Canal Lining

By

Dr. Dipankar Roy

Losses in Irrigation canals

Loss Due to Evaporation:

As canal water is exposed to the atmosphere at the surface, loss due to evaporation is obvious. It is of course true that in most of the cases evaporation loss is not significant. It may range from 0.25 to 1% of the total canal discharge.

The rate of loss of water in the process of evaporation depends mainly on the following factors:

• Temperature of the region,
• Prevailing wind velocity of the region,
• Humidity
• Area of water surface exposed to the atmosphere.

Losses in Irrigation canals

Loss Due to Seepage:

The water lost in seepage may find its way finally into the river valley on enters an aquifer where it can be utilized again. But many times the seepage water is not recoverable.

The loss due to seepage is the one which is most ignificant so far as irrigation water loss from a canal is concerned.

Losses in Irrigation canals

Loss Due to Seepage:

The seepage loss depends mainly on the following factors:

• Underground water table conditions,

• Porosity of the soil,

• Physical properties of the canal water for example its
  temperature and quantity of suspended load carried by the water
  (turbidity of water),

• Condition of the canal system.

DESIGN OF LINED CANALS

• The lined canals are not designed making use of Lacey or Kennedy Theory because the section is rigid

• Generally Manning’s equation is used in design. To carry a certain discharge number of channel sections may be designed with different bed widths and side slopes.

DESIGN OF LINED CANALS

But it is clear that each section is not equally good for the purpose. - The section to be adopted should be economical and at the same time it should be functionally efficient

• It has been found that the most suitable cross- section of a lined canal is a circular section with sloping sides. That is, the bed is not flat but it is an arc of a circle. This arc is tangential to the sloping sides

4 FUNCTIONS OF LINING (IS 10430:2000)

4.1 The functions of lining

• Seepage control,

• Prevention of waterlogging,

• Increased hydraulic efficiency,

• Increased resistance to erosion/abrasIon,

• Reduction in cross-section area and consequential smaller
  structures ,and

• Low operation and maintenance cost.

4 FUNCTIONS OF LINING

4.1 The functions of lining

• Maximum hydraulic efficiency;
• Impermeability;
• Resistance to erosion;
• Ability to prevent weed growth;
• Resist against burrowing animals
• Reasonable Flexibility.

The lining material shall be so selected that it should meet most of the requirements for the specific site.

5 REQUIREMENTS OF LINING (IS 10430:2000)

5.1 General

The following are the important requirements for the selection of type of canal lining:

• Economy;

• Structural stability;

• Strength and durability;

• Repairability and easy maintenance;

6 DIFFERENT TYPES OF LININGS (IS 10430:2000)

A) Rigid Lining

• Stone-pitched lining
• Burnt clay tile or brick lining;
• Precast cement concrete/stone slab lining
• In-situ cement lime/concrete lining
• Stone masonry lining
• Soil cement lining
• Shotcrete lining
• Asphaltic cement/concrete

6 DIFFERENT TYPES OF LININGS

b) Flexible Lining

• Geo membrane like High Density Polye-thylene (HDPE), Polyvinyl chloride (PVC) Low Density polyethylene(LDPE) cover comprising layer of bentonite with adequate/earth/burnt clay tile brick/precast cement concrete,

6 DIFFERENT TYPES OF LININGS

(IS 10430:2000)

b) Flexible Lining

• Bituminous or bituminous/asphaltic felt lining,
• Fibre reinforced plastic tissue asphaltic membrane,
• Composite membrane/rubber lining.
• Combination Lining (membrane in the bed and brick/tile or concrete lining on sides)

Bitumen Lining

Canal-Lined-with-Boulders

Cement Concrete Lining

Compacted Earth Lining

Construction of Brick Canal Lining

Plastic Canal Lining

Soil Cement Lining

Advantages of Lined Canals

• Reduction of seepage
• Prevention of water logging
• Increase channel capacity
• Increase in command area
• Reduction of maintenance cost
• Flood control

Design of Lined Canals

Design of Lined Canals

Design of Lined Canals

End of section