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A COLLABORATIVE RESEARCH PROJECT BETWEEN NIB AND UON Year II Project Highlights By

ASSESSING AND IMPROVING THE PERFORMANCE OF CONVEYANCE SYSTEMS: CASE STUDIES of AHERO, BURA and MWEA IRRIGATION SCHEMES. A COLLABORATIVE RESEARCH PROJECT BETWEEN NIB AND UON Year II Project Highlights By Gichuki F., Wanjogu R. K., and Okinyi ., M. D. Date: 3 rd July 2014.

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A COLLABORATIVE RESEARCH PROJECT BETWEEN NIB AND UON Year II Project Highlights By

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  1. ASSESSING AND IMPROVING THE PERFORMANCE OF CONVEYANCE SYSTEMS:CASE STUDIES of AHERO, BURA and MWEA IRRIGATION SCHEMES Mwea, Ahero and Bura Irrigation Schemes case studies A COLLABORATIVE RESEARCH PROJECT BETWEEN NIB AND UON Year II Project Highlights By Gichuki F., Wanjogu R. K., and Okinyi., M. D. Date: 3rd July 2014

  2. Presentation outline • Development and research objectives • Project elements and its organization • Year I highlight • Year II Results and their implications • Project outputs

  3. Introduction • Irrigation in Kenya faces serious challenges which have negatively affected the productivity, profitability and sustainability of most irrigation schemes. The following is a partial listing of the main challenges • High pumping costs; • High levels of siltation; unpredictable flooding & drought • High conveyance and application losses; • High mismatch between water demand and supply; • Inadequate drainage of excess water and removal of excess salts; and • Inequity in water delivery in different irrigation blocks and irrigated fields. • Inadequate irrigation skills among farmers and other stakeholders Source: NIB Strategic Plan 2008-2012 MIS, AIS & BIS water loss study-NIB & UON

  4. RATIONALE FOR CONVEYANCE SYSTEM RESEARCH: • Low efficiency (30-70%) of conveyance and distribution system with major implications on: • Scheme water intake sub-system • Operation and maintenance of conveyance sub-system • On-farm sub-system

  5. RATIONALE FOR CONVEYANCE SYSTEM RESEARCH:Implication on water intake subsystem • Irrigation scheme withdraws 30-70% more water than it needs – This increase potential for water use conflicts in dry seasons; • Large intake infrastructure are required resulting in high development costs • High pumping (O&M) costs

  6. RATIONALE FOR CONVEYANCE SYSTEM RESEARCH:Implication on conveyance subsystem • 30-70% more silt brought into the scheme; • Large conveyance infrastructure are required resulting in high development costs • High conveyance (O&M) costs

  7. RATIONALE FOR CONVEYANCE SYSTEM RESEARCH:Implication on on-farm subsystem • 30-70% more silt brought into the fields; • May enhance soil fertility • Will over time raise field levels making it less commandable • 30-70% more salts brought into the field will enhance the rate of salt build up • May enhance drainage problems • High on-farm (O&M) costs

  8. Hypothesis • The main hypothesis of this research is that the performance of water delivery and application sub-systems can significantly be improved-hence irrigated agriculture- by reducing irrigation water loss. AIS & BIS water loss study-NIB & UON

  9. Key issues that will addressed • Assess performance and opportunities and constraints for improving performance; • Identify innovative solutions that will enhance the performance of the water delivery and water application sub-systems; • Evaluate technical performance of the innovative solutions; • Evaluate costs and benefits of performance improvements; • Formulate strategies and plans for performance improvements; • Identify investment priorities; and • Propose financing/ options. AIS & BIS water loss study-NIB & UON

  10. Main deliverables (outputs) • Reports on the status and performance of irrigation subsystems for the past 5 years- from abstraction point thru conveyance to the farm • Report on cause, effect and magnitude of conveyance and distribution losses in MIS, AIS and BIS • Options for reducing irrigation water losses and improving delivery performance including lining options • Information on improving delivery performance will be available to irrigation engineers, managers, farmers and policy makers AIS & BIS water loss study-NIB & UON

