Assessing levels of reliability for design criteria for hurricane and storm damage risk reduction structures

In the wake of Hurricane Katrina, the U.S. Army Corps of Engineers (USACE) updated design methodologies and required factors of safety for hurricane and storm damage risk reduction system (HSDRRS) structures to incorporate lessons-learned from the system performance during Katrina and results of state-of-the-art research in storm surge modeling and foundation behavior. However, the criteria (USACE 2008) were not calibrated to a target reliability, which creates the need to understand the reliability provided by designs using those criteria, especially for pile-founded structures subject to global instability. This dissertation presents a methodology for quantifying the reliability of pile-founded structures that can be applied to hurricane risk reduction structures or more broadly to other types of pile-founded structures. The emphasis of this study is on a representative hurricane risk reduction structure designed using the new USACE criteria, for which the reliability is quantified for comparison to industry target reliabilities. A designer-friendly methodology for quantifying the reliability of hurricane risk reduction structures is presented, along with recommendations developed from a state-of-the-art review of geotechnical, hydraulic, and structural uncertainty data. This methodology utilizes commercial software and routine design methods for the development of inputs into an overarching framework that includes point estimate simulation models and event tree methods to quantify the structure’s system reliability. The methodology is used to illustrate differences in analysis results with and without accounting for variance reductions due to spatial correlation are also presented through stability and flowthrough limit states. Element reliabilities and overarching “system” reliabilities for a representative structure are quantified for hydrostatic hurricane storm surge loadings, soil loading, and dead loads. Wave loadings and impact loadings are not considered. The use of variance reductions on undrained shear strengths for point estimate simulations produced higher system reliability indices than the simulations not considering variance reductions for the stability and flowthrough limit states. Using the reduced variances, computed element and system reliabilities were above the industry target reliability indices presented in the literature

Studies on Hazard Characterization for Performance-based Structural Design

Performance-based engineering (PBE) requires advances in hazard characterization, structural modeling, and nonlinear analysis techniques to fully and efficiently develop the fragility expressions and other tools forming the basis for risk-based design procedures. This research examined and extended the state-of-the-art in hazard characterization (wind and surge) and risk-based design procedures (seismic). State-of-the-art hurricane models (including wind field, tracking and decay models) and event-based simulation techniques were used to characterize the hurricane wind hazard along the Texas coast. A total of 10,000 years of synthetic hurricane wind speed records were generated for each zip-code in Texas and were used to statistically characterize the N-year maximum hurricane wind speed distribution for each zip-code location and develop design non-exceedance probability contours for both coastal and inland areas. Actual recorded wind and surge data, the hurricane wind field model, hurricane size parameters, and a measure of storm kinetic energy were used to develop wind-surge and wind-surge-energy models, which can be used to characterize the wind-surge hazard at a level of accuracy suitable for PBE applications. These models provide a powerful tool to quickly and inexpensively estimate surge depths at coastal locations in advance of a hurricane landfall. They also were used to create surge hazard maps that provide storm surge height non-exceedance probability contours for the Texas coast. The simulation tools, wind field models, and statistical analyses, make it possible to characterize the risk-consistent hurricane events considering both hurricane intensity and size. The proposed methodology for event-based hurricane hazard characterization, when coupled with a hurricane damage model, can also be used for regional loss estimation and other spatial impact analyses. In considering seismic hazard, a risk-consistent framework for displacement-based seismic design of engineered multistory woodframe structures was developed. Specifically, a database of probability-based scale factors which can be used in a direct displacement design (DDD) procedure for woodframe buildings was created using nonlinear time-history analyses with suitably scaled ground motions records. The resulting DDD procedure results in more risk-consistent designs and therefore advances the state-of-the-art in displacement-based seismic design of woodframe structures

Climate Change and Sea Level Rise Projections for Boston

While the broad outlines of how climate change would impact Boston have been known for some time, it is only recently that we have developed a more definitive understanding of what lies ahead. That understanding was advanced considerably with the publication of Climate Change and Sea Level Rise Projections for Boston by the Boston Research Advisory Group (BRAG).The BRAG report is the first major product of "Climate Ready Boston," a project led by the City of Boston in partnership with the Green Ribbon Commission and funded in part by the Barr Foundation. The BRAG team includes 20 leading experts from the region's major universities on subjects ranging from sea level rise to temperature extremes. University of Massachusetts Boston professors Ellen Douglas and Paul Kirshen headed the research.The BRAG report validates earlier studies, concluding Boston will get hotter, wetter, and saltier in the decades ahead (see figures below). But the group has produced a much more definitive set of projections than existed previously, especially for the problem of sea level rise. BRAG also concluded that some of the effects of climate change will come sooner than expected, accelerating the urgency of planning and action

