Review of Flow Through Open Channels by Rajesh Srivastava

The material presented in this book is an expansion of Srivastava’s lecture notes at the University of Roorkee and Indian Institute of Technology, Kanpur. The author’s lifetime of instructional and professional experience in open-channel hydraulics is reflected in this book. Flow through open channels by Srivastava is intended as a textbook, mainly for the undergraduate level; however, the content is also well suited for a first course at the graduate level when combined with complementary references. The book is well written and has a good balance between discussions on basics of open-channel hydraulics. As the author points out, the scope of the book is not as vast as classics on open-channel hydraulics such as Chow (1959) and Henderson (1966) because it is basically planned to be an instructional book. For that reason, physical problems are described prior to equations to provide motivation and build an intuition. The book’s main focus is on analytical hydraulics [similar to Subramanya (2009)] and numerical aspects are only briefly discussed.

This book contains nine chapters and three appendices. In Chapter 1, the author opens with a general overview and classification of open surface flows and lays out the format of the next chapters. Srivastava presents the importance of the subject in the context of hydraulic structures, river engineering, and riverine water quality and sediment transport. The second chapter deals with uniform free surface flow in natural and manmade channels. This chapter starts with flow in prismatic channels and continues with discussion of open-channel flow resistance, and computation of normal depth. This chapter finishes with the basics of channel design. Chapters 3 and 4 discuss nonuniform flows. Chapter 3 presents detailed classification and computation of water surface profiles in gradually varied flows (GVF). In turn, Chapter 4 deals with rapidly varied flow (RVF). It covers the basic theory of RVF and its application in one-dimensional (1D) hydraulic jumps, hydraulic structures, sluice gates, wires, and spillways. Chapter 5 discusses channel transitions including bed level fall and rise, and width contractions and expansions as well as bends. Chapter 6 is a relatively short one dealing with spatially varying flow. Chapter 7 covers unsteady flows in open channels, including small amplitude waves and dam-break problems and analysis of them with Lagrangian methods (MOC). This chapter proceeds with derivation of the 1D Saint-Venant equation and includes a brief introduction to the use of finite-difference methods (FDM) to solve it. The chapter finishes with a short review of common simplifications of the 1D Saint-Venant equation for flood routing. Chapter 8 focuses on fundamentals of alluvial hydraulics. It starts with the basics of sediment transport mechanics, bed forms, and suspended and bedload transport. Chapter 8 closes with preliminaries of design of open channels with erodible material. Chapter 9, the last chapter, describes essential mechanisms of transport and mixing in riverine environments. The final chapter also includes an introduction to molecular diffusion and hydrodynamic dispersion, and a derivation of the 1D advection-dispersion equation for a passive constituent along with its basic analytical and numerical solution techniques.

After the final chapter, Srivastava provides three appendices. It assumes a background in fluid mechanics; however, Srivastava briefly reviews the principles of fluid mechanics, roughness, and law-of-the-wall in Appendix A. Appendix B provides a qualitative overview of distributions of velocity, pressure, and shear stress in open-channel flows. Finally, Appendix C covers the required numerical methods including: root-finding methods, direct solving of a system of linear equations, ODE integration methods, and a short review of PDE discretization via the FDM. The book does not have an author index or extensive references, which are not fundamental drawbacks considering the aim of the book. Nevertheless, a comprehensive subject index is given at the end of the book.

This monograph is written for students who want to learn the basic concepts for the first time. The book is easy to read for a typical engineering student despite the fact that it does not sacrifice rigor. It is also helpful for self-study in preparation for the Professional Engineer (P.E.) and Engineer-in-Training (E.I.T) exams. Each chapter contains step-by-step worked out examples. The book has a total of 68 solved problems and contains a total of 79 exercises at the end of each chapter. The bottom-line solutions to some of the exercises are given in the book. In addition, the complete instructor’s solution manual is available through the publisher.

The technical level of the book is mostly consistent with some exceptions. The first six chapters cover the common curriculum of a typical undergraduate course in open channel hydraulics. The missing part is a standalone section on flow resistance in bends and vegetation. The book also does not have separate chapters dedicated to hydraulic structures and design of channels, unlike Montes (1998), Chanson (2004a, b), Akan (2006), Chaudhry (2008), or Sturm (2009); however, these topics are briefly visited alongside their corresponding theoretical concepts within other sections of the text. In my opinion the only deficiency of the book is Chapter 7 (unsteady flow). The 1D shallow-water-equations of flow are only briefly introduced; and the lack of two-dimensional (2D) flow theory and hierarchical simplification of 1D flow routing methods (Section 7.6) are other weaknesses of this chapter. In turn, the introduction to MOC and FDM as the numerical tools to solve flow equations given in Chapter seven is not detailed enough. Additionally, fundamental numerical concepts such as stability conditions, convergence, and appropriate discretization size are passed over, which is little disappointing. However, in fairness, Chapter 7 is well suited for students without any prior education in numerical analysis. Also, a short introduction to the capabilities of standard computer packages for solving water flow problems in open channels would be a useful addition for the readership (see Section 6.6 of Moglen 2015).

The last two chapters go beyond the territory of a first course in open channel hydraulics. Chapter 8 provides an insight into loose boundary hydraulics and sediment transport. Chapter 9 is an original and welcomed aspect of this book, covering longitudinal mixing and transport of constituents in surface water. Although environmental river hydraulics is a deep concern of the modern era, and comprehensive books on this subject exist [such as Rutherford (1994) and Chanson (2004a)], this issue is barely mentioned in analogous references (other texts) excluding French (1986) and Montes (1998).

In summary, this is a very readable book for pedagogical purposes in which open-channel flow principles are rigorously treated. It is reasonably priced and the quality of publication is good. It is concise and errors are very rare (Srivastava provides the errata on his website). I adopted it for teaching and highly recommend this book to instructors.