Pub Date : 2022-08-30DOI: 10.1080/21664250.2022.2117585
P. Momeni, K. Goda, M. Mokhtari, M. Heidarzadeh
ABSTRACT Tsunami hazard imposed by possible rupture of splay faults is important as it may significantly intensify tsunami heights locally. The Makran Subduction Zone (MSZ) in the northwestern Indian Ocean can generate large thrust earthquakes that could trigger significant tsunamis. In this paper, the effects of possible rupture of splay faults on the tsunami hazards of eastern MSZ are studied by developing a framework that uses stochastic earthquake rupture models and considers uncertainties related to rupture location, rupture geometry, seismic moment split ratio, earthquake slip asperity location within a fault plane, and earthquake slip heterogeneity. To quantify these uncertainties, 484 different parameter combinations of tsunami sources are considered systematically. The geometry of splay faults is developed using the most recent marine seismic surveys of the tectonic structure of the MSZ. A moment magnitude of 8.6 is considered as a scenario magnitude. The results of this study are generated in two parts, by considering average sources and stochastic sources. Results show significant local amplification of the maximum tsunami heights due to splay faults. For instance, the maximum wave height in Pasni, Pakistan can be amplified by a factor of four due to a single splay fault rupture scenario of average sources.
{"title":"A new tsunami hazard assessment for eastern Makran subduction zone by considering splay faults and applying stochastic modeling","authors":"P. Momeni, K. Goda, M. Mokhtari, M. Heidarzadeh","doi":"10.1080/21664250.2022.2117585","DOIUrl":"https://doi.org/10.1080/21664250.2022.2117585","url":null,"abstract":"ABSTRACT Tsunami hazard imposed by possible rupture of splay faults is important as it may significantly intensify tsunami heights locally. The Makran Subduction Zone (MSZ) in the northwestern Indian Ocean can generate large thrust earthquakes that could trigger significant tsunamis. In this paper, the effects of possible rupture of splay faults on the tsunami hazards of eastern MSZ are studied by developing a framework that uses stochastic earthquake rupture models and considers uncertainties related to rupture location, rupture geometry, seismic moment split ratio, earthquake slip asperity location within a fault plane, and earthquake slip heterogeneity. To quantify these uncertainties, 484 different parameter combinations of tsunami sources are considered systematically. The geometry of splay faults is developed using the most recent marine seismic surveys of the tectonic structure of the MSZ. A moment magnitude of 8.6 is considered as a scenario magnitude. The results of this study are generated in two parts, by considering average sources and stochastic sources. Results show significant local amplification of the maximum tsunami heights due to splay faults. For instance, the maximum wave height in Pasni, Pakistan can be amplified by a factor of four due to a single splay fault rupture scenario of average sources.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"67 - 96"},"PeriodicalIF":2.4,"publicationDate":"2022-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48729099","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 : 2022-07-17DOI: 10.1080/21664250.2022.2100179
H. Takagi, LeDuc Anh, Rezuanul Islam, Tajnova Tanha Hossain
ABSTRACT This study reviews the progress of disaster mitigation measures against tropical cyclones (TCs) in three Asian countries with different historical, social, and economic backgrounds: Bangladesh, Vietnam, and Japan. In Bangladesh, an average of 6,600 people was killed by a single TC in the 1960s, but this number had decreased to 30 in the 2010s; this reduction was due to a clear improvement in soft measures, such as weather forecasting, warning systems, and mass evacuation coordinated by volunteers. In Vietnam, several strong TCs have recently made landfall, leading to improvements in national disaster management. Although Vietnam's current disaster management budget is smaller than those of the two other countries, large-scale evacuation by local authorities is believed to have minimized casualties. In Japan, shortly after Typhoon Vera in 1959, a comprehensive law on disaster prevention was enacted, and coastal dikes were constructed nationwide, resulting in a considerable reduction in fatalities due to TCs. However, the disaster prevention facilities built in this period are now deteriorating, while Japan’s budget for disaster management is projected to be decreasing. The three countries have advanced their disaster preparedness in response to past TCs and storm surges, but new challenges have also arisen.
