1. Introduction

Experiences with the Bureau of Reclamation's Water Management Workshops, held each year in Denver, Colorado, have indicated a need to explain fundamental concepts of flowing water and its measurement. The workshops have also demonstrated the need to present concepts in simple terms using step-by-step development (Schuster, 1970). Because of more recent water measurement developments and the new chapters and sections added to this edition, this chapter has expanded the previous edition's appendix material into a more complete form. Thus, many more equations are included to maintain step-by-step development of the new material. Readers who have difficulties with algebra or the technical writing level should skim the text to provide exposure to concepts and terminology related to water measurement. More experienced water providers and users can use this chapter as a quick review of hydraulic principles related to water measurement.

Eventually, operators may wish to further investigate and seek more advanced references in hydraulics and fluid mechanics. Streeter (1951) has a chapter on flow measurement that covers tube-type flow meters. Bean (1971) has full information on fluid meter theory and provides detailed material for determining coefficients for tube-type meters. King and Brater (1963) have a thorough discussion of general critical depth relations and detailed relationships for most common hydraulic flow section shapes. Bos (1989) covers the entire field of open channel water measurement devices.