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  1. 1. Daba Coulibaly, Drissa Diallo / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 6, November- December 2012, pp.1549-1553 Control of « Horticulture Easy Drip Kit de 100 m² » hydraulic characteristics for micro irrigation in Mali Daba Coulibaly*, Drissa Diallo*** Ecole Nationale d’Ingénieurs Abderhamane Baba Touré (ENI-ABT), DER Génie Civil, BP 242, Bamako, Mali ** USTTB, Faculté des Sciences et Techniques, BPE 3206, Bamako, MaliAbstract Precarity of water resources in Mali, network of drip irrigation, using the technique ofjustify the high need to develop irrigated low pressure [4,5] (Coulibaly et al, 2009; Coulibaly,agriculture with micro irrigation system. 2011). In this kind of irrigation network, the main“Horticulture Easy Drip Kit 100 m²" is a simple objective to be achieved in the calculation as inequipment for this kind of irrigation and have standardizing operating at maximum possiblebeen imported from India for small farmers drippers debite, to avoid the great disparity betweeninterested in vegetable production. The present water volume supplied to crops [1] (FAO, 2002).study aimed to evaluate its hydraulic Several parameters may influence variations inperformance and adaptability. It is based on uniformity [6] (Zella et al, 2003): they includedirect measurements of drippers’ debit (by structural and dimensional parameters (dippers andvolumetric method), evaluation of debit variation conducts characteristics, space between betweencoefficient (VC) and calculation of Reynolds ramps, network geometric structure), functionalnumber (Re), Keller and Karmeli uniformity parameters (network head pressure) andcoefficient (UC), UC according old network environmental ones (slope, temperature of water andmethod. The study showed that the tool has a air, water quality). Several studies have focused onlaminar flow. Strong correlation between flow the design of simulation scenarios of micro-and pressure was noted, indicating normal irrigation systems in order to choose the besthydraulic functioning. Drippers debit are not combination of parameters and maximizehomogeneous (VC > 10%), as well as water agricultural production [7, 8, 9] (Christiansen, 1942;distribution to irrigation station (UC < 90%), Wu and Gitlin 1974; Zella and Kettab, 2001).indicating a malfunction of the network. The Drippers are normalized by their pressure, usuallyFunctioning Optimal Charge (FOC) are 0.6m supplied by the manufacturer (Law Flow - pressure)and 1.5m. The tank manual filling at 1.5m is very and practice debits from 2 to 50 l / h [10]difficult or impossible and not recommended for (Vermeiren and Jobbing, 1983). Considering thesmall farmers. The simplicity of tool is favorable weakness of drippers debits, a small variation offor its extension in vegetable growing areas of pressure (20%) can generate 10% debit gap,Mali. However, research is needed to improve its considered as an upper limit. Concerninghydraulic performance. Uniformity Coefficient (CU), it must be superior to 95%. A tolerance limit is imposed on the dripperKeywords: Drip irrigation, Functioning optimal itself through its technological Variation Coefficientcharge, Flow regime, Mali VCf, that does not exceed the value of 10% [11] (Solomon and Dedrick, 1995). Such information is1.Introduction lacking in the equipment "Horticulture Easy DripIrregularities in rainfall and climate crises recurring Kit 100 m²" proposed to small farmers in Mali.in the Sahelian zone of West Africa, thus justifying Assessment of hydraulic performance of thisthe shared concern of developing irrigated equipment is a necessity for users and that justifiedagriculture [1] (FAO, 2002). In this difficult climate the present study [5] (Coulibaly, 2011). It aimed tocontext, where small farmers are the majority (80% evaluate drippers’ debit variation coefficient (VC)of active population), the design of irrigation should and calculation of Reynolds number (Re),be done with attention. The drip irrigation identified Uniformity coefficient (UC) and Functioningas a relevant technique in many parts of the world Optimal Charge (FOC) of the network.