Users Guide to Physical Modelling and Experimentation: Experience of the HYDRALAB Network is part of the International Association for Hydro-Environment Engineering and Research (IAHR) series of design manuals and monographs. This particular volume falls into the former category, providing guidance on best practice in the design and execution of physical models and laboratory experiments relating to coastal and fluvial hydraulics. The book is primarily based on work carried out within HYDRALAB III, part of the European Union's sixth framework programme for research (FP6). Edited by Frostick, McLelland and Mercer from the University of Hull in the UK, it has eight other ‘lead' authors, representing the work of approximately 70 researchers from the major laboratories in Europe. The book therefore embraces a considerable body of experience and knowledge within one volume, making it a valuable reference source.
The book has an introductory chapter followed by five further chapters dealing with five main topics. Chapter 2 on ‘Waves' presents an excellent overview of the primary considerations involved in the selection, generation and measurement of wave conditions for laboratory experiments on wave–structure and wave–sediment interactions. The chapter also includes guidance on planning and execution of experiments and on managing measurement data. A section covering measurement and analysis of wave reflection, wave asymmetries and multi-directional seas is particularly informative and includes extensive references to the related literature.
Model tests on rubble mound breakwaters are carried out to investigate issues such as wave overtopping, wave transmission and reflection, armour unit stability and design optimisation. Setting up and operating model tests of this kind is the focus of Chapter 3 on ‘Breakwaters'. The chapter covers scaling and wave issues (with some overlap with the earlier chapters), model layout and structure details, as well as methods for measuring wave hydrodynamics, run-up, overtopping, wave loading and structure damage. Again, the material is well referenced.
The longest chapter in the volume is Chapter 4 on ‘Sediment dynamics'. Here the discussion applies to physical experiments aimed at investigating fundamental processes, as well as to model testing prototype scenarios. An overview of fundamental aspects of sediment transport for fluvial and coastal environments is followed by an extensive section on sediments and scaling laws. The complexity of scaling for mobile sediment bed conditions is clearly elucidated; dynamic similarity is impossible to achieve for real-case scenarios, and practitioners need experience and knowledge to select the key non-dimensional parameters for experiment design. The authors illustrate this point very well and provide the benefit of their own experiences by discussing scaling considerations for a range of practical scenarios. A section on measurements includes an overview of methods for measuring sediment transport rate, sediment concentration and morphology. There are relatively short sections on experimental procedure, handling data, reporting and uncertainty assessment, before the chapter finishes with a number of practical examples that illustrate many of the key points of the chapter.
The impact of biota on hydrodynamics and sediment dynamics in the natural environment is an area of increasing interest within environmental fluid mechanics. Laboratory experiments aimed at investigating fundamental aspects of biota–flow and biota–sediment interactions, and physical model tests that include biota or biotic effects, are becoming increasingly common. Chapter 5, ‘Ecological experiments', addresses the challenges involved in properly incorporating biota within experiments and model tests. The importance of biotic effects is discussed from the ecological and hydraulic engineering perspectives. Four examples serve to illustrate key points: the impact of biota on flow and wave hydrodynamics; the use of vegetation to enhance erosion resistance of soils; the effects of burrowing animals on sea dyke integrity; and biological effects on the erosion resistance of sediment beds. This is followed by a lengthy section on experimental design, which incorporates dimensional analysis, a discussion of scaling issues related to biophysical modelling, turbulence, sediment transport and velocity measurements. Sections on incorporating plants and small animals in physical experiments contain extensive references to the literature and conclude with important guiding principles. For this reader, the sections on turbulence and on linking ecological experiments with numerical models do not integrate well within the main theme, but overall the chapter certainly succeeds in conveying the complexities and challenges associated with laboratory experiments and hydraulic models involving biota.
The combined use of physical and numerical models is the subject of Chapter 6, ‘Composite modelling'. The chapter presents accounts of eight composite modelling exercises conducted at eight different laboratories within the Hydralab CoMibbs project. The exercises include examples of numerical models used to optimise the design of physical models, and examples of physical models used to inform numerical or analytical models. Some of the exercises appear to have been more successful than others in terms of achieving the ‘integration' and ‘balance' required by the authors' definition of composite modelling, but they represent a good set of composite modelling examples overall, indicating why and how composite modelling techniques can be used to good effect.
The book has been produced to a high standard for the most part, although there are instances when figure quality could be better and use of colour would have aided clarity. A weakness is the degree of repetition across chapters, especially, but not only, relating to scaling, but this is somewhat understandable given the multi-authored approach.
Users Guide to Physical Modelling and Experimentation: Experience of the HYDRALAB Network draws on the experience and knowledge of a large number of researchers to capture the primary considerations involved in the design and execution of a wide range of physical models and laboratory experiments within fluvial and coastal hydraulics. Its coverage and approach is quite different, and complementary, to that of other books on modelling (one of the best of which, at least in the context of coastal hydraulics, is Hughes' book Physical Models and Laboratory Techniques in Coastal Engineering, published in 1993 by World Scientific in their Advances Series on Ocean Engineering). Packed with references to the specialist literature, Users Guide provides an excellent introduction point for the researcher or practitioner encountering experiments of this kind for the first time.
