 3-D smoothed particle hydrodynamics (SPH) approach. From the SPH models output the bore velocity, maximum force, total impulse, and pressure distribution on the structures are examined. The results indicate that the V-walls can provide a similar level of protection to continuous seawalls of the same height and hence can be considered as an economic alternative to protection in tsunami prone regions. However, in order to gain the greatest benefit from the V-walls, strategic planning of the position and orientation of landward structures and the walls themselves are needed to avoid bore flow focusing and reflection effects.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"149 - 173"},"PeriodicalIF":2.4,"publicationDate":"2023-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46048758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-02DOI: 10.1080/21664250.2023.2165430
K. Iuchi, H. Takagi, Yasuhito Jibiki, T. Kondo, Ayako Kusunoki, N. Hanifa, D. Pelupessy, Rahmadiyah Tria Gayathri, R. Olshansky
ABSTRACT To reduce hazards in post-disaster rebuilding, governments often first revise existing hazard maps to update land use plans and regulations. This sequence assumes that the disaster event immediately improves knowledge of the hazard. To learn from an actual case, we document PASIGALA’s rebuilding process following the 2018 Central Sulawesi earthquake. We reviewed public documents in-depth, assessed coastal hazards with new information, and reflected on our field observations. We documented the 3.5-year situation in detail and developed recovery narratives. We also found that the actual post-disaster development does not fully incorporate the planned goals of hazard risk reduction. Reasons include: i) the need to create a hazard map before knowing the hazard’s mechanism; ii) the scale of hazard mapping does not correspond to that of individual building parcels; iii) residents, out of necessity, restart their lives in the prohibited areas, and iv) relocation plans do not attract affected residents when rebuilding their lives. Governments may create simplified hazard maps to facilitate timely rebuilding, but this overlooks nuanced problems residents face, further complicating their situation. Although the hazard maps show the region’s potential hazards, the next disaster could be different. We conclude the current practice of hazard map-based rebuilding needs more deliberation.
{"title":"Questioning the hazard map-based rebuilding process: learning from the 2018 Sulawesi earthquake in Indonesia","authors":"K. Iuchi, H. Takagi, Yasuhito Jibiki, T. Kondo, Ayako Kusunoki, N. Hanifa, D. Pelupessy, Rahmadiyah Tria Gayathri, R. Olshansky","doi":"10.1080/21664250.2023.2165430","DOIUrl":"https://doi.org/10.1080/21664250.2023.2165430","url":null,"abstract":"ABSTRACT To reduce hazards in post-disaster rebuilding, governments often first revise existing hazard maps to update land use plans and regulations. This sequence assumes that the disaster event immediately improves knowledge of the hazard. To learn from an actual case, we document PASIGALA’s rebuilding process following the 2018 Central Sulawesi earthquake. We reviewed public documents in-depth, assessed coastal hazards with new information, and reflected on our field observations. We documented the 3.5-year situation in detail and developed recovery narratives. We also found that the actual post-disaster development does not fully incorporate the planned goals of hazard risk reduction. Reasons include: i) the need to create a hazard map before knowing the hazard’s mechanism; ii) the scale of hazard mapping does not correspond to that of individual building parcels; iii) residents, out of necessity, restart their lives in the prohibited areas, and iv) relocation plans do not attract affected residents when rebuilding their lives. Governments may create simplified hazard maps to facilitate timely rebuilding, but this overlooks nuanced problems residents face, further complicating their situation. Although the hazard maps show the region’s potential hazards, the next disaster could be different. We conclude the current practice of hazard map-based rebuilding needs more deliberation.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"126 - 148"},"PeriodicalIF":2.4,"publicationDate":"2023-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48702522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-28DOI: 10.1080/21664250.2022.2159290
A. Begmohammadi, D. Wirasaet, A. Poisson, Johnathan L. Woodruff, J. Dietrich, D. Bolster, A. Kennedy
ABSTRACT Inundation models represent coastal regions with a grid of computational points, often with varying resolution of flow pathways and barriers. Models based on coarse grid solutions of shallow water equations have been improved recently via the use of subgrid corrections, which account for information (ground surface elevations, roughness characteristics) at smaller scales. In this work, numerical approaches of an established storm surge model are extended to include subgrid corrections. In an attempt to maintain continuity with existing users and results, model extensions were limited to those needed to provide basic subgrid capabilities, and included two major additions. First, a finite volume method is used to incorporate corrections to the mass and momentum equations using high-resolution ground surface elevations. Second, the no-slip condition imposed on the B-grid wet/dry interface in the model is modified to a slip condition to enable flows in channels with widths comparable to cell size. Numerical results demonstrate these numerical extensions can significantly enhance the accuracy of the model’s predictions of coastal flooding, with low additional computational cost.
