Theory:

    It was on such a day — a hot, tired day — that Ranji found the pool in the forest. The water had a gentle translucency, and you could see the smooth round pebbles at the bottom of the pool. A small stream emerged from a cluster of rocks to feed the pool. During the monsoon, this stream would be a gushing torrent, cascading down from the hills, but during the summer, it was barely a trickle. The rocks, however, held the water in the pool, and it did not dry up like the pools in the plains.
Explanation:

The narrator later revealed to his audience how Ranji discovered the forest pool. Ranji had come across a pool in the jungle on a hot, exhausting day while wandering through it. In the meantime, the narrator described the pool's cleanliness and appearance. The pool's water was so clear that one could see the small rounded pebbles covering the pool's bottom. It implies that the pool looked very clean without any impurities in it. The reason behind the pool's freshness was because the water oozed out from the rocks.
 
Later, the narrator mentioned how the pools got filled and from where the water comes to the pool. At first, the water comes out from the cluster of rocks, and then a stream emerges and forms into a pool. In this paragraph, the narrator used the phrase "feed" to describe how water from the stream fills the pool. In addition, the narrator stated that the small stream was helping the pool to fill water in it.

Furthermore, the narrator stated that the water in the same stream flows suddenly or violently during the rainy season, and the water flows down from the cluster of rocks like a waterfall. On the other hand, during the summer season, there was only a thin flow of water. It implies that the water flows from the hill remain slow during the summer season, whereas during the rainy season, the water flows from the hill as if cascading from a massive waterfall. At last, the narrator claimed that the rocks preserved the water in the pool, and it did not dry out like the other pools in the plains. It implies that the water in the forest pool did not drain as the pools in the plains.
 
waterfall.png
Water oozed out from the cluster of rocks
 
Meanings of the difficult words:
 
S.No
Words
Meanings
1
TranslucentSomething possible to see clearly
2
PlainA large area of flat land with few trees
3
Pebble A small stone made smooth and round by the action of water or sand
4
Bottom The lowest point or part of something
5
Stream A small, narrow river
6
EmergeTo appear by coming out of something or out from behind something
7
MonsoonThe season of heavy rain, the wind that brings rain, or the heavy rain that falls during the summer in hot Asian countries
8
Gushing Flowing forth suddenly or violently
9
TorrentRushing stream of water
10
Cascading Coming down like a waterfall
11
TrickleWeak or thin flow of water
Reference:
National Council of Educational Research and Training (2008). It so happened. The Fight- Ruskin Bond (pp. 45-54). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.