Evaluation of Uniformity Coefficients for Sprinkler Irrigation Systems under Different Field Conditions in Kurdistan Province (Northwest of Iran)

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1 Evlutio of Uiformity Coefficiets for Sprikler Irrigtio Systems uder Differet Field Coditios i Kurdist Provice (Northwest of Ir) Eis Mroufpoor 1, Arsl Fryi 1, Houshg Ghmri 2 d Gor Ymi Moshrefi 1 1 Deprtmet of Wter Egieerig, College of Agriculture, Uiversity of Kurdist, Sdj, Ir; 2 Deprtmet of Irrigtio d Wter Resources Egieerig, College of Agriculture, Uiversity of Rzi, Kermshh, Ir Astrct: I the pst few decdes, severl coefficiets of uiformity were developed to express the uiformity of wter distriutio for differet sprikler irrigtio systems. Christise s uiformity coefficiet seems to e the most populr uiformity coefficiet used y reserchers o the glol scle. However, more coefficiets hve lso ee proposed y other reserchers. Therefore, this study focused o evlutig differet uiformity coefficiets proposed d o ivestigtig the effects of field coditios o the results otied y mes of those coefficiets. I doig so, sprikler uiformity tests were coducted y usig ri-guge i order to mesure the uiformity coefficiets of te fields irrigted y solid set sprikler irrigtio systems i Dehgol Pli locted i the Kurdist Provice, orthwest of Ir. All fields selected differed i previlig coditios such s the wid speed, size d type of ozzle, riser height, opertig pressure d spriklers spcig. The coefficiet of uiformity for ech field ws computed usig the equtios proposed y Christise (1942), Hwii Ce Society Specilists Hrt d Reyolds (1965), Wilcox d Swiles (1947), Krmeli (1978), Criddle et l. (1956), Bemi d Hore (1964), d Bele (1966). Dt lysis ws performed usig the geerl lier model procedure of Sttisticl Alysis System Softwre. The results idicted tht should ot the field effect e cosidered i the sttisticl model, sigifict differeces (P < 0.05) would e oserved etwee the foresid coefficiets; however, y cosiderig the field effect i the sttisticl model, o sigifict differeces (P > 0.05) would e oserved. The results of this study coclusively idicted tht the pplictio of vrious coefficiets of uiformity depeds o the field coditios d s y specific coefficiet of uiformity is suitle oly for specific field coditios. Keywords: coefficiet of uiformity; Christise equtio; Ir; solid set; sprikler irrigtio The uiformity of wter pplictio i sprikler irrigtio system is importt spect of the system performce (Solomo 1979). The performce of sprikler irrigtio system is ofte evluted sed o wter uiformity coefficiets collected i rry of mesurig devices (i. e., ri-guge) (Topk et l. 2005). Such system requires miimum vlue of uiformity to e cosidered s cceptle y the ed users. Keller d Blieser (1990) clssified the irrigtio uiformity i solid set systems s low whe the Christise s coefficiet of uiformity ws elow 84%. A sprikler wter distriutio ptter depeds o the system desig prmeters such s: the sprikler spcig, opertig pressure, ozzle dimeter, d evirometl vriles such s: wid speed d directio (Keller & Blieser 1990). Severl uthors hve reported the wid to e the mi evirometl vrile ffectig the sprikler performce (Solomo 1979; Kicid et l. 1996; Dechmi et l. 2003). 139

