Short Answer:

Lined canals are canals whose bed and sides are covered with a lining material like concrete, brick, or stone to prevent water loss and erosion. Unlined canals have natural earth surfaces without any artificial lining, which makes them cheaper but more prone to seepage and damage.

The main difference lies in construction, cost, maintenance, and efficiency. Lined canals reduce water loss, increase flow speed, and require less maintenance. Unlined canals are economical to build but need frequent repairs and waste more water due to seepage and weed growth.

Detailed Explanation:

Difference between Lined and Unlined Canals

In civil engineering, canals are important for transporting water from sources to fields for irrigation. Based on whether the canal surface is treated or not, canals are divided into two main types: lined canals and unlined canals. Understanding the difference between them is important for choosing the right type based on cost, soil, and purpose.

1. Lined Canals
   Lined canals have their bed and sides covered with a lining material like cement concrete, brick masonry, stone, or plastic. The main aim is to prevent water seepage, reduce erosion, and provide smooth flow.

Key Features:

• Water Saving: Lining prevents water seepage into the ground, saving a lot of water.
• Reduced Maintenance: Smooth lining prevents weed growth and reduces erosion, lowering maintenance needs.
• Higher Flow Efficiency: Lined canals allow faster water movement due to less friction.
• Longer Life: They last longer and perform better in areas with sandy or loose soils.
• Higher Cost: Construction cost is high due to materials and skilled labor.

2. Unlined Canals
   Unlined canals are made by simply digging the earth, with no added material on the bed or sides. These are suitable in areas with less water loss risk or where the soil has natural resistance to seepage.

Key Features:

• Low Cost: Cheaper to construct, as no extra material is used.
• More Seepage: High water loss due to seepage into the ground.
• High Maintenance: Weed growth, erosion, and silt deposition are common.
• Less Efficient: Rough surface reduces flow speed and requires frequent cleaning.
• Temporary Use: Preferred for small-scale or temporary irrigation purposes.

Practical Use and Selection

The choice between lined and unlined canals depends on:

• Soil Type: In sandy soils, lining is preferred to prevent collapse and seepage.
• Water Availability: Where water is scarce, lined canals help conserve water.
• Cost Limitations: In low-budget projects, unlined canals may be used initially.
• Long-term Use: For permanent systems, lined canals are better in the long run.

Lined canals are common in modern irrigation projects where water conservation and efficiency are important. Unlined canals are still used in traditional systems, remote areas, or temporary farming needs.

Conclusion

The main difference between lined and unlined canals is that lined canals are covered with protective materials to reduce water loss and improve flow, while unlined canals are made directly in the earth and are cheaper but less efficient. Lined canals offer better performance, durability, and water-saving, making them ideal for modern irrigation systems.