Traditional design methods in coastal and river engineering have largely been based on deterministic design methods. However, they have always contained an element of probabilistic design as the design loading is taken as an acceptable extreme value. Knowing the expected design life therefore allows calculation of the probability that the design event will occur within the lifetime of the scheme. For example, a design return period of 100 years and a design life of 50 years results in a probability of failure of about 40%. At first sight, this appears to be unacceptably large and counter to our experience of actual scheme failures. This is often due to the adoption of the serviceability limit state in design, rather than the ultimate limit state and/or the liberal use of factors of safety or safety margins. This can lead to uneconomic design with unknown reliability. Probabilistic design methods allow a much clearer assessment of the risk of failure ( = hazard × consequence), accounting for uncertainties in both environmental loading and resistance (strength) of the scheme as well as the consequences of failure to meet the required service levels. Such methods were first introduced in civil engineering for the design of structures. Their uptake in coastal and hydraulic engineering has been much more recent and the methods are still evolving.
This book sets out, for the first time, a comprehensive description of all the elements involved in probabilistic design in coastal and hydraulic engineering. To set the scene, chapter 1 provides a descriptive introduction to the concepts of uncertainty, risk and reliability. In chapters 2 and 3 the author then proceeds to describe elements of probability theory and stochastic processes. The treatment is rigorous, but accessible to non-specialists. Chapter 4 contains an illuminating and practically useful discussion of the theory of extremes and is clearly informed by the author's own professional and research experience in the matter. Chapter 5 is the pivotal chapter, introducing and developing the central themes of uncertainty and reliability analysis. This includes a full discussion and mathematical description of probabilistic design methods, commonly known as Levels I, II and III. Having provided all the theoretical elements necessary, chapter 6 contains a comprehensive set of applications with fully worked examples for fluvial flood defences, coastal flood defences, flow in pipes and drains, maritime and offshore structures, coastal protection and coastal morphology. Finally, chapter 7 provides a discussion of the methods used to assess the reliability of systems, supported by some practical examples including the notable (UK) national-scale assessment of flood risk.
The intended readership, as stated on the back cover, is for advanced undergraduates and MSc students studying flood and coastal defence matters. It is also intended to serve as a source of reference for consultants, practitioners and academics. The author has succeeded in these aims, with elements to offer the entire targeted readership.
In summary, this new text provides a unique set of insights into the disparate elements required to understand and apply probabilistic design methods and to undertake reliability assessments for coastal and hydraulic engineering schemes. The concepts are well explained for readers with an engineering background, making the sometimes complex theory accessible. The author's extensive professional and research experience of such matters infuses the text with rigour and enthusiasm.
