Modeling of 500-year tsunamis for probabilistic design of coastal infrastructure in the Pacific Northwest     

Kwok Fai Cheung  Yong Wei  Yoshiki Yamazaki  Solomon C.S. Yim 《Coastal Engineering》2011

This paper describes the development of tsunami scenarios from the National Seismic Hazard Maps for design of coastal infrastructure in the Pacific Northwest. The logic tree of Cascadia earthquakes provides four 500-year rupture configurations at moment magnitude 8.8, 9.0, and 9.2 for development of probabilistic design criteria. A planar fault model describes the rupture configurations and determines the earth surface deformation for tsunami modeling. A case study of four bridge sites at Siletz Bay, Oregon illustrates the challenges in modeling of tsunamis on the Pacific Northwest coast. A nonlinear shallow-water model with a shock-capturing scheme describes tsunami propagation across the northeastern Pacific as well as barrier beach overtopping, bore formation, and detailed flow conditions at Siletz Bay. The results show strong correlation with geological evidence from the six paleotsunamis during the last 2800 years. The proposed approach allows determination of tsunami loads that are consistent with the seismic loads currently in use for design of buildings and structures.  相似文献   

What drives the global summer monsoon over the past millennium?     

Jian Liu  Bin Wang  So-Young Yim  June-Yi Lee  Jong-Ghap Jhun  Kyung-Ja Ha 《Climate Dynamics》2012,39(5):1063-1072

The global summer monsoon precipitation (GSMP) provides a fundamental measure for changes in the annual cycle of the climate system and hydroclimate. We investigate mechanisms governing decadal-centennial variations of the GSMP over the past millennium with a coupled climate model’s (ECHO-G) simulation forced by solar-volcanic (SV) radiative forcing and greenhouse gases (GHG) forcing. We show that the leading mode of GSMP is a forced response to external forcing on centennial time scale with a globally uniform change of precipitation across all monsoon regions, whereas the second mode represents internal variability on multi-decadal time scale with regional characteristics. The total amount of GSMP varies in phase with the global mean temperature, indicating that global warming is accompanied by amplification of the annual cycle of the climate system. The northern hemisphere summer monsoon precipitation (NHSMP) responds to GHG forcing more sensitively, while the southern hemisphere summer monsoon precipitation (SHSMP) responds to the SV radiative forcing more sensitively. The NHSMP is enhanced by increased NH land–ocean thermal contrast and NH-minus-SH thermal contrast. On the other hand, the SHSMP is strengthened by enhanced SH subtropical highs and the east–west mass contrast between Southeast Pacific and tropical Indian Ocean. The strength of the GSMP is determined by the factors controlling both the NHSMP and SHSMP. Intensification of GSMP is associated with (a) increased global land–ocean thermal contrast, (b) reinforced east–west mass contrast between Southeast Pacific and tropical Indian Ocean, and (c) enhanced circumglobal SH subtropical highs. The physical mechanisms revealed here will add understanding of future change of the global monsoon.  相似文献   

Evaluations on the relation of RC building damages with structural parameters after May 19, 2011 Simav (Turkey) earthquake     

Hayri Baytan Ozmen  Mehmet Inel  Erdal Akyol  Bayram Tanık Cayci  Hayri Un 《Natural Hazards》2014,71(1):63-84

An earthquake has struck Simav, Kutahya, located in the western part of Turkey on May 19, 2011. This paper focuses on the evaluation of the regional damage data and detailed investigation on a set of selected reinforced concrete buildings in Simav county center. The soil properties in Simav are examined in detail using multi-channel analysis of surface wave measurements, boreholes and laboratory test data. The damages are observed to be independent of soil conditions being hilly or plain, both in regional and Simav county center level. However, a slight relation is observed: as the soil period increases, so does the damage. The most damaged buildings are the four story buildings, resembling the case after some other earthquakes in Turkey. Regarding the detailed numerical evaluations on the building set, the properties highly correlated with seismic damage are investigated. Based on the obtained findings, it is concluded that the global building properties may not be enough to establish a strong relation with damage due to the local damages at the structural member level, especially for smaller seismic events.  相似文献   

Computational study on flow characteristics of acid mine drainage in oxidation pond with asymmetric and inclined shape     

