Agriculture sector contributes nearly 35 per cent of

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1 Interntionl Journl of Agriculturl Engineering, Vol. 2 No. 2 (October 2009 to Mrch 2010) : Hydrulic performnce of mnully operted drip irrigtion system M.L. CHAVAN, U.M. KHODKE AND S.B. JADHAV Accepted : August, 2009 See end of the rticle for uthors ffilitions Correspondence to: U.M KHODKE AICRP on Wter Mngement, Mrthwd Agriculturl University, PARBHANI (M.S.) INDIA ABSTRACT In drip irrigtion system the hydrulic prmeters such s pressure dischrge reltionship, mnufcturing coefficient of vrition, men flow rte devition, coefficient of dischrge, emitter dischrge exponent, field emission uniformity nd bsolute emission uniformity cn be used for the design, opertion nd selection of the irrigtion system. The field experiment ws conducted to evlute the performnce of mnully operted drip irrigtion system for different types of emitters. For the experiment three different types of emitter s viz. 2 lph, 4 lph nd 8 lph were fitted on three lterls ech of 10 m length. The emitters nd lterl spcing ws 1 m. The system ws operted t vrying pressures between 0.4 to 1.4 kg/cm 2 with n increment of 0.2 kg/cm 2. The emitter flow rte ws mesured in the ctch cns. Results show tht the emitters bsed on the hydrulic prmeters were chrcterized s verge. The field nd bsolute emission uniformity ws bove 90 %. The system performed better in the rnge of 0.6 to 1.0 kg/cm2 with highest emission uniformity. The overll ulity of emitters ws better for high nominl dischrge rtes. These hydrulic prmeters of emitters evluted cn be used for the design, opertion nd selection of the irrigtion system. The mnully operted system thus cn be used form smll frms. Key words : Emission uniformity, Emitting devices ulity, Pressure-dischrge reltionship, Men flow rte devition nd emitter dischrge exponent Agriculture sector contributes nerly 35 per cent of ntionl income nd engges 70 per cent of Indin popultion. Wter is the most vitl input in griculture nd hs mde significnt contribution in providing stbility to food grin production nd self-sufficiency. Efficient utiliztion of vilble wter resources is crucil for country like Indi, which shres 17 % of the globl popultion with only 2.4 % of lnd nd 4 % of wter resources. In Mhrstr while 80 % cultivble lnd depends on rinfll, efficient utiliztion of vilble wter resources in the stte is crucil for its griculturl development (Anonymous, 2006). Irrigtion meets the wter demnds of plnts by replenishment of root zone when nturl rinfll is indeute or poorly distributed. Within field, irrigtion wter needs to be distributed uniformly to ll plnts. However, in most cses nonuniformity in irrigtion wter supply is the mjor source of reduced crop yields (Wu, 1987; Bhtngr nd Srivstv, 2003). On the contrry, drip irrigtion system cn pply freuent nd smll mounts of wter t mny points in the field with minimum losses nd mintining stedy moisture in the soil profile. In ddition, drip irrigtion system is best suited for difficult topogrphy (Decroix nd Mlvl, 1985; Youngs et l., 1999 nd Wei et l., 2003) nd offers the highest irrigtion uniformity compred to other irrigtion methods. A successful uniform drip irrigtion system ppliction depends on the physicl nd hydrulic chrcteristics of the drip tubing (Al Amound, 1995). Efficiency of drip irrigtion system depends on ppliction uniformity which cn be evluted by direct mesurement of emitter flow rtes. According to Mizyed nd Kruse (1989), the min fctors ffecting drip irrigtion uniformity re mnufcturing vritions in emitters nd pressure regultors, pressure vritions cused by elevtion chnges, friction