MUCHIRI JOSPHINE MUTHONI F21/2528/2009 Supervisor : Dr. J.P. Obiero

1. DESIGN OF AN INTEGRATED CENTRE PIVOT IRRIGATION SYSTEM A case study of 100ha in Hola area in Tana River county UNIVERSITY OF NAIROBIDEPARTMENT OF ENVIRONMENTAL AND BIOSYSTEMS ENGINEERINGFEB 540: DESIGN PROJECT2013/2014 ACADEMIC YEAR MUCHIRI JOSPHINE MUTHONI F21/2528/2009 Supervisor : Dr. J.P. Obiero

2. BACKGROUND Did you know that irrigation would help utilize the potentials of arid and semi arid areas in Kenya • development of irrigated agriculture became inevitable due to rapid increase of the country’s population since the 1950s • 80% of Kenya’s land area is arid or semi-arid • Government has further stressed the importance of promoting irrigation development in the Vision 2030 for the period 2008 – 2030 so as to stabilize and improve food supply through optimum utilization of available land and water resources • conception of Bura Irrigation and Hola Settlement Project in production of cotton and maize from 1982 to 1990 with an area of 2,500 hectares being irrigated. • Tana River is considered as the major surface water source of irrigation which is considered as the important means to increase agricultural production and population intensity in the area.

3. background • Need to intensify land use in the high and medium potential areas and bring to use arid and semi-arid lands. Irrigation offers one of the best strategies in realizing these objectives • Kenya has an irrigation potential of 1.3 million hectares.-Out of this, 540,000 hectares can be developed with the available water resource, while the remaining 800,000 hectares will require water harvesting and storage equivalent to about 25 billion m³. • Currently, 114,600 hectares and 30,000 hectares are under irrigation and drainage. This translates into 21% and 5% of the existing irrigation and drainage potential respectively. However, the area under irrigation is a mere 9% of the total irrigation potential of 1.3 million hectares. • irrigation expansion may be predicted to go up as a measure to adapt to climate change, achieve food security and save for investments • irrigation expansion may be predicted to go up as a measure to adapt to climate change, achieve food security and save for investments • zones known for coffee production, bananas, maize, and many types of vegetables, legumes and fruits. Tana and Athi River, EwasoNgiro and Kerio Valley basins are in these locations

4. PROBLEM STATEMENT AND PROBEM ANALYSIS • weather patterns -erratic with no rain fed production being realized with rains falling below average-increased household poverty and lack of livelihood and income. • Flooding, soil erosion, high runoff, the need for an improved irrigation technologies that will enhance efficient use and application of water due to the high evaporation rate and runoff. Reduce social comfits between the nomadic and agricultural farmers • huge potential to exploit in terms of coverage and expansion for large scale. The land is generally very flat, thus suited for canals, sprinkler, drip, Centre pivot ,this project is expected to actualize this potential and boost food productivity in the area • Need to exploit the potential of the arid and semi arid areas of Kenya inline with the vision 2030 of Kenya.

5. SITE ANALYSIS Hola Area Tana river county

6. Site analysis • Hola is a small town in Kenya on the Tana River at 40.030E and 1.50 0S • The county has a population of 240,075,Hola with a population of 6932 , Nomadic and agricultural farmers • The terrain is mainly undulating with few hills and the land slopes gently south-eastwards from 200m in the highest hills to the coastal line • Unreliable rainfall<750mm, Precipitation is low, bimodal and quite erratic, fluctuating between 300mm to 500mm annually. • Temperatures are warm and exceed 28.80C throughout the year, with an average of 27.9°C • The area is mainly covered with open bush and rather dense shrub vegetation, Mathenge”. Currently, this is the dominant vegetation in the

