1、 Reference number ISO/TR 23211:2009(E) ISO 2009TECHNICAL REPORT ISO/TR 23211 First edition 2009-07-01 Hydrometry Measuring the water level in a well using automated pressure transducer methods Hydromtrie Mthodes automatises, utilisant des transducteurs de pression, pour mesurer le niveau deau dans u
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7、O 2009 All rights reserved iiiContents Page Foreword .v Introductionvi 1 Scope1 2 Normative references1 3 Terms and definitions .1 4 Applications of the use of pressure transducers to ground-water resource investigations 1 4.1 Ground-water monitoring .1 4.2 Long-term monitoring.2 4.3 Short-term moni
8、toring 4 4.4 Reducing well-bore storage .4 5 Planning considerations for sensor systems.8 5.1 General .8 5.2 Study duration and system reliability .8 5.3 Required accuracy 8 5.4 Installation location and site accessibility9 5.5 System components and compatibility.9 5.6 Water quality 9 5.7 Number of
9、wells.9 5.8 Well location, diameter and depth .10 5.9 Data-collection frequency.10 5.10 Data transfer 11 5.11 Cost.11 6 Assembly, calibration and testing .11 6.1 General .11 6.2 Familiarization with transducer performance.11 6.3 Linear transducer calibration.13 6.4 Sources of error in linear calibra
10、tions 14 6.5 Temperature-corrected transducer calibration 14 7 Installation16 7.1 General .16 7.2 Care and handling .17 7.3 Shelter.18 7.4 Power requirements 19 7.5 Hanging transducers in wells 20 7.6 Measuring system drift .22 7.7 Desiccation systems .23 7.8 Transducer field calibration .23 7.9 Opt
11、imizing measurement-system performance.26 8 Data collection .27 8.1 General .27 8.2 Frequency of visits27 8.3 Field checks .27 8.4 Data recording and retrieval.28 8.5 Verification .30 8.6 Use with data loggers .30 8.7 Field documentation .30 8.8 Maintenance.30 ISO/TR 23211:2009(E) iv ISO 2009 All ri
12、ghts reserved9 Data processing.31 9.1 General31 9.2 Adjustments .31 9.3 Documentation.31 Annex A (informative) Pressure transducers Characterization, common problems and solutions .33 A.1 Pressure transducer characterization .33 A.1.1 General33 A.1.2 Types of pressure measurements .33 A.1.3 Common p
13、ressure units used in hydrology .34 A.1.4 Basic types of transducers for measuring pressure .35 A.1.5 Understanding pressure-transducer specifications 47 A.2 Common problems and solutions53 A.2.1 General53 A.2.2 Leakage.53 A.2.3 Open and short circuits 55 A.2.4 Grounding problems .56 A.2.5 Diaphragm
14、 failure 56 A.2.6 Power-supply failure .56 A.2.7 Data logger channel failure.56 A.2.8 Voltage surges .57 A.2.9 Faulty shielding57 A.2.10 Over-range problems 57 Bibliography 58 ISO/TR 23211:2009(E) ISO 2009 All rights reserved vForeword ISO (the International Organization for Standardization) is a wo
15、rldwide 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 committee has been established has the right to be represented o
16、n 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 electrotechnical standardization. International Standards are drafted
17、 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 member bodies for voting. Publication as an International Standa
18、rd requires approval by at least 75 % of the member bodies casting a vote. In exceptional circumstances, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for example), it may decide by a simple m
19、ajority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does not have to be reviewed until the data it provides are considered to be no longer valid or useful. Attention is drawn to the possibility that some of the elements of
20、 this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO/TR 23211 was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 8, Ground water. This Technical Report is based on, and much of the material i
21、s from, Freeman and others 8 . It complements ISO 4373, Hydrometry Water level measuring devices. ISO/TR 23211:2009(E) vi ISO 2009 All rights reservedIntroduction Submersible pressure transducers, developed in the early 1960s, have made the collection of water-level and pressure data much more conve
22、nient than former methods. Submersible pressure transducers, when combined with electronic data recorders have made it possible to collect continuous or nearly continuous water-level or pressure data from wells, piezometers, soil-moisture tensiometers, and surface water gages. These more frequent me
23、asurements have led to an improved understanding of the hydraulic processes in streams, soils, and aquifers. TECHNICAL REPORT ISO/TR 23211:2009(E) ISO 2009 All rights reserved 1Hydrometry Measuring the water level in a well using automated pressure transducer methods 1 Scope This Technical Report pr
24、ovides information about the functional requirements of instrumentation for measuring the water level in a well using automated pressure transducer methods. This Technical Report provides guidance for the proper selection, installation and operation of submersible pressure transducers and data logge
25、rs for the collection of hydrologic data, primarily for the collection of water-level data from wells. Basic principles, measurement needs and considerations for operating submersible pressure transducers are described and the systematic errors inherent in their use are discussed. Standard operation
26、al procedures for data collection and data processing, as well as applications of transducers for specific types of hydrologic investigations are included. Basic concepts regarding the physics of pressure and the mechanics of measuring pressure are presented, along with information on the electronic
27、s used to make and record these measurements. Guidelines for transducer calibration, proper use and quality assurance of data also are presented. Ground water field applications of pressure transducer systems are discussed, as are common problems that may corrupt data, along with suggestions for fie
28、ld repairs. Annex A provides guidance on the types of pressure transducers commonly used for water-level measurement and the measurement uncertainty associated with them. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated refer
29、ences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 772, Hydrometry Vocabulary and symbols 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 772 apply. 4 A
