ASTM D5674-95(1999)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 5674 – 95 (Reapproved 1999)
Standard Guide for
Operation of a Gaging Station
This standard is issued under the fixed designation D 5674; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope of Water Indirectly by Slope-Area Method
D 5242 Test Method for Open-Channel Flow Measurement
1.1 The guide covers procedures used commonly for the
of Water with Thin-Plate Weirs
systematic collection of streamflow information. Continuous
D 5243 Test Method for Open-Channel Flow Measurement
streamflow information is necessary for understanding the
of Water Indirectly at Culverts
amount and variability of water for many uses, including water
D 5388 Test Method for Indirect Measurements of Dis-
supply, waste dilution, irrigation, hydropower, and reservoir
charge by Step-Backwater Method
design.
D 5389 Test Method for Open Channel Flow Measurement
1.2 The procedures described in this guide are used widely
by Acoustic Velocity Meter Systems
by those responsible for the collection of streamflow data, for
D 5390 Test Method for Open Channel Flow Measurement
example, the U.S. Geological Survey, Bureau of Reclamation,
of Water with Palmer-Bowlus Flumes
U.S. Army Corps of Engineers, U.S. Department of Agricul-
D 5413 Test Method for Measurement of Water Levels in
ture, Water Survey Canada, and many state and provincial
Open-Water Bodies
agencies. The procedures are generally from internal docu-
D 5541 Practice for Developing Stage-Discharge Relation
ments of the preceding agencies, which have become the
for Open-Channel Flow
defacto standards used in North America.
2.2 ISO Standards:
1.3 It is the responsibility of the user of the guide to
ISO 1100 Liquid Flow Measurement in Open Channels—
determine the acceptability of a specific device or procedure to
Part I: Establishment and Operation of a Gauging Station
meet operational requirements. Compatibility between sensors,
ISO 6416 Measurement of Discharge by Ultrasonic (Acous-
recorders, retrieval equipment, and operational systems is
tic) Method
necessary, and data requirements and environmental operating
conditions must be considered in equipment selection.
3. Terminology
1.4 The values stated in inch-pound units are to be regarded
3.1 Definitions—For definitions of terms used in this guide,
as the standard. The values given in parentheses are for
refer to Terminology D 1129.
information only.
3.2 Definitions of Terms Specific to This Standard:
1.5 This standard does not purport to address all of the
3.2.1 control— the physical properties of a channel, which
safety concerns, if any, associated with its use. It is the
determine the relationship between the stage and discharge of
responsibility of the user of this standard to establish appro-
a location in the channel.
priate safety and health practices and determine the applica-
3.2.2 datum—a level plane that represents zero elevation.
bility of regulatory limitations prior to use.
3.2.3 elevation—the vertical distance from a datum to a
2. Referenced Documents point; also termed stage or gage height.
3.2.4 gage—a generic term that includes water level mea-
2.1 ASTM Standards:
suring devices.
D 1129 Terminology Relating to Water
3.2.5 gage datum—a datum whose surface is at the zero
D 1941 Test Method for Open Channel Flow Measurement
elevation of all of the gages at a gaging station. This datum is
of Water with the Parshall Flume
often at a known elevation referenced to the national geodetic
D 3858 Practice for Open-Channel Flow Measurement of
vertical datum (NGVD) of 1929.
Water by Velocity-Area method
3.2.6 gage height—the height of a water surface above an
D 5129 Test Method for Open Channel Flow Measurement
established or arbitrary datum at a particular gaging station;
of Water Indirectly by Using Width Contractions
also termed stage.
D 5130 Test Method for Open-Channel Flow Measurement
3.2.7 gaging station—a particular site on a stream, canal,
This guide is under the jurisdiction of ASTM Committee D-19 on Water and is
the direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology,
and Open-Channel Flow. Measurement of Liquid Flow in Open Channels, ISO Standards Handbook 16,
Current edition approved February 15, 1995. Published June 1995. 1983. Available from American National Standards Institute, 11 W. 42nd St., 13th
Annual Book of ASTM Standards, Vol 11.01. Floor, New York, NY 10036.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 5674
lake, or reservoir at which systematic observations of hydro- and fill, and is free of aquatic growth.
logic data are obtained.
