1、 Reference number ISO 1100-2:2010(E) ISO 2010INTERNATIONAL STANDARD ISO 1100-2 Third edition 2010-12-01 Hydrometry Measurement of liquid flow in open channels Part 2: Determination of the stage-discharge relationship Hydromtrie Mesurage du dbit des liquides dans les canaux dcouverts Partie 2: Dtermi
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6、sion in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2010 All rights reserv
7、edISO 1100-2:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv 1 Scope1 2 Normative references1 3 Symbols1 4 Principle of the stage-discharge relationship 2 4.1 General .2 4.2 Controls3 4.3 Governing hydraulic equations .3 4.4 Complexities of stage-discharge relationships .4 5 Stage-
8、discharge calibration of a gauging station5 5.1 General .5 5.2 Preparation of a stage-discharge relationship.5 5.3 Curve fitting .11 5.4 Combination-control stage-discharge relationships.12 5.5 Stable stage-discharge relationships12 5.6 Unstable stage-discharge relationships .12 5.7 Shifting control
9、s 13 5.8 Variable-backwater effects .15 5.9 Extrapolation of the stage-discharge relationship 17 6 Methods of testing stage-discharge relationships 18 7 Uncertainty in the stage-discharge relationship18 7.1 General .18 7.2 Definition of uncertainty .18 7.3 Statistical analysis of the stage-discharge
10、 relationship .19 7.4 Uncertainty of predicted discharge .21 7.5 Uncertainty in the daily mean discharge 22 Annex A (informative) Uncertainty in the stage-discharge relationship and in a continuous measurement of discharge.23 Bibliography27 ISO 1100-2:2010(E) iv ISO 2010 All rights reservedForeword
11、ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical
12、committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of elect
13、rotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the
14、member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for ident
15、ifying any or all such patent rights. ISO 1100-2 was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 1, Velocity area methods. This third edition cancels and replaces the second edition (ISO 1100-2:1998). Most of the clauses have been updated and technically revised. Major re
16、visions have been made to Clause 5, including a new figure of a stage-discharge relationship and shift curves. Clause 7 has been revised to be consistent with new standards on uncertainty. It also incorporates the Technical Corrigendum ISO 1100-2:1998/Cor.1:2000. ISO 1100 consists of the following p
17、arts, under the general title Hydrometry Measurement of liquid flow in open channels: Part 1: Establishment and operation of a gauging station Part 2: Determination of the stage-discharge relationship INTERNATIONAL STANDARD ISO 1100-2:2010(E) ISO 2010 All rights reserved 1Hydrometry Measurement of l
18、iquid flow in open channels Part 2: Determination of the stage-discharge relationship 1 Scope This part of ISO 1100 specifies methods of determining the stage-discharge relationship for a gauging station. A sufficient number of discharge measurements, complete with corresponding stage measurements,
19、are required to define a stage-discharge relationship to the accuracy required by this part of ISO 1100. Stable and unstable channels are considered, including brief descriptions of the effects on the stage-discharge relationship of shifting controls, variable backwater and hysteresis. Methods of de
20、termining discharge for twin-gauge stations, ultrasonic velocity-measurement stations, electromagnetic velocity-measurement stations and other complex rating curves are not described in detail. These types of rating curve are described separately in other International Standards, Technical Specifica
21、tions and Technical Reports, which are listed in Clause 2 and the Bibliography. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the re
22、ferenced document (including any amendments) applies. ISO 748, Hydrometry Measurement of liquid flow in open channels using current-meters or floats ISO 772, Hydrometry Vocabulary and symbols ISO 5168, Measurement of fluid flow Procedures for the evaluation of uncertainties ISO 9123, Measurement of
23、liquid flow in open channels Stage-fall-discharge relationships ISO 15769, Hydrometry Guidelines for the application of acoustic velocity meters using the Doppler and echo correlation methods ISO/TS 24154, Hydrometry Measuring river velocity and discharge with acoustic Doppler profilers 3 Symbols Fo
24、r the purposes of this document, the symbols given in ISO 772 and the following apply: A cross-sectional area B cross-sectional width power-law exponent (slope on logarithmic plot) of the rating curve ISO 1100-2:2010(E) 2 ISO 2010 All rights reservedC Dcoefficient of discharge C Chezys channel rough
25、ness coefficient e effective gauge height of zero flow h gauge height of the water surface (h e) effective depth H total head (hydraulic head) n Mannings channel roughness coefficient N number of stage-discharge measurements (gaugings) used to define the rating curve p number of rating-curve paramet
26、ers (Q 1 , , e) estimated from the N gaugings P wwetted perimeter Q total discharge Q osteady-state discharge Q 1power-law scale factor of rating curve, equal to discharge when effective depth of flow (h e) is equal to 1 r hhydraulic radius, equal to the effective cross-sectional area divided by the
27、 wetted perimeter, A/P wS standard error of estimate S ffriction slope S owater surface slope corresponding to steady discharge t time u standard uncertainty U expanded uncertainty V wvelocity of a flood wave 4 Principle of the stage-discharge relationship 4.1 General The stage-discharge relationshi
28、p is the relationship at a gauging station between stage and discharge and is sometimes referred to as a rating curve or rating. The principles of the establishment and operation of a gauging station are described in ISO 1100-1. ISO 1100-2:2010(E) ISO 2010 All rights reserved 34.2 Controls 4.2.1 Gen
29、eral The stage-discharge relationship for open-channel flow at a gauging station is governed by channel conditions at and downstream from the gauge, referred to as a control. Two types of control can exist, depending on channel and flow conditions. Low flows are usually controlled by a section contr
