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A new tsunami hazard assessment for eastern Makran subduction zone by considering splay faults and applying stochastic modeling 考虑展断层并应用随机模型的马克兰东部俯冲带海啸危险性评价新方法
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-08-30 DOI: 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.
展断层可能破裂所造成的海啸危险是重要的,因为它可能显著地加剧局部海啸高度。印度洋西北部的马克兰俯冲带(MSZ)可以产生大型逆冲地震,可能引发严重的海啸。本文采用随机地震破裂模型,考虑了破裂位置、破裂几何形状、地震矩劈裂比、断层平面内地震滑动粗糙度位置和地震滑动非均质性等不确定性因素,研究了扇形断层可能破裂对MSZ东部海啸灾害的影响。为了量化这些不确定性,系统地考虑了484种不同的海啸源参数组合。利用最近对MSZ构造结构的海洋地震调查,发展了斜断层的几何形状。矩震级8.6被认为是情景震级。本研究的结果分为两部分,分别考虑平均源和随机源。结果表明,由于展向断层,最大海啸高度在局部有明显的放大。例如,巴基斯坦Pasni的最大波高可以被放大四倍,这是由于平均震源的单张断层破裂情况。
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引用次数: 2
Progress of disaster mitigation against tropical cyclones and storm surges: a comparative study of Bangladesh, Vietnam, and Japan 热带气旋和风暴潮减灾的进展:孟加拉国、越南和日本的比较研究
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-07-17 DOI: 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.
摘要:本研究综述了孟加拉国、越南和日本这三个具有不同历史、社会和经济背景的亚洲国家在热带气旋减灾措施方面的进展。在孟加拉国,20世纪60年代,平均有6600人死于一种TC,但这一数字在2010年代已降至30人;这一减少是由于软措施的明显改善,例如天气预报、预警系统和志愿者协调的大规模疏散。在越南,几次强台风最近登陆,导致国家灾害管理得到改善。虽然越南目前的灾害管理预算比另外两个国家要少,但据信,地方当局的大规模疏散将伤亡降到最低。1959年“维拉”台风发生后不久,日本就制定了全面的防灾法,在全国范围内修建了海岸堤坝,使台风造成的死亡人数大大减少。然而,在此期间建造的防灾设施现在正在恶化,而日本用于灾害管理的预算预计将减少。为应对过去的台风和风暴潮,这三个国家已经提高了备灾能力,但新的挑战也出现了。
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引用次数: 5
Simulated flood forces on a building due to the storm surge by Typhoon Haiyan 台风海燕风暴潮对建筑物的模拟洪水力
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-07-14 DOI: 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.
2013年的“海燕”是影响菲律宾最强大的台风之一,其所到之处摧毁了莱特岛的大部分地区,并对塔克洛班市的建筑造成了广泛的破坏。为了了解风暴潮对被认为重要的建筑物可能产生的影响,作者使用了一个耦合模型来预测海燕期间发生的洪水。该耦合模式包括:采用Bogussing方案的WRF模式模拟海盐通过过程中的大气条件,采用有限体积海岸海洋模式(FVCOM)模拟风暴潮,得到风暴潮的边界条件(水静力、水动力和破碎波),采用STAAD.Pro软件计算相应的轴向、剪切、以及基于风暴潮模拟的弯矩包络。他们对塔克洛班一所四层的公立学校建筑进行了建模,并分析了风暴潮对一根角柱的影响。结果表明,考虑洪水荷载时,角柱轴向、剪力和弯矩均显著增大,说明在基本结构设计中考虑洪水荷载的重要性。
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引用次数: 2
An effective process-based modeling approach for predicting hypoxia and blue tide in Tokyo Bay 一种有效的基于过程的东京湾缺氧和赤潮预测建模方法
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-07-03 DOI: 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.