Dong-Kil Lee  Gil-Jae Yim 《Environmental Earth Sciences》2014,72(3):757-766

A computational flow analysis was carried out to identify the retention time and flow distribution characteristics depending on the shape and depth of an oxidation pond. To evaluate the flow characteristics and efficiency of the oxidation pond with various shapes, the shape of the oxidation pond was defined by its horizontal and vertical deformation. The flow characteristics of the oxidation pond were found to be independent of the direction of the horizontal deformation angle, but dependent on the magnitude of the vertical deformation angle. The larger the vertical deformation angle, the stronger the short circulation of the mine drainage and the lower the inflow exchange efficiency in the oxidation pond. Moreover, the efficiency of the oxidation pond was increased when the dip angle direction of the pond was the same as that of the flow and the dip angle of the pond was similar to the velocity contour.  相似文献   

Comet assay for the detection of genotoxicity in blood cells of flounder (Paralichthys olivaceus) exposed to sediments and polycyclic aromatic hydrocarbons     

Woo S  Kim S  Yum S  Yim UH  Lee TK 《Marine pollution bulletin》2006,52(12):1768-1775

To investigate the genotoxic effect of marine sediments on aquatic organism, sediment samples were collected from 13 sites along the coast of Gwangyang Bay (Korea). Concentrations of polycyclic aromatic hydrocarbons (PAHs) in sediments were determined and the relationship between exposure of flounder blood cells to sediment extracts and DNA single-strand breakage in the blood cells was examined using the comet assay. Levels of DNA damage were proportionally increased by exposure concentration and the highest sediment-associated DNA damage was observed at the station showing the highest PAHs contamination. DNA damage in blood cells exposed to five types of PAHs (benzo[a]pyrene, fluoranthene, anthracene, pyrene and phenanthrene) and in flounder (Paralichthys olivaceus) exposed to benzo[a]pyrene (BaP) for 0, 2 and 4 days were assessed by measuring comet tail length. The tail lengths of five PAHs-exposed groups at 50 and 100 ppb were significantly different from the non-exposed group, and the genotoxic effect of BaP correlated with both concentration and duration of exposure. Throughout the study, significant differences in DNA breakage were recorded between cells exposed to sediment extracts or PAHs and non-exposed control. This study demonstrated the comet assay as a successful tool in monitoring contamination of marine sediments and assessing genotoxicity of PAHs in marine organisms, either in vitro or in vivo.  相似文献   

Simulating short‐circuiting flow in a constructed wetland: the implications of bathymetry and vegetation effects     

Joong‐Hyuk Min  William R. Wise 《水文研究》2009,23(6):830-841

Short‐circuiting flow, commonly experienced in many constructed wetlands, reduces hydraulic retention times in unit wetland cells and decreases the treatment efficiency. A two‐dimensional (2‐D), physically based, distributed modelling approach was used to systematically address the effects of bathymetry and vegetation on short‐circuiting flow, which previously have been neglected or lumped in one‐dimensional wetland flow models. In this study, a 2‐D transient hydrodynamics with advection‐dispersion model was developed using MIKE 21 and calibrated with bromide tracer data collected at the Orlando Easterly Wetland Cell 7. The estimated topographic difference between short‐circuiting flow zone and adjacent area ranged from 0·3 to 0·8 m. A range of the Manning roughness coefficient at the short‐circuiting flow zone was estimated (0·022–0·045 s m^?1/3). Sensitivity analysis of topographical and vegetative heterogeneity deduced during model calibration shows that relic ditches or other ditch‐shaped landforms and the associated sparse vegetation along the main flow direction intensify the short‐circuiting pattern, considerably affecting 2‐D solute transport simulation. In terms of hydraulic efficiency, this study indicates that the bathymetry effect on short‐circuiting flow is more important than the vegetation effect. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

香港近海第四纪研究──(香港)地区与全球对比表   总被引：1，自引：0，他引：1       下载免费PDF全文

严维枢 《第四纪研究》1996,16(3):283-287

通过对ＷＢ７钻孔的研究及过去资料的分析，香港近海第四纪地层层序至少可以识别出１０个海相与陆相交替的沉积序列。ＷＢ７钻孔位于香港西薄寮海峡，对该钻孔进行了连续取样。本文列出了两张地区性与全球沉积序列对比表，最早的海相沉积和陆相沉积年龄分别早于倒数第４次间冰期和倒数第５次冰期，地层对比表中把香港的第四纪地层与磁性地层、氧同位素地层、超微体化石组合及澳大利亚南部滨岸沙丘序列，新几内亚Ｈｕｏｎ半岛和印度尼西亚Ｓｕｍｂａ半岛的海岸阶地，美国大西洋海岸平原氧同位素序列，中国黄土阶段及海侵，东南亚的海岸和近海沉积进行了初步的对比。  相似文献   

