The canal aligned on the natural watershed line is called:

✔ Explanation:
🔶 Ridge Canal
→ It is also called a watershed canal.
→ Aligned along the ridge or natural watershed line.
→ Can irrigate areas on both sides of the ridge.
→ Cross drainage work not required.
→ They are economical.

🔷 Contour Canal
→ Aligned nearly parallel to the contours of the country.
→ Can irrigate areas only on one side.
→ Cross drainage works are required.

🔷 Side Slope Canals
→ Aligned roughly at right angles to the contour of the country.
→ It is neither on the watershed nor in the valley.
→ Can irrigate areas only on one side.
→ It is roughly parallel to the drainage of the country, so cross drainage works are not required.
→ It has a very steep bed slope.