Civil Engineering - Irrigation - Discussion

Watershed canal or ridge canal:

* The dividing ridge line between the catchment areas of two streams (drains) is called the watershed or ridge canal.

* Thus between two major streams, there is the main watershed (ridge line), which divides the drainage area of the two streams, as shown in figure below. Similarly, between a main stream and any of its tributary, there are subsidiary watersheds (ridge lines), dividing the drainage between the two streams on either side.

* 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.

* Since the drainage flows away from the ridge, no drainage can cross a canal aligned on the ridge. Thus, a canal aligned on the watershed saves the cost of construction of cross-drainage works.

Canals are also aligned along the contour line but it irrigates only one side (d/s) and the contour canal will need the number of cross drainage work.

Comparatively ridge all will need min no of C/D work and it can irrigate both sides of the canal so ridge line canals are preferable.

Generally, preferred to align canal along ridge line. But if hilly terrain specifically mentioned then answer will be contour canal. Because in that case, it is not economical to align canal along ridge line.

Canal align along the contour will economical, due to minimum comparative cut and fill of canal excavation and it reduces the cost& time to construct flow for gorges. So, why it could not be the answer?

If a canal is align along ridge line, the number of cross drainage works will be reduce. Hence it will economical. Aligning of canals along ridge line are suitable for plane topography.

Is we made canal along the ridge line then we can irrigate in both side of ridge line. Ridge line is the peak of a drainage area which divide the drainage area into two half.

If we provide canal on valley line, then it's require pumping to irrigate water to field, hence ridge line is most economical and suitable.

When high velocity of canal there create scoure and low velocity there deposit silt so that use ridge line of canal.

@Renuka Patyal.

If we provide in contour line its requires numerous cross-drainage works hence it is expensive.

It can irrigate both side of itself (left and right side). It is also known as Watershed canal.