{"title":"Progress of disaster mitigation against tropical cyclones and storm surges: a comparative study of Bangladesh, Vietnam, and Japan","authors":"H. Takagi, LeDuc Anh, Rezuanul Islam, Tajnova Tanha Hossain","doi":"10.1080/21664250.2022.2100179","DOIUrl":"https://doi.org/10.1080/21664250.2022.2100179","url":null,"abstract":"ABSTRACT This study reviews the progress of disaster mitigation measures against tropical cyclones (TCs) in three Asian countries with different historical, social, and economic backgrounds: Bangladesh, Vietnam, and Japan. In Bangladesh, an average of 6,600 people was killed by a single TC in the 1960s, but this number had decreased to 30 in the 2010s; this reduction was due to a clear improvement in soft measures, such as weather forecasting, warning systems, and mass evacuation coordinated by volunteers. In Vietnam, several strong TCs have recently made landfall, leading to improvements in national disaster management. Although Vietnam's current disaster management budget is smaller than those of the two other countries, large-scale evacuation by local authorities is believed to have minimized casualties. In Japan, shortly after Typhoon Vera in 1959, a comprehensive law on disaster prevention was enacted, and coastal dikes were constructed nationwide, resulting in a considerable reduction in fatalities due to TCs. However, the disaster prevention facilities built in this period are now deteriorating, while Japan’s budget for disaster management is projected to be decreasing. The three countries have advanced their disaster preparedness in response to past TCs and storm surges, but new challenges have also arisen.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"83 10","pages":"39 - 53"},"PeriodicalIF":2.4,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41260238","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 : 2022-07-14DOI: 10.1080/21664250.2022.2099683
J. Valdez, T. Shibayama, T. Takabatake, M. Esteban
ABSTRACT Haiyan in 2013 was one of the most powerful typhoons to have affected the Philippines, devastating in its path a wide portion of Leyte, and causing extensive damage to structures in Tacloban City. To understand the likely impacts that would be exerted by a storm surge on a structure deemed important, the authors used a coupled model that hindcasted the flooding that took place during Haiyan. This coupled model included the use of the Weather Research and Forecasting (WRF) Model (with Bogussing scheme) to simulate the atmospheric conditions during the passage of Haiyan, the Finite Volume Coastal Ocean Model (FVCOM) to simulate the storm surge and obtain the boundary conditions for the wind and flood (hydrostatic, hydrodynamic, and breaking wave), and the Structural Analysis and Designing Program (STAAD.Pro) to calculate the corresponding axial, shear, and bending moment envelopes based on the storm surge simulation. A 4-floor public school building in Tacloban was modeled and the effects that the storm surge would have on a corner column were analyzed. Based on the results, the axial, shear, and moment at the corner column significantly increased when considering flood loads, indicating the importance of including such loads in the design of essential structures.
{"title":"Simulated flood forces on a building due to the storm surge by Typhoon Haiyan","authors":"J. Valdez, T. Shibayama, T. Takabatake, M. Esteban","doi":"10.1080/21664250.2022.2099683","DOIUrl":"https://doi.org/10.1080/21664250.2022.2099683","url":null,"abstract":"ABSTRACT Haiyan in 2013 was one of the most powerful typhoons to have affected the Philippines, devastating in its path a wide portion of Leyte, and causing extensive damage to structures in Tacloban City. To understand the likely impacts that would be exerted by a storm surge on a structure deemed important, the authors used a coupled model that hindcasted the flooding that took place during Haiyan. This coupled model included the use of the Weather Research and Forecasting (WRF) Model (with Bogussing scheme) to simulate the atmospheric conditions during the passage of Haiyan, the Finite Volume Coastal Ocean Model (FVCOM) to simulate the storm surge and obtain the boundary conditions for the wind and flood (hydrostatic, hydrodynamic, and breaking wave), and the Structural Analysis and Designing Program (STAAD.Pro) to calculate the corresponding axial, shear, and bending moment envelopes based on the storm surge simulation. A 4-floor public school building in Tacloban was modeled and the effects that the storm surge would have on a corner column were analyzed. Based on the results, the axial, shear, and moment at the corner column significantly increased when considering flood loads, indicating the importance of including such loads in the design of essential structures.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"21 - 38"},"PeriodicalIF":2.4,"publicationDate":"2022-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44843537","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 : 2022-07-03DOI: 10.1080/21664250.2022.2119011
Kangnian Wang, Yoshiyuki Nakamura, J. Sasaki, Tetsunori Inoue, Hiroto Higa, Takayuki Suzuki, Muhammad Ali Hafeez
ABSTRACT Hypoxia and blue tide are the most significant environmental issues in Tokyo Bay as they have been damaging fisheries for a long time. Although studies on modeling these two associated phenomena have been conducted for decades, the scarcity of relevant observational datasets has greatly hindered the progress, and no study has successfully reproduced the entire processes of blue tide or predicted the time and place of its outbreak. To address the problems from limited data, this study proposed a relatively conventional benthic flux model and developed a novel method that converts the total organic carbon content into the fluxes of sediment oxygen consumption and sulfide release to represent the spatial differences in benthic fluxes. A pelagic sulfur model with only three key chemical reactions of blue tide that includes the disproportionation of elemental sulfur was proposed. The method significantly improved the results of dissolved oxygen in bottom water, as seen by the root mean square error decreasing by 15.9% and 18.9% in two simulations with largely different forcings. The sulfur model also accurately predicted the outbreaks of blue tides in each simulation, which is significant to the stakeholders as it facilitates the forecast of blue tides in Tokyo Bay.
