Geography

Topic area: Physical Geography
Sub-topic area: Drainage
Key unit competence
 By the end of this unit, you should be able to describe the drainage system of Rwanda and explain its relationship to human activities.
Unit objectives
By the end of this unit, you should be able to:
• Describe the drainage system of Rwanda.
 • List major rivers, lakes and swamps in Rwanda.
• Describe the relationship between drainage and human activities in Rwanda.
Drainage system in Rwanda
Activity 8.1
1. Name three sources of water in Rwanda.
2. State where the rain water that is not tapped by humans goes to.
 3. Name three examples of water bodies that are found in Rwanda.
 4 Discuss the importance of the water bodies that are found in Rwanda.
5. Using information from the internet and other geographical documents, describe the drainage of Rwanda
The term drainage refers to the distribution of water on the surface of the Earth. Surface water in Rwanda is distributed in rivers, lakes and wetlands such as swamps. Drainage systems are patterns formed by the streams, rivers and lakes in a particular drainage basin. The drainage pattern is determined by the topography of the land, types of rocks on the land and the gradient of the land.
A drainage basin is an area of land drained by a river and its tributaries. A river and its tributaries are referred to as a river system. A river system includes water found in the water table and surface run-off. There is an imaginary line separating drainage basins called a watershed. Usually, this is a ridge of high land.
The formation of the majority of Rwanda’s rivers is traced far back during the earth movements. Before the major mountains and the rift valley were formed, many rivers in Rwanda took the northern and western directions of flow. They flowed through the Democratic Republic of Congo on to the Atlantic Ocean.
When volcanic mountains and the Rift Valley were formed, the previous basins were destroyed. This destruction ended up forming two big river basins that were formed due to river reversal there were:
(a) Congo basin
(b) Nile basin
 A river reversal refers to the change of a river’s direction of flow due to an obstacle. For example, River Akagera used to flow through the DRC emptying its water into the Atlantic Ocean. However, after the uplift of the Congo Nile Crest, it changed its direction eastward and began flowing towards the Lake Victoria basin in the central part of Uganda where there was down warping, hence getting a new mouth at Lake Victoria. River Akagera reversed and started pouring water into Lake Victoria basin.
The Congo basin consists of short rivers that flow into Lake Kivu. The lake has River Rusizi as its outlet as it flows into Lake Tanganyika. The Nile basin covers most of Rwanda. It has rivers that originate from the Congo-Nile ridge. Rivers Akanyaru and Nyabarongo flow eastwards and join to form River Akagera which flows into Lake Victoria in Central Uganda where the Nile River begins from.


Major rivers, lakes and swamps in Rwanda
Activity 8.2
Work in groups of three.
1. Giving examples, differentiate between the following water bodies;
(i) Rivers
(ii) Lakes
 (iii)Swamps
2. Write down your findings and present them in a class discussion.
Rwanda’s drainage consists of rivers, lakes and swamps.
(a) Major rivers
They include;
 (i) River Nyabarongo and its tributaries (Mwogo,Mbirurume, Nyabugogo, Satinsyi, Base, Akanyaru, Rukarara and Mukungwa.)
(ii) River Akagera with its tributaries (Ruvubu, Muvumba, Kibaya and Kagogo.)
 (iii) River Pfunda
(iv) River Sebeya
 (v) River Koko
(vi) River Karundura
(vii) River Rusizi and its tributaries (Ruhwa and Rubyiro)

(b) Major lakes
 They include;
(i) Lake Kivu in the Western Province.
 (ii) Lakes Burera and Ruhondo in the Northern Province.
 (iii)Lakes Muhazi, Mugesera, Sake, Rweru, Cyohoha, Ihema, Nasho and Hago in the Eastern Province.
                           
(c) Major swamps
They include;
(i) Rugezi in Burera district.
(ii) Kamiranzovu in Nyungwe Forest.
 (iii) Along Rivers Akagera, Akanyaru and Nyabarongo.
                         
Task 8.1
1. Define;
 (a) Drainage
 (b) Drainage basin
. 2. Mention the main:
 (a) Lakes
(b) Rivers
 (c) Swamps of Rwanda.
Major rivers of Rwanda and drainage basins
Activity 8.3
Work in pairs. Use the Internet and your knowledge from the local environment.
1. Find out the major water bodies of Rwanda.
2. Write down your findings and present them in a class presentation.
Activity 8.4
Work in pairs.
Study the table below and fill in the missing information.


