This document discusses different types of canal lining materials and their advantages. It states that lining canals reduces water losses through seepage and prevents waterlogging of adjacent lands. It allows for smaller canal dimensions since lined canals have lower resistance to flow. Lining also reduces maintenance needs like silt removal and bank repairs. Common lining materials described include cement concrete, shotcrete, precast concrete, brick and various earth linings. Cement concrete lining provides excellent hydraulic properties but has high costs. Shotcrete and cement mortar linings use large amounts of cement. Brick lining allows for easy repair and is hydraulically efficient. Lining improves water conservation and irrigation capacity but requires heavy initial investment.
2. Advantages of Lining
Water Conservation: Lining a canal results in
reduction in water losses, as water losses in unlined
irrigation canals can be high.
No seepage of water into adjacent land or
roads: If canal banks are highly permeable, the
seepage of water will cause very wet or waterlogged
conditions, or even standing water on adjacent fields or
roads. Lining of such a canal can solve this problem.
3. Reduced canal dimensions: The resistance to flow of a lined
canal is less than that of an unlined canal, and thus the flow velocity
will be higher in the lined canal . Therefore, with the higher velocity,
the canal cross-section for a lined canal can be smaller than that of an
unlined canal.
Reduced maintenance: Maintenance costs for the following
issues are eliminated using lining of canals.
Periodical removal of silt deposited on the beds and sides of
canals.
Removal of weeds and water canals.
Minor repairs like plugging of cracks, uneven settlements of
banks, etc.
4. Advantages of Canal Lining
Prevents water seepage through surface of the canal.
Helps in preventing Water-Logging.
Increases discharge carrying capacity of the channel.
Increases channel life and reduce the maintenance cost.
Increases Gross area under cultivation.
Silting is prevented as velocity is increased.
Prevents or Reduces Weed Growth.
Increase available head for power generation due to
flatter gradient.
5. Disadvantages of Canal Lining
Heavy initial investment is required.
Difficult to shift the outlets as lining is permanent.
Difficult to repair the damaged lining.
Berm is absent in Lined channels, so safety to
vehicular and
6. Materials for Lining
Main types of concrete lining used in Indiaare:
HARD SURFACE TYPE LINING:
>> Cement concrete Lining
>>Shotcrete Lining
>>Precast concrete Lining
>>Cement Mortar Lining
>>Brick Lining
>>Stone blocks Lining
>>Asphaltic Lining
EARTH TYPE LINING:
>>Soil cement Lining
>>Clay puddle Lining
>>Sodium carbonate Lining
7. Cement Concrete Lining
It has high initial cost so its use is limited.
It has excellent hydraulic properties.
Thickness varies from 5-10cm for M 15 concrete and 7.5 to
15cm for M 10 concrete.
A subgrade is prepared and compacted.
Subgrade is saturated to a depth of 30cm in sandy soil and
15cm in other soils.
Lay a base coat of 1:4 cement and sand slurry on the
subgrade.
Spread oil paper/crude oil on the subgrade.
The concrete is usually laid in alternate blocks.
8. SHOTCRETE LINING
Shotcrete consumes large amount of cement.
Cement and Sand in the ratio (1:4) is shot at the subgrade through a
nozzle.
Thickness of this type of lining varies from 2.5 to 6.5 cm.
Shotcrete is also used for repair of old but sound concrete lining.
9. CEMENT MORTAR LINING
It is usually used as sandwich material between brick layers.
Thickness for this type of lining is kept from 1 to 4 cm.
A large amount of cement is consumed in this type of lining and thus
it is quite costly.
10. BRICK LINING
It consists of a single or double layer of brick masonry.
The size of brick is restricted to 30x15x5 cm for convenience
of handling.
This type of lining has been used in Punjab on Bhakra and Haveli
canals.
It is hydraulically as efficient as concrete lining.
In case of failure repair can be done easily.