{"title":"An effective process-based modeling approach for predicting hypoxia and blue tide in Tokyo Bay","authors":"Kangnian Wang, Yoshiyuki Nakamura, J. Sasaki, Tetsunori Inoue, Hiroto Higa, Takayuki Suzuki, Muhammad Ali Hafeez","doi":"10.1080/21664250.2022.2119011","DOIUrl":"https://doi.org/10.1080/21664250.2022.2119011","url":null,"abstract":"ABSTRACT Hypoxia and blue tide are the most significant environmental issues in Tokyo Bay as they have been damaging fisheries for a long time. Although studies on modeling these two associated phenomena have been conducted for decades, the scarcity of relevant observational datasets has greatly hindered the progress, and no study has successfully reproduced the entire processes of blue tide or predicted the time and place of its outbreak. To address the problems from limited data, this study proposed a relatively conventional benthic flux model and developed a novel method that converts the total organic carbon content into the fluxes of sediment oxygen consumption and sulfide release to represent the spatial differences in benthic fluxes. A pelagic sulfur model with only three key chemical reactions of blue tide that includes the disproportionation of elemental sulfur was proposed. The method significantly improved the results of dissolved oxygen in bottom water, as seen by the root mean square error decreasing by 15.9% and 18.9% in two simulations with largely different forcings. The sulfur model also accurately predicted the outbreaks of blue tides in each simulation, which is significant to the stakeholders as it facilitates the forecast of blue tides in Tokyo Bay.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"64 1","pages":"458 - 476"},"PeriodicalIF":2.4,"publicationDate":"2022-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44273936","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 : 2022-07-03DOI: 10.1080/21664250.2022.2116775
Shota Okura, S. Hosokawa
ABSTRACT The sea surface temperature estimated by satellites (SSTskin) may facilitate the understanding of processes that affect water quality in semi-enclosed bays. However, the representativeness and certainty of SSTskin in semi-enclosed bays have not been fully investigated. We investigated the SSTskin from MODIS in Tokyo Bay and Ise Bay to test the hypothesis that water-mass structure and proximity to land would affect SSTskin. Results showed that the SSTskin from MODIS in two semi-enclosed bays can be as representative and certain as the data from previous studies in the open ocean. We found that horizontal gradients of water temperature had little effect on the certainty of SSTskin. However, we found that both the representativeness and certainty of satellite-based estimates of SSTskin in semi-enclosed bays were reduced by seasonal and location characteristics. The representativeness and certainty of SSTskin near the mouth of Ise Bay were compromised by the complex vertical structure of water temperature in summer. Because SSTskin may greatly enhance understanding of the processes that affect water quality in semi-enclosed bays, our results indicate that prior validation of SSTskin by comparison with in-situ sea surface temperature (SSTdep) is important.
