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1、BRITISH STANDARD BS ISO 1100-2:1998 Incorporating corrigendum no. 1 Measurement of liquid flow in open channels Part 2: Determination of the stage-discharge relation ICS 17.120.20 ? Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:23:04 GMT+00:00 2007, Uncontr
2、olled Copy, (c) BSI BS ISO 1100-2:1998 This British Standard was published under the authority of the Standards Board and comes into effect on 15 July 1998 BSI 2007 ISBN 978 0 580 60528 4 National foreword This British Standard is the UK implementation of ISO 1100-2:1998, incorporating corrigendum A
3、ugust 2000. It supersedes BS 3680-3C:1983 which is withdrawn. The start and finish of text introduced or altered by corrigendum is indicated in the text by tags . Text altered by ISO corrigendum August 2000 is indicated in the text by . The UK participation in its preparation was entrusted by Techni
4、cal Committee CPI/113, Flow measurement of surface and ground water, to Subcommittee CPI/113/1, Velocity-area methods. A list of organizations represented on this subcommittee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a
5、contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments 17462 Corrigendum No. 1 31 October 2007See national foreword Licensed Copy: London South Bank Unive
6、rsity, London South Bank University, Fri Nov 16 07:23:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:23:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 1100-2:1998 ii Contents Page Forewordiii 1Scope1 2Norma
7、tive references1 3Definitions and symbols1 4Units of measurement1 5Principle of the stage-discharge relation1 6Stage-discharge calibration of a gauging station3 7Methods of testing stage-discharge relations16 8Uncertainty in the stage-discharge relation16 Annex A (informative) Uncertainty in stage-d
8、ischarge relation and in continuous measurement of discharge 20 Annex B (informative) Bibliography 21 Figure 1 Arithmetic plot of stage-discharge relation6 Figure 2 Relation of channel and control properties to rating curve shape7 Figure 3 Logarithmic plot of stage-discharge relation8 Table 1 Typica
9、l list of discharge measurements4 Table 2 Tabulated values required to calculate se and smr18 Table 3 Typical computation for the uncertainty in the daily mean discharge, using hourly values of discharge19 Descriptors: Liquid, water flow, open channel flow, flow measurement, gauging stations. BSI 20
10、07 Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:23:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 1100-2:1998 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bod
11、ies). 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 committee has been established has the right to be represented on that committee. International organizations, governmental and
12、 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 electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bod
13、ies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 1100-2 was prepared by Technical Committee ISO/TC 113, Hydrometric determinations, Subcommittee SC 1, Velocity-area methods. This second edition
14、 cancels and replaces the first edition (ISO 1100-2:1982), which has been technically revised. Annex A and Annex B of this part of ISO 1100 are for information only. BSI 2007 Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:23:04 GMT+00:00 2007, Uncontrolled C
15、opy, (c) BSI iv blank Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:23:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 1100-2:1998 1 1 Scope This part of ISO 1100 specifies methods of determining the stage-discharge relation for a gauging station. A su
16、fficient number of discharge measurements, complete with corresponding stage measurements, is required to define a stage-discharge relation 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-dischar
17、ge relation of ice and hysteresis. Methods for determining discharge for twin-gauge stations, ultrasonic velocity stations, electromagnetic velocity stations, and other complex ratings are not described in detail. These types of rating are described in other International Standards and Technical Rep
18、orts, namely ISO/TR 9123, ISO 6416 and ISO 9213, as shown in clause 2. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 1100. At the time of publication, the editions indicated were valid. All standards
19、 are subject to revision, and parties to agreements based on this part of ISO 1100 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 31:1992 (a
20、ll parts), Quantities, units and symbols. ISO 772:1996, Hydrometric determinations Vocabulary and symbols. ISO 1000:1992, SI units and recommendations for the use of their multiples and of certain other units. ISO/TR 5168: , Measurement of fluid flow Evaluation of uncertainties1). ISO 6416:1992, Liq
21、uid flow measurement in open channels Measurement of discharge by the ultrasonic (acoustic) method. ISO/TR 9123:1986, Liquid flow measurement in open channels Stage-fall-discharge relations. ISO 9196:1992, Liquid flow measurement in open channels Flow measurements under ice conditions. ISO 9213:1992
22、, Measurement of total discharge in open channels Electromagnetic method using a full-channel-width coil. 3 Definitions and symbols For the purpose of this part of ISO 1100, the definitions and symbols given in ISO 772 apply. Those that are not covered by ISO 772 are given in the text of this part o
23、f ISO 1100. The symbols used in this part of ISO 1100 are given below: 4 Units of measurement The International System of Units (SI Units) is used in this part of ISO 1100 in accordance with ISO 31 and ISO 1000. 5 Principle of the stage-discharge relation The stage-discharge relation is the relation
24、 at a gauging station between stage and discharge, and is sometimes referred to as a rating or rating curve. The principles of the establishment and operation of a gauging station are described in ISO 1100-1. 1) To be published. (Revision of ISO 5168:1978) Across-sectional area, CDa coefficient of d
25、ischarge, CChezys channel rugosity coefficient, hgauge height of the water surface, slope of the rating curve, Qtotal discharge, Qosteady-state discharge, rhhydraulic radius, equal to the effective cross-sectional area divided by the wetted perimeter (A/P) Sffriction slope, Sowater surface slope cor
26、responding to steady discharge, vwvelocity of a flood wave, Bcross-section width, eeffective gauge height of zero flow, Htotal head (hydraulic head), nis Mannings channel rugosity coefficient, pis a constant that is numerically equal to the discharge when the effective depth of flow (h e) is equal t