{"title":"Numerical extensions to incorporate subgrid corrections in an established storm surge model","authors":"A. Begmohammadi, D. Wirasaet, A. Poisson, Johnathan L. Woodruff, J. Dietrich, D. Bolster, A. Kennedy","doi":"10.1080/21664250.2022.2159290","DOIUrl":"https://doi.org/10.1080/21664250.2022.2159290","url":null,"abstract":"ABSTRACT Inundation models represent coastal regions with a grid of computational points, often with varying resolution of flow pathways and barriers. Models based on coarse grid solutions of shallow water equations have been improved recently via the use of subgrid corrections, which account for information (ground surface elevations, roughness characteristics) at smaller scales. In this work, numerical approaches of an established storm surge model are extended to include subgrid corrections. In an attempt to maintain continuity with existing users and results, model extensions were limited to those needed to provide basic subgrid capabilities, and included two major additions. First, a finite volume method is used to incorporate corrections to the mass and momentum equations using high-resolution ground surface elevations. Second, the no-slip condition imposed on the B-grid wet/dry interface in the model is modified to a slip condition to enable flows in channels with widths comparable to cell size. Numerical results demonstrate these numerical extensions can significantly enhance the accuracy of the model’s predictions of coastal flooding, with low additional computational cost.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"175 - 197"},"PeriodicalIF":2.4,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46068740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-28DOI: 10.1080/21664250.2022.2161124
Sindhu Sreeranga, H. Takagi, Shin-ichi Kubota, J. Mitsui
ABSTRACT Approximately half of the world’s mangroves are concentrated in Asia, but they have been logged at an alarming rate. To compensate for this, mangrove plantations are being attempted at various sites but with many failures. In this study, we investigated the role of a small portable reef in protecting young mangrove plants from hydrodynamic disturbances caused by short-period waves. To investigate the effectiveness of such a small reef, an experiment using a large wave flume was conducted with two types of real-sized portable reefs (stone and block reefs). A numerical wave model was also constructed to analyze in detail the turbulence around the reef. Our previous study showed that short-period waves can cause resonant oscillations in young mangrove plants. To confirm whether this occurs even behind a reef system, a young mangrove model made of flexible olefin resin was tested with a small wave flume placed behind porous and non-porous reefs, and its oscillation was precisely measured using a high-speed camera. These experiments yielded several new findings. If appropriately designed, small porous reefs can minimize oscillations with adverse effects and provide a favorable environment for the initial growth of mangroves at restoration sites.
{"title":"An experimental study on oscillatory characteristics of young mangroves behind a portable reef","authors":"Sindhu Sreeranga, H. Takagi, Shin-ichi Kubota, J. Mitsui","doi":"10.1080/21664250.2022.2161124","DOIUrl":"https://doi.org/10.1080/21664250.2022.2161124","url":null,"abstract":"ABSTRACT Approximately half of the world’s mangroves are concentrated in Asia, but they have been logged at an alarming rate. To compensate for this, mangrove plantations are being attempted at various sites but with many failures. In this study, we investigated the role of a small portable reef in protecting young mangrove plants from hydrodynamic disturbances caused by short-period waves. To investigate the effectiveness of such a small reef, an experiment using a large wave flume was conducted with two types of real-sized portable reefs (stone and block reefs). A numerical wave model was also constructed to analyze in detail the turbulence around the reef. Our previous study showed that short-period waves can cause resonant oscillations in young mangrove plants. To confirm whether this occurs even behind a reef system, a young mangrove model made of flexible olefin resin was tested with a small wave flume placed behind porous and non-porous reefs, and its oscillation was precisely measured using a high-speed camera. These experiments yielded several new findings. If appropriately designed, small porous reefs can minimize oscillations with adverse effects and provide a favorable environment for the initial growth of mangroves at restoration sites.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"110 - 125"},"PeriodicalIF":2.4,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42466666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-02DOI: 10.1080/21664250.2022.2143750
Takayuki Suzuki, Kiichi Tajima, R. Jayaratne
ABSTRACT A comprehensive set of laboratory experiments were conducted to investigate the spatial distributions of mixing depth in the surf zone. A wooden sandbox of 0.15-m-deep and 1.0-m-long is fabricated and placed in the middle of the bed slope. In the experiments, five different sediment diameters were used and the same diameters of fluorescent sand tracers were sprinkled on the sand bed surface to investigate the mixing depth. After a specific duration of regular wave generation , core samples were taken at six different cross-shore locationsand analyzed the mixing depth. Moreover, the flow velocity field in the surf zone was obtained by using a Large Eddy Simulation model and discussed the relationship with spatial distributions of mixing depth. The results reveal that the mixing depth has cross-shore spatial variation and the maximum mixing depth occurred at the impinging point for all tested sediment diameters. The spatial distributions for each diameter were repeatable; however, the depth decreases in a logarithmic manner from smaller to larger grain size. Furthermore, the spatial distribution of mixing depth is correlated with the bottom root mean square vertical velocity and proposed a new simple mathematical relationship for mixing depth that shows good accuracy with experimental data.
{"title":"Laboratory modelling of vertical sediment mixing in the surf zone","authors":"Takayuki Suzuki, Kiichi Tajima, R. Jayaratne","doi":"10.1080/21664250.2022.2143750","DOIUrl":"https://doi.org/10.1080/21664250.2022.2143750","url":null,"abstract":"ABSTRACT A comprehensive set of laboratory experiments were conducted to investigate the spatial distributions of mixing depth in the surf zone. A wooden sandbox of 0.15-m-deep and 1.0-m-long is fabricated and placed in the middle of the bed slope. In the experiments, five different sediment diameters were used and the same diameters of fluorescent sand tracers were sprinkled on the sand bed surface to investigate the mixing depth. After a specific duration of regular wave generation , core samples were taken at six different cross-shore locationsand analyzed the mixing depth. Moreover, the flow velocity field in the surf zone was obtained by using a Large Eddy Simulation model and discussed the relationship with spatial distributions of mixing depth. The results reveal that the mixing depth has cross-shore spatial variation and the maximum mixing depth occurred at the impinging point for all tested sediment diameters. The spatial distributions for each diameter were repeatable; however, the depth decreases in a logarithmic manner from smaller to larger grain size. Furthermore, the spatial distribution of mixing depth is correlated with the bottom root mean square vertical velocity and proposed a new simple mathematical relationship for mixing depth that shows good accuracy with experimental data.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"64 1","pages":"619 - 629"},"PeriodicalIF":2.4,"publicationDate":"2022-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45137588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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