A Presentation on Canal Irrigation versus Piped Irrigation...

A Presentation on Canal Irrigation

versus

Piped Irrigation:

General Issues and a Case Study

Sabarna Roy Vice President & Head – Business Development, Electrosteel Castings Limited, Kolkata.

Part –A

Dis-advantages of Canals

for Conveyance of

Irrigation Water

Components of Pipe Flow

In all piped systems the main component parts are:

• the control station (head control unit);

• the mains and sub-mains (pipelines);

• the hydrants;

• the manifolds (feeder pipelines);

• the laterals (irrigating pipelines) with the emitters.

Part –A: Dis-advantages of Canals for conveyance of Irrigation Water

Water is conveyed from the water source to the cropped areas in networks of Open

Canals and / or Pipelines. Canals are meant to transport of water from a source to

the point of application with minimum losses. Open canals may be lined or

unlined.

Pipelines have several advantages over open canals. They are:

1. Requirement of Land

Canal Based Irrigation System are facing cost and time over runs due to

the problem of land acquisition, whereas in case of Pipelines, land

acquisition is not required.

In pipeline, only Right of Way is required during the construction phase

of the project.

2. Water Losses by way of Seepage & Evaporative Losses

Water in an open canal may be lost to seepage, leakage or both.

This seepage loss can be significant when a canal is constructed from

materials, which have high permeability.


Moreover, seepage loss through the canal bed is difficult to detect

because water goes down and does not appear on the nearby ground

surface.

Water is lost by way of evaporation from the irrigation canal also. Losses

on account of evaporation mostly depend on the surface area, temperature

difference between canal water and surrounding air, the air humidity and

the wind speed.

3. Erosion & Siltation

If water in a canal is allowed to flow at a higher velocity, it can cause

severe erosion.

Canal bends are particularly susceptible to erosion because turbulence is

created due to changes in the direction of water flow.

Canal banks can be eroded by over-topping water or by rainfall.

Eroded soil may be deposited in the canal and causes siltation, which in

turn reduces the canal's capacity.


4. Frequent Over-topping

Water in a canal may rise unexpectedly due to the following reasons:

• The incoming flow through the canal off-take may be much greater

than the canal capacity;

• Obstacles such as stones, blocks or plants growth in the canal;

• Outlets from a canal may be closed, which should be open;

• Rain or other water may be draining into the canal.

If no action is taken, the water level can reach the top of the canal banks

and overtop. Over-topping causes erosion of the canal banks and may

lead to serious breaches.

5. Weed / Plantation Problems

Weeds grow vigorously on and adjacent to canal embankments. They

choke canals and reduce their capacities.

Together, weed growth and siltation can completely obstruct the flow of

water in a canal.

The result can be over-topping and collapse of the canal embankments.

Plant roots can penetrate canal embankments and cause them to leak.


6. Unsafe from Safety (humans & equipment can fall into the water stream)

Any external materials like equipment & humans can fall inside the canal

as most of the canals in India do not have safety / protective barriers.

These canals remain full during the warmer months of the year to

distribute water. As such, there is a chance of falling of domestic animals,

human beings, equipment etc. inside the canal either by way of accident

or intentionally, thus making the canal water polluted.

7. Water Losses by way of Pilferage

Unaccounted drawal of water from canal is a major problem particularly

in water starved areas.

People draw unauthorized water either for drinking purpose or for

irrigation purpose from the canal as a result sufficient water does not

reach to the end point of the canal. In fact, in a bid to check the theft of

water, most of the states in India like Punjab, Andhra Pradesh etc.

stipulated stringent laws for unauthorized drawal of water from its

canals.


8. Execution Time

Construction of earthen canal is comparatively more time consuming

compared to installation of pipelines.

Moreover, skilled labour along with proper quality control for

maintenance of side slope, longitudinal slope etc. is required for

construction of canal.

9. The water flow regime

With traditional surface methods the size of the stream should be large,

while in pressure piped irrigation systems very small flows, even 1 m3/h,

can be utilized.

10. The route direction of the flow

With traditional surface methods the irrigation water is conveyed from

the source and distributed to the field through open canals and ditches by

gravity following the field contours. The piped system conveys and

distributes the irrigation water in closed pipes by pressure following the

most convenient (shortest) route, regardless of the slope and topography

of the area.


