sukumani bomake FA Report - Swaziland

Restructuring and Diversification 

Management Unit (RDMU) 

to coordinate the implementation of 

the National Adaptation Strategy to 

the EU Sugar Reform, Swaziland 

Service Contract No 2007 / 147-446 

EuropeAid/125214/C/SER/SZ: Restructuring and 

Diversification Management Unit to coordinate the 

implementation of the National Adaptation Strategy to the 

EU Sugar Reform, SWAZILAND 

EC General Budget – SU-21-0603 

SWAZILAND Technical Audit of Farmers Association 

S u k u m a n i B o m a k e F a r m e r s A s s o c i a t i o n 

Submitted to: 

The Delegation of the European Commission to Swaziland 

4 th Floor Lilunga House, Somhlolo Road, Mbabane, Swaziland 

Ministry of Economic Planning and Development 

P.O. Box 602 

Mbabane H100, Swaziland

Your contact persons 

with GFA Consulting Group GmbH are 

Dr. Susanne Pecher 

Anke Schnoor 

Restructuring and Diversification Management Unit 

(RDMU) 

to coordinate the implementation of the National Adaptation 

Strategy to the EU Sugar Reform, Swaziland 

Technical Audit of Farmers Association 

Author: Tiekie de Beer, 

Designer Member of the South African Irrigation 

Institute (SABI) 

& 

Bongani Bhembe 

Mission Report 

Address 

GFA Consulting Group GmbH 

Eulenkrugstraße 82 

D-22359 Hamburg 

Germany 

Phone +49 (40) 6 03 06 – 111 

Fax +49 (40) 6 03 06 - 119 

Email: afrika@gfa-group.de 

[Sukumani Bomake Farmers Association Report - 2008] 

Page ii

DISCLAIMER 

The contents of this report are the sole responsibility of the RDMU and can in no way 

be taken to reflect the view of the European Union. 


Page iii

TABLE OF CONTENTS 

LIST OF TABLES ............................................................................................................................................ vi 

LIST OF FIGURES ......................................................................................................................................... vii 

LIST OF APPENDICES ................................................................................................................................ viii 

ABBREVIATIONS ........................................................................................................................................... ix 

1 INTRODUCTION ............................................................................................... - 1 - 

2 BACKGROUND ON IRRIGATION DEVELOPMENT ....................................... - 2 - 

3 TECHNICAL AUDIT REPORT ..........................................................................- 3 - 

3.1.1 REVIEW OF THE IRRIGATION DESIGN CRITERIA AND SPECIFICATIONS .........................- 3 - 

3.1.1.1 Irrigation Design Criteria and Specifications by consulting engineer ......... Error! Bookmark not 

defined. 

3.1.1.1.1 Planning ................................................................................... Error! Bookmark not defined. 

3.1.1.1.2 Mainline, sub-mains and irrigation system layout ................... Error! Bookmark not defined. 

3.1.1.1.2.1 Mainline and sub-mains ........................................................ Error! Bookmark not defined. 

3.1.1.1.2.2 Hydrants ................................................................................ Error! Bookmark not defined. 

3.1.1.1.2.3 Laterals ................................................................................. Error! Bookmark not defined. 

3.1.1.1.2.4 Pump control valve in booster pump station ......................... Error! Bookmark not defined. 

3.1.1.1.3 Booster Pump Sets ................................................................. Error! Bookmark not defined. 

3.1.1.1.3.1 Performance criteria .............................................................. Error! Bookmark not defined. 

3.1.1.1.4 River Pump Sets....................................................................... Error! Bookmark not defined. 

3.1.1.2 Irrigation Design and Specifications by the contractor ..............................................................- 3 - 

3.1.1.2.1 Planning: .................................................................................. Error! Bookmark not defined. 

3.1.1.2.2 Mainline: .................................................................................. Error! Bookmark not defined. 

3.1.1.2.3 Sub mains: ............................................................................... Error! Bookmark not defined. 

3.1.1.2.4 Hydrants ................................................................................... Error! Bookmark not defined. 

3.1.1.2.5 In - Field .................................................................................. Error! Bookmark not defined. 

3.1.1.2.6 Booster Pump Sets ................................................................. Error! Bookmark not defined. 

3.1.1.3 Review Consulting Engineer and Contractor Irrigation Design Criteria and Specifications .....- 3 - 

3.1.1.3.1 Planning ................................................................................................................................- 3 - 

4 FIELD EVALUATION OF IRRIGATION SYSTEM ..........................................- 12 - 

4.1.1 Pumps And Pump Stations ...............................................................................................................- 12 - 

4.1.1.1 Pump Suction Side ...................................................................................................................- 12 - 

4.1.1.1.1 Suction Pipe Flow Rate .......................................................................................................- 12 - 

4.1.1.1.2 Requirements for Fittings ...................................................................................................- 13 - 

4.1.1.1.3 Suction Pipe Inlets ..............................................................................................................- 15 - 

4.1.1.1.4 Suction side losses ..............................................................................................................- 18 - 

4.1.1.1.5 Suction height .....................................................................................................................- 18 - 

4.1.1.2 Pumps............................................................................................ Error! Bookmark not defined. 

4.1.1.2.1 Power required on the pump shaft ........................................... Error! Bookmark not defined. 

4.1.1.2.2 Pump Operation ....................................................................... Error! Bookmark not defined. 

4.1.1.2.3 General ..................................................................................... Error! Bookmark not defined. 

4.1.2 Power Supply And Consumption .....................................................................................................- 23 - 

4.1.3 Supply System ..................................................................................................................................- 25 - 

4.1.3.1 Mainline size ............................................................................................................................- 25 - 

4.1.3.2 Mainline class ..........................................................................................................................- 25 - 

5 FIELD EVALUATION OF SPRINKLER AND CENTER PIVOT IRRIGATION 

SYSTEM ................................................................................................................ - 27 - 


Page iv

5.1 Pressure readings ................................................................................................................................- 28 - 

5.1.1 Pressure at hydrant ............................................................................................................................- 28 - 

5.1.2 Sprinkler pressure .............................................................................................................................- 28 - 

5.2 Delivery tests ........................................................................................................................................- 31 - 

5.2.1 Sprinkler discharge ...........................................................................................................................- 31 - 

5.3 Distribution tests .................................................................................................................................- 34 - 

5.3.1 Importance of CU and DU ................................................................................................................- 35 - 

5.3.2 Christiansen’s uniformity coefficient (CU): .....................................................................................- 37 - 

5.3.3 Distribution uniformity (DU): ..........................................................................................................- 40 - 

5.3.4 Application efficiency (AE): ............................................................................................................- 41 - 

5.4 Field evaluation Centre Pivot Irrigation Systems ..................................... Error! Bookmark not defined. 

5.4.1 Pressure measurements .......................................................................... Error! Bookmark not defined. 

5.4.2 Distribution tests .................................................................................... Error! Bookmark not defined. 

5.4.3 Uniformity coefficients .......................................................................... Error! Bookmark not defined. 

5.4.4 Distribution uniformity (DU)................................................................. Error! Bookmark not defined. 

5.4.5 Application efficiency, AE .................................................................... Error! Bookmark not defined. 

5.4.6 System efficiency (SE) .......................................................................... Error! Bookmark not defined. 

6 ASSESSMENT OF OPERATION, MANAGEMENT AND MAINTENANCE OF 

THE IRRIGATION SYSTEM .................................................................................. - 42 - 

6.1 Operation .............................................................................................................................................- 42 - 

6.2 Management Practices ........................................................................................................................- 42 - 

6.3 Maintenance Survey ...........................................................................................................................- 43 - 

7 CONSTRAINTS TO EFFICIENT SYSTEM PERFORMANCE ........................- 45 - 

8 RECOMMENDATIONS ...................................................................................- 47 - 

9 CONCLUSION ................................................................................................- 49 - 

10 LITERATURE REFERENCES .....................................................................- 51 - 

11 PRODUCT INFORMATION .........................................................................- 53 - 

12 APPENDICES .............................................................................................- 60 - 


Page v

LIST OF TABLES 

TABLE 1. BOOSTER PUMPS EVALUATION ......................................................... ERROR! BOOKMARK NOT DEFINED. 

TABLE 2. EAC CALCULATIONS FOR INTAMAKUPHILA FA .................................. ERROR! BOOKMARK NOT DEFINED. 

TABLE 3. SPRINKLER VALUATED BLOCK SUMMARY ......................................... ERROR! BOOKMARK NOT DEFINED. 

TABLE 4. CENTRE PIVOT NO. 2 DETAILS ........................................................... ERROR! BOOKMARK NOT DEFINED. 

TABLE 5. OPTIMAL OPERATING PRESSURE VS NOZZLE DIAMETER FOR SPRINKLERS ........................................- 28 - 

TABLE 6. INFIELD PRESSURE MEASURE FOR SPRINKLER IRRIGATION .............. ERROR! BOOKMARK NOT DEFINED. 

TABLE 7. DISCHARGE VARIATION CALCULATED FROM FIELD MEASUREMENTS ................................................- 32 - 

TABLE 8. TECHNICAL PROPERTIES OF SPRINKLERS FOUND ON SITE AT 35M OPERATING PRESSURE ...............- 33 - 

TABLE 9. GAR AND NAR UNDER FIELD CONDITIONS AND AS SPECIFIED DURING DESIGN BY CONTRACTOR AND 

CONSULTING ENGINEERS ........................................................................ ERROR! BOOKMARK NOT DEFINED. 