摘要缺氧和赤潮是东京湾最严重的环境问题,因为它们长期以来一直在破坏渔业。尽管对这两种相关现象建模的研究已经进行了几十年,但相关观测数据集的稀缺极大地阻碍了这一进展,也没有任何研究成功再现了蓝潮的整个过程或预测了其爆发的时间和地点。为了解决数据有限的问题,本研究提出了一个相对传统的海底通量模型,并开发了一种新的方法,将总有机碳含量转换为沉积物耗氧量和硫化物释放通量,以表示海底通量的空间差异。提出了一个只有三个蓝潮关键化学反应的远洋硫模型,其中包括元素硫的歧化。该方法显著改善了底层水中溶解氧的结果,在两次不同强迫的模拟中,均方根误差分别降低了15.9%和18.9%。硫模型还在每次模拟中准确预测了赤潮的爆发,这对利益相关者来说意义重大,因为它有助于预测东京湾的赤潮。
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引用次数: 2
Representativeness and certainty of sea surface temperature from MODIS in semi-enclosed bays 半封闭海湾MODIS海表温度的代表性和确定性
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-07-03 DOI: 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.
摘要卫星估算的海面温度有助于了解影响半封闭海湾水质的过程。然而,半封闭海湾SST表皮的代表性和确定性尚未得到充分研究。我们调查了东京湾和伊势湾MODIS的SST表皮,以检验水体结构和接近陆地会影响SST表皮的假设。结果表明,两个半封闭海湾MODIS的SST表皮与以往公海研究的数据一样具有代表性和确定性。我们发现水温的水平梯度对SST表皮的确定性几乎没有影响。然而,我们发现,基于卫星的半封闭海湾SSTskin估计的代表性和确定性都因季节和位置特征而降低。伊势湾河口海温的代表性和确定性受到夏季水温垂直结构复杂的影响。由于SSTskin可以极大地提高对影响半封闭海湾水质的过程的理解,我们的研究结果表明,通过与现场海面温度(SSTdep)进行比较来预先验证SSTskin是重要的。
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引用次数: 0
A new criterion for critical suspension of nonuniform sediment 非均匀泥沙临界悬浮的新判据
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-07-03 DOI: 10.1080/21664250.2022.2120584
Zhi-lin Sun, Yun Gao, Lixia Sun, Haolei Zheng, Wengang Xiang, Yimeng Gao
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.
悬移临界条件作为悬移颗粒的下边界,是非均匀输沙理论的重要组成部分,在悬移运动的数值计算中具有重要作用。以往关于临界悬架的研究多基于罗斯数和希尔兹数。本文从最大粒径角度出发,通过水槽试验对非均匀泥沙的临界悬浮进行了研究。根据最大颗粒雷诺数的概念和对实验数据的分析,提出了一种新的非均匀泥沙临界悬浮判据。除非颗粒雷诺数小于或等于与流动和边界条件有关的最大雷诺数,否则沉积物不会悬浮。根据实验数据建立了粒子最大雷诺数与弗劳德数的3次幂和相对粗糙度的1/5次幂成正比的公式。该公式作为一种新的临界悬架判据,合理地描述了悬架初始运动的物理机制。该公式不仅与实验室和现场数据吻合较好,而且与传统准则相比也具有优势。
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引用次数: 0
Experimental and numerical investigation of breaking bores in straight and meandering channels with different Froude numbers 不同弗劳德数直槽和曲流槽破孔的实验与数值研究
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-07-03 DOI: 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.
摘要研究了弯曲河道中破孔的传播特性,重点研究了弗劳德数(F)对破孔的影响。实验采用不同的弗劳德数条件(高F = 3.99,低F = 1.53)在直流和曲流通道中进行。实验结果与浅水方程(SWE)模型和三维计算模型的计算结果进行了比较。在低F条件下,观察到像孤子裂变一样的水位振荡,并在曲流河道两岸被放大。这是用SWE模型计算的横向水面梯度的时间变化来解释的,它与非静水压力分量和速度的垂直分布无关。高F工况的特点是由大的能量损失引起的井口纵向梯度。在曲流河道中,SWE模式过高估计了两岸孔前附近的波高。这是因为与低F工况相比,曲流通道中的二次流增加了河床附近的流速和流动阻力,降低了波高。
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引用次数: 2
Impacts in ports on a tectonically active coast for climate-driven projections under the RCP 8.5 scenario: 7 Chilean ports under scrutiny 在RCP 8.5情景下,构造活跃海岸上的港口对气候驱动预测的影响:7个智利港口正在接受审查
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-06-25 DOI: 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.