hed losses throughout the pipe network, emitter sensitivity to pressure, irrigtion wter temperture chnges nd emitter clogging. Similrly, Cpr nd Scicolone (1998) indicted tht the mjor sources of emitter flow rte vritions re emitter design, the mteril used to mnufcture the drip tubing nd precision. The uniformity nd generl performnce of drip irrigtion systems re ffected by hydrulic design, emitter mnufcturer s coefficient of vrition, grouping of emitters, nd emitter clogging mongst other fctors (Mofoke et l., 2004). Coefficient of vrition gives more criticl interprettion of hydrulic chrcteristics s compred to emission uniformity (Mokshi et l., 1998). Most of the time ctul coefficient of vrition ws higher thn those climed by mnufcturers for pressure compensting emitters (Ozenkici nd Sneed, 1995) hence the design should be bse on relible test dt nd not on dt supplied by mnufcturers. HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE

2 M.L. CHAVAN, U.M. KHODKE AND S.B. JADHAV 274 Mny different systems for drip irrigtion re in use in the modern griculture. Their min dvntges re tht they permit the economicl usge of wter (up to 50% reduction in the untity of wter used), the utomtion of the irrigtion processes nd the bility to mke locl wter irrigtion in steep terrin. Although mjor prt of irrigtion is surfce irrigtion, in recent yers frmers hve slowly ccepted drip irrigtion technology for irrigting vegetbles nd horticulture crops. More thn 70 per cent of Indin frmers re smll-scle opertors cultivting plots of less thn one hectre. Errtic rinfll pttern plys n importnt role for smll frmers who do not hve ny lternte supply of wter (Florov, 2002). The studies on evlution of the hydrulic chrcteristics of drip irrigtion tubing sold in the region re limited. Therefore, the study ws imed t compring the mnufcturers reported dischrge rte nd the coefficients of mnufcturing vrition vlues of populr drip tubes widely used in the region with mesured vlues. The drip irrigtion is one of the methods tht cn help to increse irrigtion potentil by optimizing the use of limited vilble wter resources. However, the frmers of Konkn region of Mhrshtr re mrginl frmers hving terrin nd sloping smll fields with limited wter vilble for irrigtion. In ddition there re other problems in dopting drip systems in the region such s high initil cost, high opertionl nd mintennce cost, irregulr supply of electricity in rurl res. The pumps for regulr drip systems re not economicl nd effective for smll fields. A mnully operted drip irrigtion system cn overcome these limittions, which does not need electricity or ny fuel energy nd cn be operted with vilble mn power. Studies on hydrulic performnce of such mnully operted systems re lso lcking. The present study therefore is imed t developing mnully operted drip irrigtion system nd testing its hydrulic performnce for smll field. cns were plced below the emitter for dischrge mesurements (Fig.1). Fig. 1 : Pressure (Kg/cm 2 ) Experimentl set up for ctch cns The prime mover ws rocker spryer which cretes the pressure in the system. The pressure chmber mde up of brss with pressure guge ws ttched to the system. The hndle of the regulr rocker spryer ws replced by the pedl operted cycle mechnism. The chin is mde up of number of rigid links which re hinged together by pin joints in order to provide the necessry flexibility for wrpping round the driving nd driven wheels. These wheels hve projecting teeth of specil profile nd fit into the corresponding recesses in the links of the chin. The power trnsmission to the spryer ws given by reciprocting motion. The min frme of M.S. ngle of size 89x84x90 cm ws fbricted