{"title":"Representativeness and certainty of sea surface temperature from MODIS in semi-enclosed bays","authors":"Shota Okura, S. Hosokawa","doi":"10.1080/21664250.2022.2116775","DOIUrl":"https://doi.org/10.1080/21664250.2022.2116775","url":null,"abstract":"ABSTRACT The sea surface temperature estimated by satellites (SSTskin) may facilitate the understanding of processes that affect water quality in semi-enclosed bays. However, the representativeness and certainty of SSTskin in semi-enclosed bays have not been fully investigated. We investigated the SSTskin from MODIS in Tokyo Bay and Ise Bay to test the hypothesis that water-mass structure and proximity to land would affect SSTskin. Results showed that the SSTskin from MODIS in two semi-enclosed bays can be as representative and certain as the data from previous studies in the open ocean. We found that horizontal gradients of water temperature had little effect on the certainty of SSTskin. However, we found that both the representativeness and certainty of satellite-based estimates of SSTskin in semi-enclosed bays were reduced by seasonal and location characteristics. The representativeness and certainty of SSTskin near the mouth of Ise Bay were compromised by the complex vertical structure of water temperature in summer. Because SSTskin may greatly enhance understanding of the processes that affect water quality in semi-enclosed bays, our results indicate that prior validation of SSTskin by comparison with in-situ sea surface temperature (SSTdep) is important.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"64 1","pages":"428 - 441"},"PeriodicalIF":2.4,"publicationDate":"2022-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43615272","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}
ABSTRACT As the lower boundary of suspended particles, the critical condition of suspension is an important component in the theory of nonuniform sediment transport and plays a significant role in the numerical computations in the suspended sediment movement. Previous studies on critical suspension are mostly based on Rouse number and Shields number. From the perspective of maximum particle size, this paper conducted research on the critical suspension of nonuniform sediment by flume experiment. A new criterion for critical suspension of nonuniform sediment is proposed according to the concept of maximum particle Reynolds number and analysis of experimental data. Sediments will not be suspended unless the particle Reynolds number is less than or equal to the maximum one related to flow and boundary conditions. A formula, established from experimental data, indicates that the maximum particle Reynolds number is proportional to 3 power of Froude number and 1/5 power of relative roughness. As a new criterion for critical suspension, this formula offers a reasonable description of the physical mechanism for the initial movement of the suspended load. Not only does the proposed formula agree well with laboratory and field data, but it also has its advantages compared with traditional criteria.
{"title":"A new criterion for critical suspension of nonuniform sediment","authors":"Zhi-lin Sun, Yun Gao, Lixia Sun, Haolei Zheng, Wengang Xiang, Yimeng Gao","doi":"10.1080/21664250.2022.2120584","DOIUrl":"https://doi.org/10.1080/21664250.2022.2120584","url":null,"abstract":"ABSTRACT As the lower boundary of suspended particles, the critical condition of suspension is an important component in the theory of nonuniform sediment transport and plays a significant role in the numerical computations in the suspended sediment movement. Previous studies on critical suspension are mostly based on Rouse number and Shields number. From the perspective of maximum particle size, this paper conducted research on the critical suspension of nonuniform sediment by flume experiment. A new criterion for critical suspension of nonuniform sediment is proposed according to the concept of maximum particle Reynolds number and analysis of experimental data. Sediments will not be suspended unless the particle Reynolds number is less than or equal to the maximum one related to flow and boundary conditions. A formula, established from experimental data, indicates that the maximum particle Reynolds number is proportional to 3 power of Froude number and 1/5 power of relative roughness. As a new criterion for critical suspension, this formula offers a reasonable description of the physical mechanism for the initial movement of the suspended load. Not only does the proposed formula agree well with laboratory and field data, but it also has its advantages compared with traditional criteria.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"64 1","pages":"477 - 487"},"PeriodicalIF":2.4,"publicationDate":"2022-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44126179","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 : 2022-07-03DOI: 10.1080/21664250.2022.2118431
Daisuke Kobayashi, T. Uchida
ABSTRACT This study investigates the propagation characteristics of breaking bore in meandering channels focusing on the effects of Froude number (F) on the breaking bore. The experiments are conducted with different Froude number conditions of F = 3.99 for high F and F = 1.53 for low F in a straight and meandering channel. The experimental results are compared with calculated results by Shallow Water Equation (SWE) model and three-dimensional calculation model. In the low F condition, the oscillation of water level like a soliton fission was observed and it was amplified along both banks in the meandering channel. This was explained using the temporal variation of the transverse water surface gradient calculated by SWE model, that is not related with non-hydrostatic pressure component and vertical distribution of the velocity. The high F condition is characterized by the longitudinal gradient of bore head caused by large energy loss. In the meandering channel, the SWE model overestimated the wave height near the bore front along both banks. This is because the secondary flow in the meandering channel increases the velocity near the bed and the flow resistance compared with low F condition and reduces the wave height.