7. OBJECTIVESThe overall objective is to design an automated Centre Pivot irrigation system • Specific objectives • The specific objectives of the project are: • To identify the crop water requirements and irrigation parameters • Use the parameters in (1) above in design the system components of the Centre pivot irrigation system which are the pumping system, pipe work, water sump, pump houses, Hydrants, and pivot. • Analyze the cost benefit effectiveness of the various energy sources

8. SCOPE OF WORK • The scope of this project was on the design of Centre pivot irrigation system located in HolaTana River County. • The design involved the determination of the field layout, • estimation of the crop water requirements to schedule the system, • conveyance of the water to the field, • determination of the power requirements cost estimates of the system. • Carry out design process showing the components of the Centre pivot irrigation system • Do accost benefit analysis of the system comparing solar system to a diesel engine system. • Limitation of my scope is large scale farmers of about 50ha to 100 ha of land or groups of farmers with large schemes.

9. LITERATURE REVIEW • Irrigation is an artificial application of water to the soil • Appropriate Technology: Technology that is socially acceptable (SA), economically viable (EV) and technically feasible (TF) • Factors considered: water , soil, topography, climate, energy cost, crop, labour, capital cost, personal considerations • Irrigation systems: drip, furrow, travelling gun system • History of centre pivot system, justification, advantages • Components of the irrigation system: The water source, The intake facility, The conveyance system, The piping system

10. Literature • Purpose for irrigation: Increase area under the crop to enable crop to be grow where natural rainfall is too low to grow normal crops, Provide additional water to optimize crop production, Weed control and Enable crops out of season production • Factors considered in the selection of irrigation methods: Natural conditions, type of crop, type of technology, previous experience with irrigation, required labour inputs, costs and benefits • Potential of the area

11. Literature review cont’d Advantages of center pivot • Well suited for irrigating larger and small areas, • Precise application of water, • Low maintenance and labor costs, • Financially viable even on such small areas. • Easily automated, • Accurate water distribution at low pressure, • No blockages as compared to drip irrigation. • Pests are washed out hence low use of chemicals. • 20 years lifespan with low maintenance, basically requiring routine checks • Centre pivot increases water efficiency by some 85-95 percent, according to The Groundwater Foundation.

12. METHODOLOGY • Collection of agro-climatic data, included. • Identification of irrigation land • Collection of meteorological data, i.e. temperature and rainfall • Identification of water resource • Collection of agricultural data, i.e. crop varieties, seeds, diseases and pests, post-harvest practices, cropping patterns and cultivation practices Preliminary site visit and survey work was done • Inspection of Hola site • Study of the vegetation • Study of suitable crops in the area • Assessment of the infrastructure • Soil and water sampling and testing was done

13. Methodology cont'd • Primary data was collected by the use of formal and informal survey methods. • Formal surveys with the help of direct interviewing of relevant local members. • Discussion was with key informants • The current situation on the ground was assessed through Observation • The design was carried out showing: Centre pivot system , the mainline size and outlet spacing, length, including the number of towers, drive mechanisms, application rate of the pivot. • The market survey was done showing the cost effectiveness, durability and reliable materials/ equipment’s appropriate for the energy source mainly solar, diesel and electricity. • Analyze demerits of each of the options and make recommendations on the most suitable option: cost benefit analysis of the energy system was compared.

14. METHODOLOGY Data collection Primary &secondary Determine system parameters Analysis of Soil infiltration rates Pipe sizing Flow requirements of the system Speed and working hours of pivot Selecting pump, requirements and performance chart Sizing solar panel Power rating

15. PRODUCT DESIGN

16. Design process cont'd • Crops selected were maize, sorghum, cotton and groundnuts

17. Product Design • CROP WATER REQUIREMENT ETC:ETcrop = kc x Eto x Kr ETC = 5.53 x 1.2 x 1.0 = 6.636mm/day • DEPTH OF APPLICATION : dnet= (FC-PWP) x RZD x P dnet= (140mm/m) x 0.53x 0.5=37.1mm • VOLUME OF WATER TO BE APPLIED (m3) = 10 x A x d Volume of water to be applied (m3) = 10 x 100ha x 37.1mm=37100m3 • IRRIGATION FREQUENCY (IF) = 37.1mm/6.00mm/day=6.183days, Irrigation frequency(IF)=6days • DEPTH OF APPLICATION: dgross=dnet /E dgross = 37.1/0.70 = 53mm

