Question

What are rivers? Also explain the various stages in the course of a river. Also state its importance.

Answer 1

Instruction:

• Define river. (1 mark)
• Explain the three stages in the course of a river. (3 marks)
• Importance of rivers on human civilisation. (1 mark)

Answer:
A river is a channel of water, usually flowing from highland to lowland and finally meets a lake or sea. The place from where a river starts, is called the Source of the river while the place where a river meets a lake or sea is called its mouth.
Stages in course of river

• Upper stage - usually involves the source of a river like a lake or glacier, which is in a highland like mountainous areas, from here the river starts flowing down with great speed. It also carries a huge amount of sediments with it because of valley formation.
• Middle stage - river enters in the plain areas which has a very gentle slope, so the speed of the river decreases in this stage. And with decreasing speed, the river cannot carry this huge amount of sediments, so it starts depositing these particles on the sides and bottom of the seabed. Meanders and ox-bow lakes are features of this stage.
• Lower stage - In this stage, the speed of the river further reduces and becomes difficult for the river to move with these sediments. So huge deposits are made here called alluvium, and because of these deposits and slow speed, the river cannot continue ahead, so it gets divided into many smaller rivers known as Distributaries. Delta formation is a feature of this stage.

Historically, river plains, that is area near a river, are ideal places for habitation and many people live in these river plains because these areas are suitable for agriculture, industries also need water and most importantly, people can get freshwater for drinking and other domestic purposes on a regular basis. So near river plains the population density is high.