This is a revised introduction to the physical concepts and mathematics of fluid mechanics. It reinforces concepts with equations and solutions for relatively simple geometrics, through examples, worked problems and derivations, demonstrated in easy stages. Although the book emphasizes SI units, approximately one quarter of the worked examples and problems are duplicated with English units, and all properties and dimensional constants are provided in both SI and English units. It also includes computer-based Basic and spread sheet solutions in the sections on open channel and pipe network flows. In Chapter 14, where the emphasis is on mass transport in surface water systems which contain turbulent flows, a thorough introduction to environmental fluid mechanics has been included. In addition, a section on fluid transients has been added in this edition.