Explanation:

Lining of irrigation channels refers to the process of constructing a protective layer on the inner surface of the channel. This layer can be made up of various materials such as concrete, tiles, bricks, stones, etc. The purpose of lining the channels is to reduce the seepage losses, increase the life of the channel, and improve the water conveyance efficiency. However, lining of irrigation channels can have both positive and negative impacts on the irrigation system.

Increases command area
One of the positive impacts of lining irrigation channels is that it increases the command area. This is because when the seepage losses are reduced, more water is available for irrigation, which can be used to irrigate a larger area of land.

Increases channel cross section
Lining of irrigation channels can also increase the channel cross section. This is because the lining material takes up some space, which reduces the effective cross-section of the channel. To compensate for this, the channel needs to be widened, which increases the cross-section.

Increases chances of breaching
However, one of the negative impacts of lining irrigation channels is that it increases the chances of breaching. This is because the lining material makes the channel walls smoother, which reduces the friction between the water and the channel walls. As a result, the water can flow faster, which can cause erosion and breach the channel walls.

Increases water logging
Another negative impact of lining irrigation channels is that it can increase waterlogging. This is because the lining material reduces the seepage losses, which means that more water is retained in the soil. If the soil is not able to absorb this additional water, it can lead to waterlogging, which can damage the crops and reduce their yield.

Conclusion:
In conclusion, lining of irrigation channels can have both positive and negative impacts on the irrigation system. While it can increase the command area and channel cross-section, it can also increase the chances of breaching and waterlogging. Therefore, the decision to line irrigation channels should be based on a careful analysis of the local conditions and requirements.