ASTM D5129-95(2014)

Standard Test Method for Open Channel Flow Measurement of Water Indirectly by Using Width Contractions

SIGNIFICANCE AND USE
5.1 This test method is particularly useful to determine the discharge when it cannot be measured directly by some type of current meter to obtain velocities and with sounding weights to determine the cross section.  
5.2 Even under the best conditions, the personnel available cannot cover all points of interest during a major flood. The engineer or technician cannot always obtain reliable results by direct methods if the stage is rising or falling very rapidly, if flowing ice or debris interferes with depth or velocity measurements, or if the cross section of an alluvial channel is scouring or filling significantly.  
5.3 Under the worst conditions, access roads are blocked, cableways and bridges may be washed out, and knowledge of the flood frequently comes too late. Therefore, some type of indirect measurement is necessary. The contracted-opening method is commonly used on valley-floor streams.
SCOPE
1.1 This test method covers the computation of discharge (the volume rate of flow) of water in open channels or streams using bridges that cause width contractions as metering devices.2  
1.2 This test method produces the maximum discharge for one flow event, usually a specific flood. The computed discharge may be used to help define the high-water portion of a stage-discharge relation.  
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Dec-2013
• ICS: 17.120.20 - Flow in open channels
• Technical Committee: D19 - Water
• Drafting Committee: D19.07 - Sediments, Geomorphology, and Open-Channel Flow

Relations

• Replaces: ASTM D5129-95(2008) - Standard Test Method for Open Channel Flow Measurement of Water Indirectly by Using Width Contractions
• Effective Date: 01-Jan-2014
• Referred By: ASTM D5674-22 - Standard Guide for Operation of a Gaging Station
• Effective Date: 01-Jan-2014

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D5129 −95(Reapproved 2014)
Standard Test Method for
Open Channel Flow Measurement of Water Indirectly by
1
Using Width Contractions
This standard is issued under the fixed designation D5129; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers the computation of discharge
3.1 Definitions—For definitions of terms used in this test
(the volume rate of flow) of water in open channels or streams
method, refer to Terminology D1129.
using bridges that cause width contractions as metering de-
2 3.2 Definitions of Terms Specific to This Standard:
vices.
3.2.1 alpha (α)—a velocity-head coefficient that adjusts the
1.2 This test method produces the maximum discharge for
velocity head computed on basis of the mean velocity to the
one flow event, usually a specific flood. The computed dis-
true velocity head.
charge may be used to help define the high-water portion of a
stage-discharge relation. 3.2.2 area (A)—the area of a cross section, parts of a cross
section, or parts of bridges below the water surface. Subscripts
1.3 Thevaluesstatedininch-poundunitsaretoberegarded
indicate specific areas as follows:
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
A = area of subsection i,
i
and are not considered standard.
A = area of piers or piles that is submerged,
j
1.4 This standard does not purport to address all of the A = area of total cross section 1 (see Fig. 1), and
1
A = gross area of section 3.
safety concerns, if any, associated with its use. It is the
3
responsibility of the user of this standard to establish appro-
3.2.3 conveyance, (K)—a measure of the carrying capacity
priate safety and health practices and determine the applica-
of a channel cross section, or parts of a cross section, and has
bility of regulatory limitations prior to use.
units of cubic feet per second or cubic metres per second.
Conveyance is computed as follows:
2. Referenced Documents
3
*1.486
2.1 ASTM Standards:
2/3
K 5 AR
n
D1129Terminology Relating to Water
D2777Practice for Determination of Precision and Bias of
where:
Applicable Test Methods of Committee D19 on Water
n = the Manning roughness coefficient,
D3858Test Method for Open-Channel Flow Measurement
2 2
A = the cross-section area, ft (m ), and
of Water by Velocity-Area Method
R = the hydraulic radius, ft (m).
4
2.2 ISO Standard:
*in SI units = 1.0
ISO 748Liquid Flow Measurements in Open Channels—
The following subscripts refer to specific conveyances for
Velocity-Area Measurements
parts of a cross section:
1
This test method is under the jurisdiction ofASTM Committee D19 on Water K,K = conveyances of parts of the approach section to
a b
and is the direct responsibility of Subcommittee D19.07 on Sediments,
either side of the projected bottom width of the
Geomorphology, and Open-Channel Flow.
contracted section (see Fig. 2). K is always the
d
Current edition approved Jan. 1, 2014. Published March 2014. Originally
smaller of the two,
approved in 1990. Last previous edition approved in 2008 as D5129–95 (2008).
DOI: 10.1520/D5129-95R14. K = conveyance at the upstream end of the dikes,
d
2
This test method is similar to methods developed by the U.S. Geological
K = conveyance of subsection i,
i
5
Survey and described in documents referenced in Footnote 5.
K = conveyance of the part of the approach section
q
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
corresponding to the projected bottom-width, and
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
K = total conveyance of cross section.
Standards volume information, refer to the standard’s Document Summary page on
T
the ASTM website.
4 3.2.4 depth (y)—depth of flow at a cross section. Subscripts
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. denote specific cross section depths as follows:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D5129−95 (2014)
FIG. 1 Definition Sketch of an Open-Channel Contraction
3.2.7 Froude number (F)—an index to the state of flow in a
y = depth of flow in cross section 1(approach section), and
1
y = depth of flow in cross section 3(contracted section). channel. In a rectangular channel, the flow is tranquil or
3
subcritical if the Froude number is less than 1.0 and is rapid or
3.2.5 eccentricity (e)—a measure of the symmetry of
...