[2,1,3] (Bralts and Edwards, 1986; FAO, 2002;Elattir, 2002) seems to be proposable in this 2. Material and methodsenvironment. So Winrock International imported 2.1 Equipmentfrom India a simple equipment ("Horticulture Easy "Horticulture Easy Drip Kit 100 m²" IDADrip Kit 100 m²") for small farmers involving in design, imported from India is the subject of thevegetable production in Mali. It is a comprehensive present study. In this micro irrigation equipment, water supply is made by a metal drum as tank, 1549 | P a g e
  2. 2. Daba Coulibaly, Drissa Diallo / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 6, November- December 2012, pp.1549-1553which capacity is 200 liters ; usually this tank isworn at 0.4 to 1.5m height, above the ground, with0.6m as the value recommended by NGO diffuser ofthe equipment among gardeners. The kit iscomposed, from upstream to downstream, by afilter, a door ramp (about 14m long and 16.4mm indiameter), 5 ramps (10m long and 12.8mm indiameter each) and drippers in capillary blackpolyethylene (0.6m long and 1mm in diameter).Each ramp has 10m long and serve 30 drippersgrouped into 15 pairs. The entire unit has 150drippers and works with debit along and zero at theextremity. The experimental plan is shown in Fig.1and 2. 1550 | P a g e
  3. 3. Daba Coulibaly, Drissa Diallo / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 6, November- December 2012, pp.1549-1553 If Re < 2000, is facing a laminar flow; if Re> 20002.2 Experimental apparatus and debit it is a turbulent flow.measurements The Uniformity coefficient (UC) of water In order to measure the dripper’s debit, two distribution in irrigation station was calculated usingfunctioning diagrams of the network have been two methods: Keller and Karmeli method andinstalled: the lateral service (standard), keeping the control method of closure and homogeneity ofpressure system by its lateral bordered and the drippers for old network.central one, keeping the pressure system from the According to Keller and Karmeli (1974):center. Three different pressures were tested: H1, 𝑞 𝑚𝑖𝑛H2 and H3, corresponding respectively to 0.6m, 1m 𝑈𝐶 = 100 𝑀 𝑟 𝑓(𝑒) (2) 𝑞and 1.5m. These values are the pressure applied by qmin: minimum flow of drippers, determinedthe farmers in vegetable production. Each dripper according to the law flow- pressure as a function ofdebit was measured 18 times, that equals to 2,700 the minimum pression; 𝒒 = average flow ofmeasurements for 150 drippers of the experimental drippers of the network; Mr : quality coefficient ofdispositive. It should be noted that these measures the fabrication equipment; f (e) = correction factorwere divided between lateral and central services. taking into account the number of dripper per plant. According to the control method of closure and2.3 Hydraulic parameters calculation homogeneity of drippers for old network This calculation concern: Reynolds number :(Re) and Uniformity Coefficient (UC). It permit to 𝑞 𝑚𝑖𝑛know the Functioning Optimal Charge Fixing 𝑈𝐶 = 100 (3) 𝑞(COF).The flow regime of the network defined by the q min: minimum measured flow of drippers; 𝑞 =Reynolds number Re (a dimensionless number) was average measured flow of dripperscalculated in capillary tubes: It should be noted that this last method is applied to networks already in operation and is 𝑉𝑑 made mandatory at the beginning of every cropping 𝑅𝑒 = (1) season. It can be performed in cases where drippers 𝑣 are old and where the network is poorly maintained,Re = Reynolds number, V = flow velocity in the and each time we find heterogeneity in irrigation. Itconduct (m/s) d = diameter of conduct (m); ν = consists in measuring debits (by the volumetrickinematic viscosity of water (m2/s). method) of 4 drippers by ramp, among 5 ramps. Ramps chosen here are the 2 first and the 2 last of the network. On a ramp, the first and the last 1551 | P a g e