11. Irrigation efficiency

In open canal distribution networks, the water losses are estimated at up

to 40 percent in unlined ditches and up to 25 percent in lined canals.

These losses are due to seepage, phreatophytes and leakage in gates,

spillways, etc. In piped systems, no such losses occur. As a result, water

losses can be minimized and an irrigation efficiency of 75–95 percent can

be achieved. In open canals, the irrigation application efficiency ranges

from 45 percent to a maximum of 60 percent.

12. Economic return per unit of water

Piped systems facilitate the manipulation of the irrigation water under

more favourable conditions than do open canals. This can result in a yield

increase of 10–45 percent and an improvement in quality.


13. Operation and maintenance (O&M)

The man-hours needed in the piped systems range from one-tenth to one-

quarter of those required for open canals. Any person can easily operate

the piped systems, while the open canals can require skilled labour. In the

open canals, expensive operations are carried out to prevent damage

caused by roots; seepage through banks; the spread of weeds; siltation

and sedimentation; clogging of outlets and gates; etc. In the piped

systems, no maintenance or continuous repair of constructions is

required.

Part – B

A Case Study of a Sample

Irrigation Project

Part – B: Hydraulic Requirement for the Project

(Total command area = 35,000 Ha)

Sl. No Description PS Length Value Unit

1Water discharge (from 0 Chainage to

8340 Chainage) - 8340 m lengthPS1 8340 6.5 cumecs

2Water discharge (from 8340 Chainage

to 17730) - 9390 m lengthPS2 9390 5.6 cumecs

3Water discharge (from Chainage 17730

to Chainage 23640) - 5910 m lengthPS3 5910 4.07 cumecs





Part – B: One Sample Irrigation Project –Abstract of Main and Feeder CanalS

l. N

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(mm) (mm) From To (m) (m/sec)(Kg/

cm²)(Kw)

(In

Crores)

(In

Crores)

(In

Crores)

PS1

DI

Pip

e (t

win

lin

e)

2 X DN 1200 K7 1212 0 8340

Main

Canal

8,340 2.82 6.71 8,550 71.74 15.39 87.13 114.67

PS2 2 X DN 1100 K7 1111 8340 17730 9,390 2.89 7.18 8,580 63.58 15.44 79.02 106.66

PS3 2 X DN 1000 K7 1012 17730 23640 5,910 2.53 5.69 4,542 30.54 8.18 38.72 53.34

PS4 2 X DN 900 K7 910 23640 32040 8,400 2.07 5.98 3,166 36.38 5.70 42.08 52.26

PS5 2 X DN 700 K7 708 32040 40590 8,550 1.74 4.34 1,166 23.16 2.10 25.26 36.52

FC 2 X DN 1200 K7 1212Feeder

Canal3,600 2.82 7.71 9,824 30.96 17.68 48.64 102.84

Grand Total = 44,190 35,828 256.36 64.49 320.85 466.29

Part – B: One Sample Irrigation Project –Abstract of MinorsS

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(mm) (mm) From To (m) (m/sec) (Kg/cm²) (Kw) (In

Crores)

(In

Crores)

(In

Crores)

(In

Crores)