TABLE 10. UNIFORMITY YIELD RELATIONSHIP FOR SUGARCANE ( SOLOMON, 1990) .......................................- 35 - 

TABLE 11. IRRIGATION EQUIPMENT, WATER AND POWER COSTS FOR A RANGE OF DISTRIBUTION UNIFORMITIES 

(SOLOMON, 1988A) ...................................................................................................................................- 36 - 

TABLE 12. CLIMATIC INFORMATION ..................................................................................................................- 38 - 

TABLE 13. MAINTENANCE SCHEDULE FOR SPRINKLER IRRIGATION SYSTEMS ...................................................- 43 - 

TABLE 14. MAINTENANCE PRACTICES IMPLEMENTED BY INTAMAKUPHILA FA ................................................- 43 - 


Page vi

LIST OF FIGURES 

FIGURE 1. RIVER PUMPS AND INTAKE SUMP ................................................... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 2. STORAGE RESERVOIR AND BOOSTER PUMP STATION .................... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 3. TELEMETRY SYSTEM ON RIVER PUMP STATION .............................. ERROR! BOOKMARK NOT DEFINED. 

FIGURE 4. BOOSTER PUMPS FOR PHASE 1, 2, 3 AND CENTRE PIVOTS PUMPS ERROR! BOOKMARK NOT DEFINED. 

FIGURE 5. HYDRANT VALVE ASSEMBLY ............................................................ ERROR! BOOKMARK NOT DEFINED. 

FIGURE 6. MCC FOR RIVER PUMPS .................................................................. ERROR! BOOKMARK NOT DEFINED. 

FIGURE 7. CENTRE PIVOT NO. 2 ....................................................................... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 8 SAPWAT SCREEN WITH REFERENCE EVAPOTRANSPIRATION ........... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 9 CROP COEFFICIENTS SCREEN IN SAPWAT ........................................ ERROR! BOOKMARK NOT DEFINED. 

FIGURE 10 SUMMER RAINFALL SCREEN IN SAPWAT ....................................... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 11 WINTER RAINFALL SCREEN IN SAPWAT .......................................... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 12 SAPWAT SCREEN INDICATING WATER REQUIREMENT FOR SPRINKLER IRRIGATION WITH RAINFALL 

TAKEN INTO ACCOUNT ................................................................................................................................ - 7 - 

FIGURE 13. SAPWAT SCREEN INDICATING WATER REQUIREMENT FOR CENTRE PIVOT IRRIGATION WITH 

RAINFALL TAKEN INTO ACCOUNT............................................................ ERROR! BOOKMARK NOT DEFINED. 

FIGURE 14. RESERVOIR WATER LEVEL AT HALF CAPACITY CONSTRUCTED NEXT TO A BOOSTER PUMP STATION 

................................................................................................................. ERROR! BOOKMARK NOT DEFINED. 

FIGURE 15. REQUIRED RADIUS OF 90 BENDS (SOURCE: ARC (2007)) ................................................................ - 13 - 

FIGURE 16. 90° BENDS INSTALLED ON RIVER PUMPS SUCTION ......................................................................... - 14 - 

FIGURE 17. 90° BENDS IN RIVERS PUMPS .......................................................................................................... - 14 - 

FIGURE 18. 250MM 90° BEND ON THE DELIVERY SIDE OF BOOSTER PUMP NO 1 ........... ERROR! BOOKMARK NOT 

DEFINED. 

FIGURE 19. 90° BENDS ON BOOSTER PUMPS SUCTION ................................... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 20. CONCENTRIC AND ECCENTRIC REDUCERS ....................................................................................... - 14 - 

FIGURE 21. CORRECT INSTALLATION OF ECCENTRIC REDUCERS ON BOOSTER PUMPS .................................... - 15 - 

FIGURE 22. SPACING AND PLACING OF SUCTION PIPE INLETS........................................................................... - 16 - 

FIGURE 23. UNACCEPTABLE INSTALLATION OF SUCTION PIPE .......................................................................... - 16 - 

FIGURE 24. MINIMUM WATER DEPTH ABOVE SUCTION PIPE INLET ................................................................. - 17 - 

FIGURE 25. ATMOSPHERIC PRESSURE VS. HEIGHT ABOVE SEA LEVEL ............................................................... - 19 - 

FIGURE 26. PRESSURE VERIFICATION AT HYDRANT ......................................... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 27. FULLY EQUIPPED PRESSURE CONTROL VALVE AT BLOCK HYDRANT ............. ERROR! BOOKMARK NOT 

DEFINED. 

FIGURE 28. PRESSURE MEASUREMENT WITH A PITOT TUBE END PRESSURE GAUGE ............ - 29 - 

FIGURE 29. POSITIONS OF COMPLETE SPRINKLER PRESSURE MEASURES IN AN IRRIGATION BLOCK ............... - 30 - 

FIGURE 30. MEASURING APPARATUS FOR SPRINKLER NOZZLE SIZE ............... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 31. MEASURING OF SPRINKLER DISCHARGE ........................................................................................ - 32 - 

FIGURE 32. RAIN GAUGE SET-UP AT A SPRINKLER SYSTEM TO MEASURE THE DISTRIBUTION ......................... - 37 - 

FIGURE 33. RAIN GAUGE SET-UP IN PRACTICE TO MEASURE THE DISTRIBUTION ............................................. - 38 - 

FIGURE 34. MEASUREMENT OF WIND VELOCITY ............................................. ERROR! BOOKMARK NOT DEFINED. 

FIGURE 35.CU, DU, AND AE FIELD EVALUATION RESULTS ................................................................................. - 39 - 

FIGURE 36. LINEAR AVERAGE APPLICATION OF CENTRE PIVOTS ..................... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 37. VERTICAL ALIGNMENT ON PHASE 2 SEMI PERMANENT ............... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 38. POOR CROP COVER ....................................................................... ERROR! BOOKMARK NOT DEFINED. 

FIGURE 39. PHASE THREE SPRINKLER WITH PRESSURE REGULATORS ............. ERROR! BOOKMARK NOT DEFINED. 

FIGURE 40. PHASE 1 AND 2 SPRINKLERS WITHOUT PRESSURE REGULATORS . ERROR! BOOKMARK NOT DEFINED. 

FIGURE 41. CORRODED STRAINERS IN STORAGE RESERVOIR .......................... ERROR! BOOKMARK NOT DEFINED. 


Page vii

LIST OF APPENDICES 

Appendix 1: block layout ........................................................................................ Error! Bookmark not defined. 

Appendix 2: EAC calculation ................................................................................. Error! Bookmark not defined. 


Page viii

ABBREVIATIONS 

Abbreviation 

AE 

ARC 

ASAE 

CU 

CV 

DU 

EAC 

EU 

FA 

GAR 

HDPE 

MCC 

NAR 

NPSH 

PVC 

RSSC 

SABI 

SE 

SSA 

SWADE 

Us 

Description 

Application Efficiency 

Agricultural Research Council 

American Society of Agricultural Engineers 

Christiansen’s uniformity coefficient 

Coefficient of Variation 

Distribution Uniformity coefficient 

Equivalent Annual Cost 

Emitter Uniformity 

Farmers Association 

Gross Application Rate 

High Density Polyethylene 

Motor Control Centre 

Net Application Rate 

Net Positive Suction Head 

Polyvinyl Chloride 

Royal Swaziland Sugar Corporation 

South African Irrigation Institute 

System Efficiency 

Swaziland Sugar Association 

Swaziland Water & Agricultural Development Enterprise 

Statistical Uniformity 


Page ix

ACKNOWLEDGEMENTS 

A special thanks to everyone who contributed during the evaluation; 

Mr. P. Ntuli 

Mr. F.B. Reinders 

Mr. O. Magwenzi 

Mr. G. Dlamini 

Swaziland Sugar Association 

Agricultural Research Council 

Ubombo Sugar out growers Department 

Ubombo Sugar out growers Department 

Evaluation team 

Mr. T. de Beer 

Mr. B. Bhembe 

Ms F. Mavuso 

Mr. S. Ndlandla 

Mr. E. Dlamini 

Ms T. Kunene 

Sukumani Bomake FA farm manager, irrigators and pump attendants 


Page x

1 I N T R O D U C T I O N 

Association general information 

1. Farm name: Swazi Nation Land 

2. Name of Association: Sukumani Bomake Farmers Association 

3. Location: 

Latitude 

26.6869°S 

Longitude 

31.6687°E 

Altitude 218 

Maximum Temperature 36 

Minimum Temperature 8 

4. Postal address: 221 Siphofaneni 

5. Contact Details: 

Chairman – Mrs C. Mamba 

Na 

Farm Supervisor- Mr. Mazibuko 635 8809 

6. Area of farm (ha) 28 

7. Crops irrigated: Sugarcane 

8. Designers name and details: Mr. Petros Dlamini 

9. Date of evaluation: 27 October 2008 

10. Evaluators: Tiekie de Beer and Bongani Bhembe 

[Sukumani Bomake Farmers Association Report - 2008] Page - 1 -

2 B A C K G R O U N D O N I R R I G A T I O N 

D E V E L O P M E N T 

Sukumani Bomake Farmers Association’s project of 28 Ha was designed and installed by a 

Mr Petros Dlamini of which no record or information could be found in the industry. Mr. Petros 

Dlamini is however a well known political figure in the country as he is a former Member of 

Parliament. This Farmers Association consist of only women, hence the name. Adjacent to 

this Farm is another project memberships of which are only men, husbands to Sukumani 

Bomake FA. 

2 . 1 P r o j e c t 

The initial design was for 20ha dragline irrigation system and the current area of 28ha is a 

result of expansion initiated and implemented over the years by management. Recently an 

expansion of 3ha was planted and this was done by connecting two laterals spaced 51m 

directly. Approximately, 15ha is still available for expansion; information on suitability of these 

soils is contained in the report. For all this development no design information or maps is 

available. In fact the contractor never produced drawings, not even construction drawings. 

This development has one main irrigation pump station housing one irrigation pump and a 

motor. A diversion channel was constructed to divert irrigation water from the Lusuthu River 

to the intake sump. This pump station is approximately 1 kilometre for the irrigated area and 

is supplied by a 160mm PVC delivery manifold. 

