Lining of irrigation channels is necessitated to achieve all or some of the objectives, keeping in view economy as well.

These are [1] Reduction of seepage losses through unlined canal section thereby making available additional supplies for extension of irrigation to new areas.

[2] Prevention of water-logging in the area adjacent to the canal by reducing seepage of canal water to water table.

[3] Improvement of discharging capacity of existing channel.

[4] Improvement of discharging capacity of existing channel.

[5] Elimination of slitting problems inherent in unlined canals due to higher velocities possible in lined channels.

[6] Reduction in maintenance cost.

[7] Reduction in cost of excavation due to reduced cross section (and thereby saving in land) with increased velocity permissible in lined section.

[8] Increase in available head for power generation as also to command more area as a flatter gradient can be provided in lined channels and

[9] Prevention of weed growth. The necessity of lining has to be established by quantifying the contribution of each of the above factors and assessing the overall economy to be achieved by lining a canal.

The benefits that accrue from lining of the channels generally justify the initial capital cost and as a consequence there is now better appreciation of the need for lining of channels.