As earlier discussed, there are two drainage basins in Rwanda. The drainage basins are discussed in association with the river basin they occupy
(a) Congo basin
The rivers found in this river basin are those whose direction of flow was changed by the Earth’s movements. They started pouring into Lake Kivu. They include rivers listed in the following table.
                              
(b) Nile basin
This covers a larger area than the Congo basin. It starts from the eastern part of the Congo Nile Crest, extending towards the Eastern part of Rwanda. Rivers that are found within this basin include the following. (i) River Nyabarongo and its tributaries which include:
 • The Rukarara River
 • The Mbirurume River
 • The Kiryango River
• Satinsyi River
River Nyabarongo captured River Mukungwa and changed its direction to the south. As it flows to the south, other rivers join it as tributaries. They include:
 • River Base
 • River Bakokwe
• River Nyabugogo
• River Akanyaru
(ii) River Akagera which has its source from Lake Rweru. It is one of the longest rivers of Rwanda. It has several tributaries which include the following:
• River Kibaya
• River Kagogo
 • River Ruvubu (From Burundi)
• River Karangazi
• River Muvumba
Activity 8.5
 1. Draw a drainage sketch map of Rwanda.
 2. Pin it up on the classroom notice board for assessment.
The major lakes and their mode of formation
Activity 8.6
Do this in pairs.
1. Draw a sketch map of Rwanda and on it, locate the lakes found in the country. 2. Classify the major lakes of Rwanda according to their mode of formation. 3. Write down your explanations and present them in a class discussion.
Rwanda has different types of lakes which are classified according to their formation. They include the following:
(a) Rift valley lakes
Lake Kivu located in the Western Province of Rwanda. This was formed as a result of faulting, therefore it is called a graben lake.
                           
(b) Volcanic lakes Lake
Burera and Lake Ruhondo, situated in the Northern Province of Rwanda. These two lakes were formed as a result of lava damming that blocked the rivers which originated from the Rugezi marshy area. The damming led to back ponding of water hence the formation of the two lava dammed lakes. There are also crater lakes on the volcanoes of Rwanda. They are on Muhabura, Karisimbi, Gahinga and Bisoke.
                             
(c) Alluvial deposition lakes Lakes of Akagera and Bugesera which include the following:
(i) Bilira (Ox bow lake)
 (ii) Hago (Ox bow lake)
 (iii) Ihema
(iv) Mihindi
(v) Nasho
(vi) Rwampanga
(vii) Rwanyakizinga
(viii) Rweru
                      

(d) Depression lakes/downwarped
These lakes are found in the Eastern Province. They include the following:
(i) Sake
(ii) Muhazi
 (iii) Mugesera
                               
(e) Man-made lakes These lakes are not common in Rwanda. However, a few of them have been created. They include the following:
 (i) Lake Rwagitima
(ii) Lake Kabgayi located near the town of Muhanga along Huye road
 (iii) Lake Cyabayaga in Nyagatare
                       
Mode of formation
Activity 8.7
 Work in pairs. Use the Internet and other geographical documents;
 1. Using the knowledge acquired on the drainage of Rwanda, explain the mode of formation of the following lakes;
 (i) Lake Kivu
 (ii) Lake Burera
 (iii) Lake Mugesera
 (iv) Lake Cyabayaga
2. Write down your explanations and discuss them in a class presentation.
The Rwandan lakes were formed in different ways. Below is a detailed description of how lakes were formed.


Task 8.2
1. Describe the major drainage basins of Rwanda.
2. Giving examples, discuss the mode of formation of the main lakes in Rwanda.
Major wetlands in Rwanda
Activity 8.8
Work in pairs.
 1. Giving examples, identify the main wetlands in Rwanda.
2. Write down your findings and present them in a class discussion.
A wetland is an area that is either permanently or seasonally saturated with water. Such areas are always wet with large volumes of stagnant water. In Rwanda, wetlands are protected areas.
The major swamps of Rwanda are divided into two categories. They are:
(a) The valley or low altitude swamps. These include:
 • Swamps of Nyabarongo
 • Swamps of Akanyaru Valley
 • Swamps of Akagera
 (b) High altitude swamps which include the following:
 • Kamiranzovu swamp
 • Rugezi swamp
 • Pfunda swamp
(c) Other wetlands and swamps of Rwanda include the following:
 • Mutobo
• Gishoma
• Mwogo
• Base
• Nyabugogo
• Rwasave
• Sake
• Ngenda
• Ntende
 • Bugarama
• Muganza
• Mugonero
• Koko
                          
