Consider the following sources of world water supply and arrange them in descending order. 1. Oceans 2. Rivers 3. Polar ice and Glaciers 4. Ground water Select the correct answer from the code given below :
- (a)1, 3, 4, 2
- (b)1, 2, 3, 4
- (c)1, 2, 4, 3
- (d)1, 4, 3, 2
Correct — A, 1, 3, 4, 2 — that is Oceans, then Polar ice and Glaciers, then Ground water, then Rivers. The oceans dominate the hydrosphere so completely that nothing else is close: about 1,338 million cubic kilometres of water, roughly 96.5 per cent of all the water on Earth. Ice caps, glaciers and permanent snow come second at about 24.4 million cubic km (about 1.76 per cent), and groundwater follows very closely at about 23.4 million cubic km (about 1.69 per cent) — a gap of well under a tenth of a percentage point, which is precisely what makes this a testable ordering. Rivers finish last and are not in the same league as anything above them: all the water flowing in the world's river channels at any given moment adds up to only about 2,120 cubic km, roughly 0.0002 per cent of the global total. So the descending sequence is 1, 3, 4, 2.
- (b)1, 2, 3, 4 — This puts Rivers second, immediately after the oceans. Rivers are in fact the smallest of the four stores by a huge margin — about 2,120 cubic km against roughly 24 million cubic km in ice and 23 million cubic km in groundwater. River water is small in volume precisely because it is fast-moving: it is the flow that matters, not the standing stock.
- (c)1, 2, 4, 3 — Wrong at both ends of the sequence. It again promotes Rivers to second place, and it pushes Polar ice and Glaciers down to last — yet ice and snow are the single largest store of water after the oceans and hold roughly 68 per cent of all the fresh water on Earth.
- (d)1, 4, 3, 2 — The near-miss, and the option most candidates lose the mark to. It gets the first and last places right but swaps the middle two, placing Ground water above Polar ice and Glaciers. The volumes are genuinely close (about 1.69 per cent versus about 1.76 per cent of all water), but ice still edges ahead — and the margin widens if you count only fresh water, where glaciers hold about 69 per cent against groundwater's roughly 30 per cent.
The hydrosphere holds roughly 1.386 billion cubic kilometres of water, and it is distributed with extreme unevenness. About 96.5 per cent sits in the oceans as salt water. Of the small remainder, most is not available to us: it is locked in polar ice caps, glaciers and permanent snow, or stored deep underground as groundwater (a large part of which is itself saline). Surface fresh water in lakes, rivers, swamps, soil moisture and the atmosphere together account for a tiny sliver of the total, and rivers — the water humans most obviously live off — are the smallest slice of all.
Ordering questions on world water supply are decided by two facts and one trap. The two facts: oceans always first, rivers always last. The trap sits in the middle, between ice and groundwater, where the two shares are only about 1.76 per cent and 1.69 per cent — close enough that a candidate who has memorised 'groundwater is huge' will invert them. The safe way to reason is by scale of magnitude rather than by exact figure: oceans are of the order of 10^9 cubic km, ice and groundwater of the order of 10^7 cubic km, and rivers only of the order of 10^3 cubic km. Once you see that rivers are four orders of magnitude below ice and groundwater, options (b) and (c) fall away instantly and the paper reduces to a straight choice between (a) and (d).
- Oceans hold about 1,338 million cubic km of water — roughly 96.5 per cent of all water on Earth
- Ice caps, glaciers and permanent snow store about 24.4 million cubic km (about 1.76 per cent of all water) — the second largest reservoir
- Groundwater totals about 23.4 million cubic km (about 1.69 per cent), of which only about 0.76 per cent of global water is fresh groundwater and about 0.93 per cent is saline
- All the world's rivers together carry only about 2,120 cubic km at any instant — about 0.0002 per cent of global water; lakes hold about 176,400 cubic km
- Of the fresh water alone, roughly 69 per cent is frozen in ice and glaciers and about 30 per cent is groundwater, leaving under 1 per cent as accessible surface fresh water
Answer (a) 1, 3, 4, 2. The two highlighted rows are what the question actually turns on — ice (about 1.76%) narrowly beats groundwater (about 1.69%), which is why (d) is wrong. Rivers being last is what eliminates (b) and (c).
- Ranking groundwater above polar ice — the shares are close (about 1.69 vs 1.76 per cent) but ice wins on both the all-water and the fresh-water measure
- Assuming rivers must be large because they are the visible source of most human water use; their standing volume is minuscule, it is their rapid turnover that matters
- Mixing the 'share of all water' frame with the 'share of fresh water' frame — the ordering here happens to survive both, but the percentages are entirely different
UPPSC prefers the ordering or sequence wrapper — arrange these reservoirs in ascending or descending order — while UPSC has asked the same distribution as a two-statement comparison (2021) or as a 'largest proportion of the remaining fresh water' single-choice (2013).
With reference to the water on the planet Earth, consider the following statements: 1. The amount of water in the rivers and lakes is more than the amount of groundwater. 2. The amount of water in polar ice caps and glaciers is more than the amount of groundwater. Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer(b) 2 only
The same ranking, asked as statements instead of an ordering. UPSC's key confirms both halves of what decides this UPPSC item: rivers and lakes hold LESS than groundwater (so rivers cannot come second), and polar ice caps and glaciers hold MORE than groundwater (so ice must rank above groundwater).
On the planet Earth, most of the freshwater exists as ice caps and glaciers. Out of the remaining freshwater, the largest proportion
- (a) is found in the atmosphere as moisture and clouds
- (b) is found in freshwater lakes and rivers
- (c) exists as groundwater
- (d) exists as soil moisture
Answer(c) exists as groundwater
The next rung of the same ladder. Once ice and glaciers are set aside, groundwater is the largest remaining store — which is exactly why the UPPSC sequence runs ice, then groundwater, then rivers.
Consider the following statements: 1. On the planet Earth, the fresh water available for use amounts to about less than 1% of the total water found. 2. Of the total fresh water found on the planet Earth 95% is bound up in polar ice caps and glaciers. Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer(a) 1 only
The scale half of the same topic: usable fresh water is under 1 per cent of all water, and the '95 per cent locked in ice' figure in its second statement is an overstatement of the roughly 69 per cent that is actually correct — useful calibration for the percentages this question is built on.
- practice — not a real PYQ
Approximately what proportion of the total water found on Earth is fresh water?
- (a)About 2.5 per cent
- (b)About 10 per cent
- (c)About 25 per cent
- (d)About 45 per cent
Answer(a) About 2.5 per cent — the other roughly 97.5 per cent is saline, overwhelmingly in the oceans, and most of the fresh share is locked in ice or underground.
- practice — not a real PYQ
Which one of the following holds the largest share of the Earth's FRESH water?
- (a)Rivers and lakes
- (b)Soil moisture
- (c)Glaciers, ice caps and permanent snow
- (d)Groundwater
Answer(c) Glaciers, ice caps and permanent snow — they hold roughly 69 per cent of fresh water, with groundwater next at about 30 per cent.