The Relief Regions and Drainage of Africa

The Relief Regions and Drainage of Africa

Introduction
The African continent has varied relief regions and drainage features that influence the way people carry out activities on a daily basis. The major landforms in Africa are; coastal plains, high plateau, low plateau lands, rift valley, basins and mountains. It also consists of drainage features for example oceans, seas, lakes and rivers. In this chapter you are going to study the relief regions of Africa, the major landforms and drainage features, understand how they were formed and the effects of the relief and drainage on development.
The Major Relief Regions of Africa
In Senior One, you learnt about the relief regions of East Africa where you probably noted that it has varied relief. You discuss them. When you look around your community or area around your school you will realise that it is also made up of different aspects of relief. Africa is also made up of such regions. After doing tasks in activity 21.1 you will find out more about Africa’s relief regions and the size covered by each.

Activity 21.1
Exploring the relief regions of Africa
In groups, carry out a textbook or internet research and do the tasks that follow.
1 On a manila or other paper draw a map of Africa and on it mark and label the major relief regions.
2 Describe the relief region labelled on the map including its position and characteristics.
3 Study table 21.1 showing the approximate sizes of Africa’s major relief regions and then do the tasks that follow.
Table 21.1 Approximate sizes of Africa’s major relief regions

(a) Calculate the approximate area covered by the plateaus in Africa.
(b) State the largest and smallest relief region of Africa.
(c) Identify where each of the relief region is found.
(d) What is the dominant type of relief in the area where you live or the area where I your school is located?
4 Present your work to the teacher for further guidance.

From activity 21.1 you have learnt that Africa has varied relief regions. You have also learnt that these relief regions cover different areas whereby some are larger than others. Some relief regions are dominant in particular parts of Africa than others. The plateau covers the largest area, it is divided into the low plateau and the high plateau. The low plateau has an average height of 900 metres above sea level
but can rise to 1200 metres above sea level in some areas.
It is found in areas of Ahaggar, Tibesti, Fouta Djalon and Ennedi. The high plateau lands are found in the eastern and southern areas of the continent. Examples include the Ethiopian plateau, East African plateau, Zimbabwen veld and the Drakensburg. It important is to note that these plateau lands are not continuous
but some are separated by basins.

Formation of Landforms in Africa
In Senior One, you learnt about landforms where you noted that they are natural features found on the earth’s surface. Name some landforms that you remember. You also learnt about the different processes responsible for the formation of different landforms. You can name them and discuss with your neighbor.
In chapter eight, you also learnt about plate tectonics and how they lead to the formation of landforms in East Africa. You also learnt that the Earth is a combination of various land masses, called tectonic plates.
These plates are constantly moving and they tend to collide with each other.

The collusion usually causes the land to fold between them, leading it to rise above the surface and form a fold mountain. After doing tasks in activity 21.2 you will be able to
find out the effect of plate tectonism on relief in Africa.

Activity 21.2
Movement of tectonic plates and its effect on relief
In groups,
1.Get a suitable material like manila, other foldable paper or thin sponge mattress and do the tasks that follow.
2.Cut the paper about 30 cm by 5 cm dimension.
3.Place the paper on a flat table or ground.
4.Let two volunteers push from either side towards the centre. Note and record what happens to the material.
5.Repeat the process in 1-3, this time one limb of the material pushing below the other. Again, describe what you have observed and draw a diagram to represent it.
6. What were the two illustrations representing?
7.Present your work to the rest of the class through a discussion.

You have learnt that tectonic forces led to the splitting of the current continents. This process still occurs accompanied by earth quakes and volcanic eruptions. The rift valley in Africa was formed through the same process.
The rift valleys demarcate the zones where plate movements continue. Africa thus acquired rings of escarpments, rifts, rivers, lakes as well as interior basins. Have you ever been to an area with a mountain? A large area of Africa is covered by mountains of different categories. After doing tasks in activity 21.3, you will be able to
learn about the categories of mountains and the processes responsible for their formation.

Activity 21.3
Exploring the major mountains of Africa
In pairs, use wall maps, atlas maps and carry out a textbook or internet research and do the tasks that follow.
1 Draw a sketch map to show the distribution of major mountains in Africa.
2 Draw a table in your notebook and classify the mountains according to their modes of formation.
3 Classify the mountains and indicate the country in which each class is found as in table 21.2.
Table 21.2 Categories of mountains in Africa

4 Present your work to the rest of the class through a discussion.
You have found out that Africa is made up of different types of mountains such as block mountains, volcanic mountains and folded mountains. The mountains of Africa are classified according to their mode of formation for example fold mountains result from folding, volcanic mountains from volcanicity
and block mountains from faulting. After doing tasks in activity 21.4, you will understand how these mountains were formed.

Activity 21.4
Describing the formation process of African mountains
In groups, study photographs A-C in figure 21.1, and do the tasks that follow.