18. design • SYSTEM CAPACITY: Q = 10 x A x dgross/ (I x Ns x T) CP2: Q = 10 x 60.77 x 53mm/ (7 x 2 x 10) =230.05m3/hr CP7 : Q = 10 x 38.79 x 53mm/(7 x 2 x 10)=146.85m3/hr • Net irrigation requirement: NIR = ETC – Pe- Ge- Wb (mm/day) NIR = 6.0 -0=6.0 m/day • Irrigation efficiencies: Ep = Ec x Ea x Ed 0.95 x 0.95x 0.90 =0.81225% • Gross irrigation requirement: GIR = NIR/E GIR = 6.0/0.81225=7.387mm/day • Actual scheme water requirements: Qwr= 10 x A x GIR x () x () (m3/day) =10 x 7.387x 100x 24/20x7/6 = 10341.644m3/day

19. design • Field Irrigation rate: Etc. = 6.0 mm, Number of days = 7 days, Number of shifts per week = 6 irrigation application rate will be; = 6.0 x 7/6 = 7mm • Factoring in the irrigation efficiency of 0.81225%, then the gross application rate will be; =7.0/0.81225 = 8.6180mm • CP2, Considering the efficiency of the system of 81.225% 0.37709m3/hr X 0.7695=0.3063 m3/hr since 1 hr=0.3063 m3/hr. To get 6.0m3/day then ==19.59hrs=20hrs • CP7, Considering the efficiency of the system of 81.225% 0.377645m3/hr X 0.7695=0.3067m3/hr since 1 hr=0.3067 m3/hr To get 6.0 m3/day then ==19.56=20hrs • The system will operate for 20 hours for 6 days. This is to allow for one day servicing of the system.

20. COMPONENTS DESIGN • POWER REQUIREMENTS IN KW =Q x H/360 x e CP7: 146.85*28/(360*.75)=15.23kW CP2: 230.05*35/(360*0.75)=29.82kW • Choosing from lowara pumps we get A pump of FHE-FHS-FHF SERIES OF 80-160/150 with 15kW and 20 HP A pump of FHE-FHS-FHF SERIES OF 100-200/370 with 37kW and 50 HP Selection of nozzles Precipitation =Dischrge/area of coverage Area irrigated 254.469-78.54=175.929m2 Precipitation=8.6180mm in 20hrs 8.6180 =discharge/175.929=676.856/20hrs=1.516m3 /hr

21. Design of the mainline • The size of mainline is determined by: Required flow rate through the pipe, Overall length of line, Static height, Flow velocity, Factor of safety • the following factors should be kept in mind: Maximum permissible velocity should be 1.8 m per second not exceeding 2.5m per second based on hydrocalc software. • Maximum friction losses should be limited to 50 m per 1000 meters of pipe • Elevation and pipe pressure rating: minimize high pressure rated pipes on elevated grounds and vice versa. • Mainlines should follow the shortest possible route • Provide air release, vacuum valves, non-return valves, pressure reducing and pressure sustaining valves at the correct positions. • The size determines the initial cost • The length of the mainline = 900m, The total flow = 228 m3, The pipe size = 200mm PVC Class PN6, The pipe loss = 6.36m (0.74%) • The length of the mainline = 1000m, The total flow = 146 m3/hr, The pipe size = 200mm PVC Class PN6, The pipe loss = 5.16m

