Service Contract No 2007 / 147-446 NYANYALI ... - Swaziland

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Possible ways of improving the hydraulic variation include the installation of pressureregulating device (installing hydraulic valves) repair and/or removal of pinched lateral/submainlines and the redesign of the hydraulic system.Sprinkler pressure regulators:The project was implemented on an uneven topography and this directly effect sprinkleroperating pressure. When flow is downhill pressure is gained and the reverse is true.Sprinkler pressure regulators were installed by the contractor but were later removed onsome sprinklers by management. Some pressure regulators are damaged/brake when thesprinkler falls.LeaksTimely maintenance and repair of minor leaks are often neglected in this system. The leaks inthe pipes of the supply network of this irrigation system caused a drop in operating pressureand an increase in pump flow. This increase in pump duty reduces the efficiency at which thepump operates, causing further pressure and delivery reductions. A drop in the operatingpressure causes a change in the performance of sprinkler. Mainly, these leaks are observedin sprinklers, sprinkler stand-dragline connections, broken dragline, pipelets, hydromatics,sub-mains, mainline, etc. it is important that all leaks are located quickly and repaired. A leakprevention program should include regular replacement of damaged draglines.Gross application rate (GAR)The gross application rate (GAR) of the sprinkler was thereafter calculated, by means of thefollowing formula;GAR qe1000A ....…………………………………. (10) mm/hWhere; GAR = Gross Application RateA = wetted area (m 2 )The GAR is a fraction of emitter discharge and sprinkler spacing as indicated by equation 10above. The nozzle sizes found in this development (table 3) has an average GAR of3.6mm/hr and is lower than the recommended GAR for sugarcane of 4.2mm/hr.Nyanyali Farmers Cooperative Report - 2009 Page - 29 -
6 A S S E S S M E N T O F O P E R A T I O N , M A N A G E M E N TA N D M A I N T E N A N C E O F T H E I R R I G A T I O NS Y S T E M6 . 1 O p e r a t i o nAs-built drawings and design information not availableThe fact that no design or installation information is available consigns a huge constraint onmanagement. Forward planning on aspects related to the irrigation infrastructure cannot bedone, i.e. replacement stock purchase; item like pipes, fittings, etc are procured afterbreakages because the details of that particular pipe, fitting, etc is obtained from the brokenpart. This increases their down time and negatively impacts on crop production.Operation and maintenance manual not availableThe different components forming the irrigation system require different operating proceduresand these are obtained from an operation and maintenance manual. This document, like allother documents, is not available and for efficient performance of these components, it mustbe compiled. The consequence of not having this document is seen during this evaluation inthat incorrect sequences are followed in opening and closing the pump. Also, this documenthelps in the formulation of a maintenance plan and provides guidelines to be followed duringmaintenance.Financial viability for smallholder growerThe late conclusion of loan agreements (seasonal loans) results in the late delivery of inputsand late application of fertilizers and chemicals, which reduces yields and sucrose content,resulting in reduced financial returns per hectare and inability to recoup invested capital. Inaddition, the absence of any dividends for distribution to farming association members at theend of each season can lead to a decline in the cohesion of farmers’ associations/cooperatives,a cohesion which is essential to increasing on-farm efficiency.Yields records for only three production season were found and the highest being 104.7tones per hectare (figure16).Nyanyali Farmers Cooperative Report - 2009 Page - 30 -
Page 1: Restructuring and DiversificationMa
Page 5 and 6: 8 RECOMMENDATIONS .................
Page 7 and 8: ABBREVIATIONSAbbreviationAEARCASAEC
Page 9 and 10: 2 B A C K G R O U N D O N I R R I G
Page 11 and 12: 3 T E C H N I C A L A U D I T R E P
Page 13 and 14: 7,1 Type type Vyrsa 70 Vyrsa 707,2
Page 15 and 16: Soil informationSoil properties use
Page 17 and 18: 4 F I E L D E V A L U A T I O N O F
Page 19 and 20: Figure 5. 2 x 300mm x 45° bends on
Page 21 and 22: 4.1.1.1.3 Suction Pipe InletsSpacin
Page 23 and 24: hf6375kQ4d2……………………
Page 25 and 26: Table 1. pump and motor specificati
Page 27 and 28: Figure 13. Inside Nyanyali pump hou
Page 29 and 30: pipe:Filters:Pumpingequipmentand el
Page 31 and 32: 4.1.3 S u p p l y S y s t e mThe ev
Page 33 and 34: When down -stream pressure falls be
Page 35: 5.1.1 S p r i n k l e r p r e s s u
Page 39 and 40: indication of the amount small grow
Page 41 and 42: 7 C O N S T R A I N T S T O E F F I
Page 43 and 44: ‣ The optimum sprinkler operating
Page 45 and 46: 8 R E C O M M E N D A T I O N STo e
Page 47 and 48: ‣ A consortium could be formed fo
Page 49 and 50: Accurate details are required also
Page 51 and 52: 12. Solomon K.H. 1988a, Irrigation
Page 53 and 54: Nyanyali Farmers Cooperative Report
Page 57 and 58: SEB usage for River pump station Ph

Service Contract No 2007 / 147-446 NYANYALI ... - Swaziland

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