Application of the hybrid ABV procedure for assessing community risk to hurricanes spatially

In 2011, the National Oceanic and Atmospheric Administration (NOAA) reported that the coastal population of the US that lives within 50 miles of the shoreline exceeded 50 % for the first time in history in spite of a high level of exposure to hurricanes and related flooding. Hurricane Andrew (1992), Mitch (1998), Ivan (2004), Katrina (2005), and Sandy (2012) are recent reminders of both the financial and human toll that result from hurricanes. Generally, hurricanes bring with them torrential rains and storm surges which enable destructive flooding inland and at the coastal (land–sea) interface and cause extensive and severe damages to residential structures and fatalities. An improved understanding of hurricanes and its interactive effects on the built environment will significantly reduce structural and non-structural damage and loss of life. This paper presents the method and results of a study that focused on application of a hybrid loss model which combines structural and non-structural damage vulnerabilities to quantify the damage and subsequent loss as a result of hurricanes, but particularly the extension to the community level. The methodology presented in this paper will help enable designers and/or planners to assess the change in anticipated losses at the community level as a result of one or more mitigation strategies as well as provide insight into land use planning.     

Large shear zones with no relative displacement

In the Oman ophiolite, the large scale Makhibiyah shear zone, in Wadi Tayin massif was generated with no or little relative motion between the two adjacent blocks, in contrast with what is reported from otherwise similar shear zones in deep crust and upper mantle. This shear zone is asymmetrical with, along one margin an asthenospheric mantle (～1200 °C) and along the adjacent margin, a lithospheric mantle (～1000 °C). Within the hotter side and with increasing shear strain, horizontal flow lines smoothly swing towards the shear zone direction before abutting against the wall of the lithosphere side. Profuse mafic melts issued from the hotter mantle are frozen in the shear zone by cooling along this lithospheric wall. Tectonic and magmatic activities are entirely localized within the asthenospheric compartment. Mantle flow lines were rotated, during their channelling along this NW‐SE shear zone, in the NW and SE opposite directions. Depending on whether the flow lines are deviated NW or SE, dextral or sinistral shear sense is recorded in the shear band mylonitic peridotites. This demonstrates that the shear zone was not generated by strike‐slip motion, a conclusion supported by regional observations.     

An analysis of coastal and inland fatalities in landfalling US hurricanes

Improvements in hurricane forecasts allowing for more timely evacuations from storm-surge zones are credited with reducing lethality of US landfalling hurricanes. The deadly reach of a hurricane, however, is not limited to storm-surge zones. About 80% of direct US hurricane fatalities since 1970 occurred outside of landfall counties, with most of these fatalities caused by inland flooding. We construct a geographic information system database combining the location and cause of fatalities, estimated wind speeds, and rainfall amounts for the entire track of the storm for landfalling US hurricanes between 1970 and 2007. We analyze the determinants of total fatalities and deaths due to freshwater drowning and wind. Inclusion of inland fatalities results in no downward trend in lethality over the period, in contrast to prior research. Local storm conditions significantly affect lethality, as one-inch and one-knot increases in rainfall and wind increase total fatalities by 28 and 4%. Rainfall significantly increases freshwater-drowning deaths and is insignificant for wind deaths, while the opposite relation holds for wind speed. While coastal counties do not exhibit a significantly higher amount of lethality risk versus inland counties for total or wind-driven fatalities, freshwater-drowning fatalities occur most frequently in inland counties along the center of the storm path and its outer county tiers as we have defined them.     