This irrigation development was implemented on two main soil types, the Lesibovu and 

Rondspring series. Both this soil types are classified under type I soils and are highly suitable 

for irrigation agriculture. 

In trying to address the problem of food security there is an area of approximately 1 hectare 

under maize production and utilizes irrigation water from sugarcane fields. According to Farm 

management this area will be increased depending on demand and returns from this 

enterprise. 


3 T E C H N I C A L A U D I T R E P O RT 

3.1.1 R E V I E W O F T H E I R R I G A T I O N D E S I G N C R I T E R I A 

A N D S P E C I F I C A T I O N S 

3.1.1.1 Irrigation Design and Specifications 

Design information from the designer and from the client’s representative during construction, 

Ubombo sugar, could not be obtained. The design was therefore checked against Swaziland 

Sugar Industry Standard and SABI norms shown below. 

3.1.1.1.1 DESIGN CRITERIA 

Crop 

Irrigated Area 

Gross Application 

Net Application 

Irrigated Cycle 

Sprinkler discharge 

Sprinkler Spacing 

Precipitation Rate 

Stand time 

Annual Irrigation hours 

Sugar Cane 

23.7Ha 

52mm 

39 mm per cycle (6.5 mm/day) 

6 days (depending on soil type) 

0.39 l/s 

18m x 18m 

4.3mm/hr 

12 hours (depending on soil type) 

3 300 hours 

3.1.1.2 Review of Contractor Irrigation Design Criteria and Specifications 

3.1.1.2.1 Planning 

Of the four major input of planning namely crop, climate, soil and irrigation system, the study 

revealed that crop and climate information used as supplied by the SSA (Swaziland Sugar 

Ass) Soil types were not taken into consideration during design and or implementation of the 

project. 


Attached in appendices is a soil map of Sukumani Bomake FA indicating major soil types the 

project was developed on. Information on whether soils were taken into account during 

design could not be found. 

The purpose of this study was, therefore, to determine the quantity of water required by the 

crops per cycle during peak demand periods and how often it was to be applied taking 

practical operating practice into account. 

Taking soils into account the following planning schedule was developed; 

Peak Design-Norm For Sprinkler Irrigation At Sukumani Bomake 

Farmers association 

1 GENERAL INFORMATION 

1,1 Owner 

Sukumani Bomke 

FarmersAssociation 

1,2 Farm Name - Number - Co-ordinates Swazi nation land 

1,3 Telephone number 

1,4 Area developed 28 Ha 

1,5 Water Allocation 28 l/s 

2 CLIMATE 

2,1 Month state Jan 

2,2 Weather station state Ubombo 

2,3 Evaporation mm/day 7mm A-Pan or 5mm Grass Factor 

3 MANAGEMENT 

3,1 Available working days per week days 7 

3,2 Available working Hours per day hours 24 

4 CROP BLOCK NO Lesibovu Rondspring 

4,1 Type state Sugar Sugar 

4,2 Area Ha 14 14 

4,3 Plant spacing m NA NA 

4,4 Row spacing m 1.8 1.8 

4,5 Effective root depth m 0.45 0.45 

4,6 Plant time date August August 


5 SOIL Lesibovu Bushbaby 

5,1 Effective soil depth m 1 1 

5,2 Water holding capacity mm/m 180 180 

5,3 Easy available water (10-50 kPa) 50% mm/m 90 90 

5,4 Easy available water in root zone mm 40.5 40.5 

6 WATER 

6,1 C en S Classification of water C+S 

7 EMITTER 

7,1 Type type Vyrsa 70 Vyrsa 70 

7,2 Nozzle size mm 11/64 11/64 

7,3 Discharge l/h 1350 1350 

7,4 Working pressure kPa 350 350 

7,5 Application efficiency % 70 70 

7,6 Emitter spacing m 18 18 

7,7 Lateral spacing m 18 18 

7,8 Wetted diameter m 36 36 

7,9 Gross Application rate on wetted area mm/h 4.16 4.16 

7,10 Nett Application rate on wetted area mm/h 3.33 3.33 

8 SCHEDULING 

8,1 Crop factor (max) max 1.15 1.15 

8,2 Evaporation mm/day 5 5 

8,3 Evapotranspiration mm/day 5.75 5.75 

8,4 Net Irrigation requirement mm/day 5.75 5.75 

8,5 Gross Irrigation requirements mm/day 6.04 6.04 

8,6 Theoretical cycle length day 6.70 6.70 

8,7 Theoretical Stand time hour 12.16 12.16 

8,8 Practical Cycle length day 6 6 

8,9 Practical Stand time hours 12 12 

8,10 Working days per week days 6 6 

8,11 Irrigation hours per day hours 24 24 

8,12 Gross application rate per practical cycle mm 39.96 39.96 

8,13 Gross application per month mm 171.25 171.25 

9 SCHEDULE OF BLOCKS THAT IRRIGATE TOGETHER 

10 HYDRAULICS 

10,1 Pressure difference over block m 40 40 

10,2 

Pressure at beginning of sub main or 

lateral m 40 40 

10,3 Velocity in mainline (max) m/s 1 1 


11 

PRACTICAL STAND TIME / START TIME 

for 6 Day Cycle length 

11,1 Position 1 












11,13 Position 1 start at beginning again 

Start 

Day 1 

06,00 

Day 1 

18,00 

Day 2 

06,00 

Day 2 

18,00 

Day 3 

06,00 

Day 3 

18,00 

Day 4 

06,00 

Day4 

18,00 

Day 5 

06,00 

Day 5 

18,00 

Day 6 

06,00 

Day 6 

18,00 

Day 8 

06,00 

End 

Day 1 

18,00 

Day 2 

06,00 

Day 2 

18,00 

Day 3 

06,00 

Day 3 

18,00 

Day 4 

06,00 

Day 4 

18,00 

Day 5 

06,00 

Day 5 

18,00 

Day 6 

06,00 

Day06 

18,00 

Day 7 

06,00 

12 FILTER 

12,1 Type State 

12,2 Total total 

12,3 Filtration size micron 

12,4 Pressure loss over filter (clean) m 

12,5 Pressure lose over filter (dirty) m 

13 DESIGNER 

13,1 Name Tiekie de Beer 

13,2 Company Tiekie de Beer Consulting 

13,3 SABI Membership Designer Fellow 


Climatic information: 

Climatic information used when compiling the above schedule was obtained from SAPWAT 

and a summary of which is shown by the figures below. 

Figure 1. SAPWAT screen indicating water requirement for sprinkler irrigation with rainfall 

taken into account 

Soil information 

Soil properties used when compiling the afore schedule was obtained from the below charts. 

These are the three major soils found within the farm, an outline of which is shown on a soil 

map attached in annexes. 






4 F I E L D E V A L U A T I O N O F I R R I G A T I O N 

S Y S T E M 

4.1.1 P u m p s A n d P u m p S t a t i o n s 

4.1.1.1 Pump Suction Side 

The majority of problems occurring with pumps are usually the result of poor suction side 

design and installation. The installation and designed of the suction side must ensure that 

turbulence occurring in the suction pipe and collection of air in high places in the suction pipe, 

is prevented. In view of the above, the different suction side components were evaluated. 

4.1.1.1.1 Suction Pipe Flow Rate 

The suction pipe flow velocity of river and booster pumps was calculated as follows: 

353,68Q 

V m / s 

d 

2 ………………………………….… (1) 

Where: V = flow velocity in pipe (m/s) 

Q = flow rate (m³/h) 

d = inner diameter of suction pipe (mm). 

One KSB ETA 65-200 irrigation pump was installed in this project and was in operation during 

the evaluation. As mentioned previously no design information was obtained and based on 

the installed motor size of 37kW, the pump duty point is 120m3/hr at 80m head. Flow velocity, 

as per equation 1, through the 150mm steel suction manifold at this duty point is 1.89m/s. 

This is unacceptable. The total area of 28ha will require an operational discharge of 100m3/hr 

at 86m head and a flow rate of 1.57m/s is obtained at this discharge. Without a flow meter 

this discharge could not be confirmed but the pump was operating at 600kPa. Efforts to 

increase the operating head were futile because above this pressure strange noises are 

generated in the pump casing and both the pump and motor overheats; a clear indication of 

cavitation. 


According to the Agricultural Research Council, ARC (2007) the ideal suction pipe flow 

velocity must be 1.0 m/s, but suction pipe flow velocities up to 1.5 m/s are acceptable. The 

excessively high suction flow velocity in the suction pipe caused turbulence in the pipe, thus 

causing irregular feeding of the pump (hence the cavitation). As a result impellor wearing is 

excessive and thus explains the poor performance by this pump. Maintenance costs are high 

as a result. This pump is due for service and could fail any time. 

4.1.1.1.2 Requirements for Fittings 

90º Bends 

The radius (mm) of a 90º bend must be, at least, as shown in Figure 2 

r 

d 

Figure 2. Required radius of 90 bends (source: ARC (2007)) 

r d 100 mm 

2 …………………………………... (2) 

Where: r = radius of bend (mm) 

d = inner diameter of suction pipe (mm). 

three 150mm short radius 90° bends were installed, one on the suction manifold and two on 

the delivery manifold . The radius of these bends was 200mm and according to figure 2 and 

equation 2 above the required minimum is 400mm. there is more than five time the suction 

and delivery pipe size diameter pipe further on of these bends, hence the effects of the 

incorrect sizes were insignificant. 


