The channel sections for an irrigation canal may be of the following four types.
1. Canal in cutting.
2. Canal in filling.
3. Canal in heavy filling.
4. Canal partly in cutting and filling.
1. Canal in Cutting.
- This canal does not require any bank as F.S.L. lies below the G.L.
- If F.S.L. is just at the G.L., small banks may have to be provided.
- In this section F.S.L. of canal lies just at G.L. or slightly below it. See Fig. 19.2 (a).
2. Canal in Filling.
- In such a section the bed level of the canal lies at the G.L.
- Section whose bed level is slightly above the G.L. also comes under this category. See Fig. 19.3 (a).
3. Canal in Heavy Filling.
- In this section, the bed level of the canal lies substantially above the G.L.
- Such a section should as far as possible be avoided.
- Such sections are easily liable to breach and cause lot of damage to canal itself and surrounding areas.
4. Canal Partly in Cutting and Filling.
- In such a section the ground level lies in between the F.S.L and bed level of the canal. See Fig. 19.2 (a).
- The service road is usually provided on the left bank of the canal.
- One bank of the canal always has service road and the other bank is made banked section.
- Service road and canal berms are separat by a small bund called Dowla.