{"title":"Experimental and numerical investigation of breaking bores in straight and meandering channels with different Froude numbers","authors":"Daisuke Kobayashi, T. Uchida","doi":"10.1080/21664250.2022.2118431","DOIUrl":"https://doi.org/10.1080/21664250.2022.2118431","url":null,"abstract":"ABSTRACT This study investigates the propagation characteristics of breaking bore in meandering channels focusing on the effects of Froude number (F) on the breaking bore. The experiments are conducted with different Froude number conditions of F = 3.99 for high F and F = 1.53 for low F in a straight and meandering channel. The experimental results are compared with calculated results by Shallow Water Equation (SWE) model and three-dimensional calculation model. In the low F condition, the oscillation of water level like a soliton fission was observed and it was amplified along both banks in the meandering channel. This was explained using the temporal variation of the transverse water surface gradient calculated by SWE model, that is not related with non-hydrostatic pressure component and vertical distribution of the velocity. The high F condition is characterized by the longitudinal gradient of bore head caused by large energy loss. In the meandering channel, the SWE model overestimated the wave height near the bore front along both banks. This is because the secondary flow in the meandering channel increases the velocity near the bed and the flow resistance compared with low F condition and reduces the wave height.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"64 1","pages":"442 - 457"},"PeriodicalIF":2.4,"publicationDate":"2022-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42930430","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 : 2022-06-25DOI: 10.1080/21664250.2022.2088194
P. Winckler, César Esparza, J. Mora, O. Melo, N. Bambach, M. Contreras-López, M. Sactic
ABSTRACT Economic costs due to operational downtime and wave overtopping under the RCP 8.5 scenario are evaluated at 7 Chilean ports. Wave statistics for a historical period (1985–2004), mid-century (2026–2045), and end-of-century projections (2081–2100) are computed with a Pacific-wide model, forced by wind fields from six General Circulation Models. Offshore waves are then downscaled to each port, where a proxy of downtime is computed by comparing wave heights with vessel berthing criteria. The difference in downtime between the historical and future projections is attributed to climate change. Results show that some ports would reduce and others increase downtime for mid-century projections due to local effects. However, by the end-of-century, all ports would experience a reduction in downtime. Additionally, by mid-century, overtopping would increase in northern ports as a combination of extreme waves and sea-level rise (SLR), while in southern ports, it is expected to be slightly reduced. By the end-of century, overtopping would increase in the whole region, mainly driven by SLR. However, overtopping is significantly altered by coseismic uplift/subsidence that may occur during the design-life of coastal works. Finally, a few practical suggestions aimed atimproving infrastructure management and operational conditions at the analyzed ports are outlined.
{"title":"Impacts in ports on a tectonically active coast for climate-driven projections under the RCP 8.5 scenario: 7 Chilean ports under scrutiny","authors":"P. Winckler, César Esparza, J. Mora, O. Melo, N. Bambach, M. Contreras-López, M. Sactic","doi":"10.1080/21664250.2022.2088194","DOIUrl":"https://doi.org/10.1080/21664250.2022.2088194","url":null,"abstract":"ABSTRACT Economic costs due to operational downtime and wave overtopping under the RCP 8.5 scenario are evaluated at 7 Chilean ports. Wave statistics for a historical period (1985–2004), mid-century (2026–2045), and end-of-century projections (2081–2100) are computed with a Pacific-wide model, forced by wind fields from six General Circulation Models. Offshore waves are then downscaled to each port, where a proxy of downtime is computed by comparing wave heights with vessel berthing criteria. The difference in downtime between the historical and future projections is attributed to climate change. Results show that some ports would reduce and others increase downtime for mid-century projections due to local effects. However, by the end-of-century, all ports would experience a reduction in downtime. Additionally, by mid-century, overtopping would increase in northern ports as a combination of extreme waves and sea-level rise (SLR), while in southern ports, it is expected to be slightly reduced. By the end-of century, overtopping would increase in the whole region, mainly driven by SLR. However, overtopping is significantly altered by coseismic uplift/subsidence that may occur during the design-life of coastal works. Finally, a few practical suggestions aimed atimproving infrastructure management and operational conditions at the analyzed ports are outlined.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"64 1","pages":"387 - 405"},"PeriodicalIF":2.4,"publicationDate":"2022-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41440463","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 : 2022-06-25DOI: 10.1080/21664250.2022.2089445
Paterno S. Miranda, N. Kobayashi
ABSTRACT The erosional and accretional profile changes of an intertidal mudflat are examined using available field data and the cross-shore numerical model CSHORE that is extended to allow for a mixture of sand and mud. The semidiurnal migration of the still water shoreline and surf zone is resolved numerically to predict the net cross-shore and longshore sediment transport rates influenced by the small cross-shore (undertow) and longshore currents induced by breaking waves of about 0.2 m height. Alongshore sediment loss or gain is included by approximating the alongshore sediment transport gradient using an equivalent alongshore length. The calibrated CSHORE reproduces the measured erosional (accretional) profile change of about 0.1 m (0.1 m) over a cross-shore distance of 950 m during the erosional (accretional) interval of 206 (195) days. The mudflat profile changes are equally affected by mud characteristics, the semidiurnal tide amplitude, and the wave height, period, and direction. In addition, the alongshore water level gradient and wind stress influence longshore current and sediment transport. This study shows the importance of sediment transport in the surf zone that may have been excluded in previous numerical modeling.
