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इंटरनेट मानक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. “जान1 का अ+धकार, जी1 का अ+धकार” “प0रा1 को छोड न’ 5 तरफ” Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru “The Right to Information, The Right to Live” “Step Out From the Old to the New” IS 8389 (2003): Installation and Use of Raingauges, Recording - Code of Practice [WRD 1: Hydrometry] “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda ““IInnvveenntt aa NNeeww IInnddiiaa UUssiinngg KKnnoowwlleeddggee”” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS 8389:2003 Indian Standard INSTALLATION AND USE OF RAINGAUGES, RECORDING — CODE OF PRACTICE (Second Revision ) ICS 93.160 @ 131S2003 BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 May 2003 Price Group 8 Ground Water and Related Investigation Sectional Committee, WRD 3 FOREWORD This Indian Standard (Second Revision) was adopted by the Bureau of Indian Standards, after the draft finalized by the Ground Water and Related Investigation Sectional Committee had been approved by the Water Resources Division Council. The total amount of precipitation which reaches the ground in a stated period is expressed as the depth to which itwould cover ahorizontal projection of the earth’s surface, ifthere were no loss by evaporation, percolation or run-off and ifany part of the precipitation falling as snow or ice were melted. The simplest method of measuring precipitation is by using gauges with a horizontal circular aperture of known area and collecting and measuring at regular intervals the precipitation collected in them. It isassumed that the amount of precipitation collected in the gauge is representative of a certain area around the point where the measurement is made. The choice of the instrument and the site itself, the forin and exposure of the measuring gauge; the prevention of loss of precipitation by evaporation and the effects of wind and splashing are some of the important points to be considered in the correct measurement of precipitation. Before analyzing rainfall data from precipitation gauges, the condition of the raingauge, its maintenance, the period for which the data refers and the control exercised on the quality of data collected, shall be carefully examined. Precipitation gauges are of two types, namely (a) non-recording, and (b) recording. The non-recording type measures only the accumulated rain which has fallen inacourse of time, generally 24 h, while the recording type indicates the duration (that is, the time of onset and cessation), amount and intensity of rain whenever it occurs. However, when a recording type is desired at aparticular place it is imperative that non-recording type is also installed alongside for comparison. This code is confined to the recording type of raingauges. This standard was first issued in 1977 and revised in 1983. In this revision the major modifications are inrespect of size of collector rim of natural siphon recording raingauge and certain modifications in the ,proforma for inspection report. Among the different types ofrecording raingauges, the most videly used inIndia isthe float gauge, with, automatic siphoning arrangement. Detailed specifications for this type ofraingauge are given inIS 5235:1992’ Meteorology rainguage recording — Specification’. There is no ISO Standard on the subject. This standard has been prepared based on the data received from indigenous practioners and also taking into consideration the practice prevalent in the field in India. The composition of the Committee responsible for the formulation of this standard is given in Annex C. For the purpbse of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result ofatest oranalysis, shall be rounded off inaccordance with IS 2:1960 ‘Rules for rounding off numerical values (revise~’. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. IS 8389:2003 Indian Standard INSTALLATION AND USE OF RAINGAUGES, RECORDING — CODE OF PRACTICE (Second Revision ) 1SCOPE 3.2 The measure glass (see Fig. 3) designed for use with the raingauge has a capacity corresponding to This standard covers the procedure to bc followed in 10mm of rainfall with graduations every 0.1 mm. the installation, use and recording ofprccipitation from the natural siphon type recording raingauges. 3.3 To record the precipitation at stations where heavy rainfall is experienced regularly, collector of 2 REFERENCE lesser area (129.4 * 0.4 cm2 ) is preferable so that ‘[’he following standard contains provision which volume of water collected for certain amount of through reference inthis text, constitutes provision of rainfall will be less. With this collector, the raingauge this standard. At the time of publication, the edition has acapacity of 25 mm of rainfall for each siphoning. indicated was valid. All standards are subject to A suitable measure glass for this type of recorder has revision, and parties to agreements based on this also been provided. This has acapacity corresponding standard are encouraged to investigate the possibility to 25 mm of rainfall, with graduations at every 0.2 of applying the most recent edition of the standard mm (see Fig. 4). indicated below: 3.4 The recording raingauge having 323.7 + 0.7 cm~ I.YN(). Title rim area of collector and 10mm rainfall capacity, uses 5047: 1970 Charts for recording meteorological Chart No. DR-1 and that having (129.4+ 0.4 cn12)rim instruments area of collector with 25 mm of rainfall capacity, uses Chart No. DR-2 (see IS 5947). 