The document discusses canal lining, which involves providing an impervious layer along the bed and sides of a canal. This increases the life, discharge, and efficiency of the channel. The main types of lining discussed are precast concrete, brick, and stone block lining. The advantages are preventing seepage, waterlogging, increasing capacity and channel life. The disadvantages include high initial costs and difficulty repairing damage. The document evaluates factors like economy, durability in selecting the appropriate lining type.