Review of Wastewater Hydraulics: Theory and Practice, 2nd Ed., by Willi H. Hager: Springer-Verlag, Berlin; 2010; ISBN 978-3-642-11382-6; 652 pp.

This book is the second edition of a successful book first published in 1999. The material of this book originates from the German book Abwasser-Hydraulik: Theorie und Praxis published in 1994 (Hager 1994). The book contains 20 chapters and appendixes.

Chapter 1 deals with continuity, momentum, and energy in fluid flow. The Bernoulli equation, an application of the momentum theorem, and the Boussinesq equations are briefly reviewed. Chapter 2 presents head-loss computations, including local losses for various geometrical configurations. Chapter 3 deals with the design of sewers, including maximum and minimum discharge conditions. Chapter 4 presents an introduction to sewage pumping and throttling devices. Chapter 5 determines the normal flow depths in free surface flows for the most important cross-sectional shapes used in sewers. Computations are presented using analytical aids rather than numerical solutions. Steeply sloping sewers and air-water flows are included. Chapter 6 deals with critical flow. Its features are introduced, and explicit flow formulas are developed to avoid numerical solutions. The location of critical depth is generally discussed on the basis of the singular point method, and slope breaks are described as a particular critical flow device. Chapter 7 is devoted to the hydraulic jump. The main features of the classical hydraulic jump in a horizontal channel, including the sequent depths, energy dissipation, and roller length, are detailed. Circular sections are also considered, including a new section with recent developments on undular hydraulic jumps. The chapter further explores various outlet structures. Stilling basin design is considered, including the classical U.S. Bureau of Reclamation (USBR) stilling basin. Chapter 8 treats the equation of gradually varied flows. A general discussion of free surface profile types is presented, and a dimensionless solution of the gradually varied flow equation is given for the circular, egg-shaped, horseshoe, and rectangular cross sections. Chapter 9 deals with culverts and throttling pipes. Generalized flow diagrams for culvert design are included.

Chapter 10 treats overfalls. Flow features of sharp-crested, broad-crested, and cylindrical-crested weirs are presented for free and submerged flow conditions. Chapter 11 specifically focuses on end overfalls for rectangular channels and circular pipes. Computation of cavity flow, or the “Cola bubble,” is also included. Chapter 12 relates to the Venturi flume. The discharge characteristics are derived using the hydraulic approach and then generalized by inclusion of streamline curvature effects. Both long- and short-throated devices are discussed and design recommendations are given. Chapter 13 deals with mobile discharge measurement by using Venturi flumes. Specific devices are introduced for both rectangular and circular channels on the basis of streamline curvature theory developed in chapter 12.

Chapter 14 presents the standard manhole, discussing important aspects such as choking conditions and pressurized manhole flow. Chapter 15 treats fall manholes, including both drop and vortex manholes. Special manholes are treated in chapter 16 for both sub- and supercritical approach flow conditions, including manhole design. Chapter 17 presents the governing equations for spatially varied open channel flows with decreasing discharge, along with an application to distribution channels and channel bifurcations. A general side-weir discharge equation is provided and included in the model equations. Chapter 18 specifically focuses on the sewer side weir. Its design is considered using the theory presented in the previous chapter. Chapter 19 presents the side channel on the basis of the governing flow equations for spatially varied open channel flows with increasing discharge. Generalized dimensionless free surface profiles are presented for both critical and singular control points. Chapter 20 deals with bottom openings as a particular case of spatially varied flow with decreasing discharge. The book also contains an interesting perspective on the history of wastewater hydraulics.

The present book covers the main topics of wastewater hydraulics and is thereby an interesting and updated treatise on the topic. It is well organized, containing high-quality figures that illustrate the proposed solution for each problem. Each chapter contains informative photos that depict the governing flow phenomena. This may help instructors to get their students interested in a topic. A collection of worked examples is included in each chapter that is to be welcomed by the reader for the understanding of a design method. The huge set of references contained at the end of each chapter helps the interested reader become acquainted with the fascinating topics covered. The scientific book content is of interest not only to engineers dealing with wastewater hydraulics, but also to those who tackle general problems in open channel hydraulics. The book deals with the hydraulics of several devices involving free surface flow, such as weirs and flumes. Most of the approximations are analytical, thereby reducing the complexities of the flow phenomena to a level tractable without numerical modeling. This will be acknowledged by practitioners and also by researchers and teachers, who clearly see the role of each main variable on the flow phenomena investigated. I do miss an elementary appendix of introductory character to numerical methods, which may yield an alternative approach in several chapters, as the computation of backwater curves or the modeling of streamline curvature effects using the Boussinesq equations. The books cover in depth all the important hydraulic problems of steady, free surface flows. The unsteady flow simulation of sewer networks for rainfall-runoff processes is explicitly stated to be out of topic coverage. For these specific aspects, however, the works of the late professor Ben Chie Yen (1935–2001) are available and may be used, e.g., Yen (1986).

In short, Hager’s book is a highly welcomed addition to the literature of wastewater hydraulics, presenting the current knowledge on the topic. This book is strongly recommended to both practicing hydraulic engineers and to students and researchers working not only in wastewater hydraulics, but also in open channel flow.