2 The frequecy distriutio of the pplied wter c e ssumed s orml d uiform fuctios (Ayoji & Wu 1994; Mtovi et l. 1995; Li 1998). The sprikler irrigtio distriutio ptters hve ee chrcterised y vrious sttisticl uiformity coefficiets (Krmeli 1978) d vrious coefficiets of uiformity (CUs) hve ee developed over the pst decdes (Al-Ghori 2006). Christise s coefficiet of uiformity (Christise 1942) ws first used to itroduce uiformity coefficiet to the sprikler system (Krmeli 1978). The coefficiet is presetly widely used y reserches o the glol scle d hs ee pplied s prove criterio to defie wter distriutio uiformity (Krmeli 1978; Topk et l. 2005). The coefficiet is derived from ri-guge dt sed o the ssumptio tht the ri-guge represet the sme re d is mesure of solute differece from the me divided y the me: X i i1 CU X i i1 (1) umer of the depth mesuremets of the wter pplied, ech represetig equl irrigted re X i mesured pplictio depth (L) µ me pplictio depths of (L) CU coefficiet of uiformity (%) Whe the CU vlue is pproximtely 70% or higher, the pproximtio depths from ri-guge evlutio ted to follow orml distriutio. I this cse, whe the me pplictio depth, µ, is equl to the required et pplictio depth, d, 50% of the irrigted re will e uder-irrigted while the remiig 50% will e over-irrigted (or dequtely irrigted ). This is due to the fct tht the orml distriutio is symmetricl out the me vlue (Merkley 2001). Wilcox d Swiles (1947) used the sme method used y Christise (1942), except tht they used squres of the devitios from the me isted of the devitios themselves. Their proposed equtio is s follows: U U uiformity coefficiet (%) σ stdrd devitio of totl depths of wter (L) µ me pplictio depth (L) (2) The coefficiets of uiformity otied i this mer re ot s high s those i which the devitios from the me re used such s i Christise s equtio. Hrt d Reyolds (1965) proposed distriutio efficiecy, DE p, vlue sed o umericl itegrtios of the orml distriutio fuctio while DE p is determied y first selectig trget CU d trget percet re dequtely irrigted, P, where 50% P < 100% (which is logicl rge for P). Should the orml distriutio e ssumed 70% CU < 100%, d i1 X i 2 (3) σ stdrd devitio of ll depth mesuremets (L) Sustitutig Eq. (3) ito Eq. (1), CU (4) Criddle et l. (1956) d Bele d Howell (1966) lso used the cocepts of the devitios of the me, like Christise (1942); however, Criddle et l. (1956) limited their equtio to the lowest qurter depths of wter while Bele limited the equtio to the highest oes. Criddle et l. (1956) proposed their equtio s follows: CU i1 X i 4 (5) Bele & Howell (1966) lso proposed equtio s follows: CU X i 3 i (6) Krmeli (1978) reported tht the uiform distriutio ws cceptle form to represet the sprikler wter distriutio for sttiory systems. He expressed the coefficiet of uiformity s: CU = 100 [1 0.5(X mx µ)] (7) 140

3 This equtio is oly vlid for the vlues of CU higher th 50%. Bemi d Hore (1964) itroduced their uiformity coefficiet s A coefficiet. Their equtio is s follows: N A 166 N 2T 2T D M D M (8) A uiformity coefficiet (%) M, M mes of the mesured pplictio depths which re greter d smller th the overll me pplictio depths (L), respectively N, N umers of the mesured pplictio depths which re greter d smller th the overll me pplictio depths, respectively T, T sums of the mesured pplictio depths which re greter d smller th M d M (L), respectively D, D differeces etwee the umers of the mesured pplictio depths which re greter d smller th M d M, respectively Merrim d Keller (1978) defied their distriutio uiformity coefficiet s follows: DU 100 D lq (9) DU distriutio uiformity (%) D lq me of the lowest oe-qurter of the mesured depths (L) Hwii Ce Society Specilists (cited y Merrim d Keller 1978) lso proposed their uiformity coefficiet s follows: 2 CU (10) As stted previously, differet reserchers hve used vrious cocepts to express the coefficiets of uiformity, hece the equtios led to differet results i the expressio of the distriuted wter uiformity i the sme fields. The mi ojective of this study ws to evlute differet uiformity coefficiets proposed d ivestigte the effects of the field coditios o the ed results otied. MATERIALS AND METHODS The field experimets were coducted durig April Jue 2008 o te frmlds locted i the Dehgol Pli of the Kurdist Provice, orthwest Ir from 47 07' to 47 36'E d from 25 02' to 25 28'N. This regio hs me ul precipittio of 340 mm. Figure 1 show the loctio of the Kurdist Provice d Dehgol Pli. The lds were irrigted y solid set sprikler irrigtio systems. The sprikler uiformity tests were coducted usig ri-guge for uiformity coefficiets mesurig (Figure 2). The riguge hd dimeter of 96 mm d height of 120 mm. The irrigtio ssessmet ws crried out () () Figure 1. () Loctio of Dehgol pli o Kurdist provice mp d loctio of Kurdist provice o Ir mp () 141