1.Identify which of the photographs A-C in figure 21.2 shows
(a) Block Mountain
(b) Volcanic Mountain
(c) A folded mountain
2.With the aid of diagrams, describe the formation process of the following types of mountains.
(a) Block Mountain
(c) Fold mountain
(b) Volcanic Mountain
3.Describe the main characteristics of each type of mountain
4.Present your work to the rest of the class through a discussion.

You have learnt that highlands and mountains lie at an altitude above 2000 metres. Major highlands in Africa are; Ethiopian Highlands, East African Highlands and West African Highlands. The mountains of Africa are also distributed across the continent. Block Mountains and volcanic mountains are formed as a result of tectonic processes which involve compression, tension, uplifting and vulcanicity.

Did you know that the great rift valley runs from the Red sea in the north, through Ethiopia, Kenya, Tanzania and Malawi and extends southwards to Beira in mozambique? The great rift valley in East Africa is made up of two branches that is the western branch known as Albertine rift along the boarder of Tanzania and Uganda and the main branch which is the Eastern known as the Gregory rift valley. Photographs A and B in figure 21.2 show part of the Great African Rift Valley. After doing tasks in activity 21.5 you will learn more about the African Great rift valley.

Activity 21.5
Describing the formation of the Rift Valley
In pairs, carry out a textbook or internet research and do the tasks that follow.
1 With the aid of diagrams, describe the formation of the rift valley.
2 Identify the characteristics of the rift valley.
3 Write your findings in your notebooks.
4 Swap your work with another pair for comments.
5 Present your work to the rest of the class through a discussion.

You have found out that the rift valley was formed due to splitting of rocks in the earth’s crust. Forces within the crust pulled or pushed the rocks making them crack. The cracks caused weaknesses on the rocks. These cracks are known as faults. When the rocks are pushed together or pulled apart, they break easily in a process known as faulting. The Great Rift Valley was formed through faulting.
The land was pulled apart by forces of tension which pull away from one another, causing the middle part to sink lower than the neighbouring parts. This resulted into a depression in the middle. The depression formed a valley. As the land sunk, it formed steps on the sides of the valley. These steps are known as fault scarps. The sides of the valley are known as escarpments.
In your communities or areas around your school, you might have seen a depression or a dip. This is called a basin. Basins are shaped like bowls, with sides higher

than the bottom. They can be oval or circular in shape, similar to a sink or tub you might have in your bathroom. Some are filled with water. Figure 21.3 shows a basin.

After doing tasks in activity 21.6 you will understand more about basins
Activity 21.6
Describing the formation of basins
Carry out a textbook or internet research and do the tasks that follow.
1. With the aid of diagrams, describe the formation of basins.
2. Identify the characteristics of basins.
3. Write your findings in your notebooks.
4. Present your work to the rest of the class through a discussion.
Comment on each other’s work and make corrections if necessary.

You have learnt that much of Africa consists of very old rocks. The old rocks have become important bases of these basins. Basins in Africa are widespread. There are several types of basins. Some are above sea level and are bordered by mountains such as the Lake Victoria basin, others are filled with sediments and have
external drainage such as the Congo basin. Others are basins of inland drainage such as the Chad basin. The biggest basin is the Congo basin. Discuss with your neighbour other examples of basins in Africa.

Effects of landforms
You have realised that landforms are found on the surface of the earth. They can be categorized as relief features like mountains, hills, highlands, plateaus, depressions, basins, valleys, escarpments and plains.
Have you ever gone to a place that has been affected by a natural disaster or seen one in a photograph or television? Such a disaster is called a hazard. What hazard was it? Where did it take place?
Hazards affect lives of people whenever and wherever they occur and are related to landforms. After doing tasks in activities 21.7 and 21.8 you will find out how landforms affect people where they are found.

Activity 21.7
Finding out the influence of landforms on humans
In groups, move around your school or community and do the tasks that follow;
1 Identify the major landforms and types of land use in the area.
2 Draw a map of the area covered and on it mark and label the landforms you have identified.
3 Explain the influence of landforms on land use in the area.
4 Explain the impact of human activities on landforms in the area.
5 Write a report about your findings.
6 Present your report to the rest of the class through discussion.
Activity 21.8
Finding out the effects of landforms
In groups, study photographs A-F in figure 21.4 and do the tasks that follow.

1.Describe what is taking place in the photographs in figure 21.4.
2.How do landforms influence what you have described 1 above?
3.Discuss other effects of physical features to the people in the area in which they are located.
4.Present your work to the rest of class through a discussion.
5.Make corrections in your work where necessary.

You have learnt that landforms have a great impact on development as well as the environment. Landforms have an influence on the environment and human activities such as agriculture and transport systems. They also influence tourism and mining activities. You have also learnt that even though landforms are beneficial to the people, they have a number of negative impacts which lead to destruction of property, displacement and death. Landforms are barriers to construction of transport routes.
Some landforms lead to soil erosion and others are obstacles to settlement.
Case Study
You could have noted that Kenya experiences a number of natural hazards, the most common being weather and climate related, including floods, droughts, landslides, lightening/ thunderstorms, wild fires, and strong winds. These in most cases do occur due to the landscape of the areas where they happen.
In the recent past these hazards have increased in number, frequency and complexity. The level of destruction has also become more severe with more deaths of people and animals, destruction of infrastructure among other effects.