{"title":"Numerical modeling of intertidal mudflat profile evolution under waves and currents","authors":"Paterno S. Miranda, N. Kobayashi","doi":"10.1080/21664250.2022.2089445","DOIUrl":"https://doi.org/10.1080/21664250.2022.2089445","url":null,"abstract":"ABSTRACT The erosional and accretional profile changes of an intertidal mudflat are examined using available field data and the cross-shore numerical model CSHORE that is extended to allow for a mixture of sand and mud. The semidiurnal migration of the still water shoreline and surf zone is resolved numerically to predict the net cross-shore and longshore sediment transport rates influenced by the small cross-shore (undertow) and longshore currents induced by breaking waves of about 0.2 m height. Alongshore sediment loss or gain is included by approximating the alongshore sediment transport gradient using an equivalent alongshore length. The calibrated CSHORE reproduces the measured erosional (accretional) profile change of about 0.1 m (0.1 m) over a cross-shore distance of 950 m during the erosional (accretional) interval of 206 (195) days. The mudflat profile changes are equally affected by mud characteristics, the semidiurnal tide amplitude, and the wave height, period, and direction. In addition, the alongshore water level gradient and wind stress influence longshore current and sediment transport. This study shows the importance of sediment transport in the surf zone that may have been excluded in previous numerical modeling.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"64 1","pages":"406 - 427"},"PeriodicalIF":2.4,"publicationDate":"2022-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42853285","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 : 2022-05-17DOI: 10.1080/21664250.2022.2073748
Q. Nguyen Hao, S. Takewaka
ABSTRACT Hai Hau, located in northern Vietnam, has suffered from severe coastal erosion with a retreat rate reaching 20 m/yr in recent years. Based on a systematic review of the literature, the shoreline recession trend along the Hai Hau is associated with the decline of water and sediment discharged from the So River, assumed to be active after a great flood in 1787, resulting in channel bifurcation and abandonment of the former channel. A historical analysis of the shoreline evolution of approximately a thousand years (the year 1000 – present) was conducted along this scenario using a modified one-line model. The simulated shorelines agreed well with the results of carbon-14 dating analysis, the historical reference points and shoreline positions extracted from the old maps, and the recently measured shoreline change derived from Landsat imagery. The present study demonstrates that the erosion at the Hai Hau has been ongoing from the end of the 18th century rather than the beginning of the 20th century, as proposed by some previous works. We regard the combined effects of the decrease in river sediment load, and other processes (subsidence and sea level rise (SLR)) are the major causes of long-term erosion on Hai Hau Coast.
{"title":"Historical reconstruction of shoreline evolution at the Nam Dinh Coast, Vietnam","authors":"Q. Nguyen Hao, S. Takewaka","doi":"10.1080/21664250.2022.2073748","DOIUrl":"https://doi.org/10.1080/21664250.2022.2073748","url":null,"abstract":"ABSTRACT Hai Hau, located in northern Vietnam, has suffered from severe coastal erosion with a retreat rate reaching 20 m/yr in recent years. Based on a systematic review of the literature, the shoreline recession trend along the Hai Hau is associated with the decline of water and sediment discharged from the So River, assumed to be active after a great flood in 1787, resulting in channel bifurcation and abandonment of the former channel. A historical analysis of the shoreline evolution of approximately a thousand years (the year 1000 – present) was conducted along this scenario using a modified one-line model. The simulated shorelines agreed well with the results of carbon-14 dating analysis, the historical reference points and shoreline positions extracted from the old maps, and the recently measured shoreline change derived from Landsat imagery. The present study demonstrates that the erosion at the Hai Hau has been ongoing from the end of the 18th century rather than the beginning of the 20th century, as proposed by some previous works. We regard the combined effects of the decrease in river sediment load, and other processes (subsidence and sea level rise (SLR)) are the major causes of long-term erosion on Hai Hau Coast.","PeriodicalId":50673,"journal":{"name":"Coastal Engineering Journal","volume":"65 1","pages":"3 - 20"},"PeriodicalIF":2.4,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44847482","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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