An improved methodology for estimation of two-phase relative permeability functions for heavy oil displacement involving compositional effects and instability

In heavy oil recovery by immiscible gas injection, adverse mobility ratio and gravity segregation along with influential mass transfer are the most crucial factors controlling displacement efficiencies. Obtaining relative permeability functions using conventional techniques that are based on a stable displacement front could be highly misleading. In this work, an improved methodology was proposed for estimating relative permeability curves under simultaneous effects of frontal instability and mass transfer using history-matching techniques. The compositional analysis of produced oil from a coreflood experiment was employed, which represents dynamic interactions more realistically. For the history matching, an optimum, high-resolution, two-dimensional core model was used, as opposed to the industry standard use of a one-dimensional model. The results of the simulation were then verified by a semi-empirical approach using the Koval model, which was then used to predict a similar experiment but in a vertical orientation. A good match was obtained between the forward simulation and the experiment. To highlight the effect of mass transfer on the shape of relative permeabilities, the simulation results from two immiscible gas injection corefloods were compared: CO₂ injection with mass transfer and N₂ injection without mass transfer. The results showed that the two estimated functions were quite similar, indicating that instability levels would determine the displacement pattern rather than local mass transfer. This integrated approach, therefore, highlights the importance of employing the right fluid model and an appropriate 2D-grid model in estimating relative permeabilities in displacement with instability and mass transfer against the current industry practice.     

Lateral displacement of crustal units relative to underlying mantle lithosphere: Example from the Bohemian Massif

We propose a mechanical model of deformation of the entire lithosphere of the Bohemian Massif (BM), whose core is formed by an asymmetric block of the Teplá-Barrandian (TB) unit in between the Saxothuringian (ST) and Moldanubian (MD) units. For the modelling, we have re-processed P-wave travel times recorded during the last two decades at dense networks of seismic stations installed in the BM during several passive seismic experiments. We also use previous results of anisotropic studies based on splitting of teleseismic shear waves. This allows us to refine estimates of the lithosphere thickness and delimit deep margins of the individual mantle lithosphere domains. The domains are rigid enough to preserve pre-orogenic olivine fabrics differently oriented in each of the units. Shapes and dips of the mantle boundaries, representing major zones of weakness inherited from the Variscan amalgamation of independent microplates, indicate that north-westward subductions beneath the TB unit dominated tectonic development of the core of the BM. Two mantle lithosphere domains with different fabric orientations, separated by a WSW-ENE striking shear zone, underlie the TB crust. The NW domain is the TB mantle lithosphere, while the SE domain is the MD mantle lithosphere thrust under the TB crust. Lithosphere of the north-western TB domain, compressed between early Variscan subductions of the ST continental lithosphere from the northwest and the MD continental lithosphere from the southeast, was pushed south-westward by about 50 km. Though the crust of the south-westerly TB promontory is commonly attributed to the MD unit, apparently it preserves the TB mantle lithosphere. The shifted TB lithosphere provides compelling evidence in support of older views suggesting that the Zone Erbendorf-Vohenstrauss (ZEV) originally belonged to the tilted western rim of the TB unit. During the final phase of the assemblage of the BM, the rigid TB lithosphere was disrupted by the southward pushing ST lithosphere along the newly formed NW-SE striking Jáchymov Fault Zone (JFZ). This lithosphere-scale process most likely changed the tectonic regime, released subduction-related forces and started the gravity-dominated tectonics.     

一种基于位移场分析的临界滑动面确定方法研究

安全系数的计算和临界滑动面的确定是边坡稳定性分析的两个组成部分,强度折减法可以得到合理的安全系数,但却不能准确刻画临界滑动面的位置。基于对滑动现象的认识,提出了一种基于位移场分析的临界滑动面确定方法,认为当边坡处于临界状态时,其潜在滑动面附近的位移等值线最为密集,潜在滑动面上的点往往是在深度方向上沿垂直滑面的位移变化率达到最大值的位置。将本文方法与Spencer法、岩质边坡模型试验进行了对比,验证了该方法在曲线和折线滑动面搜索方面的适用性和可靠性。同时,探讨了单元形状、疏密程度、离散点间距等因素对滑动面的影响。     

System dynamics assessment of mitigation strategies for power distribution poles subjected to hurricanes

