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Cost‐benefit analysis (CBA) is commonly applied as a tool for deciding on risk protection. With CBA, one can identify risk mitigation strategies that lead to an optimal tradeoff between the costs of the mitigation measures and the achieved risk reduction. In practical applications of CBA, the strategies are typically evaluated through efficiency indicators such as the benefit‐cost ratio (BCR) and the marginal cost (MC) criterion. In many of these applications, the BCR is not consistently defined, which, as we demonstrate in this article, can lead to the identification of suboptimal solutions. This is of particular relevance when the overall budget for risk reduction measures is limited and an optimal allocation of resources among different subsystems is necessary. We show that this problem can be formulated as a hierarchical decision problem, where the general rules and decisions on the available budget are made at a central level (e.g., central government agency, top management), whereas the decisions on the specific measures are made at the subsystem level (e.g., local communities, company division). It is shown that the MC criterion provides optimal solutions in such hierarchical optimization. Since most practical applications only include a discrete set of possible risk protection measures, the MC criterion is extended to this situation. The findings are illustrated through a hypothetical numerical example. This study was prepared as part of our work on the optimal management of natural hazard risks, but its conclusions also apply to other fields of risk management.

This paper proposes two computation schemes for efficient evaluation of sets of reliability analyses associated with different time intervals. The first approach is based on sequential solving the reliability analyses starting from the last time interval. It enables to use the solution of a time interval as a starting point and to efficiently solve the reliability problem of preceding time intervals. Its implementation combined with Subset Simulation (SuS) and Sequential Importance Sampling (SIS) is presented. The second proposed approach is centered around reformulating the limit state function in a way that the time to failure can be described. This allows to efficiently obtain the estimates of failure probabilities and corresponding time intervals by one run of SuS. The numerical verification demonstrates that the proposed methods are capable of obtaining accurate estimates of lifetime reliability with a substantially reduced computational cost. ; The research leading to these results has received funding from the SAFEPEC project under the European Union's FP7 programme.

«Grundeinkommen von A bis Z» ist eine verständlich geschriebene Vertiefung und ein Argumentarium für die Diskussion um eine für viele irritierende Idee. Es nimmt sich die wichtigsten Fragen und Einwände für und gegen das Grundeinkommen vor: Wer arbeitet dann noch? Wer soll das bezahlen? Ist das gerecht, wenn man auch ohne Arbeit genug zum Leben hat? Ist das eine Lohnkostensubvention für private Unternehmen? Kommen dann mehr Migranten? Was ist der Wert, was die Zukunft der Arbeit? Neben den wichtigsten Fragen mit ihrem Dafür und Dawider erzählen die Autoren auch die Geschichte dieser Idee und gehen gründlich auf die Frage der Finanzierung ein. "Es gehört zu den Stärken des Buchs, dass die Autoren die Gegenargumente zur Initiative nicht nur auflisten, sondern sich damit auseinandersetzen. Auf einmal erscheint das protestantische Arbeitsethos nicht nur als Ideologie lustfeindlicher Moralapostel, es zeigt sich, dass Arbeit sozial benachteiligten Gruppen die Möglichkeit der Teilhabe an der Gesellschaft bietet... Das Buch beschränkt sich nicht auf die Schweiz, sondern beschreibt auch internationale Politprojekte mit einem Grundeinkommen. Solche Unternehmungen hat es in vier amerikanischen Bundesstaaten sowie in Kanada gegeben, aber auch in Namibia oder Indien. Die Erfahrungen zeigen, dass die Grundeinkommensidee nicht nur für westliche Wohlstandsnationen relevant ist. Das Pilotprojekt in Indien führte zu interessanten Begleiterscheinungen: Frauen mussten ein Konto unter ihrem eigenen Namen eröffnen und sich nicht wie bisher als Ehefrau ihres Mannes oder als Tochter eintragen. In letzter Konsequenz ist das bedingungslose Grundeinkommen ohnehin nur weltweit durchsetzbar. Hier zeigt sich eine Schwäche der Kampagne: Nicht die Idee, dass der Mensch auch ohne Überlebensangst arbeiten geht, ist utopisch, unrealistisch ist vielmehr, dass dies die politischen Verhältnisse das überall zulassen" (tell-review.de)

Abstract. Planning authorities are faced with a range of questions when planning flood protection measures: is the existing protection adequate for current and future demands or should it be extended? How will flood patterns change in the future? How should the uncertainty pertaining to this influence the planning decision, e.g., for delaying planning or including a safety margin? Is it sufficient to follow a protection criterion (e.g., to protect from the 100-year flood) or should the planning be conducted in a risk-based way? How important is it for flood protection planning to accurately estimate flood frequency (changes), costs and damage? These are questions that we address for a medium-sized pre-alpine catchment in southern Germany, using a sequential Bayesian decision making framework that quantitatively addresses the full spectrum of uncertainty. We evaluate different flood protection systems considered by local agencies in a test study catchment. Despite large uncertainties in damage, cost and climate, the recommendation is robust for the most conservative approach. This demonstrates the feasibility of making robust decisions under large uncertainty. Furthermore, by comparison to a previous study, it highlights the benefits of risk-based planning over the planning of flood protection to a prescribed return period.

Abstract. Different risk management activities, such as land-use planning, preparedness, and emergency response, utilize scenarios of earthquake events. A systematic selection of such scenarios should aim at finding those that are representative of a certain severity, which can be measured by consequences to the exposed assets. For this reason, defining a representative scenario as the most likely one leading to a loss with a specific return period, e.g., the 100-year loss, has been proposed. We adopt this definition and develop enhanced algorithms for determining such scenarios for multiple return periods. With this approach, we identify representative earthquake scenarios for the return periods of 50, 100, 500, and 1000 years in the Chilean communes of Valparaíso and Viña del Mar, based on a synthetic earthquake catalog of 20 000 scenarios on the subduction zone with a magnitude of Mw≥5.0. We separately consider the residential-building stock and the electrical-power network and identify and compare earthquake scenarios that are representative of these systems. Because the representative earthquake scenarios are defined in terms of the annual loss exceedance rates, they vary in function of the exposed system. The identified representative scenarios for the building stock have epicenters located not further than 30 km from the two communes, with magnitudes ranging between 6.0 and 7.0. The epicenter locations of the earthquake scenarios representative of the electrical-power network are more spread out but not further than 100 km away from the two communes, with magnitudes ranging between 7.0 and 9.0. For risk management activities, we recommend considering the identified scenarios together with historical events.