1Tail

MinorDI /K7 150 154 40590

Tail

Minor2400 1.15 2.33 10 0.35 0.01 0.37 0.41

2 LM 13 DI /K7 350 356 40590 LM13 9000 1.41 4.79 131 3.63 0.17 3.80 4.35

3 RM 15 DI /K7 450 456.8 40590 RM15 11250 1.47 4.88 230 6.39 0.30 6.69 7.66

4 LM 12 DI /K7 300 308.8 38820 LM12 7050 1.75 6.46 166 2.28 0.22 2.50 3.19

5 RM 14 DI /K7 400 406.4 38820 RM14 16050 1.71 10.26 444 7.74 0.59 8.33 10.19

6 LM 11 DI /K7 450 456.8 35010 LM11 13500 1.48 5.91 281 7.67 0.37 8.04 9.22

7 RM 13 DI /K7 500 508 35010 RM13 11925 1.67 5.76 383 7.98 0.50 8.48 10.08

Total Cost of PS 5= 40.39 1646 36.04 2.17 38.21 45.10

8 LM 10 DI /K7 300 308.8 32040 LM10 3000 1.18 1.44 25 0.97 0.03 1.00 1.11

9 RM 12 DI /K7 450 456.8 32040 RM12 18300 1.83 11.62 681 10.40 0.90 11.29 14.14

10 LM 9 DI /K7 200 206 30540 LM9 3150 1.32 2.82 24 0.61 0.37 0.98 0.41

11 RM 11 DI /K7 300 308.8 30540 RM11 5175 1.19 2.45 43 1.67 0.06 1.73 1.91

12 LM 8 DI /K7 350 356 28380 LM8 8700 1.68 6.34 208 3.50 0.27 3.78 4.65

13 RM 10 DI /K7 400 406.4 28380 RM10 8925 1.43 4.23 154 4.31 0.20 4.51 5.15

14 LM 7 DI /K7 400 406.4 26100 LM7 16200 1.70 10.29 444 7.82 0.58 8.40 10.26

15 RM 9 DI /K7 200 206 24660 RM9 3225 1.57 3.89 40 0.63 0.05 0.68 0.85

Total Cost of PS 4= 43.08 1618 29.90 2.47 32.37 38.47


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Crores)

(In

Crores)

(In

Crores)

(In

Crores)

16 LM 6 DI /K7 450 456.8 23640 LM6 15750 1.83 9.98 584 8.95 0.77 9.72 12.16

17 RM 8 DI /K7 300 308.8 23640 RM8 4425 1.20 2.14 37 1.43 0.05 1.48 12.88

18 LM 5 DI /K7 700 708 20700 LM5 23100 1.95 10.00 1501 27.61 1.98 29.59 35.87

19 RM 7 DI /K7 300 308.8 20700 RM7 6000 1.39 3.66 74 1.94 0.10 2.04 2.35

20 RM 6 DI /K7 250 257.4 18990 RM6 5400 1.48 4.52 68 1.38 0.09 1.47 1.75

Total Cost of PS 3= 30.29 2264 41.31 2.98 44.29 65.01

21 RM 5 DI /K7 300 308.8 17730 RM5 5850 1.58 4.52 105 1.89 0.14 2.03 2.47

22 LM 4 DI /K7 600 609.6 17730 LM4 15450 2.06 8.75 1027 13.65 1.35 15.00 19.30

23 RM 4 DI /K7 500 508 13800 RM4 25380 2.01 16.81 1341 16.98 1.29 18.27 22.37

24 LM 3 DI /K7 400 406.4 13800 LM3 13350 1.38 5.91 208 6.44 0.03 6.47 7.83

25 RM 3 DI /K7 250 257.4 11640 RM3 6750 1.55 6.13 97 1.73 0.13 1.85 2.26

26 LM 2 DI /K7 300 308.8 11640 LM2 5745 1.48 3.94 86 1.86 0.11 1.97 2.33

Total Cost of PS 2= 46.06 2864 42.54 3.06 45.59 56.55

27 RM 2 DI /K7 350 356 8340 RM2 10200 1.61 6.86 216 4.11 0.28 4.39 5.30

28LM

1BDI /K7 250 257.4 8340 LM1B 2760 1.24 1.76 22 0.71 0.03 0.73 0.83


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Crores)

(In

Crores)

(In

Crores)

(In

Crores)

29 RM 1 DI /K7 300 308.8 4230 RM1 3668 1.25 1.91 35 1.19 0.03 1.22 1.39

30LM

1CDI /K7 500 508 4230 LM1C 15000 1.65 7.02 459 10.03 0.60 10.64 12.56

31LM

1ADI /K7

300 308.8 1800 LM1A 50001.25 2.59 47 1.62 0.06 1.68 1.88

Total Cost of PS 1 20.13 779 17.65 1.01 18.66 21.95

Grand Total (PS 1+PS2+PS3+PS4+PS5) = 179.95 9170.92 167.43 11.69 179.12 227.09

Part – B: Project Cost Comparison

Sl. No Description of activity / work

Cost C1 Cost C2

Remarks

Open channel Pipe flow

DI pipe in Main &

feeder Canal, Minors

and distribution

(Rs. in crores) (Rs. in crores)