This paper presents a system dynamics-based method to evaluate the cost-effectiveness of mitigation strategies for the replacement of power distribution poles subjected to hurricanes. The method demonstrates how the performance of poles distributed over a certain region, as well as the cost of maintenance and replacement, varies with time. Compared to a static assessment, the dynamic analysis provides more information for decision-making about replacement strategies, e.g., the changing trend of cost and performance in a period, and thus a potential trade-off between short-term and long-term benefits. Also, some variables and features that play an important role in cost-effectiveness are examined using sensitivity analysis, so that refinement of pole replacement strategies can be made. The model depicts the systemic and dynamic natures of long-term cost-effectiveness of pole maintenance and assists in the development of a better replacement strategy for multipole systems. In a case study, the model was applied to a typical region subjected to hurricanes, i.e., Miami-Dade County in Florida, USA. The simulation results from the model led to a maintenance strategy optimization that included both selection of class of poles and ways of replacement.     

A disaster risk management performance index

The Risk Management Index, RMI, proposed in this paper, brings together a group of indicators that measure risk management performance and effectiveness. These indicators reflect the organizational, development, capacity and institutional actions taken to reduce vulnerability and losses in a given area, to prepare for crisis and to recover efficiently from disasters. This index is designed to assess risk management performance. It provides a quantitative measure of management based on predefined qualitative targets or benchmarks that risk management efforts should aim to achieve. The design of the RMI involved establishing a scale of achievement levels or determining the distance between current conditions and an objective threshold or conditions in a reference country, sub-national region, or city. The proposed RMI is constructed by quantifying four public policies, each of which is described by six indicators. The mentioned policies include the identification of risk, risk reduction, disaster management, and governance and financial protection. Risk identification comprises the individual perception, social representation and objective assessment; risk reduction involves the prevention and mitigation; disaster management comprises response and recovery; and, governance and financial protection policy is related to institutionalization and risk transfer. Results at the urban, national and sub-national levels, which illustrate the application of the RMI in those scales, are finally given.     

Surrogate modeling of time-dependent metocean conditions during hurricanes

Metocean conditions during hurricanes are defined by multiple parameters (e.g., significant wave height and surge height) that vary in time with significant auto- and cross-correlation. In many cases, the nature of the variation of these characteristics in time is important to design and assess the risk to offshore structures, but a persistent problem is that measurements are sparse and time history simulations using metocean models are computationally onerous. Surrogate modeling is an appealing approach to ease the computational burden of metocean modeling; however, modeling the time-dependency of metocean conditions using surrogate models is challenging because the conditions at one time instant are dependent on not only the conditions at that instant but also on the conditions at previous time instances. In this paper, time-dependent surrogate modeling of significant wave height, peak wave period, peak wave direction, and storm surge is explored using a database of metocean conditions at an offshore site. Three types of surrogate models, including Kriging, multilayer perceptron (MLP), and recurrent neural network with gated recurrent unit (RNN-GRU), are evaluated, with two different time-dependent structures considered for the Kriging model and two training set sizes for the MLP model, resulting in a total of five models evaluated in this paper. The performance of the models is compared in terms of accuracy and sensitivity toward hyperparameters, and the MLP and RNN-GRU models are demonstrated to have extraordinary prediction performance in this context.

     

An intelligent displacement back-analysis method for earth-rockfill dams

An intelligent method for the effective displacement back-analysis of earth-rockfill dams was proposed by combining artificial neural networks and evolutionary calculation. This method employs artificial neural networks, with optimal architecture trained by the evolutionary calculation and Vogl’s algorithm, instead of the time-consuming finite element analysis. In the back analysis, the soil parameters were optimized by performing evolutionary calculations on the tested neural network. The proposed method was verified by applying it to the displacement back-analysis of two projects in China, and the influence of generation number and set size on the simulation ability of neural networks was investigated.     