Figure 3. Bends installed on river pump suction and delivery manifold 

Reducers 

The inlet on the pump suction side must be eccentric with the straight side towards the top, to 

prevent air collecting in the suction pipe and causing cavitation (ARC, 2006). The length of 

both eccentric and concentric reducers were evaluated against equation 3 (figure 4) below, 

adopted from the ARC 

Figure 4. Concentric and eccentric reducers 

( d 2 

d ) ………………………... (3) 

5 

1 

Where: = length of the reducer (mm) 

d1 = smaller inner diameter (mm) 

d2 = larger inner diameter (mm) 


A 150-80 eccentric reducer was installed on the suction side and a 150-65 concentric reducer 

on the delivery side, as per ARC requirement. The eccentric reducer was installed with the 

straight side towards the top, to prevent air collecting in the pipe and concentric reducers on 

the delivery pipe (figure 5). Both the eccentric and concentric reducers were incorrectly 

dimensioned and, again, the unacceptable dimensions of the concentric reducer had 

negligible effects on the performance of the pump and the entire system. The concentric 

reducer on the other hand is directly attached to the pump and the sudden restriction in size 

increases turbulence occurrences and causes irregular feeding of the pump hence cavitation. 

With such an installation, wearing and maintenance cost of the pump would increase. 

Figure 5. Correct installation of eccentric reducer but incorrectly length 

4.1.1.1.3 Suction Pipe Inlets 

Spacing and placing of suction pipe inlets 

The inlet of the suction pipe were not installed in accordance to the requirements of at least 

0,5d (d = inner diameter of the suction pipe) from the bottom of the pump sump (figure 6). 

The requirement that the suction pipe must be of at least 1,5d away from the side of the 

pump sump was also not satisfied. 


d 

1.5d 

0.5d 

d 

3d 3d 1.5d 

Figure 6. Spacing and placing of suction pipe inlets 

There was no proper intake sump instead the 150mm foot valve is at the end of a diversion 

channel from the Lusuthu River (figure 7). The foot valve is not protected in any form and is in 

direct contact with the bottom of the channel and debris carried with the river water. This is 

not acceptable as illustrated above, the foot valve is supposed to be at least 75mm from the 

bottom of the channel and 225mm from the embankment wall (figure 8). 

Figure 7.Unacceptable installation of suction position 

The minimum water depth above suction pipe inlet depends on the suction pipe velocity and 

was evaluated using the graph shown in figure 8 below. Site investigation revealed a water 

depth of approximately 500mm and with a maximum velocity of 1.89m/s the depth should be 

at least 1.2m. With the recommended velocities this depth is unacceptable. At the minimum 

river level water depth decrease substantially. This channel and the depth of the suction pipe 


must be designed according to the minimum water level. The effects of the shallow depth on 

the pumps were reflected through vortex especially on pump number 1, the shallowest pump 

(figure 9). 

Figure 8. Minimum water depth above suction pipe inlet 

Figure 9. Vortex observed in irrigation pump 


Foot valves 

The area around the foot valve was not clean and the total area of the openings from the 

suction sieve was more than the minimum ARC requirement of 1.5 times larger than the 

cross-sectional area of the suction pipe to prevent partial blockages of the suction sieve. 

4.1.1.1.4 Suction side losses 

During the evaluation of the pump station, attention was also given to the length of the 

suction pipe and fittings that were used. Friction losses for pipes were calculated as for any 

other pipe (using Hazen-Williams equation) and secondary losses for fittings were calculated 

with the aid of the following formula: 

h 

f 

6375kQ 

4 

d 

2 

………………………………….. (4) 

Where: hf = secondary friction loss in fitting (m) 

k = friction loss factor (annexure 1) 

Q = flow rate in the fitting (m³/h) 

d = inner diameter of the fitting (mm). 

A summation of friction loss across the foot valve, the suction pipe, and the eccentric reducer 

gave a total hf of 0.63 meters. Friction in the suction pipe has a direct effect of maximum 

suction height and consequently the available net positive suction head (NPSH) and is 

discussed below. 

4.1.1.1.5 Suction height 

The essence of this evaluation was to determine the actual static suction head of the installed 

pumps and then compare it to the designers suction height assumption. The maximum 

suction height was calculated using equation 5 below; 


h 

s(max) 

hd 

hf 

hvp 

NPSH 

required ………………. (5) 

Where: hs (max) = maximum suction height (m) 

hd = atmospheric pressure on terrain (m) – figure 10 

hf = suction side losses (friction losses, as well as secondary losses in fittings, m 

hvp = vapour pressure of water (m) 

NPSH required = net positive suction head from the pump curve (m). 

Figure 10. Atmospheric pressure vs. height above sea level 

The suction height of the river pump was measure to be 4.8 meters. The NPSH required of 

the river pumps (from a pump curve) is 4.6m and from the above calculation the maximum 

allowable suction height is 4.47 m. This calculation confirms that the river pump was 

incorrectly positioned. The major contributing factor in this incongruity is the high suction 

height. Various alternatives are must be implemented to solve this discrepancy. 

Further analysis compared NPSH available to NPSH required. NPSH requirements of 3.77 

meters are below the available NPSH of 4.6 meters. A safety factor of 0.5 was factored in this 

calculation as per manufacture’s requirement. This was not within the requirements of 

NPSHrequired

4.1.1.2 Pump evaluation 

Table 1 below indicates Sukumani Bomake FA irrigation pump specifications as observed 

from the information plate and tender document. 

Table 1. Evaluated pump and motor specifications 

Pump specification from information plate and tender document 

Number of units 1 

Model KSB ETA 65-250 

Pump duty point 

120m3/hr @ 800kPa 

Pump efficiency,% 71% 

Impellor diameter 

259 mm 

Motor specification from information plate and tender document 

Motor size, kW 37 

Revolution speed (rpm) 2940 

Motor efficiency, 93.6 

Power factor, cos Q 0.89 

4.1.1.2.1 Power required on the pump shaft 

The power required on the pump shaft was calculated as soon as the total pump head and 

delivery was measured. The pump efficiency was obtained from the pump curve. 

Power required on the pump shaft was calculated with the following formula and establishes 

whether motors were sized accurately. 

P 

g H Q 

36,000 

………………………………………. (6) 

Where: P = power required on the pump shaft (kW) 

ρ = density of water (1000 kg/m³) 

g = gravity acceleration (9.81 m²/s) 


H = pump pressure at service point (m) 

Q = pump delivery at service point (m³/h) 

η = pump efficiency at service point (%). 

With a calculated operational duty point of 100m3/hr at 860kPa, the pump efficiency is 70%. 

The required power on the pump shaft is therefore a theoretical value of 31.77 kW. The pump 

duty point shown in table 1 above corresponds to 37kW. According the ARC, 2007, the power 

output of the motor must be 10-15% greater than the power required on the pump shaft. The 

37kW motor evaluated on site is therefore of the correct size in all aspects. 

4.1.1.2.2 Pump Operation 

Pump curves of all the pumps were to be used to evaluate whether these pumps function as 

indicated by the pump curve. Measurements of the operational pressure and discharge from 

these pumps were to be used to determine the required power by these pumps. But because 

no flow meters were installed in this project this exercise could not be carried out. 

The require power 

P 

required 

of all the pumps was then compared with the output power (Pu) of 

the electric motor obtained from measurements of voltage and current. The output power of 

the motor was calculated using equation 7 below 

3IV cos 

1000 

P u ……………………………………….. (7) 

Where: Pu = output power of the motor (input power of the pump) (kW) 

I = average measured current (A) 

V = average measured voltage (V) 

η = motor efficiency (fraction) 

cos ø = power factor (factor). 

The output power of the motors was calculated to be 28.6 kW and the required power from 

the pump curve under the operational duty point could not be identified due to a lack of flow 

readings. After closing the pump control valve pressure, current and voltage readings were 

taken and from these measurements a conclusion was made that the pump is operating 


under capacity. For example, at closed valve the pump pressure must be 94m but it was 

780kPa. Amongst other things the impellor is worn out. 

4.1.1.2.3 General 

The pump house was generally in good condition. All doors could lock, had good ventilation, 

electric light well installed and both pumps had protective cover on couplings. Of concern 

were severe cooling leaks (figure 11) and no structure was constructed to facilitate 

dismantling and loading of both the pump and motor for maintenance purposes. The pump 

house is used as a storeroom for some farm chemicals and thus reduces working space and 

ventilation compromised. Unhygienic conditions and compromised safety (e.g. unprotected 

electric cables) were also of major concern. 

Figure 11. Improper drainage in pump house 

The alignment of the pump and the motor was also evaluated. This was done by placing the 

edge of a straight steel ruler over the coupling flanges at four points, 90º apart. This straight 

edge rested equally on all points on the flanges to ensure parallel alignment. The distance 

between the coupling levels at 90º intervals was also measured. A Vernier calliper was used. 

Measurements were the same on all the points, and on all pump and that meant the unit was 

squarely aligned. 


4.1.2 P o w e r S u p p l y A n d C o n s u m p t i o n 

Power consumption 

A basic economic analysis was undertaken to ascertain the trade-off between capital and 

energy costs. For this economic analysis the Equivalent Annual Cost method (EAC) was 

used. The EAC adjusts the costs of items to a stream of equal amounts of payment over 

specified periods (equivalent annual costs) in order to enable comparison. 

Items costed were: 

‣ Infield irrigation (tape and fittings including flusher lines and valves - considered as 

polythene). Including installation costs. 

‣ Distribution system - pipelines (main lines and submains - considered as PVC). 

Including installation costs. 

‣ Pumping plant (including pump control valves, flow meters, electrical components, 

motors etc). Included installation costs. Where no new pumps were included, all and 

any supplementary equipment/operations connected with pumping e.g. upgrades, 

new impellors, new switchgear, new valves were included 

‣ Primary filter station (only filters and associated pipework, valves etc). 

Excluded were: 

‣ All existing infrastructure (e.g. AC pipe, balancing dam, MCC housing, etc) 

‣ Buildings (e.g. cluster houses, pump stations, filter station structure) 

‣ Valves external to pump stations and filter stations. 

‣ Irrigation controller systems 

‣ Fertigation systems 

The operational costs for the schemes were confined to energy costs and maintenance 

(excluded labour. Admin etc). 