1 Preliminary cost 3.54 3.54

2 Land acquistion 348.91 34.89RoU cost considered

10% in pipe flow

3 Works of Intake 94.69 94.69

4 Regulators 1.73 0.00 Eliminated in pipe flow

5 Cross drainage works 0.84 0.84

6 Bridges 20.40 10.20Cost considered 50% in

pipe flow

7 Escapes 0.53 0.00

8 Buildings 5.98 5.98

9 Earthworks 10.85 0.00 Eliminated in pipe flow

10 Lining of Main Canal 19.20 0.00 Eliminated in pipe flow

11 Plantation 0.49 0.49

12 Miscellaneous 14.19 2.84Assumed 20% in pipe

flow

13 Maintenance 3.54 3.54

14 Special tools and plants 0.70 0.70

15 Communication 4.00 4.00

16 Construction / drinking water 0.89 0.89


Sl. No Description of activity / work

Cost C1 Cost C2

Remarks

Open channel Pipe flow

DI pipe in Main &

feeder Canal, Minors

and distribution

(Rs. in crores) (Rs. in crores)

17 Distribution and Minors 49.30 179.38 See Note 1

18

V-CDA & WM, Diigie, Sumpwell,

pumpwell, HDPE pipe netwrok for

irrigation of 34, 465 Ha land

151.22 100.00Diggies and pumps

eliminated

19 Environment and ecology 1.47 1.47

20 Losses on stock 0.89 0.89

21 Establishment 38.02 38.02

22 Tools and Plants 3.54 3.54

23 Receipt of Capital outlay 0.17 0.17

24 Indirect charges 7.18 7.18

25Pipeline for Main and Feeder

Canal supply and execution320.85 See Note 2

Total project cost 782.27 814.10


Note 1: Capitalized pump and energy cost for the minors for 30 years will be Rs.227 crores.

The pumps for the minors will be as follows :

a) RM2 to LM 1A = PS 1

b) LM2 to RM 5 = PS 2

c) RM6 to LM6 = PS 3

d) RM9 to LM10 = PS 4

e) RM 13 upto Tail Minor = PS 5

Note 2: Capitalized pump and energy cost for Main and Feeder Canal for 30 years will be

Rs.466 crores.

Assumptions :

1 Energy cost = Rs.2.5/- per unit.

2 Pump cost = Rs.18,000/- per KW

3

Each pumphouse PS1 to PS 5 have the capacity of additional 40 m to cater to the

distribution.

Hence all costs of diggies and pumps in the field distribution will be eliminated.

4 Interest rate = 10%

5 Residual head = 1.0 m

6 Pumping hours = 24

7 Duration of pumping per year = 4 months

Guidelines for use of Type of Pipeline Material for Pressurized Pipe Irrigation

Schemes being followed by the Department of Water Resources,

Government of Madhya Pradesh

The type of pipeline used for construction plays vital role in providing durability

to the project, therefore looking to this fact that the aimed life of project projected

as 50 years the following type of pipeline for different sizes of diameter as per

design requirements are recommended to be used in future works.

Rising Main DI pipes as per BIS 8329 and

MS pipes (Outside coating 3LPE or Polyurethane and Inside lining

food grade epoxy) to be designed as per BIS 5822/AWWA(M11).

Gravity Main DI pipes as per BIS 8329

MS pipes (Outside coating 3LPE or Polyurethane and Inside lining

food grade epoxy) designed as per BIS 5822/AWWA(M11)

PCCP as per BIS 784/ AWWA (M9) depending upon design

requirement.

Distribution Network Below 300 mm – HDPE – PE 100 (BIS 4984); PN-4/6 depending upon

working pressure

300 mm upto 1000 mm – DI K7 – (BIS 8329)

More than 1000 mm DI as per BIS 8329/MS as per BIS 5822/

AWWA(M11)/PCCP Pipes as per BIS 784/ AWWA (M9) depending

upon design requirement.

Guidelines for use of Type of Pipeline Material for Mega Lift Irrigation Schemes

being followed by the Department of Water Resources,

Government of Odisha

Sl. No.Components of the Mega Lift

SystemType of pipes to be provided

1 Intake pipes RCC Hume pipes/MS pipes with proper

coating.

2 Rising Main or Distributaries Main

pipes

DI (Ductile Iron) pipes with internal and

external coating as per detailed

specifications.

3 Distribution pipes below 300 mm

diameter

HDPE make pipes as per detailed design and

specification.

The minimum cover on top of pipe shall be

1.2 meter.

A Presentation on Canal Irrigation versus Piped Irrigation...

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Transcript of A Presentation on Canal Irrigation versus Piped Irrigation...