摘要:在RCP 8.5情景下,对智利7个港口的运营停工和波浪漫顶造成的经济成本进行了评估。历史时期(1985-2004年)、本世纪中叶(2026-2045年)和本世纪末预测(2081-2100年)的波浪统计数据是用一个太平洋范围的模型计算的,由六个环流模型的风场强迫计算。然后,将海上波浪缩小到每个港口,通过将波浪高度与船舶停泊标准进行比较来计算停机时间的代理。历史预测和未来预测之间的停机时间差异归因于气候变化。结果显示,根据本世纪中期的预测,由于局部影响,一些港口将减少停机时间,而另一些港口将增加停机时间。然而,到本世纪末,所有港口的停机时间都将减少。此外,到本世纪中叶,由于极端海浪和海平面上升(SLR)的共同作用,北部港口的漫顶将增加,而南部港口的漫堤预计将略有减少。到本世纪末,整个地区的漫顶将增加,这主要是由SLR驱动的。然而,在海岸工程的设计寿命期间,可能发生的同震抬升/沉降会显著改变漫顶。最后,概述了一些旨在改善所分析港口基础设施管理和运营条件的实用建议。
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引用次数: 2
Numerical modeling of intertidal mudflat profile evolution under waves and currents 波浪和海流作用下潮间带泥滩剖面演变的数值模拟
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-06-25 DOI: 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.
利用现有的野外数据和扩展到允许砂和泥混合的跨岸数值模型CSHORE,研究了潮间带泥滩的侵蚀和增生剖面变化。对静水岸线和冲浪带的半日移进行了数值解析,以预测在约0.2 m高的破浪引起的小滨(底流)和滨流影响下的净跨岸和滨岸输沙率。通过使用等效岸线长度近似岸线输沙梯度,包括岸线输沙损失或增加。校准后的CSHORE重现了在206(195)天的侵蚀(增积)间隔内,在950米的跨海岸距离上测量到的约0.1米(0.1米)的侵蚀(增积)剖面变化。泥滩剖面的变化同样受到泥质特征、半日潮幅、波浪高度、周期和方向的影响。此外,岸线水位梯度和风应力对岸线流输沙也有影响。这项研究显示了在以往的数值模拟中可能被排除在外的冲浪带沉积物输运的重要性。
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引用次数: 0
Historical reconstruction of shoreline evolution at the Nam Dinh Coast, Vietnam 越南南定海岸海岸线演变的历史重建
IF 2.4 3区 工程技术 Q3 ENGINEERING, CIVIL Pub Date : 2022-05-17 DOI: 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.
摘要:位于越南北部的海口,近年来遭受了严重的海岸侵蚀,后退速度达到20米/年。根据对文献的系统回顾,海口沿岸的海岸线退缩趋势与苏河的水量和输沙量下降有关,苏河在1787年的一次大洪水后被认为是活跃的,导致河道分叉和前河道废弃。使用改进的单线模型对大约一千年(1000年至今)的海岸线演变进行了历史分析。模拟的海岸线与碳-14测年分析的结果、从旧地图中提取的历史参考点和海岸线位置以及从陆地卫星图像中获得的最近测量的海岸线变化非常一致。本研究表明,海口的侵蚀从18世纪末开始,而不是像以前的一些著作所说的那样,从20世纪初开始。我们认为,河流输沙量减少和其他过程(沉降和海平面上升)的综合影响是造成海口海岸长期侵蚀的主要原因。
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引用次数: 7
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Coastal Engineering Journal
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