Exceedance probability of multiple natural hazards: risk assessment in China’s Yangtze River Delta     

Liu  Baoyin  Siu  Yim Ling  Mitchell  Gordon  Xu  Wei 《Natural Hazards》2013,69(3):2039-2055

Natural Hazards - In recent years, greater attention has been given to advancing the theory and practice of assessing risk from multiple hazards. Most approaches calculate multi-hazard risk by...  相似文献   

Integrative assessment of sediment quality in terms of chemical contamination in Jinhae Bay,South Korea     

Sang Hee Hong  Gi Myung Han  Un Hyuk Yim  Dhong-il Lim  Sung Yong Ha  Nam Sook Kim  Won Joon Shim 《Ocean Science Journal》2014,49(3):265-278

The assessment of sediment quality by considering chemical contaminants is required for the effective management of coastal environments. In this study, complex data sets of heavy metals and organic pollutants were integrated to evaluate sediment quality. Thirty-two target pollutants were quantitatively determined in surface sediments from 80 stations in Jinhae Bay, South Korea. A sediment quality index (SQI) was derived by combining the functions of “scope” (the number of variables that do not meet guideline objectives) and “amplitude” (the magnitude by which these variables exceed the guideline objective). The SQI reflects the spatial gradient and differences in the contamination status with regard to heavy metals and organic pollutants in Jinhae Bay. Fifty-nine out of eighty stations surveyed (74%) were classified as being in “excellent” or “good” condition according to the SQI, and no stations were in a “poor” condition. The mean sediment quality guideline quotient (mSGQq) ranged from 0.06 to 0.31 (from nontoxic to marginally toxic). Acute sediment toxicity leading to amphipod mortality was recorded at 17 stations (21%) of the 80 surveyed, where the mortality rate was slightly over 20%. No significant relationship was observed between sediment toxicity and the concentration of each toxicant or mSQGq.  相似文献   

A comparison of regional monsoon variability using monsoon indices     

So-Young Yim  Bin Wang  Jian Liu  Zhiwei Wu 《Climate Dynamics》2014,43(5-6):1423-1437

The present study aims to (a) examine meteorological basis for construction of regional monsoon indices and (b) explore the commonality and differences among tropical regional monsoons, especially the teleconnection and monsoon–ENSO relationship. We show that the area-averaged summer precipitation intensity is generally a meaningful precipitation index for tropical monsoons because it represents very well both the amplitude of annual cycle and the leading mode of year-to-year rainfall variability with a nearly uniform spatial pattern. The regional monsoon circulation indices can be defined in a unified way (measuring monsoon trough vorticity) for seven tropical monsoon regions, viz.: Indian, Australian, western North Pacific, North and South American, and Northern and Southern African monsoons. The structures of the tropical monsoons are commonly characterized by a pair of upper-level double anticyclones residing in the subtropics of both hemispheres; notably the winter hemispheric anticyclone has a barotropic structure and is a passive response. Two types of upper-level teleconnection patterns are identified. One is a zonal wave train emanating from the double anticyclones downstream along the westerly jets in both hemispheres, including Indian, Northern African and Australian monsoons; the other is a meridional wave train emanating from the double anticyclones polewards, such as the South American and western North Pacific monsoons. Over the past 55 years all regional summer monsoons have non-stationary relationship with ENSO except the Australian monsoon. The regional monsoon–ENSO relationship is found to have common changing points in 1970s. The relationships were enhanced for the western North Pacific, Northern African, North American and South American summer monsoons, but weakened for the Indian summer monsoon (with a recovery in late 1990s). Regardless the large regional differences, the monsoon precipitations over land areas of all tropical monsoon regions are significantly correlated with the ENSO, suggesting that ENSO drives global tropical monsoon rainfall variability. These results provide useful guidance for monitoring sub-seasonal to seasonal variations of the regional monsoons currently done at NCEP and for assessment of the climate models’ performances in representing regional and global monsoon variability.  相似文献