  4. 4. Daba Coulibaly, Drissa Diallo / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 6, November- December 2012, pp.1549-1553drippers are chosen, as those at 1/3 and 2/3 of the the debit in the case of H1 and H2 whatever servicelength of the ramp. Debit measured are classified in (central or lateral).ascending order. We calculate the average qmin of Note that the laminar flow regime whichthe four lowest values of debit and 𝑞 of measured characterized the network here is particular in microdebit of the network. irrigation system, where turbulent flow regimes areWith these calculations of UC, it must be possible to observed [7, 12, 10] (Christtiansen, 1942; M.choose the Functioning Optimal Charge (FOC). The Carlier; 1980; Vermeiren and Jobbing, 1983). Asobjective in this selection is to identify the network noted in Table 1, there is a strong correlationsystem that has the best layout of main conducts between debit and pressure in both lateral and(ramp and ramp door) and the best installation central services. That means a normal hydraulicheight of the tank. The better FOC is the one were functioning.debit and UC are maximum. Table 1: Drippers nominal debit of "Horticulture2.4. Statistical treatment of data Easy Drip Kit 100 m²" The data collected were subjected tostatistical analysis using Excel. The means values Nominal debitdebits of drippers was calculated, as well as their Networkvariance and the correlation between debit and q qnominal (lh−1 ) rpressure driving to the drippers nominal debit. Pressi Servi ( VC on ce lh−1 %3. Result and discussion H (m) )3.1 Nominal flow (DN) of drippers Latér 0.82 q = 9.5H – 0.7 32 Nominal debit of drippers at pressures H1 al 7.23 0(0.6 m), H2 (1m) and H3 (1.5m) meets the formula: 0.6 Centr 0.87 q = 8.83H – 0.6 34 𝑥 al 7.58 5𝑞 = 𝐾𝑑 𝐻 + 𝑎 (4) Latér 0.90 q = 13.87H 0.7 41 al - 16.27 6q is the nominal debit ; Kd is the specific 1 Centr 1.07 q = 12.12H 0.7 42coefficient of each unit dripper; x is the exponent al - 15.29 3related to the flow regime equation and a is a Latér 1.15 q = 10.88H 0.7 20constant. al – 17.81 1 x=1; a<0 1.5 Centr 1.37 q = 15.70H 0.7 21This formula differs from the one accepted as a al – 26.44 8dripper nominal debit, where the constant a is zero.It remains the equation of a straight line.The value of x obtained here (x = 1) indicate a 3.2 Flow Regime in the networklaminar flow regime. Re values vary from 145 to 242 (Table 2).Statistical analysis of the measured debits (Table 1) Inertial forces are then clearly dominated by theshows a homogeneous average debit of drippers forces of friction and it is assumed that the flow(VC = 20% in central service and VC = 21% in regime is laminar in the network.lateral service) in the case of H3 and a disparity ofTable 2: Flow Regime in the network "Horticulture Easy Drip Kit 100 m²"Pression Diameter Service qmoy (l/h) Re Flow regimeH (m) (mm) Latéral 0.4 1 1450.6 Central 0.4 1 154 Latéral 0.5 1 159 < 20001 Central Dripper 0.5 1 189 laminar1.5 Latéral 0.6 1 203 Central 0.7 1 2423.3 Uniformity coefficient (UC) of water to 20% regardless of the pressure in the network.distribution These values are well below the threshold floored As shown in Table 3, the calculated values (70%). However, there is a difference according theof UC, according to Keller et Karmeli, vary from 7 pressures tested: H1 (0.6m) and H2 (1m) are much 1552 | P a g e
