Incrustation of the tubewell pipes may lead to
- Areduced discharge from the tubewellCorrect
- Bexcessive discharge of sand with water
- Cdischarge of highly alkaline water
- Ddischarge of highly acidic water
Solution
Concept
Tubewell pipes get choked with calcium and magnesium deposits over time. This reduces the flow of water into the tubewell.
Step-by-step solution
1. Understand what incrustation means: minerals in groundwater deposit on the tubewell screen and pipes. 2. This blocks the small holes or slots of the tubewell pipe. 3. Because the openings are blocked, water cannot easily enter the tubewell from the surrounding soil. 4. Therefore, the total water pumped out, or the discharge, decreases. Answer: (A) reduced discharge from the tubewell
Explanation
Incrustation is the deposition of mineral salts on the tubewell screen. This chokes the openings, lowers the permeability around the well, and reduces the discharge of water.
Why the other options are wrong
B: Sand discharge happens due to high velocity or broken screens, not incrustation. C: Incrustation is a physical mineral deposit, it does not directly change the pH to highly alkaline. D: Incrustation does not make the pumped water highly acidic.
Shortcut
Incrustation always chokes things, so discharge will decrease.
Common mistake
Students sometimes confuse incrustation with sand pumping, which happens due to high entrance velocity or improper gravel pack.
Correct answer: A) reduced discharge from the tubewell