Interest rate: 10% 

Useful life (this analysis) 

Infield irrigation (Tape etc): 

10 years 

PVC/Poly pipe: 

Filters: 

Pumping equipment and electrics 

20 years 

15 years 

15 years 


Maintenance 

Infield irrigation: 3% 

Distribution - pipelines: 2% 

Pumping plant: 1% 

Filters: 3% 

Capital Recovery Rate (CRF) 

factors: 

Volume water applied per hectare: 

SEB tariff – Consumption: 

Maximum demand: 

Efficiency of pumping plant 

(See attached table) 

9000mI\3/ha/annum 

0.22 E/kWh 

69.42 E/kVa 

Calculate at design duty point 

EAC COMPUTATION MATRIX 

These costs have been calculated only for Phase Two of the 

Project 

ITEM COST ITEM Main Bid 

1 Infield irrigation 

Capital cost (E) - 

Useful life (years) 10 

Annual maintenance (%) 3 

EAC of infield irrigation (E) - 

2 Distribution system 




EAC of Distribution system (E) - 

3 Pumping plant 




EAC of Pumping plant (E) - 

4 Filters 




EAC of Filters (E) - 

5 Annual Energy Cost (E) 72,973.43 


Total EAC (E) - 

Energy cost as a % of total EAC 

#DIV/0! 

4.1.3 S u p p l y S y s t e m 

The evaluation of the supply system is discussed under the following headings; 

4.1.3.1 Mainline size 

Pressure was measured at all block hydrants and head loses due to elevation changes were 

calculated. SABI norm suggests that for raising main lines with a diameter of 200mm or 

smaller a maximum of 1.5% is allowed (ARC, 2003). 

The biggest pipe size is 160mm class 9 PVC delivery manifold from the pump house reducing 

to a 140, 125, and ending to a 110mm class 6. The total mainline length is approximately 

650m and according to the above norm, the allowed hf should be 9.75m. Head loss due to 

elevation change was calculated to be 22m. The summation of these head losses together 

with sprinkler’s operating pressure of 35m results to 66.75m total dynamic head. H x 1.05 

(safety factor) = 70m. This calculation proves that the river pump has enough capacity but 

because it was incorrectly installed uphill blocks were under pressure. 

The pressure different between the first and the lateral is 16m over a distance of 

approximately 450m and an elevation change of 10m. This means a friction loss of 1.3% and 

is lower than the required minimum of 1.5%. The same procedure was followed in evaluating 

the mainline section from the pump house to the first lateral and a conclusion was made that 

friction losses are within the above mentioned limits. The extent of over designing could not 

be evaluated because accurate dimension of each pipe size utilized could not be obtained. 

4.1.3.2 Mainline class 

The evaluation of the supply system revealed that, pipe class selection was in accordance to 

SABI norms, recurrent pipe bursts were experienced on class six pipes but this was due to an 


air lock. Initially no air valves were installed, after the installation of this unit, breakages 

stopped. Again, for the same reason as above, this evaluation could not identify as to 

whether the mainline classes were over specified or not. 


5 F I E L D E V A L U A T I O N O F S P R I N K L E R I R R I G A T I O N 

S Y S T E M 

Table 2. summary of evaluated block 

Block No 

B 

Block Area (ha) 10.6 

Type of sprinkler system Dragline 

Name of Designer 

Mr. Petros Dlamini 

Name of contractor 

Mr. Petros Dlamini 

Design Industry specs. Measured 

Hydrant pressure (m) Na Na No pressure 

measuring point 

Sprinkler spacing (m x m) Na 18 15 - 21 

Lateral spacing (m) Na 54/72 52 - 112 

Stand pipe height (m) Na 3 3 

Pressure regulator Na Yes No 

Dragline diameter (mm) Na 20 20 

Dragline length (m) Na 18/30 50 - 100 


5 . 1 P r e s s u r e r e a d i n g s 

The following pressure readings were taken: 

5.1.1 P r e s s u r e a t h y d r a n t 

Pressure at the hydrant could not be measured because no pressure measuring points were 

assembled. Instead pressure was measured on the first hydromatic from the hydrant valve 

assembly. This was measured with a hand made pressure measuring apparatus, where a 

pressure gauge, connected to a hydromatic and pipelet, was used. Hydromatics on the 

delivery side of the hydrant were used as pressure measuring points. 

5.1.2 S p r i n k l e r p r e s s u r e 

The optimal operating pressure (kPa) of the sprinkler should be between 60 and 70 times the 

nozzle diameter (mm). This is applicable to nozzles of 3 to 7 mm diameter (ARC, 2006). 

Table 3. Optimal Operating Pressure Vs Nozzle Diameter for Sprinklers 

Nozzle diameter 

Operating pressure (kPa) 

Mm inches x 60 x 70 

1,59 

1 / 16 " 

1,98 

5 / 64 " 

2,38 

3 / 32 " 

2,78 

7 / 64 " 

3,18 

1 / 8 " 191 222 

3,57 

9 / 64 " 214 250 

3,97 

5 / 32 " 238 278 

4,37 

11 / 64 " 262 306 

4,76 

3 / 16 " 286 333 

5,16 

13 / 64 " 310 361 

5,56 

15 / 64 " 333 389 

5,95 

15 / 64 " 357 427 

6,35 

1 / 4 " 381 445 


Pressure at sprinklers was measured with a pressure gauge, fitted with a pitot tube (Figure 

12). The point of the pitot tube was held about 2 mm in front of the nozzle opening in the path 

of the jet of water to measure the “vena contracta”. Therefore, the velocity pressure, which 

indicates the pressure head and is equivalent to the total pressure, was measured. 

Figure 12. Pressure measurement with a pitot tube end pressure gauge 

The standpipes were three metres high and the pressure of the sprinklers was measured at a 

height of one metre above the ground, then 2 m (or 20 kPa) was subtracted from the 

pressure registered on the pressure gauge, in order to determine the sprinkler pressure at 

normal operating height. 

The choice of the sprinklers at which measurements were to be taken, was influenced by the 

different pressure zones in a specific irrigation block. In view of the undulating terrain (many 

height differences) in this project the total system was in operation as for normal irrigation 

before the evaluation. According to the ARC (2006) the number of measuring points must be 

representative of the block and the choice depended on the topography of the block, as well 

as the distance from the pump station. As per these recommendations complete 

measurements were taken at distances 0, L/4, L/2, 3L/4 and L on the lateral and at the same 

distance on the sprinkler lines (Figure 13). 


0 L/4 L/2 3L/4 L 

L 

3L/4 

L 

L/2 

Test block 

L/4 

Test emitter 

0 

Hydrant 

Figure 13. Positions of complete sprinkler pressure measures in an irrigation block 

Pressure variation was calculated using equation 8 below and a summary of the all results is 

outlined in table 8. 

P 

P 

max 

P 

ave 

P 

min 

………………………………………….. (8) 

Table 4. Pressure measurement results of the entire area. 

Measuring point Type of sprinkler/nozzle Measured 

nozzle 

diameter 

Measured nozzle 

pressure 

Test block Nozzle 1 RC 140 11/64'' 4.5 220 


Test block Nozzle 3 Rain bird 14070 11/64" nozzle 4.75 200 


Highest lateral - block 3 VYRSA 70 11/64’’ 4.5 200 

Lowest lateral - block 3 Rain bird 14070 11/64" nozzle 4.5 250 

Highest lateral - block 1 RC 140 11/64'' 4.5 350 

Averages 4.3 mm 4.57 mm 83.74% 

According to the SABI norms, pressures in the block may not vary more than 20% of the 

average pressure. Pressure measurement results as indicated by the above table and 

calculated by equation 8 reflect a pressure variation of 83.74% in the evaluated block. The 


highest pressure in this project was recorded in a block closest to the pump house and down 

slope. The reverse is true. 

Sprinkler pressure regulators were not installed in this project and in view of the recorded 

pressure variation; they must be installed urgently as they are required. The project is under 

pressured and sprinklers are as a result performing under capacity. All pressure 

measurements in this project do not conform to any SABI norms except for the first 

measurement of 350kPa. 

Sprinkler nozzle size also directly affected pressure variation within the project. Generally, dirt 

accumulates down-slope and nozzle wear is greatest at that point. As mentioned above, as 

the size of the nozzle increase, pressure required by the sprinkler also increase (table 5). 

From measurement of sprinkler nozzles, identifying the amount of wear (mm), an average of 

5.9% increase in nozzle diameter was recorded. In some blocks 9.5% nozzle wear was 

recorded. The allowed maximum increase of 5% in nozzle area means a 10% increase in 

flow and power demand, which relates to additional operating costs and over-irrigation. The 

ARC therefore recommends sprinkler replacement if wear is greater than 5% and in this 

project this excise must be carried out immediately. 

Nozzle were in this development is hasten by the lack of scour valves; mud and all form of 

debris must pass through sprinkler and this is not acceptable. 

Apart from nozzles, sprinklers, due to old age, are underperforming. Some sprinklers do not 

rotate; some have some parts missing from falling during operations and the rest profusely 

leaking. These require urgent replacement. 

5 . 2 D e l i v e r y t e s t s 

The following delivery tests were conducted: 

5.2.1 S p r i n k l e r d i s c h a r g e 

According to the ARC the difference in discharge in a specific irrigation block may not vary by 

more than 10% from the average discharge, hence this evaluation. The discharge of the 

sprinklers was tested by collecting water into a container of known volume with a hose pipe 

connected to the sprinkler nozzle (Figure 14). A minimum container size of 20 litres is 


ecommended and together with a stopwatch the time it took to fill the container was 

recorded. The open end of the hose pipe was not held under water in the container, but also 

not so high that the water splashed out of the container. 

