Water measurement manual a water resources technical publication

U. S. Department of the Interior

Bureau of Reclamation

WATER MEASUREMENT
MANUAL
A WATER RESOURCES TECHNICAL PUBLICATION
Water Measurement web page

A guide to effective water measurement practices for better water management

U.S. Department of the Interior
Bureau of Reclamation

In cooperation with

FIRST EDITION 1953
SECOND EDITION 1967
REPRINTED 1967, 1971
REVISED REPRINT1974
REPRINTED 1975, 1977, 1981
REVISED REPRINT 1984
REPRINTED 1993
THIRD EDITION 1997
REVISED REPRINTED 2001

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
As the Nation's principal conservation agency, the Department of the Interior has responsibility
for most of our nationally owned public lands and natural resources. This includesfostering sound
use of our land and water resources; protecting our fish, wildlife, and biological diversity;
preserving the environmental and cultural values of our national parks and historical places; and
providing for the enjoyment of life through outdoor recreation. The Department assesses our
energy and mineral resources and works to ensure that their development is in the bestinterests of
all our people by encouraging stewardship and citizen participation in their care. The Department
also has a major responsibility for American Indian reservation communities and for people who
live in island territories under U.S. Administration.

PREFACE
The mission of many public and private water resources organizations is to manage and conserve
existing water supplies. Thesemanagement efforts involve making sound technical and
economic decisions concerning new and existing water needs, while respecting the environment
by sustaining or restoring the aquatic ecosystems which may be affected. One key to better
management practices, including water conservation, is reliable and accurate water
measurement. The term "water measurement" as used in this manual refers to themeasurement
of flow (unit volume per unit time). Major advances in measurement technology along with a
continued demand for the Water Measurement Manual are responsible for initiating this revision.
The first edition of the Water Measurement Manual (1953) had a distribution of 11,000 copies
and was compiled from the Bureau of Reclamation (Reclamation) publication Manual for
Measurement ofIrrigation Water (1946). This previous manual had five earlier editions
beginning in 1913 and extending to 1940. The continual demand for the Water Measurement
Manual and the need for updating resulted in the second edition (1967). From 1967 to 1984, two
revised reprints plus five reprints of the second edition were published. The demand and need for
the second edition has continued because ofconservation pressure and increased user
competition for water; therefore, this third edition was prepared to supplement and update
information contained in the second edition.
Modern trends of technical practice, along with the developments in personal computers, have
resulted in increased emphasis on using custom-fitted, long-throated measurement structures that
can be designed to measure flowand are simpler to fabricate. Consequently, fewer short-form
flumes are being considered for new installations. Thus, information on Parshall flumes has been
reduced and incorporated in the more general "Flumes" chapter, which recommends longthroated flumes for new installation in preference to Parshall flumes.
The main Parshall flume information retained in this edition relates to maintenanceand operation
needs of existing flumes, including flume dimensions, free flow measurement, submerged flow
measurement, and head losses. The sections on size selection and setting crest elevation for
Parshall flumes have been deleted or reduced in this edition. Where Parshall flumes may be
desired or required by State law, examples in the previous editions of the manual can be referred
to...