Q.57 When the precipitation of a storm reaches the ground, it must fill up a basin, which is lower than its surroundings, before it can flow over the surface. The volume of water trapped in the basin, which is lower than its surroundings, is called
- Abasin storage
- Bdepression storageCorrect
- Cdead storage
- Dsub-surface storage
Solution
Concept
Water held in small low areas (depressions) of the ground before surface flow starts is called depression storage.
Step-by-step solution
1. Rain falls on the ground. 2. Some water fills small low pockets (depressions) on the ground surface. 3. Only after these pockets are full does overland flow start. 4. This trapped water is called depression storage. 5. Answer is (B).
Explanation
When rain falls, small low areas on the ground must fill first before water can flow over the surface. The water stored in these low areas is called depression storage. It is one of the losses (abstractions) from rainfall, and it later evaporates or infiltrates.
Why the other options are wrong
(A) Basin storage is not the standard term for this loss. (C) Dead storage is the reservoir volume below the minimum outlet level. (D) Sub-surface storage is water stored below the ground surface, not in surface depressions.
Shortcut
Low pockets on the ground = Depressions = Depression storage.
Common mistake
Confusing it with dead storage of a reservoir, or picking basin storage because the question uses the word 'basin'.
Correct answer: B) depression storage