ASSESSING AND IMPROVING THE PERFORMANCE OF CONVEYANCE SYSTEMS: CASE STUDIES OF AHERO, BURA AND MWEA IRRIGATION SCHEMES A COLLABORATIVE RESEARCH PROJECT

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: 3rd July 2014

Mwea, Ahero and Bura Irrigation Schemes case studies

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PRESENTATION OUTLINE

Development and research objectives Project elements and its organization Year I highlight Year II Results and their implications Project outputs

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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

stakeholdersSource: NIB Strategic Plan 2008-2012

MIS, AIS & BIS water loss study-NIB & UON

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RATIONALE FOR CONVEYANCE SYSTEM RESEARCH:

Low efficiency (30-70%) of conveyance and distribution system with major implications on:Scheme water intake sub-systemOperation and maintenance of

conveyance sub-systemOn-farm sub-system

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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

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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

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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 problemsHigh on-farm (O&M) costs

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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

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NKEY ISSUES THAT WILL ADDRESSED

1. Assess performance and opportunities and constraints for improving performance;

2. Identify innovative solutions that will enhance the performance of the water delivery and water application sub-systems;

3. Evaluate technical performance of the innovative solutions;

4. Evaluate costs and benefits of performance improvements;

5. Formulate strategies and plans for performance improvements;

6. Identify investment priorities; and 7. Propose financing/ options.

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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


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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


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OBJECTIVESOverall 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.


PROJECT OBJECTIVES AND MAIN TASKS

1. Objective 1: Rapid assessment

1.1 Task 1: Mapping

1.2 Task 2: Characterization

1.3 Task 3: SWOT analysis

2. Objective 2: Assess water demand and supply

2.1 Task 1: Water requirements

2.2 Task 2: Water supply

2.3 Task 3: Equity and reliability


3. Objective 3: Assess water losses3.1 Task 1: Seepage loss3.2 Task 2: Evaporation loss3.3 Task 3: Operational losses4. Objective 4: Assess loss reduction options4.1 Task 1: Earth liners4.2 Task 2: Hard surface liners4.3 Task 3: Flexible membrane liners5. Objective 5: Assess O&M costs5.1 Task 1: Pumping cost5.2 Task 2: De-silting cost5.3 Task 3: Operating cost


6. Objective 6: Assess water productivity6.1 Task 1: Yield and production6.2 Task 2: Gross product value6.3 Task 3: Water productivity7. Objective 7: Assess costs and benefits7.1 Task 1: C/B ratio for earth liners7.2 Task 2: C/B ratio for hard surface liners7.3 Task 3: C/B ratio for flexible membrane liners8. Objective 8: Synthesis, Dissemination and Mobilization for action8.1 Task 1: Synthesis8.2 Task 2: Dissemination8.3 Task 3: Mobilization for action

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YEAR 1 HIGHLIGHTS : AHERO SYSTEM


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YEAR 1 HIGHLIGHTS : AHERO SYSTEM


UCA Length(km) Area(ha) Canal density m/ha

U1 6.76 136.48 49.56

U2 5.25 110.18 47.64

U3 6.73 134.16 50.16

U4 4.63 105.07 44.10

U5 5.14 126.65 40.58

U6 3.30 59.94 55.01

U7 5.69 107.73 52.80

U8 5.23 120.94 43.24

U9 3.65 70.10 52.04

U10 3.16 61.18 51.60

U11 2.49 44.41 56.03

GrandTotal 64.48 1,076.85 59.88

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YEAR 1 HIGHLIGHTS : BURA SYSTEM


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YEAR 1 HIGHLIGHTS : BURA SYSTEM


UCA Length (km)

Area (ha) Canal density

m/ha

MainCanal 69.01 2,641.55 26.12

U1 27.54 196.32 140.27

U2 29.04 550.74 52.72

U3 33.19 433.09 76.63

U4 53.80 1,044.01 51.53

U5 16.74 361.64 46.29

U6 6.40 55.73 114.83

Total 166.71 2,641.55 63.11

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YEAR 1 HIGHLIGHTS : MWEA SYSTEM


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YEAR 1 HIGHLIGHTS : MWEA SYSTEM


UCA Length(km) Area(ha) Canallengthm/haMIAD 7.77 90.00 86.34M10 3.51 33.00 106.27M9 5.92 51.00 116.04M11 2.98 48.00 61.99M17 8.92 139.00 64.14M12 5.06 77.00 65.66M13 4.19 68.00 61.58M14 8.11 106.00 76.48M15 4.84 47.00 103.03M16 10.88 132.00 82.43H18 8.99 115.00 78.19H20 6.96 115.00 60.49H19 8.17 111.00 73.65M5 6.64 75.00 88.57M6 7.16 64.00 111.88M7 3.29 49.00 67.24M8 2.20 25.00 87.98M1 9.05 80.00 113.16M2 3.24 41.00 79.01M3 4.67 53.00 88.17M4 10.47 132.00 79.28H1 4.44 73.00 60.77H6 13.13 111.00 118.28H7 7.79 83.00 93.86H8 7.97 96.00 83.06H2 7.30 92.00 79.32H3 8.20 108.00 75.96H4 6.02 90.00 66.92H5 17.23 156.00 110.47W7 6.64 60.00 110.69W1 12.40 130.00 95.39W2 14.44 195.00 74.05W3 11.37 173.00 65.71W7 6.52 61.00 106.94W4 14.40 132.00 109.06W5 10.94 163.00 67.09W6 22.04 206.00 106.97K1 21.24 208.00 102.10K2 13.86 165.00 84.01K3 15.70 132.00 118.96K4 12.63 145.00 87.08K5 16.54 148.00 111.73K6 10.97 111.00 98.87K7 9.05 131.00 69.08K8 3.32 30.00 110.70

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SOIL PERMEABILITY TEST RESULTS

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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

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METHODOLOGY: LOSS ASSESSMENT


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METHODOLOGY: LOSS ASSESSMENT


Ponding methodTo 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.

