Canal lining is an effective technique for coating the bottom and sides of the canal with a 5 cm to 15 cm thick layer of impermeable concrete, asphalt, plastic, or clay.

It helps prevent water from seeping into the ground, reduces erosion, and keeps the water clean by blocking contaminants. It also ensures efficient water distribution, especially for irrigation, by minimising wastage and improving water flow.

Lined canals can save 60% to 80% more water compared to unlined ones, making them a reliable solution for agricultural needs. They also help prevent weed growth, waterlogging, and damage caused by animals.

Beyond saving water, canal lining supports sustainable farming practices and contributes to healthier soil and a better environment.
Here, in the article, we’ll discuss how canal lining is a smart investment in long-term water conservation and agricultural productivity. We’ll discuss its various types, advantages, and disadvantages in detail.

Types of Canal Lining

Earthen-Type Lining

1)- Compacted Earth Lining

Compacted earth lining is used in canals where soil is compacted to create a strong and dense layer that reduces water seepage and improves durability.

It works best when earth materials (such as soil, minerals, rocks, and water) are available near the construction site, as the cost will be minimal in such cases. 

The compacting process squeezes out the air and water from the tiny spaces (pores) in the soil, making it denser. This increases the soil’s strength and reduces its permeability, which helps prevent water loss.

2)- Soil Cement Lining

Soil cement lining is made from cement, soil, and water. Like concrete, it hardens quickly after construction. The soil content must be between 2% and 8%. Sometimes, the quantity of cement can be increased. The lining must be protected from weathering conditions for 7 days. 

Soil cement processing is completed using two methods.

1. Dry-mix method
2. Plastic mix method

Hard Surface Lining

1)- Cement Concrete Lining

Cement concrete lining is hydraulically efficient, reliable, and robust, so it is widely used because of these benefits. It suits large and minor canals with high or low water flow velocities.

The procedures for cement lining can be placed by machines or laid manually.

2)- Plastic Lining

A new technique for protecting seepage is the use of plastic lining. These plastics are thin polyvinyl chloride sheets, high-density polyethene, or low-density polyethene. They help layer the canal relatively quickly.

3)- Brick Or Tile Lining

This method is very much similar to cement concrete lining. Here, a bed of bricks or tiles is placed on the base and sides of the canal. After this process, cement mortar is used to smooth the surface and sides.

4)- Asphalt Concrete Lining

Asphalt is a mixture of cement, asphalt, and aggregates. The asphalt and cement are mixed in hot conditions and layered. It also works like concrete cement processes—the age of this layering is 15 to 20 years. It has the disadvantage of not protecting canals from weeds.

5)- Shotcrete Lining

Shotcrete lining involves coating canals’ irregular or curved surfaces under high pressure with a mixture of cement, water, and other aggregates. It is more costly than a cement concrete layer of the same thickness.
Shotcrete lining is used in line tunnel walls, mines, subways, and automobile tunnels.

6)- Boulder Lining

In this method, dressed boulders or stones are used to make a lining. Dress-shaped boulders are not naturally present and are broken according to need. Boulder lining methods are used where head loss is not a concern. Dressed boulders or stones are prioritized over rough boulders or stones because rough boulders or stones resist the water flow of the canal.

7)- Prefabricated Cement Concrete Lining

Prefabricated cement concrete lining is easier to lay on the steep side slope than cement concrete lining in a similar place. It is preferable because it controls moulding, mixing, and curling more than in situ concrete methods.

Prefabricated cement concrete lining methods are used where inexpensive labour, material access, and convenient transportation are easily available. Also, it takes less time than other canal-lining processes.

Advantages Of Canal Lining

There are several advantages of canal lining. these are

1) Seepage Reduction

Seepage reduction is the primary purpose of canal lining—approximately 20% to 50% of total water losses are due to seepage. Canal lining is an expensive process, but it is justifiable for efforts to save water losses by seepage.

Read About: How To Save Water?

2) Prevents Waterlogging

Canal lining helps prevent waterlogging, a primary cause of seepage from unlined canals. Seepage occurs if any permeable places are present on the side of the canal, helping to raise the water table. The excess water is soaked up by soil and propagates to low-lying areas.