30、ol, whereas high flows are usually controlled by a channel control. Medium flows can be controlled by either type of control. At some stages, a combination of section and channel control might occur. These are general rules, and exceptions can and do occur. Knowledge of the channel features that con
31、trol the stage-discharge relationship is important. The development of stage-discharge curves where more than one control is effective, where control features change and where the number of measurements is limited requires judgement in interpolating between measurements and in extrapolating beyond t
32、he highest or lowest measurements. This is particularly true where the controls are not permanent and tend to shift from time to time, resulting in changes in the positioning of segments of the stage-discharge relationship. 4.2.2 Section control A section control is a specific cross-section of a str
33、eam channel, located downstream from a water-level gauge that controls the relationship between gauge height and discharge at the gauge. A section control can be a natural feature, such as a rock ledge, a gravel bar, a severe constriction in the channel or an accumulation of debris. A section contro
34、l can also be a man-made feature, such as a small dam, a weir, a flume or an overflow spillway. Section controls can often be visually identified in the field by observing a riffle, or pronounced drop in the water surface, as the flow passes over the control. Frequently, as gauge height increases be
35、cause of higher flows, the section control will become submerged to the extent that it no longer controls the relationship between gauge height and discharge. At this point, the riffle is no longer observable, and flow is then regulated either by another section control further downstream or by the
36、hydraulic geometry and roughness of the channel downstream (i.e. channel control). 4.2.3 Channel control A channel control consists of a combination of features throughout a reach at and downstream from a gauge. These features include channel size, shape, curvature, slope and roughness. The length o
37、f channel reach that controls a stage-discharge relationship varies. The stage-discharge relationship for a relatively steep channel could be controlled by a short channel reach, whereas the relationship for a flat channel could be controlled by a much longer channel reach. Additionally, the length
38、of a channel control will vary depending on the magnitude of flow. Precise definition of the length of a channel-control reach is usually neither possible nor necessary. 4.2.4 Combination controls At some stages, the stage-discharge relationship can be governed by a combination of section and channe
39、l controls. This usually occurs for a short range in stage between section-controlled and channel-controlled segments of the rating curve. This part of the rating curve is commonly referred to as a transition zone of the rating curve and represents the change from section control to channel control.
40、 In other instances, a combination control can consist of two section controls, where each has a partial controlling effect. More than two controls acting simultaneously are rare. In any case, combination controls and/or transition zones occur for very limited parts of a stage-discharge relationship
41、 and can usually be defined by plotting procedures. Transition zones, in particular, represent changes in the slope or shape of a stage-discharge relationship. 4.3 Governing hydraulic equations Stage-discharge relationships are hydraulic relationships that can be defined according to the type of con
42、trol that exists. Section controls, either natural or man-made, are governed by some form of the weir or flume equations. In a very general and basic form, these equations are expressed as: Q = C D BH (1) ISO 1100-2:2010(E) 4 ISO 2010 All rights reservedwhere Q is the discharge, in cubic metres per
43、second; C Dis a coefficient of discharge and includes several factors; B is the cross-sectional width, in metres; H is the hydraulic head, in metres; is a power-law exponent, dependent on the cross-sectional shape of the control section. Stage-discharge relationships for channel controls with unifor
44、m flow are governed by the Manning or Chezy equation as it applies to the reach of the controlling channel downstream from a gauge. The Manning equation is: 0,67 0,5 hf Ar S Q n = (2) where A is the cross-sectional area, in square metres; r his the hydraulic radius, in metres; S fis the friction slo
45、pe; n is the channel roughness. The Chezy equation is: Q = CAr h 0,5 S f 0,5(3) where C is the Chezy form of roughness. The above equations are generally applicable for steady or quasi-steady flow. For highly unsteady flow, such as tidal or dam-break flow, equations such as the Saint-Venant unsteady
46、-flow equations would be necessary. However, these are seldom used in the development of stage-discharge relationships and are not described in this part of ISO 1100. 4.4 Complexities of stage-discharge relationships Stage-discharge relationships for stable controls (such as rock outcrops and man-ma
47、de structures such as weirs, flumes and small dams) present few problems in their calibration provided a suitable maintenance regime can be achieved. However, complexities can arise when controls are not stable and/or when variable backwater occurs. For unstable controls, segments of a stage-dischar
48、ge relationship can change position occasionally, or even frequently. This is usually a temporary condition which can be accounted for through the use of the shifting-control method. Variable backwater can affect a stage-discharge relationship both for stable and unstable channels. Sources of backwa
49、ter can be downstream reservoirs, tributaries, tides, vegetation, ice, dams and other obstructions that influence the flow at the gauging-station control. A complexity that exists for some streams is hysteresis, which results when the water surface slope changes due to either rapidly rising or rapidly falling water levels in a channel-control reach. Hysteresis is also referred to as loop rating curves and is most pronounced in relatively flat-sloped streams. On rising stages, the water surface slope is significa
