Previous Year Question
Consider the following sources of world water supply and arrange them in descending order.
Oceans
Rivers
Polar ice and Glaciers
Ground water
Select the correct answer from the code given below:
1, 3, 4, 2
1, 2, 4, 3
1, 2, 3, 4
1, 4, 3, 2
Correct Answer: A
Detailed Solution
The correct descending order is—Oceans → Polar ice and Glaciers → Ground water → Rivers.
The overwhelming majority of the Earth's total water is stored in oceans, seas and bays. They contain approximately 96.54% of the total global water, making the oceans the largest water reservoir on Earth.
Next come ice caps, glaciers and permanent snow, which contain approximately 1.74% of the Earth's total water. In terms of volume, this is about 24.064 million km³ of water. Considering freshwater alone, approximately 68.7% is locked in ice caps and glaciers.
Groundwater contains approximately 1.69% of total global water, amounting to nearly 23.4 million km³. This includes both fresh and saline groundwater. Fresh groundwater alone constitutes about 30.1% of the Earth's total freshwater.
In contrast, the quantity of water stored in rivers is extremely small. Rivers contain approximately 2,120 km³ of water, which is only about 0.0002% of the Earth's total water. Despite this small quantity, rivers are extremely important for human use because they provide readily accessible freshwater.