Figure 14. Measuring of sprinkler discharge 

Measurements were again taken at distances 0, L/4, L/2, 3L/4 and L on the lateral and the 

sprinkler line. The same points where pressure measurements were done were used and by 

taking the time it took to fill the container, the discharge was calculated with the following 

formula and results are shown in table 3. 

q 

e 

= 

average volume water measured in container 

average duration to fill container (sec) 

(litres) 

3600 

1000 

…………… (9) 

m 

3 

/hour 

Where q e = sprinkler discharge [m 3 /h] 

Table 5. Discharge variation calculated from sprinkler discharge field measurements 

Minimum Discharge (m 3 /hr) 1.15 

Maximum Discharge (m 3 /hr) 1.90 

B 


Average Discharge (m 3 /hr) 1.33 

Flow variation (%) 56.46 

Flow variation in this project was 56. 46% and the major contributing factor were found to be 

a combination of sprinkler package variation and insufficient pressure. Almost all sprinklers 

were operating below their recommended discharge of 1.39m3/hr. the effects of nozzle size 

wearing was clearly seen on the 350kPa block. Sprinklers in this block recorded a flow rate of 

1.9m3/hr, way beyond the recommended discharge mentioned above. Generally sprinklers 

ware operating outside their recommended range and this has different effects on different 

sprinklers. 

Below is a table indicating the properties of the different sprinkler packages found on site 

Table 6. Technical properties of sprinklers found on site at 35m operating pressure 

Sprinkler Package Nozzle size Discharge (m3/hr Wetted Radius (m) 

VYRSA 70 11/64’’ 1.36 15.9 

Rain bird 14070 11/64’’ 1.39 14.8 

RC 140 11/64’’ 1.36 15.9 

The evaluation also revealed that a majority of sprinklers are worn out, especially on 

bearings, this affects rotation and trajectory angle responsible for maximising sprinkler throw 

distance. These must be replaced. 

Gross application rate (GAR) 

The gross application rate (GAR) of the sprinkler was thereafter calculated, by means of the 

following formula; 

qe 

GAR 1000 

A ....…………………………………. (10) 

mm/h 

Where; GAR = Gross Application Rate 

A = wetted area (m 2 ) 


The sugar industry design GAR is 4.33mm/hr and the field evaluations revealed a GAR of 

4.0mm/hr. The GAR is a faction of emitter discharge and sprinkler spacing. The low GAR is 

mainly cause by low sprinkler application rates resulting from low operating pressure of the 

system. Another contributing factor is that of sprinkler spacing. As mentioned above, lateral 

spacing ranges from 52m to 112m and draglines from 50 – 100m. With such wide spacing, 

the 18m x 18m sprinkler grid is virtually impossible to execute. Friction losses and flow 

velocity through these long dragline is high, damages to the sprinkler, tripod and dragline are 

high as a result of the associated difficulty in moving the sprinklers under this installation. A 

compendium of problem emanate from such an installation and lateral spacing, hence 

dragline length must be reduced immediately. 

The net irrigation requirement of sugarcane is 5.78 mm per day which must be satisfied by 

irrigation. This irrigation system however can only apply 4.2mm per day. This calculation is 

based on the 8 hour stand time and 7 day cycle adopted by Sukumani Bomake management. 

Under dry periods, with the current irrigation pattern, the peak irrigation requirement can not 

be meet. Various strategies can be implemented in trying to solve this anomaly. 

5 . 3 D i s t r i b u t i o n t e s t s 

The purpose of a sprinkler system is to distribute water evenly over the surface of the soil in 

such a manner that there can be absorption without runoff. Although an absolutely uniform 

application is not possible, it can be approached under field conditions. In evaluating an 

irrigation system it is essential to obtain a measure of the application uniformity. The most 

widely accepted measure of irrigation uniformity is J. E. Christiansen “coefficient of 

uniformity”, which had been developed from a study including more than 300 tests on 

sprinklers (ARC, 2006). 

The Christiansen’s uniformity coefficient (CU) does not provide an indication of how low the 

under-watered portions of irrigation application are, the distribution uniformity (DU) was 

developed to provide a measure of this (Zoldoske and Solomon, 1988). This method sorts all 

data points in the overlap area and ranks them from low to high. The mean value for the 

lowest 25 percent divided by the mean value for the entire region yields the distribution 

uniformity. 


5.3.1 I m p o r t a n c e o f C U a n d D U 

Based on the yield function utilised by Solomon (1990), the relationship between 

Christiansen’s uniformity coefficient (CU) and sugar cane relative yield is shown in Table 7 

The importance of a uniform application is evident when viewing the potential yield of 

sugarcane. 

Table 7. Uniformity yield relationship for sugarcane ( Solomon, 1990) 

Coefficient of uniformity (CU) 

Sugarcane relative yield 

1.00 1.00 

0.95 1.00 

0.90 0.99 

0.85 0.98 

0.80 0.97 

0.75 0.95 

0.70 0.93 

0.65 0.90 

0.60 0.86 

0.55 0.82 

0.50 0.77 

The importance of these values of CU and their corresponding relative yield is that the 

relative crop yield does not vary significantly between CU=80% and CU = 100%. This 

indicates that the South African Irrigation Institute (SABI) standard guideline of 

recommending uniformity indicators greater than 80% as being acceptable is well informed. 

Only when the CU value reduces significantly in value does the yield reduce to unacceptable 

levels. 

The importance of a high DU value can be established when reviewing the centre for 

irrigation Technologies economic research in Table 6. Initial investment costs increase with 

DU, while water and power costs decrease (Solomon, 1988a). Solomon (1988a) utilizes a 

water cost of 1.2 USA cents per cubic meter and a power cost of 8 cents per kilowatt hour. 

The water and power cost savings amount to approximately USA$1.40 per acre per year for 

each percentage point of DU improvement (1 hectare=2.47 acres). This is enough to pay 

back the increased cost of the higher DU. In agricultural areas with higher water costs, the 

savings due to improved efficiencies would be even higher. For this example the lowest 

annual cost coincides with the highest DU value. 


Table 8. Irrigation equipment, water and power costs for a range of distribution 

uniformities (Solomon, 1988a) 

Distribution Uniformity 

(DU) 

Initial cost 

$/acre) 

Investment 

($/acre/yr) 

Power 

($/acre/yr) 

Water 

($/acre/yr) 

Total 

($/acre/yr) 

94% 809 129.26 19.34 36.23 184.83 

92% 798 127.52 20.73 37.01 185.26 

90% 800 127.88 22.89 37.84 188.61 

88% 795 127.06 23.91 36.69 189.66 

86% 788 125.98 25.76 39.59 191.33 

84% 780 124.66 27.84 40.54 193.04 

82% 775 123.77 30.14 41.53 195.44 

80% 774 123.63 32.59 42.56 198.78 

Many farmers and designers are under the impression that to decrease the DU to very high 

uniformity levels the increased initial investment cost of a system will be inhibitive. Table 8, 

however, shows that an increased initial investment cost, with time, is compensated for by 

reduced power and water costs. This table suggests that achieving a high DU is justifiable, 

now only in engineering terms, but in financial terms. 


5.3.2 C h r i s t i a n s e n ’ s u n i f o r m i t y c o e f f i c i e n t ( C U ) : 

The CU was determined by placing 36 rain gauges on a grid between two adjacent lines and 

sprinklers. The semi-permanent irrigation systems had a design spacing of 18 x 18m. The 36 

catch cans were placed so that each catch can covers an area of 3 x 3 m in the block and 

were placed 1.5m from the boundary lines of the block (Figure 15). 

1.5m 

18.0m 

3.0m 

1.5m 

1.5m 

3.0m 

Rain gauges 

3.0m 

3.0m 

18.0m 

3.0m 

3.0m 

1.5m 

Sprinkler position 

Test block 

Figure 15. Rain gauge set-up at a sprinkler system to measure the distribution 

This evaluation was conducted on blocks where vegetation could not influence the water 

distribution in the rain gauges, recently harvested blocks were preferred. The system was 

switched on for one hour, during which water was collected by rain gauges. A one hour test 

was adopted because according to ARC (2006) when four sprinklers, one at each corner of 

the block were evaluated, one hour duration is recommended. 


Figure 16.Rain gauge set-up in practice to measure the distribution 

As mentioned, climatic factors especially wind has an important influence on the distribution 

of water and wind velocity measurements, as well as the wind direction were taken at the 

beginning, in the middle and end of the test. The wind velocities were measured at least two 

metres above the ground and not further than 200 metres from the test set-up. If high wind 

speeds (2 m/s) prevailed during the evaluation, it was indicated in the results, as it had 

influence on the distribution of the water. The test was not be performed when the wind 

speed exceeded 5.0 m/s. Climatic information gathered during the evaluation is summarised 

is table 9 below. 

Table 9.Climatic information 

Block no. 

B 

Average wind velocity 1.1 

Temperature 28.8 

Relative Humidity 68 

After completion of the test, the readings in the meters were taken. The meters were kept 

upright and the bottom of the meniscus read. The CU-value was calculated by means of the 

following formula and the results shown in figure 17: 


CU 

100 

1 

x 

i 

xn 

x 

…………………………………….. (11) 

Where: 

CU = Christiansen's uniformity coefficient (%) 

x = average application (mm) 

n = number of measuring points or rain gauges 

x i 

n 

x i = application depth at point i as collected in the meter (mm). 

Figure 17 below indicates a simple plot of emitter discharge data, as collected during the 

evaluated of block 3 

Figure 17. Application per rain gauge 


The CU-value as measured in the field and calculated using equation 10 above is an 

unacceptable value of 76.4%. 3.6% deviation from the accepted minimum of 80% 

(Koegelenberg et al., 1996). Reasons of this unacceptable value as identical to the once 

mention in ealiar sections. 

5.3.3 D i s t r i b u t i o n u n i f o r m i t y ( D U ): 

The water distribution uniformity (DU) value was also calculated using equation 13 from the 

distribution data collected above. 