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PRELIMINARY RESULTS: LOSS ASSESSMENT


Distance from point [m]

Depth [m]

Width [m]

Area [m^2]

Velocity 1 [cm/s]

Velocity 2

[cm/s]

Velocity 3

[cm/s]

Average

Velocity at Point [cm/s

]Discharge [m^3/s]

2.3 0 0 0 0 0 0.00 0.0002.1 0.25 0.2 0.05 23.5 24.1 20.2 22.60 0.0111.8 0.42 0.3 0.126 51.9 50.4 49.5 50.60 0.0641.5 0.47 0.3 0.141 44.2 40.3 39.5 41.33 0.0581.2 0.43 0.3 0.129 27.7 28 28.5 28.07 0.0360.9 0.35 0.3 0.105 22.1 22.1 21.6 21.93 0.0230.6 0.2 0.3 0.06 4.1 3.9 2 3.33 0.0020.4 0 0.2 0 0 0 0 0.00 0.000

Total Discharge [m^3/s] 0.195

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PRELIMINARY RESULTS: LOSS ASSESSMENT


Site Offtake

Gross loss m/day Efficiency

% loss to closed offtakes

Gross loss due to INFILTRATION and EVAPO. mm/day

% % Site 1 Site 2 0.094 0.98 0.70 28.05Site 3 0.358 0.89 0.80 71.53 Site 4 Site 5 0.470 0.88 0.85 70.48 Site 6

Site 7 0.707 0.51 0.90 70.73Site 8 Site 9 0.177 0.85 0.50 88.33

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Character of material Seepage loss in Cumecs per Million sq. m of wetted perimeter_____________________________________________________________________

Impervious clay Loam 0.90 to 1.20Medium clay loam under laid with hard pan at depth 1.20 to 1.80of not over 0.60 to 0.90m below level Ordinary clay loam silt soil 1.80 to 2.70Gravelly or sandy clay loam, cemented gravel, 2.70 to 3.70Sand and claySandy loam 3.60 to 5.20Loose sandy soils 5.20 to 6.10Gravelly to sandy soils 7.00 to 8.80Porous gravelly soil 8.80 to 10.70Very gravelly soils 10.70 to 21.30

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PRELIMINARY RESULTS: SEEPAGE LOSSES IN UNLINED CANALS

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METHODOLOGY: WATER BALANCE MODELING Thiba system linkages


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METHODOLOGY: WATER BALANCE MODELING Elements of the water balance model


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PRELIMINARY RESULTS: WATER BALANCE MODEL


Unit IWR m3/day SL m3/day EL m3/day

Main Canals - 179.56 359.11

U1 11,792.28 32.47 64.94

U2 9,519.29 24.94 49.89

U3 11,591.65 33.99 67.99

U4 9,078.19 22.41 44.82

U5 10,942.63 25.11 50.23

U6 5,178.76 18.20 36.39

U7 9,308.14 27.12 54.24

U8 10,449.02 24.95 49.89

U9 6,056.82 16.48 32.97

U10 5,285.65 14.72 29.44

U11 3,837.36 12.04 24.08

Grand Total 93,040 432

864

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ON-GOING SIMULATION STUDIES

Design, operation and maintenance issues for example what is the effect of changes on cropping calendar and system layout


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NPRELIMINARY SIMULATION RESULTS - MWEA

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NECONOMICS OF CANAL LINING

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

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 decreases from LC to zero in N years]

The total annual costs of lining = LC/N + LC/2(r/100)


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* 10-6 cumec/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



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.



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.


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1. Solving Conveyance and On-farm Water Management Problems

2. Irrigation Water Research: Priority issues and the potential outcomes and impacts

3. Benchmarking irrigation performance: Issues, Concepts and Methods

4. Water Conveyance Study: Ahero Irrigation Scheme Case Study

5. Water Conveyance Study: Bura Irrigation Scheme Case Study

6. Water Conveyance Study: Mwea Irrigation Scheme Case Study

7. Ahero Irrigation water loss assessment

8. Bura Irrigation water loss assessment

9. Mwea Irrigation water loss assessment10. Irrigation water measurement: Developing flow rating curves

11. Ahero Flow Measurement

12. Bura Flow Measurement

13. Mwea Flow Measurement

14. A literature review on seepage assessment and remediation

LIST OF PROJECT OUTPUTS

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THANK YOU

Documents

ASSESSING AND IMPROVING THE PERFORMANCE OF CONVEYANCE SYSTEMS: CASE STUDIES OF AHERO, BURA AND MWEA IRRIGATION SCHEMES A COLLABORATIVE RESEARCH PROJECT