4 Tle 1. The experimetl fields meteorologicl dt d other detils Experimetl fields wid speed (m/s) Averge Sprikler Averge sprikler temperture ( C) spcig (m) height (m) pressure (kp) dischrge (l/s) itesity (mm/h) Sprikler type Nozzle dimeters (mm) F S PEROT (ZK30) 8 d 3.5 F R AMBO 8 d 7 F S AMBO 8 d 7 F S PEROT (ZM22) 10 d 3.5 F R AMBO 8 d 7 F S AMBO 8 d 7 F R AMBO 8 d 7 F R AMBO 8 d 7 F S AMBO 8 d 7 F R PEROT (ZK30) 8 d 3.5 to mesure the wter distriutio o the surfce followig the methodology proposed y Merrim d Keller (1978). I ech field, the coefficiet of uiformity ws computed usig the equtios proposed y Christise (1942), Hwii ce society specilists (cited i Merrim & Keller 1978), Wilcox d Swiles (1947), Criddle et l. (1956), Bemi d Hore (1964), Hrt d Reyolds (1965), Bele & Howell (1966), d Krmeli (1978). Dt lysis ws performed usig the geerl lier model (GLM) procedure of Sttisticl Alysis System (SAS 2003) softwre. Two sttisticl models were used to compre the results of differet uiformity coefficiets. The first sttisticl model ws s elow: y ij = μ + C i + e ij (11) y ij mesured vlue µ overll me C i effect of the uiformity coefficiet e ij rdom error with me 0 d vrice σ 2 The field meteorologicl d other dt such s: the wid speed, size d type of ozzle, riser height, opertig pressure, d sprikler spcig Figure 2. Oe exmple of sprikler uiformity test usig ri-guge for mesurig uiformity coefficiets of selected frms; ri-guge hd dimeter of 96 mm d height of 120 mm 142

5 Tle 2. Compriso of the uiformity coefficiets mes (i %) usig the first sttisticl model SEM Bemi & Hore Hwi ce society specilist Hrt & Reyolds Christise Wilcox & Swiles Krmeli Merrim & Keller Criddle et l. Bele c 51.2 cd 51 cd 49.9 cd 42.5 d SEM stdrd error of the me; differet letters meigful levels were ot similr for ll frms (Tle 1); thus, the secod sttisticl model ws used s follows: y ij = μ + C i + F j + e ijk (12) y ijk mesured vlue F j field effect e ijk rdom error with me 0 d vrice σ 2 Filly, the dt me differeces were determied usig Duc test t 95% cofidece level; d the the dt sigifictio levels were reported s the mes of tretmets with the stdrd error mes. RESULTS The results of computig differet CUs for ll fields re preseted i Figure 3. As Figure 3 shows, the horizotl xis represets differet CUs d the verticl xis represets their vlues i percetges. Te existig series of dt i this figure represet the vlues of vrious coefficiets of uiformity for te experimetl frms. The results of this study usig the first sttisticl model (Eq. (11)), idicted tht sigifict differeces (P < 0.05) exist i the ove give coefficiets. Tle 2 lso shows the levels of differeces d the mximum d miimum vlues for the me of CUs ws otied with Bemi d Hore d Bele equtios, respectively. The results of the secod sttisticl lysis showed tht there were o sigifict differeces (P > 0.05) i the uiformity coefficiets. DISCUSSION The results of computig differet CUs for experimetl frms re show i Figure 3. This figure shows the geerl tred of uiformity coefficiet vritios for ech of the experimetl frms. The results of this study, usig the first sttisticl model (Eq. (11)), idicted tht sigifict differeces (P < 0.05) existed etwee the coefficiets stted. Vlueofuiformitycoefficiets(%) F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 Christise Bemi&Hore Hrt&Reyolds Hwicesocietyspecilist Krmeli Criddleetl. Wilcox&Swiles Bele Merrim&Keller Uiformitycoefficiets Figure 3. The results of computig differet CUs for ll frms; this figure shows the geerl tred of uiformity coefficiet vritios for ech of the experimetl frms 143

