5. DEFINITION OF CANAL:
• AcanalisanArtificialChannel, generally Trapezoidal inshape
constructedonthegroundto Carry Water tothefields either
fromtheriver orfromatankorreservoir.
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8. CANAL ALIGNMENT:
• A canal has to be aligned in such a way that it covers the
entire area proposed to be irrigated, with shortest
possible length and at the same time its cost including
cost of drainage works is a minimum.
9. TYPES OF CANAL ALIGNMENT:
• Ridge / watershed Canal.
• Contour Canal.
• Side slope Canal
10. RIDGE CANAL:
• The dividing ridge line between the catchment areas of two
streams (drains) is called the watershed or ridge canal.
• It is suitable for plain areas, where slopes are relatively flat
and uniform.
• This type alignment ensures gravity irrigationon both sides of
the canal
11. Advantages:
• Canal supply water on both side and thus large area
may be taken under cultivation.
• It is the best irrigation canal and most economical
Disadvantages:
• Suitable only for plain area not for hilly area.
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14. CONTOUR CANAL:
• Canal aligned nearly parallel to the contour line is
called contour canal
• They are aligned generally when canals take off from
river.
• Culturable area lies on one side of it. as one of banks
on the higher side.
• Sometime it is called single bank canal
15. Disadvantages
• It can only irrigate one side.
Advantages
• Low initial cost.
• Discharge capacity increases as rain water from
higher side is collected in the canal
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17. SIDE SLOPE CANAL:
• A side slope canal is that which is aligned at right
angles to the contours; i.e. along the side slopes.
• It is a canal which is aligned roughly at right angle to
contours of the country but not on watershed or
valley. The canal thus runs roughly parallel to the
natural drainage of the country and as are such cross
drainage works avoided.
18. Advantages:
• Construction of cross drainageworkis notnecessary.
Disadvantages:
• Itcanirrigateonlyone side.
• Slope ismore if itisunlined canalerosion will takes place.
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22. FACTORS TO BE CONSIDERED
DURING CANALALIGNMENT:.
• It should serve the entire areaproposed to be irrigated.
• Cost of construction includingcross drainage works
should beminimized.
• Where canal crosses valleys, different types Of cross
drainage works are required.
• There should be Consideration of economy in of
contour canals
23. NECESSITY OF CANAL LINING:
• Maximum velocity limited to prevent erosion
• Seepage of water into the ground
• Possibility of vegetation growth in banks, leading to
increased friction
• Possibility of bank failure, either due to erosion or
activities of burrowing animals
• To avoid water logging
• To avoid movement of contaminated groundwater
• To avoid piping through and underchannel banks.