3 DESCRIPTION 3.1 The natural siphon recording raingauge (see Fig. 1) 4 EXPOSURE OF RAINGAUGE consists ofacollector and rainfall recording mechanism 4.1 In a perfect exposure the catch of the mingauge (.YL’FCig. 2) mounted on abase. The rainfall recording would accurately represent the precipitation falling on uni[ consists of afloat chamber containing alight metal the surrounding area. This is, however, difficult to floal Jnd a siphon chamber. Rain from the collector is attain inpractice because of the effect of the wind and Id into the float chamber through a n inlet tube and as much care has to be given to the choice of the site. The d~cfloilt rises, apen fixed to the float, rod draws a line catch in a raingauge depends on the exposure of the ~Itl:] chart W’L)Lilldon a rotating drum driven by gauge tothe wind and also on the disposition and height clocklt ork. The discharge tube is inside and coaxial of the surrounding terrain and objects. The result of ){ith the outer tube of the siphon chamber. The top of the former is generally to reduce the amount of water this outer tube has a polished glass cap and the collected, while the effects of the latter are more discharge tube comes to within every short distance of important and can give rise both to an increase or [his. Lk’hcnthe level of water in the outer tube rises decrease in the recorded value. It is important that the \\’ith that of the water in the float chamber and flOWS observations made at different stations under similar over tbc bend at the top of the discharge tube, capillary environmental and topographic setting should be action causes all the air to be pushed out and down the comparable and that their exposures should be similar. discharge tube so that a full flow is started at once. At The rules given in 4.1.1 to 4.1.3 for the setting of the the end of this siphoning, air finds access to the top of gauges shall be followed. the tube and the siphoning action is topped immediately. As the water from the float chamber 4.1.1 The gauge shall be exposed with its rim empties out, the float descends and the pen attached to horizontal, over as level a ground as possible. It shall rhe float rod slowly falls to the zero mark on the chart not be located on a slope with the ground sloping iihen siphoning is complete. The gauge is now ready sharply away in any direction, especially if this [(~record rainfal} again. The gauge generally has a direction is the same as the prevailing wind or on a cap;iciotfy1()mm of rainfall for each siphoning; and terrace and never on awall, roof or similar other object. I)w a colicctor having a rim area of 323.7 * 0.7 cm2 1203 J-0.2 n)m dia). NOTE—Thelevelgroundmayhaveanareaof6x6m. 1 IS 8389:2003 GUNMETAL RIM----\ & 128.6 OR 203.4mm ++ FUNNEL ,— \\ HOLES= \ -DRUM -PEN ~~ FILTER FLOAT CHAMBER INLET TUBE GLASS CAP \ 67 m COLLECTOR SIPHON CHAMBER= BASE> -&’ FLOAT -FLOAT A FOUNDATION BOLT F IG. 1NATURAL. -S IPIIOYRECORDINGRAINGAUGE 4.i.2 The distance of the raingauge from any hard surface is not reached at the prescribed depth, it surrouociing object shall generally be four times the may be dug deeper and filled in with boulders and huigh: of the object, but shall never be less than twice rubbles up to a depth of 525 mm below ground level. [he height of object. 5.2 A-150 mm Iong foundation bolt is fixed in the 4.1.3 Where the observations have to be made on an centre ofthe platform sothat 50 mm of the bolt projects cl~ensive sloping surface, such as the side of a above the top of the platfonm After the bolt has set in mountain. effort shall be made to expose the gauge on the cement, fix the base of the raingauge on the a smooth site which is sufficiently large in area and platform, asfollows. Remove the three thumb nuts (see l~hosc slope and orientation correspond tothe average Fig. 2) and raise the recording mechanism straight up s!(~pcand orientation of the surrc~undings. However, from its seat. Place the base on the platform so that the [hc instrument under no circumstances should be foundation bolt passes through the hole in the centre ln~tallcd on unstable slopes or intheir close proximity. of the angle iron piece and fix it with the fly nut. This can be done through the opening inthe base. Place the 5 lXSTALLATION OF THE RECORDING collector and see that the instrument rests firmly on R,\ ING.