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Subject: hazard assessment × WGL Institute: PIK ×

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Now showing 1 - 5 of 5
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    The effect of univariate bias adjustment on multivariate hazard estimates
    (Göttingen : Copernicus Publ., 2019) Zscheischler, Jakob; Fischer, Erich M.; Lange, Stefan
    Bias adjustment is often a necessity in estimating climate impacts because impact models usually rely on unbiased climate information, a requirement that climate model outputs rarely fulfil. Most currently used statistical bias-adjustment methods adjust each climate variable separately, even though impacts usually depend on multiple potentially dependent variables. Human heat stress, for instance, depends on temperature and relative humidity, two variables that are often strongly correlated. Whether univariate bias-adjustment methods effectively improve estimates of impacts that depend on multiple drivers is largely unknown, and the lack of long-term impact data prevents a direct comparison between model outputs and observations for many climate-related impacts. Here we use two hazard indicators, heat stress and a simple fire risk indicator, as proxies for more sophisticated impact models. We show that univariate bias-adjustment methods such as univariate quantile mapping often cannot effectively reduce biases in multivariate hazard estimates. In some cases, it even increases biases. These cases typically occur (i) when hazards depend equally strongly on more than one climatic driver, (ii) when models exhibit biases in the dependence structure of drivers and (iii) when univariate biases are relatively small. Using a perfect model approach, we further quantify the uncertainty in bias-adjusted hazard indicators due to internal variability and show how imperfect bias adjustment can amplify this uncertainty. Both issues can be addressed successfully with a statistical bias adjustment that corrects the multivariate dependence structure in addition to the marginal distributions of the climate drivers. Our results suggest that currently many modeled climate impacts are associated with uncertainties related to the choice of bias adjustment. We conclude that in cases where impacts depend on multiple dependent climate variables these uncertainties can be reduced using statistical bias-adjustment approaches that correct the variables' multivariate dependence structure. © 2019 Copernicus GmbH. All rights reserved.
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    Flood risk in a range of spatial perspectives – from global to local scales
    (Katlenburg-Lindau : European Geophysical Society, 2019) Kundzewicz, Zbigniew W.; Su, Buda; Wang, Yanjun; Wang, Guojie; Wang, Guofu; Huang, Jinlong; Jiang, Tong
    The present paper examines flood risk (composed of hazard, exposure, and vulnerability) in a range of spatial perspectives – from the global to the local scale. It deals with observed records, noting that flood damage has been increasing. It also tackles projections for the future, related to flood hazard and flood losses. There are multiple factors driving flood hazard and flood risk and there is a considerable uncertainty in our assessments, and particularly in projections for the future. Further, this paper analyses options for flood risk reduction in several spatial dimensions, from global framework to regional to local scales. It is necessary to continue examination of the updated records of flood-related indices, trying to search for changes that influence flood hazard and flood risk in river basins.
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    Preface Sea hazards
    (Göttingen : Copernicus GmbH, 2013) Pelinovsky, E.; Didenkulova, I.; Mendez, F.; Rybski, D.; Tinti, S.
    [No abstract available]
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    Assessing social capacity and vulnerability of private households to natural hazards - Integrating psychological and governance factors
    (Göttingen : Copernicus GmbH, 2013) Werg, J.; Grothmann, T.; Schmidt, P.
    People are unequally affected by extreme weather events in terms of mortality, morbidity and financial losses; this is the case not only for developing, but also for industrialized countries. Previous research has established indicators for identifying who is particularly vulnerable and why, focusing on socio-demographic factors such as income, age, gender, health and minority status. However, these factors can only partly explain the large disparities in the extent to which people are affected by natural hazards. Moreover, these factors are usually not alterable in the short to medium term, which limits their usefulness for strategies of reducing social vulnerability and building social capacity. Based on a literature review and an expert survey, we propose an approach for refining assessments of social vulnerability and building social capacity by integrating psychological and governance factors.
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    Adapting flood preparedness tools to changing flood risk conditions: The situation in Poland
    (Sopot : Polish Academy of Sciences, 2014) Kundzewicz, Z.W.
    Flooding is the most destructive natural hazard in the Baltic Sea Basin in general and in Poland in particular. The notion includes floods from rivers and mountain torrents, as well as floods from sea surges in coastal areas, and floods from sewage systems. There have been several large floods in Poland in the last century and in recent decades, with damage exceeding 1% of the Polish GDP. The spatial and temporal characteristics of the flood risk in Poland are reviewed and observations and projections of changes in the flood hazard in the country are discussed. Furthermore, flood defences and flood preparedness systems in Poland are examined, with particular reference to the European Union (EU) Floods Directive, which is being implemented in Poland, an EU country. Finally, the public debate on flood risk and flood preparedness is reviewed.