地下水易污性评价方法——DRASTIC指标体系

本文较详细地介绍了目前欧美国家在地下水易污性评价中所广泛采用的ＤＲＡＳＴＩＣ指标体系方法,对其中所含的地下水埋深,含水层的净补给,岩性,土壤类型,渗流区介质,水力传导系数７个参数的评分以及在评分过程中所应注意的问题进行了具体的阐述,最后简要介绍了ＤＲＡＳＴＩＣ易污性指标体系法在大连沿海地区地下水易污性评价中应用的情况,实际应用表明该方法可适用于我国广大地区的地下水易污性评价工作。     

Impact of hurricanes storm surges on the groundwater resources

Ocean surges onto coastal lowlands caused by tropical and extra tropical storms, tsunamis, and sea level rise affect all coastal lowlands and present a threat to drinking water resources of many coastal residents. In 2005, two such storms, Hurricanes Katrina and Rita struck the Gulf Coast of the US. Since September 2005, water samples have been collected from water wells impacted by the hurricanes’ storm surges along the north shore of Lake Pontchartrain in southeastern Louisiana. The private and public water wells tested were submerged by 0.6–4.5 m of surging saltwater for several hours. The wells’ casing and/or the associated plumbing were severely damaged. Water samples were collected to determine if storm surge water inundated the well casing and, if so, its effect on water quality within the shallow aquifers of the Southern Hills Aquifer System. In addition, the samples were used to determine if the impact on water quality may have long-term implication for public health. Laboratory testing for several indicator parameters (Ca/Mg, Cl/Si, chloride, boron, specific conductance and bacteria) indicates that surge water entered water wells’ casing and the screened aquifer. Analysis of the groundwater shows a decrease in the Ca/Mg ratio right after the storm and then a return toward pre-Katrina values. Chloride concentrations were elevated right after Katrina and Rita, and then decreased downward toward pre-Katrina values. From September 2005 to June 2006, the wells showed improvement in all the saltwater intrusion indicators.     

The contribution of satellite SAR-derived displacement measurements in landslide risk management practices

Natural Hazards - Landslides are common phenomena that occur worldwide and are a main cause of loss of life and damage to property. The hazards associated with landslides are a challenging concern...     

Factors influencing cost-effectiveness of maintenance of power distribution poles subjected to hurricanes: a system-dynamics-based analysis

Based on a system dynamics (SD) model of long-term cost-effectiveness of power pole maintenance over 50 years, the influence of factors that affect cost-effectiveness was examined. Taking a typical region subjected to hurricanes (i.e., Miami-Dade County, USA) as a case, the SD model was established and tested with scenarios of power poles maintenance strategies. Factors such as wind speed variation (due to climate change), regional annual growth rate of the pole population, and discount rate were explored. It was shown that changing the parameters for these factors results in the following: The variation of wind speed due to climate change produces a negative impact on cost-effectiveness under the given replacement strategy; the factors of wind speed and annual growth rate of poles have a significant influence on the replacement ratio of poles particularly in the later period such as later 30 years; similarly, the discount rate has a marked impact on cumulative cost in the later decades. The difference between the contribution of factors is more significant in the later stages of the design life. The simulation results indicate how the change of these factors can lead to an impact on cost-effectiveness over time. The results have meaningful strategy implications, allowing an optimization of the timing of maintenance and a focus on different critical factors at various time periods.     

Regional-scale landslide risk assessment on Mt. Umyeon using risk index estimation

Landslides - The frequency of landslides and their magnitude are increasing worldwide due to global climate change, causing damage to people and infrastructure. Therefore, landslide risk assessment...     

基于DEM的活动构造研究

地形地貌参数指标是分析区域活动构造的有力工具。本文以渭河上游流域的活动构造研究为例,通过提取地貌的参数指标,如面积-高程积分(Hi)、流域盆地不对称度(AF)、山前曲折度(Smf)以及谷底宽度与谷肩高度的比值(Vf)、盆地形状指数(Bs)等,然后对地貌参数指标等级进行算术平均化(S/n),可得到区域的相对构造活动程度(Iat),分为:低、中等、高、较高四类等级。研究认为渭河上游流域的构造活动程度相对高(Iat=1.50),这种方法对探讨整个区域活动构造的差异性具有很好的效果和意义。