Q.Which one of the following rivers was known as the 'Sorrow of Bengal'?

Think of a river not as a single line on a map, but as a whole family. When you stand on a bridge and watch water flow past, you are seeing only the youngest, most visible member of that family. The river you see is fed by smaller streams, which are fed by even smaller rivulets, which begin as rainwater soaking into a hillside or melting snow on a distant peak. That entire network — from the tiniest trickle to the wide, slow channel near the sea — is the river system. It is the river plus every stream, tributary, and seasonal channel that ever delivers water to it.

The everyday intuition is simple: a river system is like the veins in a leaf. The main vein is the trunk river, the side veins are its tributaries, and the fine network between them is the countless small streams that only flow after rain. Just as a leaf’s veins all carry sap toward the stem, a river system carries water and sediment from higher ground toward a lake, a sea, or an ocean. The whole thing works because of gravity — water always moves downhill, and it carves its own path as it goes.

Now the precise meaning. A river system is the entire drainage network of a river, including its main channel, all its tributaries (streams that join it), and the entire area of land that feeds it — that area is called the catchment or drainage basin. The boundary between two neighbouring basins is a watershed or divide, which is simply the ridge of higher land that sends rain on one side to one river and rain on the other side to a different river. So when a geographer speaks of a river system, they are really speaking of a whole landscape: the hills that collect rain, the valleys that guide it, and the single channel that finally delivers it to the sea.

Why does this matter? Because a river system is not just water — it is a moving conveyor belt of soil, sand, and dissolved minerals. As the river flows, it erodes the land, carries the eroded material downstream, and deposits it where the current slows. That is how floodplains, deltas, and fertile agricultural land are formed. For a humanities or commerce student, the practical consequences are everywhere: cities grow where rivers meet the sea because trade and transport are easy; farms thrive on river plains because the soil is renewed by floods; and disputes between states or countries often arise over who gets to use the water of a shared river system. The river is not scenery — it is infrastructure, economy, and politics rolled into one moving body of water.

A few things to hold onto:

• Tributary — a smaller stream that joins a larger river. The point where they meet is a confluence.
• Distributary — a channel that branches away from the main river, common near the delta where the river splits before entering the sea.
• Drainage basin — the entire land area drained by a river and its tributaries. Think of it as the river’s “territory.”
• Watershed — the high ground that separates two drainage basins. Rain falling on one side of the watershed goes to one river; rain on the other side goes to a different one.
• River regime — the pattern of how a river’s flow changes through the year, depending on rainfall, snowmelt, and seasons.