The lining like cement concrete, pre-cast cement concrete, etc. gives a smooth surface to the canal. Smoothness of the canal bed and the sides _____________ the discharge of the canal and the duty of water.

Explanation:

• The smoothness of the canal bed and sides increases the velocity of flow which further increases the discharge of the canal.
• Due to the increased discharge, the duty of water will be more. So, to increase the duty, the canal surface should be made smooth.
• The lining like cement concrete, pre-cast cement concrete etc gives smooth surface to the canal.

 Additional InformationLining of canal: It is the process of reducing seepage loss of irrigation water by adding an impermeable layer to the edges of the canal trenches.

Concrete canal lining:

1. It is often used due to its high structural strength.
2. They are tough, durable, relatively impermeable and hydraulically efficient.
3. It is suitable for both small and large channels and both high and low flow velocities.

The lining of canal is performed for the following purposes:

1. To minimize seepage loss in canal
2. To increase the discharge in the canal section by increasing the velocity.
3. To reduce maintenance of canals and weed growth
4. To prevent the erosion of bed and sides of canals