Study table 21.3 showing natural hazards, physical features which lead to such hazards,
areas mostly affected by those hazards and their effects on people’s lives.

Table 21.3: Natural hazards, physical features which lead to such hazards, areas mostly affected by those hazards and their effects on people’s lives

Other countries in East Africa have similar and more natural hazards, physical features which lead to such hazards, areas mostly affected by those hazards and their effects on people’s lives. You will understand more about hazards after doing tasks in activity 21.9.

Exploring natural hazards in East Africa through case studies
Activity 21.9
Basing on the case study provided, carry out a text book or internet research on
the following countries.
(a) Uganda (b) Tanzania
Find out;
1. Natural hazards that occur.
2 Physical features where they occur
3 Areas mostly affected
4 Effects of the natural hazards on people’s lives

You have learnt that natural hazards are extreme natural events that can cause loss of life, extreme damage to property and disrupt human activities. They include earthquakes, volcanic explosions, flooding, drought, tropical storms
The drainage of Africa
In senior one, you learnt about drainage of East Africa. Africa has major drainage features distributed all over the continent. Drainage features like rivers and lakes are very important to people of Africa. Figure
21.6 shows some of the drainage features in Africa. After doing tasks in activity 21.10, you will learn about the location of the major rivers and lakes of Africa.

Activity 21.10
Map showing the distribution of major rivers and lakes in Africa
Study the map of Africa in Figure 21.7 and do the tasks that follow.

Figure 21.6: Africa
1.Copy the map in figure 21.7 in your notebook and on it mark and label the;
(c) seas and oceans
(b) lakes
(a) rivers
2.Using knowledge gained in Senior One explain how lakes were formed
3.Exchange your work with your neighbour and comment on each other’s work.
4.Make corrections in your work where necessary.

Importance of rivers and lakes to development of Africa
Do you live or have you ever lived near a river or lake? Or do you have relatives or friends who live near or by the river or lake side? Rivers and lakes play a great role towards the economic development of places. After doing tasks in activity

21.11, you will be able to find out more about benefits of rivers and lakes.
Discovering the importance of lakes and rivers to development In groups, study photographs A-D in figure 21.8 and do the tasks that follow.

I.Identify the human activities taking place in photographs A-D in figure 21.8
2.Other than the activities in photographs in figure 21.8, describe how else rivers and lakes benefit the people of Africa.
3.Present your work in class for discussion.
4.Make corrections in your work where necessary.

You have learnt that lakes and rivers are important to Africa because they; help in development of hydroelectric power, provide water supply for the purpose of irrigation, provide fresh water for drinking, industries and factories use river and lake water for their functioning, they act as tourist attraction sites, they are used in navigation and help to develop the fisheries.

Problems the people of Africa face when using lakes and rive
In activity 21.11 you learnt that lakes and rivers are of great importance to the people Of Africa. However, it is important to note that people face a number of problems while using lakes and rivers as you will discover after doing tasks in activity 21.12

Activity 21.12Understanding the problems the people of Africa face in using lakes and rivers
In groups, study photographs A-D in figure 21.9 and do the tasks that follow.

1 Identify the problems faced while using lakes and rivers in Africas shown in figure 21.9.
2 Suggest other problems that the people of Africa face in using rivers and lakes.
3 Present your work to the rest of the class through a discussion
How water resources are used and controlled
Water resources are important but irresponsible use of water resources can lead to their destruction in many ways. Find out in which ways this happens in your community and in Africa. In activity 21.13 you will find out how water resources are controlled.

Activity 21.13 Understanding how water resources are used and
controlled in Africa
In pairs, carry out a textbook or internet research and do the following tasks
1 Make a list of the major water resources in Africa.
2 Describe how each resource you have listed is used.
3 How is each water resource controlled?
4 Exchange your work with other pairs and comment on each other’s work.
5 Make corrections in your work where necessary.
You have realised that Africa has a number of water resources ranging from water itself, fish, vegetation and sand. People have used these resources for different purposes. Water resources are important for fishing, providing water for irrigation, industrial and domestic use.

Chapter Summary
In this chapter you have learnt that;
there are different types of landforms which include; mountains, plateaux, rift
valleys and hills, drainage features like lakes, rivers and basins,
the mountains of Africa are distributed across the continent. There are three major categories; Fold Mountains, Block Mountains and Volcanic Mountains.
there are different processes responsible for the formation of different landforms which include faulting, folding, vulcanicity and volcanicity.
many areas in Africa contain very old rocks that are not very good for soil formation but rich in minerals.
the landforms affect development, including agriculture and mining.
rivers and lakes help in the formation of rainfall, tourism, water transportation,
generating hydro electric power, fishing and habitants for water animals.
a number of negative impacts which lead to destruction of property, displacement and death of people.
the physical features affect the lives of people in different areas of East Africa.
you can use field work to study any of the physical features in the local area.