6.2.4 The banks are sufficiently high to contain flow at all
3.2.8 discharge— the volume of water flowing through a
stages.
cross-section in a unit of time, including sediment or other
6.2.5 A natural feature such as ledge rock outcrop or stable
solids that may be dissolved in or mixed with the water; usually
gravel riffle, known as a “control,” is present in the stream. It
cubic feet per second (f /s) or metres per second (m/s).
is necessary and practical in some cases to install a low-head
3.2.9 national geodetic vertical datum (NGVD) of 1929—
dam or artificial control to provide this feature. Additional
prior to 1973 known as mean sea level datum, a spheroidal
information on man-made structures is given in Test Methods
datum in the conterminous United States and Canada that
D 1941, D 5242, and D 5390.
approximates mean sea level but does not necessarily agree
6.2.6 A pool is present behind the control where water-level
with sea level at a specific location.
instruments or stilling well intakes can be installed at a location
3.2.10 stilling well—a well connected to the stream with
below the lowest stream stage. The velocity of water passing
intake pipes in such a manner that it permits the measurement
sensors in a deep pool also eliminates or minimizes draw-down
of stage in relatively still water.
effects on stage sensors during high flow conditions.
6.2.7 The site is not affected by the hydraulic effects of a
4. Summary of Guide
bridge, tributary stream entering the gaged channel, down-
4.1 A gaging station is usually installed where a continuous
stream impoundment, or tidal conditions.
record of stage or discharge is required. A unique relationship
6.2.8 A suitable site for making discharge measurements at
exists between water surface elevation and discharge (flow
all stages is available near the gage site.
rate) in most freely flowing streams. Water-level recording
6.2.9 There is accessibility for construction and operation of
instruments continuously record the water surface elevation,
the gage.
usually termed stage or gage height. Discharge measurements
6.3 Site Selection— An ideal site is rarely available, and
are taken of the stream discharge to develop a stage-discharge
judgement must be exercised when choosing between possible
curve. The discharge data are computed from recorded stage
sites to determine that meeting the best combination of
data by a stage-discharge rating curve.
features.
6.3.1 Offıce Reconnaissance—The search for a gaging sta-
5. Significance and Use
tion begins with defining the limits along the stream at which
5.1 This guide is useful when a systematic record of water
the gage must be located on topographic maps of the area. The
surface elevation or discharge is required at a specific location.
topographic information will indicate approximate bank
Some gaging stations may be operated for only a few months;
heights or overflow areas, general channel width, constrictions,
however, many have been operated for a century.
slope, roads, land use, locations of buildings, and other useful
5.2 Gaging station records are used for many purposes:
information so that promising locations can be checked out in
5.2.1 Resource appraisal of long-term records to determine
the field.
the maximum, minimum, and variability of flows of a particu-
6.3.2 Field Reconnaissance—If the range of possible gage
lar stream. These data can be used for the planning and design
locations is large, flying over the stream at a low altitude in a
of a variety of surface water-related projects such as water
small aircraft is an efficient way of checking for promising
supply, flood control, hydroelectric developments, irrigation,
sites. The view from the air on a clear day is much more helpful
recreation, and waste assimilation.
than peering off of a few highway bridges. Traversing the
5.2.2 Management, where flow data are required for the
channel in a canoe or small boat is an alternative method. Field
operation of a surface-water structure or other management
reconnaissance is best performed during low flow conditions;
decision.
however, additional reconnaissance at high flow conditions and
under ice-covered conditions for northern streams adds data
6. Site Location
that result in improved site selection.
6.1 The general location of the station will be dependent on
6.3.3 Logistical Reconnaissance—Once a site has been
the purpose for which the station is established. Location
selected that meets hydraulic considerations, and before design
constraints for a resource appraisal-type station may be quite
or construction begins, the following should occur:
broad, for example, between major tributaries. Constraints for
6.3.3.1 Property ownership must be ascertained and legal
a management-type station may require a location just below a
permission secured to install and maintain the gage. This may
dam, contaminant discharge point, or other point at which
include multiple landowners, especially if a cableway is
discharge information is required specifically.
required from which to make discharge measurements.