22. Summary of the Centre Pivot Details • The system was designed to deliver a gross application of 8mm/day • the other crop require less water applications hence the speed is adjusted to provide that requirements. • The irrigation schedule is to irrigate three days a week, if you irrigate on Monday with 8mm/day then on Tuesday the Etc of the crop is 5mm/day hence a reminder of 3mm/day, then irrigate on Wednesday 8mm/day having a total of 11mm/day, the Etc on Thursday and Friday will be 10mm, hence the need to irrigate again on Saturday with 8mm/day and no irrigation on Sunday

23. CONCLUSION • The irrigation design is successful if managed to meet the crop water requirements since the system is installed on soils having infiltration rates matching or exceeding the system application rate • The design of the centre pivot irrigation system meets the general design criteria for irrigation systems. • The site so selected for its location is ideal as it offers suitable area for expanding large scale irrigation system. • The operation of the centre pivot has less expenditure in terms of cost since it only require greasing and repair unlike other systems the operators has to be ever present. • This system consumes a lot of power and the best source selected properly to cover the economies of scale. Solar energy has a high initial capital cost but long life time hence the maintenance cost are therefore less. The diesel engine has lost capital cost and maybe preferred but the maintenance cost is very high as shown in the calculations. • The operation is fairly trouble free on level lands and uniform sloping lands with slopes up to 10%.Undulating topography usually produce more difficulties with more potential runoff.

24. RECOMMENDATON • The construction of the proposed reservoir for constant water supply to the field • The construction of another gravity canal from Tana river this will give more room for additional projects • More research on the incorporation of solar energy on large scale irrigation components and equipment’s. • On soft or erosive soils, tracks should be lined with sand where excessively deep tracks are made in the field by the drive wheels • In undulating topography to reduce surface runoff, small holes or depressions should be dug to hold water on the application points. • This center pivot moves in a circular motion thus in case of irregular shapes of land the whole area is not irrigated, some patches are left at the ends. Recommend that the structure should be designed with corner catchers that folds out to irrigate these area, thus this areas should be included in the irrigated area.

25. REFERENCES • Simiyu JN, Mwongera CN, Gohole LS and RM Muasya. (2003)Farmers’ knowledge and practices in spider plant (Cleome gynandraL.) seed production: Case study of Kakamega and Vihiga districts. Proceedings of the third workshop on sustainable horticultural production in the tropics, Maseno, Kenya 2003. • Bhattarai, M.; Sakthivadivel, R.; Hussain, I. (2002). Irrigation impacts on income inequality and poverty alleviation: Policy issues and options for improved management of irrigation systems. Colombo, Sri Lanka: IWMI. vi, 29p. (IWMIworking paper 39). • Barron, J., Rockström, J. Gichuki, N. Hatibu. (2003). Dry spell analysis and maize yields for two semi-arid locations in East-Africa. Agriculture and Forest Meteorology 177: 23-27 • Cai, X.,and M. Rosegrant. (2003). World water productivity. In Kijne, J. W.; Barker, R.; Molden. D. (Eds.), Water productivity in agriculture: Limits and opportunities for improvement. Wallingford, UK; Colombo, Sri Lanka: CABI; IWMI. • Matsuno, Y, H. S. Ko; C. H. Tan; R. Barrer; G. Levine.( 2002). Accounting of Agricultural and Nonagricultural Impacts of irrigation and drainage Systems. Working paper 43. . International Water Management Institute: Colombo, Sri Lanka. • Garg, H.P. (1987). Advances in solar energy technology, Volume 3. Reidel Publishing, Boston, MA. Halcrow, S.W. and Partners. 1981. Small-scale solar- powered irrigation pumping systems: technical and economic review • Lemma Dinku. Smallholders’ Irrigation Practices and Issues of Community. Management: The Case of Two Irrigation Systems in Eastern Oromia,Ethiopia. Faculty of Centre Pivot Irrigation System - Hortfresh Journal

26. drawings

27. Pivot drawing

28. ENGINEERING DESIGN

29. DESIGN Cont’d

30. BILL OF QUANTITIES

31. THANK YOU