nd stnd of 54x27x40 cm ws mde on which the pressure chmber of rocker spryer ws plced (Fig.2). The pedl of the rocker spryer ws replced by the chin nd ger mechnism. The velocity rtio of chin ws estimted s: METHODOLOGY The study ws crried out t the Reserch Frm of Dr. Budhjiro Mulik College of Agriculturl Engineering nd Technology, Mndki-Plvn. The emitters with rted flow rtes of 2, 4 nd 8 lph were selected for the performnce tests of mnully operted drip irrigtion system. The experimentl field consisted of three lterls ech of 10 m length on which 10 emitters spced t 1 m were plced. Similrly the lterls were lso plced t 1 m. flow rtes were mesured t the operting pressure rnge of 0.4 to to 1.4 kg/cm 2 with n increment of 0.2 kg/cm 2. The pressure ws mintined in the lterls by djusting bll vlves locted t minline. The ctch Fig. 2 : Power trnsmission system for mnully operted drip system HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE

3 275 HYDRAULIC PERFORMANCE OF MANUALLY OPERATED DRIP IRRIGATION SYSTEM VR = N1 / N2 = T2 / T1 (1) where, VR= velocity rtio; N 1 = speed of rottion of smller sprocket, rpm; N 2 = speed of rottion of lrger sprocket, rpm; T 1 = Number of teeth on the smller sprocket = 18 nd T 2 = Number of teeth on the lrger sprocket = 44. The length of chin ws 136 cm nd the center distnce between sprockets ws 47 cm. The revolutions per minutes of the sprocket reduce s the chin pitch increses for given number of teeth. The performnce of system ws tested using the following prmeters: Mnufcturing coefficient of vrition (Cv): The mnufcturing coefficient of vrition describes the ulity of process used to mnufcture them nd cn be estimted using following eution (Keller nd Krmeli, 1974): Cv = SD / (2) where, Cv = mnufcturing coefficient of vrition, SD= Stndrd devition, = verge dischrge in lph. SD ½ ( n - n x ) ½ (n - 1) (3) where, 1, 2, 3 re dischrges of emitter 1, emitter2, emitter 3; n = dischrge of n th emitter, lph; = verge emitter dischrge, lph nd n = totl number of emitters. Men flow rte devition: Qd (r - ) x 100 r (4) where, Qd = Men flow rte devition (%), r = Rted emitter dischrge, lph nd = Averge emitter dischrge, lph. The ulity of emitter bsed on the vlues of mnufcturing coefficient of vrition suggested by ASAE (ASAE, 1985) is presented in Tble 1. Tble 1 : ASAE recommended clssifiction of mnufcturers coefficient of vrition type Cv Interprettion Point Source < > 0.15 Line Source < > 0.20 Excellent Averge Mrginl Poor Uncceptble Good Averge Mrginl to uncceptble The mnufcturing coefficient of vrition (Cv) nd men flow rte devition (Qd) t nominl pressure of 1.0 kg/cm 2 for ll tested emitters were estimted. Hydrulic chrcteristics: Over the rnge of dischrge the flow chrcteristics of emitters cn be chrcterized by: Q = K d H x (5) where, = emitter dischrge, lph; K d = constnt of proportionlity tht chrcterizes ech emitter; H = working pressure hed t the emitter; m nd x = emitter dischrge exponent chrcterized by the flow regime. To determine K d nd x, the dischrges t different operting pressure heds must be known. The exponents x my be determined by mesuring the slope of log-log plot of pressure hed (H) vs dischrge () or nlyticlly by, log 1 2 X H1 log H2 (6) where, x = emitter dischrge exponent, 1 = dischrge t H 1, lph. 2 = dischrge t H 2, lph nd H 1, H 2 = Pressure heds in m. The vlue of x cn be used in eution 5 to solve for K d. the vlue of x chrcterizes the flow regime nd dischrge verses pressure reltionship of the emitter. The lower the vlue of x, the less dischrge will be ffected by pressure vritions. In fully turbulent flow x = 0.5 nd in lminr flow x = 1.0. Non-compensting orifice nd nozzle emitters re lwys fully turbulent with x = 0.5. However, the exponent of long-pth emitters my rnge nywhere between 0.5 nd 1. For different flow regime expected vlues of x re given in Tble 2. Tble 2 : ASAE recommended Emission device clssifiction (1985) Flow regime X vlue type Vrible flow pth Pressure compensting Vortex flow 0.4 Vortex Fully turbulent flow 0.5 Orifice, Tortuous Mostly Turbulent flow 0.6 Longer spirl pth Mostly lminr flow 0.9 Micro tube Fully lminr flow 1.0 Cpillry HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE

4 M.L. CHAVAN, U.M. KHODKE AND S.B. JADHAV 276 Opertionl chrcteristics: To define uniformity of wter ppliction of micro irrigtion system, Keller nd Krmeli (1974) suggested two prmeters nmely Field Emission Uniformity nd Absolute Emission Uniformity chrcterized by, n Euf x 100 (7) where, = Averge emitter flow rte, lph nd n = verge emitter flow rte of n th emitter, lph. Eu 1 x 2 min mx x100 (8) where, Euf = Field emission uniformity, %; Eu = Absolute emission uniformity, %; = Averge emitter flow rte, lph; min = Averge of lowest ¼ of emitter flow rte, lph nd mx = Averge of highest 1 / 8 of emitter flow rte. RESULTS AND DISCUSSION Mnufcturing coefficient of vrition (Cv) nd men flow rte devition (Qd) t nominl pressure (1 kg/cm 2 ) for ll the tested emitters is shown in the Tble 3. Dt indicte tht the verge dischrge (Q) of emitters t nominl operting pressure (1 kg/cm 2 ) is higher thn the rted dischrge. The mnufcturing coefficient of vrition decreses with increse in its nominl dischrge for sme type of emitters wheres men flow rte devition for tested emitter ws minimum for 4 lph emitter nd mximum for 8 lph emitters. The tested emitters were found to be verge in ulity s per ASAE (1985) recommendtions, t operting pressure of 1 kg/cm 2. The reltionship between operting pressure nd corresponding emitter dischrge for ll tested emitter is depicted in Fig. 3. With increse in operting pressure, emitter dischrge increses nd show liner trend for the rnge of pressures used in this study (Fig.3). Theoreticlly the coefficient of dischrge of n emitter should remin constnt. However there exists slight vrition with pressure (Tble 3). It ws observed tht the K d is greter thn its nominl vlue becuse of improper punching of lterls. Dischrge (lph) Fig. 3 : Pressure (Kg/cm 2 ) Similrly the emitter dischrge exponent vlue (x) should be constnt for n emitter hoverer, for some emitter the vritions in the vlue of x re observed (Tble 4). hving minimum (K d ) vlue my be suitble for use in pressure rnge but, here it cn be seen tht for most of emitters, x vlue lies from 0.3 to 0.7 i.e. from vortex flow to mostly turbulent flow rnge ccording to ASAE -emission device clssifiction. When the vlue of x is less thn 0.30 then the flow is vrible nd pressure compensting. Remining tested emitter s lies in fully turbulent flow to mostly turbulent flow regime ccording to exponent x. Tble 4 : dischrge exponent of the tested emitter for different pressure rnge Pressure rnge (kg/cm 2 ) type lph lhp lph lph 4 lph 2 lph Reltion between operting pressure nd corresponding emitter The field emission uniformity nd bsolute emission uniformity of the emitters t different operting pressures is presented in Tble 5 nd 6, respectively. The dt indicte tht the vlue of emission uniformity of ll the emitters under study remins bove 90 per cent (Tble 5). All the emitters performed better t the pressure rnge of 0.6 to 1.4 kg / cm 2 with the emission uniformity of bove 95 %. It cn lso be seen tht vritions in bsolute Tble 3 : Coefficient of dischrge of emitter t different pressure rnges Pressure rnge (kg/cm 2 ) type lph lhp lph Tble 5 : Field emission uniformity, Euf (%) of emitters t different operting pressures Operting pressure (kg/cm 2 ) type lph lhp lph HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE

5 277 HYDRAULIC PERFORMANCE OF MANUALLY OPERATED DRIP IRRIGATION SYSTEM Tble 6 : Absolute emission uniformity Eu (%) of emitters t different operting pressures Operting pressure (kg/cm 2 ) type lph lhp lph emission uniformity with pressure were similr to the field emission uniformity. However the vlues of field emission uniformity re lower thn the bsolute emission uniformity. The results thus indicte tht the hydrulic prmeters such s mnufcturing coefficient of vrition, men flow rte devition, coefficient of dischrge, emitter dischrge exponent, field emission uniformity nd bsolute emission uniformity cn be used for design nd opertion of mnully operted drip irrigtion system. The study indicted tht the operting pressure ffects flow rtes of emitters nd their reltionship is liner. The operting pressure of 1.0 kg/cm 2 is optimum for verge emitter performnce. Conclusion: Bsed on the hydrulic chrcteristics of the mnully operted drip irrigtion system it cn be concluded tht such system operted by the rocker spryer cn successfully to be used in smll frm. Authors ffilitions: M.L. CHAVAN AND S.B. JADHAV, Deprtment of Irrigtion nd Dringe Engineering, College of Agriculturl Engineering nd Technology, Mrthwd Agriculturl University, PARBHANI (M.S.) INDIA REFERENCES Anonymous (2006). Hndbook of Agriculture. Fifth edition, Directorte of Informtion nd Publictions of Agriculture, ICAR, New Delhi: Al Amound, A. I. (1995). Significnce of energy losses due to emitter connection in trickle irrigtion lines. J. gric. Eng. Res., 60: 1-5. ASAE (1985). Design, instlltion nd performnce evlution of trickle irrigtion system. Sent Josph, 37th Edition, ASAE Publictions, EP Bhtngr, P.R nd Srivstv, R.C. (2003). Grvity fed drip irrigtion system for hilly terrces of the northwest Himlys. Irrig. Sci., 21: Cpr, A. nd Scicolone, B. (1998). Wter ulity nd distribution uniformity in drip/trickle irrigtion systems. J. Agric. Eng. Res., 70 : Decroix, M. nd Mlvl, A. (1985). Lbortory evlution of trickle irrigtion euipment for field system design. Proceedings of the third Interntionl Drip/trickle Irrigtion Congress, Volume I, Cliforni, USA: Florov, V. (2002). Min spects of drip irrigtion design, construction nd scope of ppliction. Institute of Lnd Reclmtion nd Agriculturl Mechniztion, 136, Tzr Boris III, 1618 Sofi. Keller nd Krmeli, D. (1974). Trickle irrigtion design prmeters. Trns. ASAE., 17 (4) : Mizyed, N. nd Kruse, E. G. (1989). dischrge evlution of subsurfce trickle irrigtion systems. Trns. ASAE, 32 : Mofoke A.L.E. (2004). Design, construction nd evlution of n ffordble continuous flow drip irrigtion system. J. Applied Irrigtion Science, 39 : 253. Mokshi, A.R., Rmsey Kumr, Shinde, R.Y. (1998). Hydrulics of trickle irrigtion. B. Tech disserttion, Dept.of Irrigtion nd Dringe Eng., College of Agriculturl Engineering, University of Agriculturl Sciences, Richur. Ozenkici, B. nd Sneed, R.E. (1995). Mnufcturing coefficient of vrition for vrious Trickle irrigtion online emitters, Applied Engineering in Agriculture, pp: 235 to 240. Wei, Z., Tng, Y., Zho, W. nd Lu, B. (2003). Rpid development techniue for drip irrigtion emitters. Rpid Prototyping J., 9 : Wu. I.P. (1987). An ssessment of hydrulic design of micro irrigtion systems. Agriculturl Wter Mngement, 32 : Youngs, E.G., Leeds-Hrrison, P.B. nd Alghusni, A. (1999). Surfce pounding of course-textured soils under irrigtion with line of surfce emitters. J. gric. Eng. Res., 73 : *** HIND AGRICULTURAL RESEARCH AND TRAINING INSTITUTE