30、pplications of the use of pressure transducers to ground-water resource investigations 4.1 Ground-water monitoring Submersible pressure transducers can be used for long-term and short-term applications. This clause discusses both applications. In addition, in 4.4, information is provided on the tech
31、nique of reducing well-bore storage so that the user can apply this technique to reduce the effective diameter of wells during slug tests or aquifer tests. ISO/TR 23211:2009(E) 2 ISO 2009 All rights reserved4.2 Long-term monitoring 4.2.1 General Many hydrologic investigations require continual monit
32、oring (over periods of weeks to years) of water levels in wells. Examples of such studies include monitoring water levels for indication of earth tides 10, 16 , indication of earthquakes 6, 26 , determination of temporal variation in vertical or horizontal hydraulic gradients 11, 28 , determination
33、of timing and magnitude of recharge to ground water following precipitation events23, 28 , and monitoring of pump-and-treat operations at ground-water reclamation sites. For many studies, even if continual data collection is not necessary, it is cost effective to monitor water-level fluctuations in
34、wells with a sensor rather than using human resources to collect discrete measurements. Submersible pressure transducers have long been used for monitoring water-level fluctuations in wells 11, 29 . Buried in the soil, these devices also have been used for decades to monitor pressure heads. Sensors
35、used in this way have historically been called the “Casagrande type” pressure transducers, and are commonly used to monitor pressure heads in and around dams. While other automated water-level sensor systems also can provide continual water-level data in wells, submersible pressure transducers are p
36、articularly well suited for some applications. Typically small, and requiring little maintenance because they are immersed in water, their environmental conditions are relatively stable. Some examples of applications in which submersible pressure transducers are particularly well suited are listed b
37、elow. 4.2.2 Pressure range considerations Submersible pressure transducers can be selected to monitor a small or large range of expected water-level conditions. Transducers designed to measure a small pressure range can monitor stage changes of 3 m (10 ft) or less with a very high degree of resoluti
38、on and accuracy. However, higher range pressure transducers can monitor water level changes on the order of 100 m (300 ft) with little loss of resolution or accuracy. Pressure transducers are well suited when large and sometimes rapid stage changes are expected, such as monitoring head changes in ka
39、rst terrain, production wells, or pressure pulses associated with earthquakes. 4.2.3 Non-vertical or irregular situations Submersible pressure transducers can be used in non-vertical or irregular wells when other systems cannot operate effectively. For a non-vertical well, a properly calibrated pres
40、sure transducer will indicate changes in vertical head in the well, requiring no adjustment to the data, whereas data from a float installed in the same well would require adjustment to compensate for the wells non-vertical orientation. Also, severe irregularities or deviations in the bore of a well
41、 could render acoustic-velocity devices or float mechanisms inoperative, while data from a pressure transducer would not be affected. 4.2.4 Severe environments Submersible pressure transducers are well suited for data collection in severe environmental conditions, such as arctic or low-latitude dese
42、rt climates. The relative stability of ground-water temperature provides a much more suitable environment for submersible pressure transducers than for sensors that are mounted above ground or inside a well but above the water table. During freezing conditions, other types of sensors mounted to the
43、top of a well can be disabled by freezing of water that has condensed on the sensor 28 . Not only is the submersible pressure transducer usually not exposed to such extreme temperatures, if the water level in the well is shallow enough to freeze, the pressure transducer can continue to register pres
44、sure fluctuations below ISO/TR 23211:2009(E) ISO 2009 All rights reserved 3the ice lens. If ice were present in the well, an acoustic-velocity system or a float would indicate a constant water level. Relic ice lenses still frozen to the side of a well can hinder the operation of sensors. 4.2.5 Flowi
45、ng wells In flowing artesian wells (wells with potentiometric heads above land surface), a submersible pressure transducer can provide potentiometric-head data. This transducer is especially well suited to provide data when the potentiometric head fluctuates both above and below land surface. If pot
46、entiometric head rises to the point where a standpipe is impractical, or if heads frequently drop below land surface, a submersible pressure transducer may be the only practical option for providing continuous potentiometric-head data. 4.2.6 Large depth-to-water considerations Wells with a depth to
47、water greater than 100 m (300 ft) present special problems for most submersible pressure transducers. Cable or line stretch, thermal expansion, vent-tube blockage, and signal loss can introduce significant errors in deep wells or where sensors are located far from a logging device. OBrien 24noted th
48、at voltage problems caused by lead lengths of up to 1 500 m (5 000 ft), and blocked vent tubes, led to problems when monitoring water-level fluctuations in deep wells. Well-bore deviation, a problem common to deep wells, is magnified by the depth to water. Submersible pressure transducer models capa
49、ble of making an analogue to digital conversion before transmitting the signal up the well to the data logger can overcome many of these problems. 4.2.7 Small diameter situations To mitigate problems associated with hydraulic lag time, small-diameter piezometers commonly are installed in wells drilled in geologic materials with low hydraulic conductivity. Although other types of sensors have been used for monitoring water-level fluctuations in small-diameter wells 21 , most sensors are too large to
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