Averageapplication ( lowest 25%) x25 

DU lq 

100 100……………….. (12) 

Averageapplication ( total system) 

x 

A DU value of less than 60% is unacceptable and a value of more than 75% is recommended 

(Keller and Bliesner, 1990). A DU of 64.1% was obtained and is above the unacceptable 

60%. This, together with the CU value obtained, implies that the system is operating 

adequately but not excellent. There is still room for improvement. 

A low mean DU indicates the influence of critical points in the irrigation application block and 

could further be investigated by scheduling coefficient. One low application many benefit from 

an adjacent large application and the effect of a low DU could be significantly reduced. 

The relationship of the uniformity indicators to the specific climatic parameters cannot easily 

be established due to the continually varying weather, which is a function of several variables. 

Controlled conditions or a computer programme, where variables can be changed 

independently, would facilitate this. Literature has been reviewed and the influence of wind 

velocity on the performance of sprinkler systems is paramount. 


5.3.4 A p p l i c a t i o n e f f i c i e n c y ( A E ) : 

Various efficiencies of an irrigation system can be determined during an evaluation. This 

includes the efficiency of the distribution system which takes water from the source to the 

irrigation system, the irrigation system itself, the water delivered by the sprinkler and that 

which eventually reaches the root zone of the plant. The efficiency that is however of 

importance when sprinkler operation is evaluated, is the application efficiency (ARC, 2006). 

AE is the ratio between the amount of water that leaves the sprinkler nozzle and the amount 

of water that eventually falls on the soils, infiltrates the soil and is available for the plant. The 

application efficiency was also calculated from the distribution data and is shown in figure 35 

above. The purpose was to determine the loss of water as a result of evaporation and wind. 

The application efficiency was calculated by means of the following two formulas: 

AE 

x 

GAR 

100 

………………………………………. (13) 

Where: AE = application efficiency (%) 

x 

= average depth irrigation water applied (mm) 

GAR = theoretical gross sprinkler application rate (mm/h) 

6.9% losses were experienced between emitter and the ground surface. This therefore 

means an AE of 93.1%. For sprinkler irrigation the recommended minimum design application 

efficiency is 70%. Wind velocities during the evaluation of this block were lower than 2m/s. 

An important point to take note of is that if the CU-value of one evaluated system is higher 

than that of another system, the former is not necessarily the best system. The CU-value 

must be considered together with the application efficiency, in order to make a conclusion 

about the distribution of the system and/or to make a sprinkler choice. Various factors, such 

as leakages, vertical alignment of stand pipes and filter blockage, had an influence on the 

CU-value of a sprinkler system. 


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 T 

A 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 N 

S Y S T E M 

6 . 1 O p e r a t i o n 

The fact that no design or installation information is available places a huge constraint on 

management. Forward planning on aspects related to the irrigation infrastructure can not be 

done, i.e. replacement stock; item like pipes, fittings, etc are purchased after breakages 

because the details of that particular pipe, fitting, etc is obtained from the broken part. This 

increases their down time and negatively impacts crop production. 

The different components forming the irrigation system require different operating procedures 

and these are obtained from an operation and maintenance manual. This document, like all 

other documents, is not available and for efficient performance of these components, it must 

be compiled. The consequence of not having this document was seen during this evaluation 

in that incorrect sequences were followed in opening and closing the pump. 

Of essence in this irrigation development is that the current farm manager requires urgently, 

training in sugarcane agriculture and irrigation. He has limited information not only on 

sugarcane production but also on the bases of irrigation. He is highly experience and 

equipped with indigenous knowledge and based on the status of the farm, this is not enough. 

6 . 2 M a n a g e m e n t P r a c t i c e s 

Scheduling 

Effective scheduling ensures that the correct amount of water is applied at the right time and 

the correct place. Irrigation scheduling was not practiced. Instead an 8 hr stand time, and a 7 

day cycle was adopted. The two shifts per day implemented indicate the lack of either 

information or commitment by management into the project. They have a18 hour working day 

starting at 0600hrs to 2200hrs; at this time the system is switched off. 


6 . 3 M a i n t e n a n c e S u r v e y 

When the impact of maintenance practices was evaluated, it was decided to classify the 

existing maintenance practices followed by the producer, according to existing literature 

sources as acceptable if it will not influence the performance of the system adversely and 

unacceptable/ineligible if it will impair the performance. The acceptable values are viewed as 

the absolute minimum values for the sustaining of an acceptable Us value in the system 

Table 10. Maintenance schedule for sprinkler irrigation systems 

Inspect the system for leakages 

Monitor With each cycle Annually 

Check system pressure and system flow 

Service air valves and hydrants 

Check sprinklers for wear and replace springs, 

washers and nozzles where necessary 

X 

X 

X 

X 

Flush mainlines 

X 

Table 11. Maintenance practices implemented by FA 

Monitor Results Classification 

Inspect the system for leakages Attend to leaks only Unacceptable 

Check system pressure and system flow Never Unacceptable 

Service air valves and hydrants Never Unacceptable 

Check sprinklers for wear and replace springs, 

washers and nozzles where necessary 

Never 

Unacceptable 

Flush mainlines Never Acceptable 

The following is a list of items that require urgent maintenance 

Intake sump require urgent attention 

Pump and mechanical control valve 

Installation of vacuum gauge and one pressure gauge before the control valve 

Replace all damaged and hardened gaskets 

Replace all worn male and female pipe fittings 


Attend to leakages in air valves and hydrants 

Replace all draglines that have more than three joints 

Drill correctly sized saddle holes for lateral off takes 

Replace leaking and corroded hydromatics, pipelets, and sprinkler stands 

Replace plastic with brass, correctly sized and identical nozzles 

Replace old and worn out sprinklers with the correct type of sprinkler 

Fix malfunctioning scour valves 

Observations 

The following photo gallery is a presentation of failure by management to attend to defects on 

the system. Irrigation efficiency is substantially reduced as a result of this negligence. 


7 C O N S T R A I N T S T O E F F I C I E N T S Y S T E M 

P E R F O R M A N C E 

PUMPS 

River pump station: 

‣ Suction pipe flow velocity for the pump exceeded the 1,5m/sec maximum allowed in norms 

- causing pump cavitations hence frequent wearing of impellers and high maintenance 

cost. 

‣ Radius of 90º bend radius was too small and the eccentric reducer had a short length that 

required. These increased secondary friction loses, causing pump cavitation hence 

frequent wearing of impellers, high maintenance cost. 

‣ The sump in the river was in a bad shape and need attention. 

‣ The installation of this pump does not meet NPSH and flow velocity requirement and this 

must be rectified urgently. 

MAIN LINE 

‣ Diagnosis of over designing could not be evaluated because accurate dimension of each 

pipe size utilized could not be obtained. 

‣ Only one air valve was installed and in view of the undulating terrain, at least 3 extra air 

valves are required 

‣ Some draglines are connected directly on the mainline through and this is not acceptable 

SPRINKLER INFIELD IRRIGATION 

‣ Pressure control valves at the beginning of the laterals were malfunctioning and some 

laterals did not have hydraulic pressure control valves. 

‣ Pressure and flow variation exceed recommended maximum of 10 and 20% respectively 

‣ Sprinklers were working under pressure. 

‣ Sprinkler nozzle wear is up to 9.5% 

‣ CU, DU, and AE are within acceptable ranges 

‣ Due to the adopted irrigation pattern, the system can not meet peak crop requirements 

‣ Laterals were space 112m apart and some draglines are 100m long. This place a 

constraint on moving sprinklers hence the reduced efficiency. 


OVERALL MANAGEMENT AND MAINTENANCE 

Management 

‣ The farm manager require urgent training on sugarcane agriculture and irrigation practice 

for the success of the farm 

‣ No scheduling measurements were followed 

‣ Theft of irrigation equipment becoming a challenge to management 

Maintenance 

‣ Companies used to service pump and outlets used for replacement stock are reliable 

‣ Without an operation and maintenance manual, management have difficulty in managing 

the system. 

‣ Old equipment reduces efficiency of system. This equipment includes hydromatics, 

draglines, tripod stands, sprinkler and nozzles. The most economic decision would be to 

replace this equipment instead of maintenance. 


8 R E C O M M E N D A T I O N S 

To evaluate the constraints of the project properly we have decided to categorised the 

recommendations in four categories namely 

A. Immediately: This has to been done direct after harvesting. 

B. Short term: This has to been done this season 

C. Medium term: This has to been done before replant 

D. Long term: This has to be rectified with replant. 

PUMP 

Immediately: 

‣ Clean the sump area and lower the pumps suction. E 30 000.00 

Medium term: 

‣ Replace the river pump stations suction pipes with the proper size. E 35 000.00 

‣ Replace the bends, eccentric reducer, and concentric reducer connected on the suction 

and delivery manifold of the pump with correctly dimensioned fittings E 10 000.00 

‣ Construct a proper intake sump E 150 000.00 

MAIN DISTRIBUTION LINE 

Immediately: 

‣ Install three additional air valves in mainline E 7 500.00 

‣ Fix all leaking Air valves and control valves. E 2 500.00 

Short term: 

‣ Do routine maintenance on all equipment. E 2 500.00 


SPRINKLER INFIELD IRRIGATION 

Immediately: 

‣ Fix all control valves at beginning of blocks. E 10 000.00 

‣ Create open drains in waterlogged areas. 400m x E 30 / m E 12 000.00 

‣ Install hydraulic valves in all lateral hydrants E 20 000.00 

‣ Adopted a proper scheduling strategy. 

Short term: 

‣ Install pressure regulators on all sprinklers E 4 000.00 

‣ Fix all damaged sprinkler stands. E 5 000.00 

‣ Replaced all stolen sprinklers and those not correct E 5 000.00 

Long term: 

‣ Replant the areas that perform badly. 