GMES-service for assessing and monitoring subsidence hazards in coastal lowland areas around Europe. SubCoast D3.5.1

This document is version two of the user requirements for SubCoast work package 3.5, it is SubCoast deliverable 3.5.1. Work package 3.5 aims to provide a European integrated GIS product on subsidence and relative sea level rise. The first step of this process was to contact the European Environment Agency as the main user to discover their user requirements. This document presents these requirments, the outline methodology that will be used to carry out the integration and the datasets that will be used. In outline the main user requirements of the EEA are: 1. Gridded approach using an Inspire compliant grid 2. The grid would hold data on: a. Likely rate of subsidence b. RSLR c. Impact (Vulnerability) d. Certainty (confidence map) e. Contribution of ground motion to RSLR f. A measure of certainty in the data provided g. Metadata 3. Spatial Coverage - Ideally entire coastline of all 37 member states a. Spatial resolution - 1km 4. Provide a measure of the degree of contribution of ground motion to RSLR The European integration will be based around a GIS methodology. Datasets will be integrated and interpreted to provide information on data vlues above. The main value being a likelyhood of Subsidence. This product will initially be developed at it’s lowest level of detail for the London area. BGS have a wealth of data for london this will enable this less detialed product to be validated and also enable the generation of a more detailed product usig the best data availible. One the methodology has been developed it will be pushed out to other areas of the ewuropean coastline. The initial input data that have been reviewed for their suitability for the European integration are listed below. Thesea re the datasets that have European wide availibility, It is expected that more detailed datasets will be used in areas where they are avaiilble. 1. Terrafirma Data 2. One Geology 3. One Geology Europe 4. Population Density (Geoland2) 5. The Urban Atlas (Geoland2) 6. Elevation Data a. SRTM b. GDEM c. GTOPO 30 d. NextMap Europe 7. MyOceans Sea Level Data 8. Storm Surge Locations 9. European Environment Agencya. Elevation breakdown 1km b. Corine Land Cover 2000 (CLC2000) coastline c. Sediment Discharges d. Shoreline e. Maritime Boundaries f. Hydrodynamics and Sea Level Rise g. Geomorphology, Geology, Erosion Trends and Coastal Defence Works h. Corine land cover 1990 i. Five metre elevation contour line 10. FutureCoas

A flood vulnerability index for coastal cities and its use in assessing climate change impacts

Worldwide, there is a need to enhance our understanding of vulnerability and to develop methodologies and tools to assess vulnerability. One of the most important goals of assessing coastal flood vulnerability, in particular, is to create a readily understandable link between the theoretical concepts of flood vulnerability and the day-to-day decision-making process and to encapsulate this link in an easily accessible tool. This article focuses on developing a Coastal City Flood Vulnerability Index (CCFVI) based on exposure, susceptibility and resilience to coastal flooding. It is applied to nine cities around the world, each with different kinds of exposure. With the aid of this index, it is demonstrated which cities are most vulnerable to coastal flooding with regard to the system's components, that is, hydro-geological, socio-economic and politico-administrative. The index gives a number from 0 to 1, indicating comparatively low or high coastal flood vulnerability, which shows which cities are most in need of further, more detailed investigation for decision-makers. Once its use to compare the vulnerability of a range of cities under current conditions has been demonstrated, it is used to study the impact of climate change on the vulnerability of these cities over a longer timescale. The results show that CCFVI provides a means of obtaining a broad overview of flood vulnerability and the effect of possible adaptation options. This, in turn, will allow for the direction of resources to more in-depth investigation of the most promising strategies

Process-based indicators to assess storm induced coastal hazards

Storms are responsible for several hazards (e.g. overwash, erosion, inundation) in coastal areas, leading to the destruction of property and loss of life in populated areas. Various indicators are used to express potential storm impact and describe the associated hazards. The most commonly used indicators include either forcing parameters (e.g. wave height, sea level) or coastal morphologies (e.g. dune height or berm width). Whereas they do not represent the processes associated with storm induced hazards in coastal areas. Alternatively, a hazard could be better characterised if process-based indicators are used instead. Process-based indicators express the result of the forcing mechanisms acting over the coastal morphology and reflect both hydrodynamic and morphological characteristics. This work discusses and synthesizes the most relevant process-based indicators for sandy shores subject to overwash, erosion and inundation promoted by storms. Those include: overwash depth, potential and extent; shoreline, berm or dune retreat; vertical erosion; and inundation depth and extent. The selection of a reduced set of process-based indicators to identify coastal hazards induced by storms in sandy coasts will facilitate comparison of different coastal behaviours for distinct storm return periods, and help to optimise coastal management plans, thereby contributing to the reduction of coastal risks.info:eu-repo/semantics/publishedVersio

