1、 Reference number ISO 21413:2005(E) ISO 2005INTERNATIONAL STANDARD ISO 21413 First edition 2005-10-15 Manual methods for the measurement of a groundwater level in a well Mthodes manuelles pour le mesurage du niveau de leau souterraine dans un puits ISO 21413:2005(E) PDF disclaimer This PDF file may
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6、ght 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 2005 All rights reservedISO 21413:2005(E) ISO 2005 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope1 2 Terms and d
7、efinitions .1 3 Water-level measurement using a graduated steel tape .2 3.1 Purpose.2 3.2 Materials and instruments 2 3.3 Data accuracy and limitations2 3.4 Advantages and disadvantages.3 3.5 Assumptions 3 3.6 Procedures.3 4 Water-level measurement using an electric tape .6 4.1 Purpose.6 4.2 Materia
8、ls and instruments 6 4.3 Data accuracy and limitations6 4.4 Advantages and disadvantages.7 4.5 Assumptions 7 4.6 Procedures.7 5 Water-level measurement using an air line.10 5.1 Purpose.10 5.2 Materials and instruments 10 5.3 Data accuracy and limitations10 5.4 Advantages and disadvantages.11 5.5 Ass
9、umptions 11 5.6 Procedures.11 6 Water-level measurement in a flowing well 13 6.1 Purpose.13 6.2 Materials and instruments 13 6.3 Data accuracy and limitations14 6.4 Advantages and disadvantages.15 6.5 Assumptions 15 6.6 Procedures.15 6.6.1 Low-pressure head measurement (direct measurement) .15 6.6.2
10、 High-pressure head measurement (indirect measurement) .15 7 Establishing a permanent measuring point16 7.1 Purpose.16 7.2 Materials and instruments 16 7.3 Data accuracy and limitations17 7.4 Assumptions 17 7.5 Procedure.17 Annex A (informative) Corrections for water levels measured in deep wells by
11、 steel tapes subject to temperature changes and tape stretch .26 Annex B (informative) Corrections for water levels measured in wells with the air-line method.28 Bibliography 30 ISO 21413:2005(E) iv ISO 2005 All rights reservedForeword ISO (the International Organization for Standardization) is a wo
12、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
13、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
14、 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
15、rd 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 identifying any or all such patent rights. ISO 21413 was prepared by
16、Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 8, Ground water. ISO 21413:2005(E) ISO 2005 All rights reserved v Introduction The measurement of a water level in a well constitutes a data-collection process that provides fundamental information about the status of a groundwater system.
17、Accordingly, measured water levels should be sufficiently accurate and reproducible to meet the needs of most data-collection and monitoring programs. Several manual methods commonly used to collect water-level data in wells employ relatively simple measuring devices such as graduated steel tapes, e
18、lectric tapes, and air lines. In some cases, water-level measurements are required in flowing wells. The procedures associated with each of these methods are intrinsically different and subject to varying limitations and accuracies. Standardization of these methods would ensure that the procedures a
19、nd associated equipment used by the international community to collect water-level data in a well are consistent, and that the results can be compared with minimal concern about the relative accuracies and/or the procedures use in collecting the data. INTERNATIONAL STANDARD ISO 21413:2005(E) ISO 200
20、5 All rights reserved 1 Manual methods for the measurement of a groundwater level in a well 1 Scope This International Standard develops procedures and prescribes the minimum accuracy required of water- level measurements made in wells using graduated steel tapes, electric tapes and air lines. Proce
21、dures and accuracy requirements for measuring water levels in a flowing well are also included, as are procedures required to establish a permanent measuring point. This International Standard discusses the advantages and limitations of each method and requirements for recording the data. This Inter
22、national Standard does not include methods that use automated electrical or mechanical means to measure and record water levels. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply: 2.1 air line water-level measuring device consisting of a small diame
23、ter open-ended tube fixed in position that is accessible from the top of the casing and extends to below the water level in a well where pressurized air measurements can be used to determine the depth to water 2.2 casing (well casing) tubular retaining structure, which is installed in a drilled bore
24、hole or excavated well, to maintain the borehole opening. Plain (unscreened) casing prevents the entry of water and fine material into the well, while open (screened) casing allows water ingress but should exclude fines 2.3 electric tape water-level measuring device that uses an electrical signal, s
25、ent through a cable with fixed distance marks, to determine the water level relative to a fixed reference point. The electrical signal, which is induced when the sensor makes contact with the water surface, activates an indicator (typically a light, buzzer or needle) 2.4 flowing well (or overflowing
26、 well) well from which groundwater is discharged at the ground surface without the aid of pumping NOTE A deprecated term for this definition is an artesian well. 2.5 graduated steel tape water-level measuring device consisting of a flat measuring tape with permanently fixed distance marks that can b
27、e wound on a reel 2.6 groundwater water within the saturated zone ISO 21413:2005(E) 2 ISO 2005 All rights reserved2.7 land surface datum average altitude of land surface at a referenced well 2.8 measuring point permanent reference marked on well casing 2.9 static water level (or static head) height,
28、 relative to an arbitrary reference level, of a column of water that can be supported by the static pressure at a given point 2.10 well hole sunk into the ground for abstraction of water or for observation purposes 3 Water-level measurement using a graduated steel tape 3.1 Purpose The purpose of thi
29、s method is to measure the depth to the water surface (level) below a measuring point using the graduated steel tape (wetted-tape) method. 3.2 Materials and instruments The following materials and instruments are required. 3.2.1 Steel tape graduated in metres and centimetres. A black tape is preferr
