Abstract
This book presents foundational principles in fluvial geomorphology and explains why these principles are important for understanding rivers as dynamic agents of change in the Earth’s system. It provides a detailed analysis and information on all the main topics in fluvial geomorphology, from sediment and flow dynamics, the complex processes in rivers and their floodplains, to their main impacts and management implications. The goal is to offer a resource both for scientists interested in fluvial geomorphology and for practitioners carrying out river management issues.
The author and his credentials need no introduction, and this book allows him to draw upon his knowledge and experience after more than 30 years as a professor. In the preface, the author reasonably argues that the structure and content of this book represents an approach to teaching that allows “those students with advanced math and science background to feel challenged, while not overwhelming those without advanced training in those sciences”. Personally, I have found this to be the case when reading the book. It can be used at different levels of information, from the main principles and concepts to the exhaustive and complex analysis of, for example, hydraulic processes in Chapter 4.
The book is divided into 16 chapters and each chapter is organized using headings and subheadings in the form of questions, which is quite informative for the reader. The introduction provides a general overview of the relevance of rivers, and main concepts such as what a river system is or what fluvial geomorphology is. After this general introduction, Chapter 2 is a complete guide to how rivers form, which is fundamental prior to considering their dynamics. The author highlights the relevance of the dynamics of drainage basins and stream networks in shaping the Earth’s surface, as fluvial action is a key agent contributing to landscape dynamics over geological time spans. Questions related to how the formation of channels on hillslopes is related to overland flow, or how river networks form, grow and evolve, are answered in depth.
In Chapters 3–8, the main drivers and fluvial processes are carefully presented and explained, with a lot of detail, including all the geomorphological implications for rivers. All the chapters start by explaining the relevance of the processes dealt with in the chapter, presenting strong arguments that encourage the reader to continue learning more about it. How important rivers are in transporting sediment and dissolved material on a global scale is the subject of Chapter 3, in which the author describes factors controlling the total sediment flux from drainage basins, and the controlling variables for influencing sediment flux. Chapter 4 presents the basic principles of open-channel hydraulics, providing the foundation for subsequent chapters that relate these principles to the fluvial processes involved in the dynamics of river channels. This chapter is particularly profuse in equations and diagrams to fully cover all the concepts that the chapter deals with. Furthermore, Chapter 5 presents the basic principles of sediment transport in rivers, from the major sources of sediment to the factors controlling the mobilization of bed material. In Chapter 6 the fundamental hydrological principles and their relation to river morphology are examined, with particular emphasis on the magnitude and frequency of hydrological events, as well as their relationship with the form and morphodynamics of rivers.
Chapter 7 focuses specifically on the factors that influence channel geometry, particularly width and depth, while Chapter 8 introduces the major planform types and the environmental conditions that influence the development of different planform characteristics. The pattern of a river when viewed from directly above is one of the most distinctive characteristics of river morphology. Over the past six decades, the classification of rivers on the basis of differences in planform has been the focus of considerable attention in fluvial geomorphology. Various typologies and forms have been selected by the author to explain the dynamics and processes occurring in them; not only in meandering rivers (Chapter 9), braided rivers (Chapter 10) and anabranching rivers (Chapter 11), but also in complex fluvial zones, such as river confluences (Chapter 12). Chapter 13 is a masterclass on the vertical dimension of rivers, gathering essential concepts and tools in river research and management, such as longitudinal profiles and adjustments and step-pool morphology descriptions. River dynamics used to be intimately connected to processes of floodplain development and change, and those aspects are described in Chapter 14.
From a geomorphological perspective, humans alter river systems both directly and indirectly, and this is precisely the classification that the author uses in the enumeration of the long list of pressures that humans trigger on river dynamics in Chapter 15. Regarding indirect effects, starting with changes in land cover and use that affect river systems, the author describes the main impacts brought about by agriculture, timber harvesting, surface mining and urbanization. Moreover, human-induced climate change is presented as another relevant indirect human effect, although not so profusely explored and discussed as the others. With regards to direct effects, dam and reservoir construction, channelization and mining of river sediments are offered as the most frequently occurring.
Finally, since the title of the book includes the phrase “geomorphology to support river management”, Chapter 16 discusses river management in a way that effectively integrates basic and applied science. I completely agree with the author that geomorphological assessment of rivers provides the opportunity for the input of this type of information into the watershed planning process, which is the ideal context in which environmental management of rivers should occur. Its contribution to the development of management strategies is indisputable and involves the participation of fluvial geomorphologists in the formulation of river management strategies, including approaches to river restoration, naturalization and mitigation, to achieve societal goals.
The book has a profuse reference list, with an excellent equilibrium between classic references, which provided the basis of this subject, and the more modern research developments, letting the reader realize how ideas and knowledge have advanced to the present day, while also pointing out ongoing discussions and questions. The text is supplemented with an abundance of high-quality photographs, maps, graphs, diagrams and sketches, reinforcing the illustrative value of the book and exemplifying many of the features and processes mentioned. Moreover, there are numerous tables where the author has carefully collected results of past studies, providing a resource for future work. For instance, Table 6.2 with examples of effective discharge determinations, Table 7.4 with examples of multivariate models of channel forms and Table 13.1 showing examples of functional forms used to depict river longitudinal profiles. Despite the fact that some of the concepts and processes commented on in this book frequently require in-depth explanations and complex mathematical expressions, the author employs a clear and concise language, often resorting to uncomplicated explanations that try to facilitate the understanding for readers. Sometimes the author uses diagrams to explain basic concepts, for example, Figure 4.3, showing a Cartesian coordinate system for a three-dimensional velocity vector, or Figure 4.7, showing the force components of the weight of a solid object on an inclined surface, which makes the book more accessible to a wider audience.
In my opinion, this book provides a firm scientific basis supporting the sustainable management of rivers and catchments framed on a thorough understanding of principles, processes and dynamics. It will be of interest to students, geomorphologists, ecologists, engineers, restoration practitioners and river managers seeking to learn more about how rivers function.