27、o 1, tis time. BSI 2007 Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:23:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 1100-2:1998 2 5.1 Controls 5.1.1 General The stage-discharge relation for open-channel flow at a gauging station is governed by cha
28、nnel conditions 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 control, whereas high flows are usually controlled by a channel control. Medium flows may be controlled by eith
29、er type of control. At some stages, a combination of section and channel control may occur. These are general rules and exceptions can and do occur. Knowledge of the channel features that control the stage-discharge relation is important. The development of stage-discharge curves where more than one
30、 control is effective, where control features change, and where the number of measurements is limited, usually requires judgement in interpolating between measurements and in extrapolating beyond the highest or lowest measurements. This is particularly true where the controls are not permanent and t
31、end to shift from time to time, resulting in changes in the positioning of segments of the stage-discharge relation. Controls and their governing equations are described in the following clauses. 5.1.2 Section control A section control is a specific cross-section of a stream channel, located downstr
32、eam from a water-level gauge, that controls the relation between gauge height and discharge at the gauge. A section control can be a natural feature such as a rock ledge, a sand bar, a severe constriction in the channel, or an accumulation of debris. Likewise, a section control can be a manmade feat
33、ure such as a small dam, a weir, a flume, or an overflow spillway. Section controls can frequently 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 because of higher flows, t
34、he section control will become submerged to the extent that it no longer controls the relation 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 hydraulic geometry and roug
35、hness of the channel downstream (i.e. channel control). 5.1.3 Channel control A channel control consists of a combination of features throughout a reach downstream from a gauge. These features include channel size, shape, curvature, slope, and rugosity. The length of channel reach that controls a st
36、age-discharge relation varies. The stage-discharge relation for relatively steep channels may be controlled by a relatively short channel reach, whereas, the relation for a relatively flat channel may be controlled by a much longer channel reach. In addition, the length of a channel control will var
37、y depending on the magnitude of flow. Precise definition of the length of a channel-control reach is usually neither possible nor necessary. 5.1.4 Combination controls At some stages, the stage-discharge relation may be governed by a combination of section and channel controls. This usually occurs f
38、or a short range in stage between section-controlled and channel-controlled segments of the rating. This part of the rating is commonly referred to as a transition zone of the rating, and represents the change from section control to channel control. In other instances, a combination control may con
39、sist of two section controls, where each has partial controlling effect. More than two controls acting simultaneously is rare. In any case, combination controls, and/or transition zones, occur for very limited parts of a stage-discharge relation and can usually be defined by plotting procedures. Tra
40、nsition zones in particular represent changes in the slope or shape of a stage-discharge relation. 5.2 Governing hydraulic equations Stage-discharge relations are hydraulic relations that can be defined according to the type of control that exists. Section controls, either natural or manmade, are go
41、verned by some form of the weir or flume equations. In a very general and basic form, these equations are expressed as: where Q = CDBH1,5 (1) Qis discharge, in cubic metres per second (m3/s), CDis a coefficient of discharge and may include several factors, Bis cross-section width, in metres (m), and
42、 His hydraulic head, in metres. BSI 2007 Licensed Copy: London South Bank University, London South Bank University, Fri Nov 16 07:23:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 1100-2:1998 3 Stage-discharge relations for channel controls with uniform flow are governed by the Manning or Chez
43、y equation, as it applies to the reach of controlling channel downstream from a gauge. The Manning equation is: where The Chezy equation is: where C is the Chezy form of rugosity. The above equations are generally applicable for gradually varied, uniform flow. For highly varied, nonuniform flow, equ
44、ations such as the Saint-Venant unsteady flow equations would be appropriate. However, these are seldom used in the development of stage-discharge relations, and are not described in this part of ISO 1100. 5.3 Complexities of stage-discharge relations Stage-discharge relations for stable controls su
45、ch as a rock outcrop, and manmade structures such as weirs, flumes, and small dams usually present few problems in their calibration and maintenance. However, complexities can arise when controls are not stable and/or when variable backwater occurs. For unstable controls, segments of a stage-dischar
46、ge relation may 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 relation, both for stable and unstable channels. Sources of backwater can
47、 be downstream reservoirs, tributaries, tides, ice, dams and other obstructions that influence the flow at the gauging station control. Another complexity that exists for some streams is hysteresis, which results when the water surface slope changes due to either rapidly rising or rapidly falling wa
48、ter levels in a channel control reach. Hysteresis is sometimes referred to as loop ratings, and is most pronounced in relatively flat sloped streams. On rising stages the water surface slope is significantly steeper than for steady flow conditions, resulting in greater discharge than indicated by th
49、e steady flow rating. The reverse is true for falling stages. See 6.8.4 for details on hysteresis ratings. The succeeding clauses of this part of ISO 1100 will describe in more detail some of the techniques available for analyzing the various complexities that may arise. 6 Stage-discharge calibration of a gauging station 6.1 General The primary object of a stage-discharge gauging station is to provide a record of the discharge of the between two gauges, or rate-of-change in stag
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