V. Tsimopoulou

Economic optimization of flood prevention systems in the Netherlands

After the flood disaster of 1953, the Netherlands adopted a rational approach to flood risk management with the use of protection standards determined by means of cost-benefit analysis. Due to scientific and political developments that have recently taken place, an update of the Dutch protection standards is being undertaken. One of the major priorities considered, is the need to address three issues, namely: (1) expressing the protection standards as failure probabilities of the flood defences, i.e. probabilities of breaching, instead of exceedance frequencies of water levels that is currently the case, (2) taking into account a spatial variability of those failure probabilities, and (3) considering various flooding scenarios. These aspects have been comprehensively addressed within a national flood risk analysis project, and partly considered in a numerical cost-benefit analysis approach, developed for the determination of new protection standards in the Netherlands. This paper presents an analytical economic optimization approach that makes an explicit link with all results of the national flood risk analysis project. In particular, an approach is outlined for the approximation of economically optimal design values of the failure probabilities along dyke-ring segments, which are treated as a series system of flood defences. The approach can assist in the determination of new protection standards in the Netherlands, but also in the design of flood prevention systems elsewhere.

The Emergence of Global Tsunami Awareness: Analysis of Disaster Preparedness in Chile, Indonesia, Japan, and Vietnam

The 2004 Indian Ocean tsunami was the first significant transoceanic tsunami in the digital age, allowing the population of the entire world to witness the destructive power of such phenomena. Despite the fact that such events form part of the culture of countries such as Chile and Japan, many other places had virtually not heard about them before 2004. However, subsequent events in the past 10 years have led to the emergence of a heightened stage of tsunami awareness not only in countries affected recently by these events, but also in other countries which have not experienced them for a long time, such as Vietnam. The present chapter will analyze tsunami awareness in 3 countries—Chile, Indonesia, and Japan—that recently experienced a tsunami and contrast them to the case of Vietnam. The analysis will include observations on whether a multi-layer-countermeasure system existed in each area, together with interviews conducted with local residents to understand their awareness about such events. It is clear that awareness in all countries has greatly increased, though further efforts are required to increase resilience so that the inhabitants of coastal areas are adequately protected.

Cost-Efficient Design of Multilayer Safety Systems Against Large-Scale Coastal Disasters

A great deal of coastal communities throughout the world are threatened by large-scale flooding caused by tsunamis, tropical cyclones, or extra-tropical storms. In order for those areas to stay protected, investments in multi-layer safety projects are often contemplated. This chapter presents a procedure to derive cost-efficient design specifications for multi-layer safety systems in disaster-prone areas. Its main objective is to provide guidance on how to determine an economically optimal set of measures representative of different safety layers by means of cost-benefit analysis. The proposed procedure is meant to assist engineers, spatial planners, or decision-makers involved in the development of high-risk areas or the reconstruction of destroyed areas. To showcase how the method works a hypothetical example of its application is given for the case of Rikuzentakata, a city on the coast of Tohoku in Japan that was afflicted by the 2011 tsunami.