  11. Anticipated outcomes and impacts • Enhanced adoption of water saving technologies; • Increased irrigated areas, cropping intensities and crop yields; • Increased yield, production and net benefits; • Increases in farmer contribution to O&M expenses; • Irrigation water savings; • More efficient and productive use of water. • More equitable water allocation among sectors and users; • More reliable yields and production. • Reduced environmental degradation; • Reduced impacts of extreme events, particularly flood and destruction of irrigation infrastructure; • Reduced mismatch between water demand and supply; • Reduced water use conflicts associated with more equitable water distribution; • Yield, production and profit increases; and • Reduced variability in irrigated agricultural production AIS & BIS water loss study-NIB & UON

  12. Objectives Overall goal: • To generate and enhance utilization of data, information and knowledge on irrigation water management in ways that promote innovation and effective and efficient utilization of the resources. AIS & BIS water loss study-NIB & UON

  13. Project Objectives and Main Tasks

  14. Project Objectives and Main Tasks

  15. Project Objectives and Main Tasks

  16. Year 1 Highlights : Ahero system AIS & BIS water loss study-NIB & UON

  17. Year 1 Highlights : Aherosystem AIS & BIS water loss study-NIB & UON

  18. Year 1 Highlights : Burasystem AIS & BIS water loss study-NIB & UON

  19. Year 1 Highlights : Burasystem AIS & BIS water loss study-NIB & UON

  20. Year 1 Highlights : Mweasystem AIS & BIS water loss study-NIB & UON

  21. Year 1 Highlights : Mwea system AIS & BIS water loss study-NIB & UON

  22. Soil Permeability test results AIS & BIS water loss study-NIB & UON

  23. Year II Methodology: Loss assessment • Canal loss mainly comprise of seepage, evapotranspiration (EVT) & leakages • The water balance (inflow/outflow) method used for quantifying canal loss-this will not interrupt irrigation program • Seepage rates measured using inflow/outflow, ponding and seepage meter methods • Calibration and possibly repair of all measuring/regulating canal structures to facilitate flow measurements-critical in this study AIS & BIS water loss study-NIB & UON

  24. Methodology: Loss assessment AIS & BIS water loss study-NIB & UON

  25. Methodology: Loss assessment Ponding method To eliminate the effect of wind, the rate of drop was measured at each end of the pool and averaged. Staff or hook gauges attached to existing structures or stakes driven into the canal bed were used as shown in the figure below. AIS & BIS water loss study-NIB & UON

  26. Preliminary results: Loss assessment AIS & BIS water loss study-NIB & UON

  27. Preliminary results: Loss assessment AIS & BIS water loss study-NIB & UON

  28. Preliminary results: SEEPAGE LOSSES IN UNLINED CANALS -------------------------------------------------------------------------------------------------------------------- Character of material Seepage loss in Cumecs per Million sq. m of wetted perimeter _____________________________________________________________________ Impervious clay Loam 0.90 to 1.20 Medium clay loam under laid with hard pan at depth 1.20 to 1.80 of not over 0.60 to 0.90m below level Ordinary clay loam silt soil 1.80 to 2.70 Gravelly or sandy clay loam, cemented gravel, 2.70 to 3.70 Sand and clay Sandy loam 3.60 to 5.20 Loose sandy soils 5.20 to 6.10 Gravelly to sandy soils 7.00 to 8.80 Porous gravelly soil 8.80 to 10.70 Very gravelly soils 10.70 to 21.30 ___________________________________________________________________

  29. Methodology: Water balance modeling Thiba system linkages AIS & BIS water loss study-NIB & UON

  30. Methodology: Water balance modeling Elements of the water balance model AIS & BIS water loss study-NIB & UON

  31. Preliminary results: Water balance model AIS & BIS water loss study-NIB & UON

  32. Preliminary results: Water balance model AIS & BIS water loss study-NIB & UON

  33. Preliminary results: Water balance model AIS & BIS water loss study-NIB & UON

  34. On-going simulation studies Design, operation and maintenance issues for example what is the effect of changes on cropping calendar and system layout AIS & BIS water loss study-NIB & UON

