Which of the following is not correct for lining of canal?

Explanation:

Advantages of canal lining or lining an irrigation canal serves the following purposes:

• It helps to reduce seepage losses which saves water Ulat can be utilised to irrigate additional areas.
• It reduces maintenance costs and the probability of canal breaching as a result of the increased stability that is achieved by the canal section.
• It reduces percolation to the groundwater reservoir and thus prevents waterlogging. However, the water thus saved should not be used to carry out more intensive irrigation in the same area as this will promote waterlogging itself.
• The lined canal surface is generally smooth and allows water to flow with high velocity compared to an unlined channel. The higher the velocity of flow greater the capacity of the channel and hence channel capacity will increase by providing lining.
• It helps, where the ground slope is mild, in improving the command due to flatter slopes. In situations where the canal is also used for power generation, this is an additional benefit since the lined canal can be given a flatter slope resulting in a higher head that would be available for the power generation. 
• It prevents the growth of weeds.

Regarding the lining of canal statement Increase in maintenance cost is incorrect. Hence option (3) is the correct answer.