Question

On sloping fields the submain pipe should be laid

• A. at 500m distance from the source
• B. along the contour
• C. along the slope
• D. across the slope

Hint:

Remember this standard rule of thumb for pressurized irrigation layouts on hillsides:
- Laterals run across the slope (along the contour) for pressure uniformity.
- Submains run along the slope (perpendicular to laterals) to connect them efficiently.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
In pressurized irrigation systems (such as sprinkler or drip irrigation) on sloping fields, proper layout of the pipe network is essential to maintain uniform operating pressure.
Pressure variations in pipes occur due to friction losses and changes in elevation (gravity).
To minimize these pressure variations, lateral pipes and submain pipes must be laid in specific directions relative to the slope.

Step 2: Detailed Explanation:
Let us analyze the pressure distribution requirements in a pressurized irrigation pipe network:
1. Laterals:
Laterals carry the actual water emitters (sprinklers or drippers).
To ensure that every emitter along a lateral operates at nearly the same pressure and delivers a uniform amount of water, laterals must be laid across the slope, parallel to the contours of the land.
This minimizes pressure differences caused by changes in elevation along the lateral.
2. Submain Pipes:
The submain pipe supplies water to these lateral lines.
Because the laterals run along the contours (across the slope), the submain pipe must run perpendicular to them to feed them efficiently.
This means the submain pipe must be laid along the slope (down the slope).
Laying the submain along the slope allows it to feed the contour laterals at right angles, which simplifies the system design and facilitates pressure regulation using control valves along the main slope.

Step 3: Final Answer:
On sloping fields, the submain pipe should be laid along the slope.
Hence, the correct option is (C).