Question

Explain the work of a river.

Answer 1

Hint: A river has three basic functions: erosion, transportation and deposition. It is the combination of these three processes that lead to the formation of various landforms by the action of a river.

Complete answer: 

The erosional work of streams/rivers carves and shapes the landscape through which they flow. Load carried by a river will grind against its bed and sides. This process slowly wears the bed and sides away. When thrown against the sides and bed of rivers, the load gets broken into smaller pieces.

The running water of the river erodes the earth's surface resulting in the formation of different landforms with the help of several other factors. When the river falls at a steep angle over very hard rocks or down a deep valley side it results in the formation of a waterfall. While the river enters the plain it twists and turns forming large bends which are referred to as meanders. Due to the  routine erosion and deposition along the edges of a meander, the ends of the meander loop come closer and closer.

In due course of time the meander loop cuts off from the main river and forms a cut-off lake, which is also known as an ox-bow lake. Sometimes, the river overflows the banks causing flood in the neighboring areas. As it floods, it  also deposits the layers of fine soil and other material called sediments along its banks. This results in the formation of a fertile floodplain. The raised banks on each side of the river  are known as levees.

When the river approaches a sea, the speed of the flowing water decreases, and therefore the river starts to interrupt up into several streams referred to as distributaries. Then there  comes a time when the river becomes very slow and it starts to deposit its load. Each distributary forms its own mouth and therefore the sediments collected from all the mouths forms a delta, which may be a triangular landmass.

Note: There are different landforms formed by the action of a river. There are landforms that are formed as the result of the erosion process. Alternatively, there are also landforms that are formed as the result of deposition.