Back to: Primary seven social studies notes sst

THE DRAINAGE SYSTEM OF AFRICA

 Drainage is the water ground system of an area.

-The following are the main features of drainage features:

• Drainage basins         
•  Lakes
•  Rivers
•  Swamps

RIVERS:

1. A river is a mass of flowing water
2. Tributary is a small river that flows into the main river.
3. Distributary is a small river that flows away from the main river.
4. Source is where a river starts flowing.
5. Mouth is where a river pours its water.
6. Confluence is where two or more rivers meet.
7. Course is the direction a river moves in.
8. Watershed is a line of highland separating two streams which flow into different rivers.
9. River bank is a side of a river.
10. Estuary is where a river widens as it reaches its mouth.
11. Delta is where a river forms several streams as it ends its course.

Rivers of Africa:

Africa is drained by many rivers.

The rivers are in two types.

1. Perennial or permanent rivers
2. Seasonal rivers

 -Perennial rivers: are rivers that flow throughout the year.

-Seasonal rivers: are rivers that flow mainly during the rainy season.

Examples of seasonal rivers:

• i)       R. Agago – Uganda
• ii)      R. Turkwel – Kenya Major rivers in Africa:

Major rivers in Africa:

-Rivers originate from the following features;

• i)             Lakes                                                  
• ii)         Highlands
• iii)            Melting snow / Glaciers                 
• iv)        Springs

Stages of a river:

•  A river has three stages / courses
• Upper course / Youth stage
•  Middle course
•  Lower course / old stage

Characteristics of Upper course:

•  -Waterfalls and rapids are formed.
•  -The river is narrow.
•  -The river is so destructive with gorges formed.
•  -The river forms steep slopes.
•  -The river erodes down wards.
•  -The river flows zig zag course.

Characteristics of the middle course:                                                                           –

•  -The river is wide.
•  -It carries many objects.
•  -It erodes its sides.
•  -It begins to form meanders.
•  -It has large amount of water.                                                                                                        

Characteristics of the lower course:

•  -Ox-bow lakes are formed.
•  -The rivers form deltas.

Waterfalls:

•  -Waterfall is where flowing water in a river falls from high altitude to low altitude.
•  -Waterfalls are formed when water flows over a cliff (steep slope) or hard rock.

Importance of waterfalls:

•  -They are used to generate hydro electricity.
•  -They attract tourists who bring income
•  -They are used for rafting

Economic importance of rivers

•  -They attract tourist for income.
•  -They help to generate hydro electricity power.
•  -They provide fish to people.
•  -They provide water for industrial use.
•  -They provide water for irrigation.
• -Some rivers are used for transport. Other uses of rivers
•  -They help in the formation of rainfall.
•  -They are used for recreation.
•  -They provide materials for craft work.
•  -They have fertile soils for farming.
•  -They provide water for domestic use.

Questions:

1. Why do many rivers in East Africa flow towards Indian Ocean?
2. Give two reasons why most rivers have their source in mountain areas.
3. In which way do rivers influence human settlement?
4. Give two reasons why R.Congo drains a lot of water into Atlantic Ocean.
5. In which way can rivers be a disadvantage to people?
6. Give three reasons why some rivers are not used for transport?
7. Give two reasons why it is believed that early civilization started along river valleys.
8. Mention three problems faced by rivers in Africa.
9. In which way do rivers influence the way of living of:
   1. Animals
   2. Plants

10.            How do rivers promote industrial development?