‣ Install proper sub-surface drainage. 10Ha x E 8500 E 85 000.00 

‣ Re install the laterals at a correct spacing or change irrigation system from dragline to 

semi permanent 

OVERALL MANAGEMENT AND MAINTENANCE 

Management 

‣ Adopted a proper scheduling strategy. 

‣ Adopt proper theft prevention strategy 

Maintenance 

‣ Compilation of an operation and maintenance manual to assist in the implementation of a 

proper operation and maintenance strategy for the association. 

‣ Replace all old equipment 


9 C O N C L U S I O N 

River Pump Station 

The sump in the river was too shallow for the foot valve and a vortex kept forming during 

pumping this need urgent fixing. Because there is no proper intake sump, the cleaning of 

the suction area must be done frequently to avoid mud accumulation. This exercise is 

labour intensive; a proper sump must therefore be constructed and will cost around 

E150 000.00 

The installation of this pump does not meet NPSH and flow velocity requirement and this 

must be rectified urgently. There are various ways of solving this discrepancy and 

increasing the suction manifold from 150 to 200 is the most economical strategy. This 

will cost roughly E 35 000.00 

The incorrectly dimensioned eccentric reducer installed on the suction manifold of the 

pump could cause damage to the pump on the long term. To refurbish this and all other 

fittings will cost approximately E10 000.00 

Main Distribution Line 

Diagnosis of over designing could not be accurate because dimension of each pipe size 

utilized could not be obtained. The hydraulic pressure control valves at the beginning of 

each lateral was not functioning correctly which allow the sprinklers to operate outside 

there design pressure. On some blocks this was worse in that hydraulic valves were not 

installed in some laterals. Pipe brakeage was recurrent until the installation of an air 

valve, in view of the undulating terrain, three additional air valves must be installed in 

this system. 

Infield Sprinkler Irrigation 

The lateral spacing ranged from 100 – 112m and draglines of 20mm diameter ranged 

from 50 – 100m. The long draglines are difficult to move during operations and this leads 

to a reduced accuracy in maintaining the 18m x 18m. 


Pressure and flow variation are above recommended maximums and this irrigation 

system does not meet peak crop requirement. This is caused by the incorrect irrigation 

pattern adopted by management. The 8hrs stand time and 6 day cycle result to a NAR of 

5.3mm/day vs. peak irrigation requirements of 5.78mm/day. The 5.78mm/day does not 

account for rainfall; therefore, the measured NAR might be sufficient in this regard. CU, 

DU and AE are within acceptable ranges. 

Apart from fixing all leakages in the blocks and replacing stolen equipment, identical 

sprinkler packages must replace all alien sprinklers. The cost of this exercise will be 

approximately E20 000.00. 

Management: 

The farm manager of this project requires training in sugarcane agriculture and irrigation. 

He has limited information not only on sugarcane production but also on basic irrigation. 

He is highly experience and equipped with indigenous knowledge and, based on the 

status of the farm, this is not enough for increasing productivity. 

In view of the seriousness of theft in this farm, an effective theft prevention strategy will 

have to be crafted and implemented before the replacement of old equipment. 


10 L I T E R A T U R E R E F E R E N C E S 

1. ARC- Institute for Agricultural Engineering,1998. In-field Evaluations of the 

Performance of two Types of Irrigation Emitters executed on behalf of the water 

Research Commission. Water Research Commission, Republic of South Africa. 

2. ASAE Standards. 1997. Field evaluation of micro-irrigation systems, ASAE EP458. 

3. ASAE Standards. 1998. Design and installation of micro-irrigation systems, ASAE EP 

405.1 

4. Burt, C.M. & Styles S.W. 1994. Drip and micro-irrigation for Trees, Vines, and Row 

Crops. Irrigation Training and Research Centre (ITRC). USA. 

5. Keller, J, and Bliesner, RD. 1990. Set Sprinkler Uniformity and Efficiency Sprinkle and 

Trickle Irrigation. Chapman and Hall, New York. 

6. Koegelenberg, F. H. & others. 1996. Irrigation Design Manual. Agricultural Research 

Council - Institute for Agricultural Engineering. RSA. 

7. Koegelenberg, F. H. 2002. Norms for the design of irrigation systems. Agricultural 

Research Council - Institute for Agricultural Engineering. RSA. 

8. Reinders, F.B. 1986. Evaluation of irrigation systems. Directorate of Agricultural 

Engineering and Water provision. RSA. 

9. Reinders, F.B. 1996. Irrigation Systems: Evaluation and Maintenance. SA Irrigation, 

Vol. 5-7. 

10. Scott, K. 1997. Designing with Sprinklers. Unpublished literature. ARC- institute For 

Agricultural Engineering. Silverton, Republic of South Africa. 

11. Scott, K. 1998. The effects of wind in sprinkler irrigation. ARC- Institute for Agricultural 

Engineering. Republic of South Africa. 


12. Solomon K.H. 1988a, Irrigation Systems and Water Application Efficiencies. Centre 

for Irrigation Technology, California State University, Fresno, California. 

13. Solomon K.H. 1988b.A new way to view Sprinkler pattern, Center for irrigation 

Technology, California State University, Fresno, California. 

14. Solomon, K.H. 1990. Sprinkler Irrigation Uniformity, center for irrigation Technology, 

California State University, Fresno,California. 

15. Solomon, KH Zoldoske, DF and Oliphant, JC. 1996. Laser Optical Measurement of 

Sprinkler Droplet Sizes. Center for irrigation Technology, California State University, 

Fresno, California. 

16. SSA.2001. Sugar Production Manual. Swaziland Sugar Association. Mbabane 

17. Zoldoske, D.F. and Solomon, K.H. 1988. Coefficient of Uniformity- What it tells us. 

Center for irrigation Technology, California State University, Fresno, California. 


11 P R O D U C T I N F O R M A T I O N 

River pumps technical details; 


Sprinkler equipment specifications from the manufacture 





Soils classification according to SSA 



12 A P P E N D I C E S 

Attached are the following documents 

Appendix 1: SEB usage for river pump station phase 2 

Appendix 2: capital recovery factors (CRF) 

Appendix 3: soil map and block layout 


SEB usage for Main pump 

station 

Annual Water 

Water requirement use 14000m³/Year 28 Ha Total water use in year 392000 m³/Year 

Months Jan Feb Mar Apr May Jun Jul Aug Sep Okt Nov Des 

% use per month 8.1 7.7 9.88 9.09 8.79 4.96 2.86 5.43 9.18 11.5 11.95 10.56 

Watter use per month 

main 31752 30184 

38729. 

6 35632.8 34456.8 19443.2 11211.2 21285.6 35985.6 45080 46844 41395.2 

Water use per hour 44 42 54 49 48 27 16 30 50 63 65 57 

Main pumps Needed 0.5 0.5 0.6 0.6 0.6 0.3 0.2 0.4 0.6 0.7 0.8 0.7 

River Pumps practical 1 1 1 1 1 1 1 1 1 1 1 1 

kW use for Main Pump 27.1 27.1 27.1 27.1 27.1 27.1 27.1 27.1 27.1 27.1 27.1 27.1 

Total kVa Demand 54.2 54.2 54.2 54.2 54.2 54.2 54.2 54.2 54.2 54.2 54.2 54.2 

Total kw use for the 

month 

10243. 

8 

9737.9 

3 

12494. 

9 

11495.8 

2 

11116.4 

2 

6272.74 

7 

3616.94 

7 6867.14 

11609.6 

4 

14543.66 

7 

15112.7 

7 

13354.8 

8 

Total Max. Demand 

costs 

3762.5 

6 

3762.5 

6 

3762.5 

6 

3762.56 

4 

3762.56 

4 

3762.56 

4 

3762.56 

4 

3762.56 

4 

3762.56 

4 3762.564 

3762.56 

4 

3762.56 

4 

Total kW cost 

2253.6 

4 

2142.3 

5 

2748.8 

8 2529.08 2445.61 1380.00 795.73 1510.77 2554.12 3199.61 3324.81 2938.07 

Total Energy Cost / 

month 6016.2 

5904.9 

1 

6511.4 

4 

6291.64 

4 

6208.17 

6 

5142.56 

8 

4558.29 

2 

5273.33 

5 

6316.68 

5 

6962.170 

7 

7087.37 

3 

6700.63 

8 

72973.4 

3 


Appendix 2: capital recovery factors (CRF) 

CAPITAL RECOVERY FACTORS (CRF) 

Interest Rates 

Years 

% 2 3 4 5 6 7 8 9 10 15 20 

5 0.538 0.367 0.282 0.231 0.197 0.173 0.155 0.141 0.130 0.096 0.080 

6 0.545 0.374 0.289 0.237 0.203 0.179 0.161 0.147 0.136 0.103 0.087 

7 0.553 0.381 0.295 0.244 0.210 0.186 0.167 0.153 0.142 0.110 0.094 

8 0.561 0.388 0.302 0.250 0.216 0.192 0.174 0.160 0.149 0.117 0.102 

9 0.568 0.395 0.309 0.257 0.223 0.199 0.181 0.167 0.156 0.124 0.110 

10 0.576 0.402 0.315 0.264 0.230 0.205 0.187 0.174 0.163 0.131 0.117 

11 0.584 0.409 0.322 0.271 0.236 0.212 0.194 0.181 0.170 0.139 0.126 

12 0.592 0.416 0.329 0.277 0.243 0.219 0.201 0.188 0.177 0.147 0.134 

13 0.599 0.424 0.336 0.284 0.250 0.226 0.208 0.195 0.184 0.155 0.142 

14 0.607 0.431 0.343 0.291 0.257 0.233 0.216 0.202 0.192 0.163 0.151 

15 0.615 0.438 0.350 0.298 0.264 0.240 0.223 0.210 0.199 0.171 0.160

sukumani bomake FA Report - Swaziland

Create successful ePaper yourself

Delete template?

Save as template?