3) Reduced Canal Dimensions

A smooth, lined canal surface provides a water flow with less resistance. When the slope of the canal bed is the same, it provides a higher velocity of water flow. A lined canal with a smaller cross-section area provides 1.5 to 2 times the flow speed in the canal.

An unlined canal with a broad and irregular cross-section area of earthen materials resists the water flow.

4) Less Maintenance

The canal lining is made from bricks, concrete, stone, and plastic, which prevents the growth of water weeds and rat holes. Maintenance of lined canals is easier and takes less time than unlined canals. Also, the water’s high velocity prevents soil from settling in the canal’s path.

5) Helps In Water Conservation

Water conservation is the primary cause of canal lining—canals lose 15% to 20% of their total carried water through seepage and weed consumption. The lining does not reduce the water loss, but lined canals save 70% to 80% of water loss due to seepage.

Read More About: Advantages Of Water Conservation

6) Prevents Soil Erosion

The canal lining works as a barrier for water, not seepage into the adjacent soils, which degrades the soil.

7) Increase In Command Area

Canal lining overcomes the seepage problem; more water is conserved than in unlined canals. This conserved water can be used to irrigate land, which shows an increase in command areas—enhanced channel capacity.

8) Safety From Flood Risks

The lined canal is made from hard concrete, plastics, and stones that resist flooding. However, the unlined canals are destroyed by floodwater.

Disadvantages Of Canal Lining

1) High Cost Of Construction

Canal lining is an expensive process. It is also more expansive in the case of large canals.

2) Regular Maintenance Needed

Canal lining needs regular maintenance to check its effectiveness, which is time-consuming and costly.

3) Complex Construction

It is a complex construction process that requires highly skilled labour, a long time for construction, and essential equipment. It is also difficult to repair after damage.

4) Environmental Concern

Canal lining affects the natural habitats of some species, hydrology, and wildlife. Environmental biodiversity is also a concern that must not be ignored before constructing canal lines.

5) Hard To Shift

The shifting process of canal lining is complex. It needs to be dismantled or relayed.

Factors Influencing Canal Lining Selection

1) Soil Type

The soil type affects the seepage rate and groundwater interactions. Sandy soil can significantly reduce seepage, while clayey soil cannot prevent it.

2) Availability Of Materials

The availability of materials impacts the canal lining selection process. If earthen materials are unavailable at the site, the construction of the canal lining will be costly.

3) Costs

The costs of canal lining depend on the type of materials, availability, labour, and construction period. It is also costly during repair.

4) Hydraulic Efficiency

The continuous water flow reduces the canal’s hydraulic efficiency as the surface becomes rough, increasing erosion.

Hydraulic efficiency is important because smooth linings reduce friction, allowing water to flow faster and more evenly. This improves water delivery, prevents blockages, and reduces maintenance costs.

5) Durability

The canal should be less affected by weather conditions, changes in temperature, empty conditions, and chemical actions. However, the growth of rats and weeds has affected its durability, so periodic inspection is essential.

6) Weed Growth Potential

Weeds impact the flow of canals. They catch sediments and debris and create resistance to the water flow. These are also breeding and feeding habitats for disease-causing agents.

7) Water Velocity

The water velocity depends upon the type of lining, soil, and materials.

Water velocity for some different soils-

• For stones: 1.6–1.8 m/s
• For bricks: 1.4–1.6 m/s
• For precast cement concrete: 2.0 meters per second (m/s)

Conclusion

Canal lining is a sustainable water management practice that helps conserve water and improve agricultural efficiency. Maintaining water canals can help economic and environmental systems grow.

Lined canals reduce water loss through seepage and evaporation and make sure that more water reaches the areas of irrigation. This helps conserve water and ensures crops get the right amount of water without wasting it. They also help prevent issues like soil erosion and waterlogging.

Investing in canal lining is a smart way to make sure you’re using water efficiently and supporting agriculture in a sustainable way.

Read More About: Water Conservation Methods