Question

The most desirable alignment of an irrigation canal is along
1. the ridge line
2. the contour line
3. the valley line
4. None of the above

Answer 1

Correct Answer - Option 1 : the ridge line

Concept:

Based on alignments canals can be classified in following three categories –

1. Ridge or watershed canals
2. Contour canals
3. Side slope canals

 

Ridge/watershed canals:

A canal that is aligned along natural watershed is known as ridge or watershed canal. These canals are usually taken off from contour canals.

These canals are suitable for plain areas where slopes are relatively flat.

These canals ensure gravity irrigation on both sides of the ridge line. Thats why, the most desirable alignment of an irrigation canal is along ridge line.

The water-shed line should be abandoned for aligning an irrigation canal if –

1. Water-shed forms a sharp loop
2. Canal has taken off from the river
3. Towns and villages are located on the water-shed line i.e. densely populated.

 

Note: As per IS 5968 -1987; Main canals should be aligned as contour canals while branch and distributaries should be aligned as watershed canals.