The importance of wetlands to the development of Rwanda Activity 8.9 In groups, use geographical information, personal experience, other academic resources.
1. Find out the importance of wetlands to human activities.
2. Discuss the value of wetlands to the socio-economic development of Rwanda.
 3. Write down your findings for a class presentation.
Wetlands are important to the development of the country as well as to human activities. Some of the importances of wetlands include the following:
(a) They are a source of water
Wetlands are sources of water for both domestic and industrial purposes.
(b) Natural water purification system
 Wetlands play a role in filtering water naturally. They trap and absorb toxins, sediments and dirt from water. This purification avails fresh water that reaches the lakes and rivers of Rwanda.
(c) Fishing activities
Wetlands support fishing activities by providing suitable breeding and feeding grounds for fish. They also offer refuge to the young fish. They are therefore important sources of fish. The swamps of Bugesera in the Eastern Province provide suitable breeding places for tilapia and cat fish.
(d) Homeland for flora and fauna
There is a wide variety of biodiversity in wetland areas. These are important in the development and promotion of tourism in the country. For example, the Akagera swamps where there are different bird species, various swamp vegetation and animals such as hippos, crocodiles, varans and snakes.
(e) Source of raw materials
Wetlands are rich in materials that are used in the production of art and craft products. These raw materials include papyrus, palms and other swamp vegetation. They are used in weaving.
(f) Provision of clay
These areas have been and are still areas where good clay can be found. Clay is used in pottery, ceramics and brick making. A good example is the establishment of Ruliba factory that entirely depends on clay got from Nyabarongo swamp.
(g) Source of food
Swamps in Rwanda support the growth of specific types of crops. These have enhanced food security in the country. The crops grown in wetlands are water tolerant and require highly saturated soils. They include; yams along Nyabugogo swamp, rice at Muhanga in the valley of Rugeramigozi River and Cyabayaga in Eastern Province.
Grazing areas
There are plants that grow near or within the wetlands that are used as pasture for domestic animals such as goats, sheep and cattle. The plants include sedges and different types of grasses. The wetlands provide a secure alternative grazing land during the dry seasons.
(i) Modification of climate
 Wetlands play a great role in the hydrological cycle which is the main component in the modification of climate. They contribute to the formation of convectional rainfall, hence influencing the micro-climate of the surrounding areas.
(j) Source of medicine
The wetlands of Rwanda have swamp vegetation, some of which are medicinal. These include the roots of Mondia whitei and Phoenix reclinata which are used in treatment of various diseases.
(k) Reduction of the occurrence of floods
 Wetlands trap sediments which would otherwise find their way to river channels, narrowing the carrying capacity of rivers causing floods. They also store much water that would otherwise increase the water volume in rivers and lakes and causing floods.
(l) Recreational resource
Wetlands provide good sites for peaceful relaxation and walks. Some of them support hunting and fishing sports that attract tourists who bring foreign exchange to the country.

(m)Sanctuary for birds
Wetlands are homelands to a wide variety of bird species in Rwanda. This explains why Akagera and Bugesera areas have many birds and host birding activities.These areas are tourist attraction sites.

Wetland destruction
Activity 8.10
Study the extract below and answer the questions that follow. “Enormous pressure, over the recent years, has been exerted on the water and wetland resources through various emerging and increasing uses driven by the growing population. Some of these threats include agricultural intensification, pollution, invasive species, overuse and inadequate institutional frameworks to manage the wetlands. Some of these threats, in the case of water, have affected both the quantity and quality of water available. Climate change is also contributing to degradation of swamps. With decreasing amounts of rainfall, the hydrological regime of wetlands is being threatened”. Source: Rwanda state of environment and outlook report.