  35. Preliminarysimulation results - Mwea AIS & BIS water loss study-NIB & UON

  36. Economics of canal lining AIS & BIS water loss study-NIB & UON

  37. Economics of canal lining: Calculation Annual benefits: • (a) Saved seepage water by lining: • Let, the rate of water is sold to the cultivators = c/cumec • If m cumecs of water is saved by lining the canal annually, then the money saved by lining = c. m/yr Saving in maintenance cost: • Let, the average cost of annual upkeep of unlined channel = Cuc • If p is the percentage fraction of the saving achieved in maintenance cost by lining the canal, then the amount saved = pCuc • The total annual benefits = c. m/yr + pCuc

  38. Economics of canal lining: Calculation Annual Costs: • Let, the capital expenditure required on lining is LC and the lining has a life of N years.Annual depreciation charges = LC/N. • Interest of the capital LC = LC(r/100) [r= percent of the rate of annual interest] • Average annual interest = LC/2(r/100) [v Since the capital value of the asset decreasesfrom LC to zero in N years] • The total annual costs of lining = LC/N + LC/2(r/100)

  39. Economics of canal lining: Calculation Benefit/Cost ratio example: Annual Benefits (a) Seepage loss • Seepage loss in unlined canal @3.3 cumec per million sq. m = (3.3/106)* 18,800 cumec/km= 62,040* 10-6cumec/kmFor seepage loss in lined channel at 0.01 cumesc per million square meter of wetted perimeterSeepage loss in unlined canal = (0.01/106)x18,800= 188*10-6cumecs/kmNet saving = (62,040* 10-6 - 188* 10-6) cumec/km = 0.06185 cumec/kmAnnual revenue of water = 35 ksh • Annual revenue saved per km of channel = (0.06185*35) = 216,480. (b) Saving in maintenance • Annual maintenance cost of unlined channel for 10 square meter = 10 • Total wetted perimeter per 1 km length = 18,800 m" • Annual maintenance charge for unlined channel per km = 18,800 • Assume that 40% of this is saved in lined channel • Annual saving in maintenance charges = (0.4* 18,800) = 7,520 • Total annual benefits per km = (216,480 + 7,520) = 224,000

  40. Economics of canal lining: Calculation Benefit/Cost ratio example: Annual Costs • Area of lining per km of channel= 18.5*1000= 18500 m2 • Cost of lining per km of channel @ 1800 per 10 m2= (18500*1800/10) = 3,330,000.Assume, life of lining as 40 years • Depreciation cost per year = (3,330,000/40) = 83250Assume 5% rate of interest • Average annual interest = C/2 (r/100) = 3,330,000/2*(5/100) = 83,250 • Total annual cost = (83,250 + 83,250) = 166,500Benefit cost ratio = Annual benefits/Annual costs = 224,000/166,500 = 1.35Benefit cost ratio is more than unity, and hence, the lining is justified.

  41. Economics of canal lining: Calculation Benefit/Cost ratio example: Benefit cost ratio = Annual benefits/Annual costs = 224,000/166,500 = 1.35Benefit cost ratio is more than unity, and hence, the lining is justified.

  42. List of project outputs • Solving Conveyance and On-farm Water Management Problems • Irrigation Water Research: Priority issues and the potential outcomes and impacts • Benchmarking irrigation performance: Issues, Concepts and Methods • Water Conveyance Study: Ahero Irrigation Scheme Case Study • Water Conveyance Study: BuraIrrigation Scheme Case Study • Water Conveyance Study: Mwea Irrigation Scheme Case Study • AheroIrrigation water loss assessment • Bura Irrigation water loss assessment • MweaIrrigation water loss assessment • Irrigation water measurement: Developing flow rating curves • Ahero Flow Measurement • BuraFlow Measurement • MweaFlow Measurement • A literature review on seepage assessment and remediation AIS & BIS water loss study-NIB & UON

  43. THANK YOU AIS & BIS water loss study-NIB & UON

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