6.2 Site Requirements—Certain hydraulic characteristics of
6.3.3.2 Necessary permits must be obtained from applicable
the stream channel are desirable for collecting high-accuracy
governing agencies for, but not limited to, building and
data of minimal cost. Hydraulically difficult sites can still be
excavation, stream bank permits, and FAA notification for
gaged; however, accuracy and cost are affected adversely.
cableways or other local requirements.
Desirable conditions include the following:
6.3.3.3 Where electrical or phone service is required for
6.2.1 The general course of the river should be straight for
approximately 300 ft (100 m) above and below the gage. operation, the availability of this service should be verified.
6.2.2 The flow is confined to one channel at all stages. 6.3.3.4 Most gaging stations are intended to record over the
6.2.3 The stream bed is stable, not subject to frequent scour range of stream stages. It is therefore important to obtain any
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 5674
local information available on historical flood levels and to 7.2.2 Bubbler-type gages consist of a gas supply, usually
make estimates of stage for a 100-year event using locally used nitrogen, which is fed through a controller and tube to an
flood-frequency equations. A cross-section survey of the chan- orifice attached near the bed of a stream. The gas pressure is
nel should be obtained during field reconnaissance to aid in equal to the liquid head in the stream. A pressure transducer,
estimating high flow stage. mercury, or balance-beam manometer senses this pressure and
6.4 More detailed information is available in Refs (1-3) passes this information either mechanically or electronically to
and ISO-1100. a compatible recorder (Fig. 2). The advantage to this system is
less expensive construction costs, which is especially desirable
7. Types of Gaging Stations
for short-term gages or in locations in which stilling well
7.1 Non-recording stations can be as simple as a permanent
installations are difficult. Disadvantages are maintaining the
staff gage attached to a bridge, pier, or other structure, which is
orifice in a stable mounting on the river bed. Keeping the
read and recorded manually in an appropriate notebook once or
orifice from being buried in silty streams is also a problem. For
more each day. For details on non-recording gages, see Test
details on bubble-gages, see Test Methods D 5413, ISO 1100,
Methods D 5413, ISO 1100, and Refs (1-4).
and Refs (1-3, 5, 6).
7.2 Recording gages are usually nonattended installations
7.2.3 Acoustic Velocity Meter (AVM) stations directly sense
that require a sensor in direct contact with the water that is
and record the velocity observed between two transducers at
connected mechanically or electrically to a recording device.
fixed elevations in the channel cross section. The AVM gages
7.2.1 Stilling well-type gages use a vertical well installed in
are used in locations in which stage-discharge relations are
the stream bank with small-diameter intake pipes connecting
unreliable, usually in deep, slow-moving channels or where
the river to the well. In this type of installation, a float on the
tidal or bidirectional flow occurs. Additional information is
water surface in the well drives a recorder housed in a shelter
given in Test Method D 5389.
over the well by mechanical means (Fig. 1). Stilling well gages
8. Gaging Station Structures
tend to provide more reliable data because water-level sensing
as well as recording components of the system are protected
8.1 Stilling Well Functional Requirements—A stilling well
from direct installation in the stream. Disadvantages are
must provide a water surface at the same elevation as that of
locations with unstable stream channels that may move away
the stream at any point in time, dampen out the effect of surface
from the intakes and higher initial cost. For details on stilling
waves, and provide a sensor, usually a float and recording
well gages, see Test Methods D 5413, ISO 1100, and Refs (1-3,
system.
5).
8.1.1 The stilling well must be sufficiently long to cover the
entire range of stages that might occur reasonably.
The boldface numbers in parentheses refer to the list of references at the end of
8.1.2 The stilling well can be any shape in plan view;
this standard.
however, most are either round or square. Permanent long-term
FIG. 1 Stilling Well Gage
...