+UCE the platform and is vertical. A spirit level should be 5.1 ‘1’ilc raingauge shall be instalied on a concrete or placed across the rim in three different directions and l[ltis~)nry plutform 600 mm cube as shown in Fig. 5, the horizontality checked. Now replace the recording CICUICYtiIom hard soil surface. If the soil is loose, and mechanism in itsplace and lock itwith the three thumb 1S8389:2003 FILTER INLET TUBE t I DRUM –J SETSCREW FOR COLLAR SMALL OPENING \I\I T co UT SIPHON BER FIG. 2 THE RECORDINGMECHANISM nuts. The float chamber should be levelled by means 6 PROTECTION OF RAINGAUGE of the three nuts below the thumb nuts. 6.1 The raingauge shall be protected from damage by 5.3 The gauge shall be so installed that the rim of the installing it inside a suitable protective fencing as t’unncl is truly horizontal and at a height of exactly shown in Fig. 6. The fence shall be of such height that 750 mm above the ground level. the top of the fence isnot higher than half the distance of the fence from the gauge. Though a suggested size s.4 Suitable arrangements for draining the water from forthe fence isshown inFig. 6,itisdesirable, wherever the surface of the platform shall be made such that the possible, to enlarge the size to meet stipulations laid water never stagnates on the top surface ofthe platform. down in 4.1.2. 5.S The recording raingauge shall be installed in an 6.2 The raingauge shall always be kept locked. enclosure by the side of the non-recording raingauge preferably at a distance of about 3 m from it; if this is 7 METHOD OF USE AND MAINTENANCE OF not possible for any reason, the two raingauges shall THE RECORDING RAINGAUGE be separated from each other by a distance not less 7.1 Remove the cover and wrap the appropriate chart, than 1.5m (see Fig. 6). 3 Is 8389:2003 1 < I /7 25mm i J!_ 2min. — ~2 min 29 10 1 295:10 t 235T11 235t10 I i-++ A)! dimcns)oms ]nmillimctres. All dimensions inmillimetres. ]1(,. g MF,4SURE~1..\SS 10R 325 C1112 Fl~. 4 MEASURE GLASS FOR 130 cmz Rf;coRl)i N(i RAi N(;A LI( it. WKORDING RAINGAUGF. clihci Ijf{- 1or DR-2, on the clock-dram, t:iking care the chart, The water should now be poured in drop by 10 scc that corresponding horizontal lines on the drop until the instrument siphons. This should occur ()~crlapping portions arc coincident and that the bottom when the top line is reached and there is no water left of tbc chart is as near to the flange at the bottom as inthe measure glass. Ifthe pen does not rise to the top pt,isiblc. The instrumcmt isset asgiven in7.1.1 to7.1.4. line of the chart, loosen the setscrew fixing the collar in the lid and slightly raise the collar by turning it. 7,1.1 I’our sufficient water into the tube leading to the Adjust till the correct range is obtained on the chart ilt)at cluimber till the water begins to siphon. After ~!photling iscomplctc, and the pen has become steady, when 10or 25 mm of water is added. The raingauges tile pen point should rest against the zero line on the are set and calibrated before they are dispatched to the c!);lrt. Ifit does not, loosen the setscrew fixing the pen station and itwill not normally be necessary to set the L)IIth~?IIO:It I-Odand move the pen carrier on the float headed collar at the outstation, or to read just the P(K]u];[ii tilt: pen point is exactly on the zero line. Now discharge tube. tighten the sctscreyv. 7.1.3 Put sufficient ink in the pen, taking care to see 7.1.2 Measure out the equivalent of 10 or 25 mm of that ink does not hang in a drop from the underside ir.lin(’:]1]l’roln the appropriate measure glass. Pour this of the pen. The pen reservoir can hold more than i,,:I[cr :ctiti} into the inlet tube until tbc pen reaches sufficient ink for a normal week’s record and IIICi)ori~ontal” line immediately below the top line on therefore need not be filled to overflowing daily. 4 IS 8389:2003 128”6 2::.4 rl 7 “ 750 1 ANWLRON 1 9 _—---_____—-— —-- ---- 2-- 150 ! 75 GL 1,. b g ‘<~ ,- ~-= I 1;0 I 1=+ 4 1 I I 1 MASONRY OR CEMENT CONCRETE PLATFORM I 60x60 x60cm 1 I I \ I I I l–_EA!!=pkRl~c~–- J All dimensions in millimetres, F1~.5 INSTAL L ATION OF NATURAL SIPHON RECORDING RAINGAUGE ‘;onle[imes no trace is obtained owing to tip of the 7.2.2 Unlock and remove the cover and place iton the pm being nol wet and touching the paper at the slit ground nearby with the rim at top. Lift off the pen by in the pcn through which ink flows. To adjust the loosening the setscrew fixing the pen to the float rod. pen. loosen the setscrew fixing the pen on the float Take off the old chart after removing the clip, put on NJCIand rotate the pen carrier about the float rod till it new chart correctly and replace the chart clip. marks correctly. Tighten the screw. Care should be 7.2.3 Wind the clock, ifnecessary. The clock need be taken to see that the pen is not displaced vertically wound filly only once in seven days. ~vbile doing this. 7.2.4 See that there is sufficient ink in the pen and that 7.1.4 Wind the clock and set the pen to the correct itmarks. tinlc to record. 7.2.5 Set the pen to zero as follows. Pour sufficient 7.2 Daily Routine Operation water into the receiver from the measure glass slowly till the pen reaches the top and water siphons out. After 7.2.1 The chart ischanged at the same time each day, all the water has drained out, the pen should be on the Lisually behvecn O830 h and O900 h Indian Standard zero line. If not, adjust as described in 7.1.2. Repeat Tinlc (1ST). The daily routine given in 7.2.2 to 7.2.7 the operation, if necessary, until a correct trace is lllay befollowed. obtained at the extreme left of the chart grid. 5