  5. 5. Daba Coulibaly, Drissa Diallo / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 6, November- December 2012, pp.1549-1553better than H3 (1.5m). Unlike the other two cases, Referenceswith pressure H3, the central service seems to work [1] FAO (2002). La lutte contre la faim dans lebetter than the lateral one (respectively 10% and 7% monde http://www.aidh.org/alimentation/as values of UC). 4_insecure.htm. According to the control method of closure [2] Bralts YE., Edwards D.M., 1986. Fieldand homogeneity of drippers for old network, only evaluation of drip i r r i g a t i o n submainthe lateral service of H3 has an acceptable units. Trans. ASAE, 29(6):1659-1664.homogeneity (UC = 71%> 70%). In all other cases, [3] Elattir H., 2002. La conduite et le pilotagethe values are below the threshold UC floored de l’irrigation goutte à goutte en(Table 3). These results are not conform to those of maraîchage.Institut Agronomique etKeita and Leeuwen (2002) [14], who found a UC > Vétérinaire Hassan 2, Développement90% (from the formula of Keller et Karmeli) d’Horticulture Rabat au Maroc.9 pages.working on a network of micro irrigation powered [4] Coulibaly D., M’Baye B., Diallo D., 2009.by a treadle pump to irrigate 2000 m2. Irrigation goutte a goutte en productionDespite malfunction of "Horticulture Easy Drip Kit paysanne de concombre dans un100 m²," evidenced by the values of UC, we may environnement pédoclimatique sahélien duretain FOC = 0.6m according Keller et Karmeli mali (cercle de San). Revue Malienne demethod and FOC = 1.5m according the old network Science et Technologie. 11, 95-104one. [5] Coulibaly D., 2011. Irrigation goutte a goutte avec « Horticulture Easy Drip Kit deTable 3: Uniformity coefficient (UC) of water 100 m² » : adaptabilité et impact sur ladistribution of "Horticulture Easy Drip Kit 100 m²" production maraîchère en milieu paysanNetwork CU dans la zone sahélienne de San. Thèse de Keller et Old doctorat de l’Université de Bamako Mali, Karmeli networ 106p. method k [6] Zella L., Kettab A., Chasseriaux. 2003. metho Simulation hydraulique d’une rampe d do micro-irrigation par Ia méthode dite 𝑞 𝑞 𝑚𝑖𝑛 (𝑙ℎ−1 ) (% (%) des volumes de contrôle. RevuePressio Servic ( ) Agronomie, vol. 23, n° 1, pp. 37-44.n H e 𝑙ℎ−1 [7]. Christiansen J.E., 1942. Hydraulics of(m) ) sprinkling systems o f micro-irrigation. Latéra 0,82 0,30 20 37 Trans. ASCE 107:221-239. l [8] Wu L.P., Gitlin H.M., 1975. Energy0,6 gradient line for drip irrigation laterals. Centr 0,87 0,43 18 50 al Trans. ASCE 101(4): 323-326. Latéra 0,90 0,39 19 44 [9] Zella L., Kettab A., 2001. Critères de l dimensionnement d’une rampe de1 micro-irrigation. Revue La Houille Centr 1,07 0,65 14 61 al Blanche, n° 6/7, pp. 130-135. Latéra 1,15 0,81 7 71 [10] Vermeiren L., Jobling G.A., 1983. l L’irrigation localisée ; calcul, mise en1,5 place, exploitation, contrôle de Centr 1,37 0,92 10 67 al fonctionnement, Bulletin FAO d’irrigation et de drainage n°36:92 p. [11] Solomon H., Dedrick A.R., 1995. Stan-5. Conclusion Studies show that the network has a dards developments for micro-irrigation.laminar flow regime with a strong correlation Center for irrigation technology (CIT).between debit and pressure, indicating normal http:/www. CIT-Stand. Htm. [12] Carlier M., 1980. Hydraulique générale ethydraulic functioning. However the measured debits appliquée. ed.1 Eyrolles. pp. 158-269.are not homogeneous, as water distribution [13] Keita A., Leeuwen N.V 2002according to the methods used (Keller et Karmeli,old network method). So "Horticulture Easy drip Kit Expérimentation d’un système d’arrosage100 m²" is not yet adapted to the requirement of à faible coût : le système pompe à Pédales-material drip to drip. Against, its simplicity makes it Rampe à Goutteurs. Sud Sciences & Technologies : n°8, 4- 15a better material for small Sahelian farmers, hencethe need for further research to improve theuniformity of irrigation. In a temporary situation, aninstallation height of 0.6m may be advised. 1553 | P a g e