Risk-based design of large-scale flood defence systems

Civil Engineering and Geoscience

Economic optimal design of vertical breakwaters

In Europe the interest in and the importance of vertical breakwaters is growing. A central point is the optimal geometry, e.g. the width and height of the breakwater caisson chosen such that the total costs over the lifetime of the structure are minimized. Probabilistic design tools provide several methods to determine the probability of failure of a structure. In a design process however, the designer of the structure is faced with the problem of defining the acceptable probability of failure. In general there are three ways to determine the optimal probability of failure: \u95 Consider the probability of dying of an individual due to collapse of the structure (individual point of view); \u95 Consider the probability of occurrence of a certain number of casualties in case of failure of the structure (societal point of view); \u95 Minimize the sum of initial investment and capitalized risk over the lifetime of the structure (economical optimization). In the case of a breakwater without amenities the probability of loss of life due to failure is very small, but the economic losses can be severe. Therefore the application of the economical optimization is suitable. In this study a framework for the optimization of vertical breakwaters is developed. The optimization procedure has been implemented in a numerical model. In this model three failure modes are considered: \u95 Sliding of the caisson over the rubble foundation (ultimate limit state); \u95 Overturning of the caisson (ultimate limit state); \u95 Wave transmission (serviceability limit state). Several calculations have been made with the computer program. The results of the calculations show the following: \u95 The capitalized risk has a large influence on the optimal geometry of the structure; \u95 In general only one mechanism largely determines the probability of failure of an optimal designed vertical breakwater. This mechanism is in general the one which is most expensive to strengthen the breakwater for. In the situation chosen in this stUdy, this is rotation failure of the caisson. The caisson width is the most expensive design variable; \u95 The optimal design is influenced by all random variables used in the design; \u95 Wave transmission influences the optimal geometry of a breakwater towards higher and narrower caissons. In the situation chosen in this study, a caisson height such that no wave transmission occurs seems optimal. The developed model provides a good starting point for the development of more advanced optimization models.Hydraulic EngineeringCivil Engineering and Geoscience

Optimal design of flood defence systems in a changing climate

Civil Engineering and Geoscience

Applying adaptive design for the replacement of a weir in the Meuse River: a case study

The nature of the Meuse River is more than any other major river in the Netherlands formed by the presence of weirs. These were constructed almost one century ago to enable transport of coal; nowadays, the boundary conditions have changed and will continue to change in the future. The weirs reach the end of their lifetime around 2030; during their replacement, the uncertain future has to be considered. This paper presents an adaptive river design, which is able to adapt to the changing requirements. Special attention is given to the design of an adaptive weir in the Meuse River to replace the present weir at Belfeld. A new design methodology has been developed and applied. The methodology results shown in an adaptation scheme, give an overview of the required regional and weir adaptations. These adaptations are required to serve the scenario-dependent purposes in the future.Accepted Author ManuscriptHydraulic Structures and Flood Ris

Probabilistic design of breakwaters in shallow hurricane-prone areas

One of the failure mechanisms of a rubble mound breakwater is the failure of its armour layer. In order to determine the stability of an armour layer, the design load has to be defined, which is in fact the wave that attacks the structure. Being a highly stochastic phenomenon, the wave action is not easily defined, while there is always some uncertainty inherent to its definition. In a deterministic calculation this uncertainty is being left to engineering judgment, as the possible variations of the design wave height are not taken into account in a coherent way. In order to explicitly incorporate uncertainties into the design process, and therefore increase its reliability, probabilistic design methods should be applied. A commonly used approach is a semi-probabilistic computation, which introduces the application of partial safety coefficients. Nevertheless the indicated methods to derive and apply them do not clarify the uncertainties incorporated, adding an undefined degree of safety in the process, or end up with incorrect results under certain conditions. Another approach is a fully probabilistic computation. This type of design tackles explicitly a great deal of uncertainties, hence its results can be considered much more accurate. However it is not commonly used, due to the fact that there are not straightforward guidelines to support it, and therefore a number of critical decisions by the designers are required. This paper focuses on the application of probabilistic methods for armour layer design of rubble mound breakwaters. The main objective is to indicate the weaknesses of the previously mentioned methods, and to suggest a probabilistic design approach that is both attractive to designers and sufficiently reliable. This can be achieved through elaboration of a design example with the various methods, followed by a critical evaluation of the results.Hydraulic EngineeringCivil Engineering and Geoscience

Developments in the management of flood defences and hydraulic infrastructure in the Netherlands

This article highlights recent developments in flood risk management in the Netherlands and presents approaches for reliability analysis and asset management for flood defences and hydraulic infrastructure. The functioning of this infrastructure is of great importance for the country as large parts of it are prone to flooding. Based on a nationwide flood risk assessment, new safety standards for flood defences have been derived in the form of maximal acceptable failure probabilities. A framework for the reliability-based analysis of the performance of hydraulic infrastructure is introduced. Within this context, various challenges are discussed, such as the dynamic nature of loads, resistance and reliability requirements over time. Various case studies are presented to highlight advances and challenges in various application fields. The first case illustrates how structural health monitoring contributes to a better characterisation of the reliability of the defences and how innovative measures can enhance the reliability. The second case discusses how the river system can be managed in the context of the new safety standards. The third case shows how upgrades and reinforcements of hydraulic structures can be evaluated taking into account (uncertain) future developments, such as sea level rise.Hydraulic Structures and Flood Ris

Organelle Segmentation Facilitated by Correlative Light Microscopy Data

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Microscopy Instrumentation & TechniquesProduct

Constructieve Waterbouwkunde: Deel A Algemeen

Civil Engineering and GeosciencesWaterbouwkund