A Methodological Approach to Determine Sound Response Modalities to Coastal Erosion Processes in Mediterranean Andalusia (Spain)

Human occupation along coastal areas has been greatly increasing in recent decades and, in many places, human activities and infrastructures are threatened by erosion processes that can produce relevant economic and human losses. In order to reduce such impacts and design sound management strategies, which can range from the "no action" to the "protection" option, coastal managers need to know the intrinsic coastal sensitivity and the potential vulnerability and value of land uses. In this paper, in a first step, coastal sensitivity was determined by calculating the following: (i) the spatial distribution at the coast of the wave forcing obtained by using the ERA5 wave dataset and defined as the energy associated with the 50-year return period storm. Two storm conditions were considered, that is, one for the eastern and one for the western parts of the Andalusia Mediterranean coast, respectively, characterized by a height of 8.64-7.86 m and 4.85-4.68 m and (ii) the existence of a buffer zone, namely the dry beach width expressed as a multiple of the 20-year predicted shoreline position that was calculated using a dataset of aerial photographs covering a time span from 1956 to 2016. Coastal sensitivity values were divided into five classes with class 1 indicating the lowest sensitivity (i.e., the presence of a wide buffer zone associated with low wave energy flux values) and class 5 the highest sensitivity (i.e., a narrow buffer zone associated with very high wave energy flux values). In a second step, land uses were obtained from the official Land Use Map of the Andalusia Region, based on the results of the "Coordination of Information on the Environment" (CORINE) European Project. Such uses were divided into five classes from class 1 including natural areas (typologies "A" and "B" of the CORINE Project) to class 5 including very capital land uses (typologies "E1" and "E2"). In a third step, information concerning coastal sensitivity and land uses was crossed to determine the best mitigation strategies to cope with erosion processes. The "no action" option was observed at the westernmost area of Cadiz Province and at some areas from the west coast of Almeria Province, where both coastal sensitivity and land use classes show low values; the "adaptation" option was recorded along more than one half of the coast studied, essentially at natural areas with high sensitivity and at urbanized areas with low sensitivity; and the "protection" option was observed especially at some areas from the center and eastern part of Malaga Province and at the easternmost areas of Almeria Province, where both coastal sensitivity and land use classes presented high values

Economic impacts of climate change on cities: A survey of the existing literature

This paper attempts a survey of the existing literature on the direct market impacts of climate change on urban centers. In the first chapter, the argument for the importance of cities as case studies for research on the impacts of climate change is established using current population data and future projections. In the second chapter, a brief overview of how we can go from the global level to the regional level, when we consider the impacts of climate change, is given. In the third chapter, we examine the models and their estimates for the sea level rise impacts on cities. In the fourth chapter, we summarize the impacts of increasing temperature. In the last two chapters, we elaborate on the current limitations and we present some conclusions. --

Vulnerability of bangladesh to cyclones in a changing climate : potential damages and adaptation cost

This paper integrates information on climate change, hydrodynamic models, and geographic overlays to assess the vulnerability of coastal areas in Bangladesh to larger storm surges and sea-level rise by 2050. The approach identifies polders (diked areas), coastal populations, settlements, infrastructure, and economic activity at risk of inundation, and estimates the cost of damage versus the cost of several adaptation measures. A 27-centimeter sea-level rise and 10 percent intensification of wind speed from global warming suggests the vulnerable zone increases in size by 69 percent given a +3-meter inundation depth and by 14 percent given a +1-meter inundation depth. At present, Bangladesh has 123 polders, an early warning and evacuation system, and more than 2,400 emergency shelters to protect coastal inhabitants from tidal waves and storm surges. However, in a changing climate, it is estimated that 59 of the 123 polders would be overtopped during storm surges and another 5,500 cyclone shelters (each with the capacity of 1,600 people) to safeguard the population would be needed. Investments including strengthening polders, foreshore afforestation, additional multi-purpose cyclone shelters, cyclone-resistant private housing, and further strengthening of the early warning and evacuation system would cost more than $2.4 billion with an annual recurrent cost of more than$50 million. However, a conservative damage estimate suggests that the incremental cost of adapting to these climate change related risks by 2050 is small compared with the potential damage inthe absence of adaptation measures.Climate Change Mitigation and Green House Gases,Climate Change Economics,Science of Climate Change,Hazard Risk Management,Global Environment Facility