6 Vlueofuiformitycoefficiets(%) Christise Hwicesocietyspecilist Hrt&Reyolds Bemi&Hore Wilcox&Swiles Criddle Krmeli Bele Merrim&Keller F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 Frms Figure 4. Compriso of differet uiformity coefficiets for ech of the experimetl frms; usig Bemi d Hore s equtio resulted i the coefficiet of uiformity ove th 100% for oe of the frms (F 8) Tle 2 shows the levels of these differeces. Also, this tle shows tht the mximum d miimum for the me of CUs i this study were otied with Bemi d Hore d Bele equtios respectively. The clculted vlues of CUs re lso show i Figure 4. This figure clerly shows tht the equtios of Christise, Hrt d Reyolds, d Hwi ce society specilist provided very close results for ech of the experimetl fields. However, the equtio y Bemi d Hore produced the results i few cses (F 1, F 6, d F 10) while the equtio resulted i completely differet results i other fields. This equtio computed the coefficiet of uiformity ove 100% for oe of the experimetl fields (F 8). Solomo (1979) reported tht the coefficiet of uiformity depeds o the desig vriles of the system (ie the sprikler mke, size d type of ozzle, pressure d sprikler spcig), d the mi ucotrollle vrile, the wid speed. However, the field coditios were ot similr for ll of the experimetl frms. Therefore, the secod sttisticl lysis ws performed usig the secod sttisticl model (Eq. (12)) i order to compre the mes of the uiformity coefficiets. I this model, to reduce the existig errors, the field coditios effect ws tke ito ccout s F j term. The results of the secod sttisticl lysis showed tht there were o sigifict differeces (P > 0.05) etwee the uiformity coefficiets. Bsed o the compriso of the results otied from the two sttisticl lyses metioed, oe c ifer tht the existig sigifict differeces etwee the uiformity coefficiets i the first sttisticl lysis were mily due to the vryig field coditios. Filly, the results of this study emphsised the fct tht vrious coefficiets of uiformity deped o the field coditios d oe is ot llowed to use give uiformity coefficiet for y other field coditios. Refereces Al-Ghori H.M. (2006): Effect of mitece o the performce of sprikler irrigtio systems d irrigtio wter coservtio. Food Sciece & Agriculturl Reserch Ceter, Reserch Bulleti, 141: Ayoji H., Wu I. (1994): Norml distriutio wter pplictio for drip irrigtio schedules. Trsctios of the ASAE, 37: Bele J.G., Howell D.T. (1966): Reltioship mog sprikler uiformity mesures. Jourl of Irrigtio d Drige Egieerig-ASCE, 92: Bemi A., Hore F.R. (1964): A ew irrigtio sprikler distriutio coefficiet. Trsctios of the ASAE, 7: Christise J.E. (1942): Irrigtio y Spriklig. Clifori Agriculture Experimet Sttio Bulleti, No Criddle W.D., Dvis S., Pir C.H., Shockley C.D. (1956): Methods of Evlutig Irrigtio Systems. Ag- 144

7 riculture Hdook No. 82, Soil Coservtio Service, USDA, Wshigto, D.C. Dechmi F., Ply E., Fci J.M., Tejero M., Bercero A. (2003): Alysis of irrigtio district i orthester Spi. II. Irrigtio evlutio, simultio d schedulig. Agriculturl Wter Mgemet, 61: Hrt W.E., Reyolds W.N. (1965): Alyticl desig of sprikler systems. Trsctios of the ASAE, 8: Krmeli D. (1978): Estimtig sprikler distriutio ptter usig lier regressio. Trsctios of the ASAE, 21: Keller J., Blieser R.D. (1990): Sprikle d Trickle Irrigtio. AVI Book. V Nostrd Reihold, New York. Kicid D.C., Solomo K.H., Olipht J.C. (1996): Drop size distriutios for irrigtio spriklers. Trsctios of the ASAE, 39: Li J. (1998): Modelig crop yield s ffected y uiformity irrigtio system. Agriculturl Wter Mgemet, 38: Mtovi E.C., Villloos F.J., Orgz F., Fereres E. (1995): Modellig the effects of sprikler irrigtio uiformity o crop yield. Agriculturl Wter Mgemet, 27: Merkley G.P. (2001): Desig Efficiecy for Sprikler Irrigtio Systems. Lecture Notes. Uth Stte Uiversity, Log. Merrim J.L., Keller J. (1978): Frm Irrigtio System Evlutio: A Guide for Mgemet. Deprtmet of Agriculturl d Irrigtio Egieerig, Uth Stte Uiversity, Log. Solomo K. (1979): Vriility of sprikler coefficiet of uiformity test results. Trsctios of the ASAE, 22: Sttisticl Alysis System (SAS) (2003): SAS User s Guide: Sttistics. Versio 8.02, SAS Istitute, Ic., Cry. Topk R., Suheri S., Ciftci N., Acr B. (2005): Performce evlutio of sprikler irrigtio i semirid re. Pkist Jourl of Biologicl Scieces, 8: Wilcox J.C., Swiles G.E. (1947): Uiformity of wter distriutio y some uder tree orchrd sprikler. Jourl of Scietific Agriculture, 27: Received for pulictio Octoer 25, 2009 Accepted fter correctios Ferury 24, 2010 Correspodig uthor: Assist. Prof. Eis Mroufpoor, Uiversity of Kurdist, College of Agriculture, Deprtmet of Wter Egieerig, Sdj, Ir tel.: , fx: , e-mil: ismrofpoor@yhoo.com 145