Solution:

• A side slope canal is that which is aligned at right angles to the contours; i.e. along the side slopes.
• It is a canal which is aligned roughly at right angle to contours of the country but not on watershed or valley.
  Main Canal: It takes off directly from river or upstream side of head works.
  It acts as carrier canal and feeds water to branch canal and major distributaries.
• Watershed canal : The canal which is aligned along any natural watershed (ridge line) is called a watershed canal, or. a ridge canal.
• Aligning a canal (main canal or branch canal or distributary) on the ridge ensures gravity irrigation on both sides of the canal.
• A contour canal is an artificially-dug navigable canal which closely follows the contour line of the land it traverses in order to avoid costly engineering works