UPSC Prelims 2000 Q12: Geography – Oceanography
- (a) I and IV
- (b) II, III and IV
- (c) I, II and III
- (d) I, II, III and IV
Answer: (d) I, II, III and IV
Explanation
Statements about tides and tidal ports
| Statement | Correct? |
|---|---|
| I. Tides help navigation and fishing | Yes — fishermen and ships time their movement with the tide |
| II. High tide lets big ships enter or leave harbour | Yes — it raises the water level over shallow approaches |
| III. Tides prevent siltation in harbours | Yes — the ebb current scours silt out of river mouths |
| IV. Kandla and Diamond Harbour are tidal ports | Yes — Kandla on the Gulf of Kachchh, Diamond Harbour on the Hooghly |
Tides raise the water level, so big ships can cross shallow bars at high tide, and fishermen use the tidal flow to go out and come back.
The outgoing (ebb) tide carries silt away, which keeps river-mouth harbours from silting up.
Kandla on the Gulf of Kachchh, where the tidal range is high, and Diamond Harbour on the Hooghly estuary are tidal ports.
All four statements are correct.
Answer: (d) I, II, III and IV.
Why each option is right or wrong
- (a) Incorrect. Statements II and III are also true.
- (b) Incorrect. Statement I is also true.
- (c) Incorrect. Statement IV is also true; both are tidal ports.
- (d) CORRECT. All four statements about tides are true.
Key point
The Gulf of Khambhat and the Gulf of Kachchh have India's highest tidal range, the best sites for tidal energy.
Remember
All four true: tides aid shipping and fishing, flush silt; Kandla and Diamond Harbour are tidal ports.
Common mistakes
- Doubting statement III because rivers bring silt into harbours.
- Thinking Diamond Harbour is a sea port rather than a riverine tidal port.
- Forgetting that Kandla (Deendayal Port) relies on the tide in the Gulf of Kachchh.
Exam tip
Tide in = deeper water for ships; tide out = silt flushed out.
Sources
- NCERT Class XI — Fundamentals of Physical Geography, chapter 'Movements of Ocean Water' (tides)
- NCERT Class XII — India: People and Economy, chapter 'Transport and Communication' (major ports)