30、ed to a chromium-plated tape because the wetted chalk mark is easier to read against a black tape. A break-away weight should be attached to the ring on the end of the tape with wire strong enough to hold the weight, but not as strong as the tape, so that if the weight becomes lodged in the well, th
31、e tape can still be pulled free. The weight should be made of brass, stainless steel or iron. 3.2.2 Coloured chalk. 3.2.3 Clean cloth. 3.2.4 Pencil and eraser. 3.2.5 Steel tape calibration and maintenance equipment log book. 3.2.6 Water-level measurement field form (see the example in Figure 6). 3.2
32、.7 Equipment to gain access to the well (wrenches, crow bars, manhole keys, etc.). 3.2.8 Common household chlorine bleach or other suitable disinfectant. 3.3 Data accuracy and limitations The following data accuracy and limitations apply. a) Independent graduated steel tape measurements of static wa
33、ter levels should agree within 1,0 cm for depths of less than 60 m; ISO 21413:2005(E) ISO 2005 All rights reserved 3 b) For depths between 60 m and 150 m, independent measurements using the same tape should agree within 2,0 cm. When measuring deep water levels (i.e. greater than 300 m), errors due t
34、o the effects of thermal expansion and of stretch produced by the suspended weight of the tape and plumbing weight warrant consideration (see Reference 2, p. 3). An example of correcting a deep water level for thermal expansion and stretch of a steel tape is given in Annex A. However, because the eq
35、uipment required to measure temperatures at land surface and down the well may not always be readily available, the corrections described in Annex A are not required for the purposes of this International Standard, though the practitioner shall note on the water-level field form (see the example in
36、Figure 6) whether or not any such corrections were applied. c) At least once every twelve months, the steel tape should be calibrated against another steel tape that is dedicated as a calibration tape and is not used in the field. If the steel tape does not meet test criteria, then it must be remove
37、d from service. Records of these tests shall be kept. d) If the well casing is angled, instead of vertical, the depth to water will have to be corrected. If the casing angle is unknown and a correction is not feasible, this should be noted in water-level measurement field form (see the example in Fi
38、gure 6). 3.4 Advantages and disadvantages The graduated steel tape method is easy to use and is considered to be the most accurate method for measuring the water level in nonflowing wells of moderate depth. However, it may be impossible to get reliable results if water is dripping into the well or c
39、ondensing on the well casing. Also, the method is not recommended for measuring pumping levels in wells. 3.5 Assumptions The following assumptions apply in the use of the graduated steel tape method. a) An established measuring point (MP) exists and the distance from the MP to land-surface datum (LS
40、D) is known (see the example in Figure 6). See the technical procedure described in Clause 7 for establishing a permanent MP. b) The MP is clearly marked and described so that all measurements will be taken from the same point. c) The results from previous water-level measurements made at the well a
41、re available for estimating the length of the required tape. d) The steel tape will retain the chalk. e) The well is free of obstructions. Well obstructions, if present, could cause errors in the measurement if the obstructions affect the plumbness of the steel tape. 3.6 Procedures The following pro
42、cedures for measuring water levels in a well with a graduated steel tape shall be observed. a) Apply the coloured chalk to the lower metre of the tape by pulling the tape across the chalk. The wetted chalk mark will identify that part of the tape that was submerged. b) Lower the weight and tape into
43、 the well until the lower end of the tape is submerged below the water (more than one attempted measurement may be needed to determine the length of tape required to submerge the weight). Once the end of the tape is submerged, continue to lower the tape into the well until the next whole metre gradu
44、ation mark is opposite the MP. This whole number shall be recorded in the “MP HOLD” (Figure 1) column of the water-level measurements field form (see the example in Figure 6). ISO 21413:2005(E) 4 ISO 2005 All rights reservedc) Pull the tape back to the surface before the wetted chalk mark dries and
45、becomes difficult to read. Record the number of the wetted chalk mark (sometimes referred to as the cut) in the “WETTED CHALK MARK” (Figure 1) column of the water-level measurements field form (see the example in Figure 6). d) Subtract the wetted chalk mark number from the number held to the MP, and
46、 record this number in the “DEPTH TO WATER FROM MP” (Figure 1) column of the water-level measurements field form (see the example in Figure 6). The difference between these two readings is the depth to water below the MP. e) Apply the MP correction to get the depth to water below or above land-surfa
47、ce datum (LSD). If the MP is above land surface (see the example in Figure 6), the distance between the MP and land surface datum is subtracted from the depth to water from the MP (see the example in Figure 6) to obtain the depth to water below land surface. If the MP is below land surface, precede
48、the MP correction value with a minus ( ) sign and subtract the distance between the MP and land surface datum from the depth to water from the MP to obtain the depth to water below land surface. Record this number in the “DEPTH TO WATER FROM LSD” (Figure 1) column of the water-level measurements fie
49、ld form (see the example in Figure 6). If the water level is above LSD, record the depth to water above land surface as a negative number. f) Make a check measurement by repeating steps a) through e). The check measurement shall be made using a different MP hold value (see the example in Figure 6) than that used for the original measurement. If the check measurement does not agree with the original measurement to the nearest centimetre, continue to make check measurements until the reason for the lack of agreement is determined or until the res