1. Explain the meaning of wetland destruction.
2. Identify the causes of wetland destruction mentioned in the extract above.
3. Find out other causes of wetland destruction in Rwanda that have not been mention in (2) above.
4. Write down your findings and present them in a class discussion.
There is clear evidence that shows wetlands in Rwanda are being destroyed. Their existence is being threatened either through the need for land for development or need for land for agricultural projects. Some of the causes of wetland destruction in the country include the following.
(a) Need for more land for agricultural activities
 There is shortage of land in Rwanda. This has created pressure on the wetlands that are now being reclaimed to grow rice and other crops such as yams and beans.
(b) Pollution
Water pollution has become a serious threat to the wetlands in Rwanda. Both domestic and industrial wastes are secretly or sometimes openly dumped into the wetland areas. The wastes destroy the natural state of the wetlands. The most affected area is the Nyabugogo swamp in Kigali.
(c) High demand for wetland resources
There is over exploitation of resources found in wetland areas such as alluvial sand that is needed in the construction. The swamp vegetation is also endangered due to increased demand for Cyperus papyrus and Cyperus denudatus that are needed in wearing making and Vossia cuspidata that is used in roofing.
(d) Water reservoirs
The government through the Rwanda Agricultural Board (RAB) , has encouraged the creation of water dams where water is reserved for irrigation purposes. This cuts down on the natural water supply to the wetlands. There are also many irrigation schemes that have been established that all depend on water from the wetlands.
(e) Development and construction
There are many construction projects that have been put up on reclaimed wetlands. This is evidenced in Nyabugogo where houses are being set up on wetland areas and in the Gikondo industrial area which was established on a wetland.
(f) Fire outbreaks
There are many occurrences of fire outbreaks in swampy areas. This degrades the wetlands where the burnt vegetation dwells. When this happens, both vegetation and animals that depend on wetlands are destroyed.
(g) Weeds and aquatic animals
There are water weeds in wetlands that never existed in Rwanda before. The weeds now compete with the swamp vegetation and may eventually replace the indigenous vegetation. The most serious weed affecting wetlands is the water hyacinth. The affected areas are the Rweru swamps.

Straightening and dredging of rivers
This has drained more water from wetlands leaving behind less saturated areas. This has led to drying up of swamp vegetation. The regular dredging of River Nyabugogo is responsible for the extinction of some plant species.
(i) Climatic changes
Global warming has affected the wetlands which have drastically decreased in size due to the reduction in water supply.
(j) Urbanisation
The growth and development of towns and cities in Rwanda is associated with increased housing demands. The construction activities have reduced the infiltration of run-off. The run-off that carries wastes dumps them into the wetlands affecting their natural state.

Measures to promote the sustainable use of wetlands
Case study
Work in groups of five. Miss Mumararungu Yvone, a resident of Huye wanted to establish a fruit processing company in her home area. When she went to the Rwanda Development Board (RDB) offices to seek authorisation, she was asked to present an environmental assessment report. Unfortunately, she did not have one. She was then sent to the Rwanda Environment Management Authority (REMA) offices to seek help from there. When she got REMA, an environmental assessment team was sent to do an environmental impact assessment on the proposed project. The team found that the industry would affect the wetland where she wanted to establish it. The report they gave did not allow RDB to give her any authorisation document. She was advised to look for another place in Bugesera where the land is dry.
 (a) Give reasons why you think the RDB denied Miss Mumararungu permission to set up her fruit processing plant.
 (b) Discuss why it is important for the RDB to regulate the establishment of industries and other development projects on wetlands?
 (c) Explain the importance of the environmental impact assessment study that was carried out by REMA on the environment and on securing wetland areas.
 (d) Describe other measures that the Rwandan Government and population can put in place to conserve the wetlands.
 (e) Prepare a campaign on sustainable utilisation of wetlands around your school and sensitise the local population about it.
 (f) Discuss your findings and answers in a class discussion.
Owing to the importance of wetlands, it is important for the country and the local populations to develop positive values and attitudes towards proper management, conservation and protection of wetlands. Below are some of the ways that can be used to conserve wetlands so as to enable proper and sustainable utilisation of the areas.
 (a) The people should be made aware of the need to conserve and protect the wetlands. The population should be educated on the importance of wetlands to the environment and to them. These can be done through the use of mass media, posters, brochures and local village meetings. The local leaders and environmental officers should educate the people on the importance of wetlands, proper management and utilisation.
 (b) The government agencies involved in the conservation and protection of wetlands such as REMA should conduct research studies. This will come up with workable solutions on the proper use, conservation and management of wetlands.
(c) New guidelines on the proper use, conservation and management of wetlands should be formulated to guide the local populations.
(d) The government through parliament should enact new laws that deal with wetlands. In this way, it becomes a criminal offence to destroy or misuse the wetlands.
 (e) There should be compulsory eviction of people who have settled on wetland areas or those who use the wetlands without authorisation from the relevant authorities.
(f) More effort should be put in preventing fire outbreaks that have continued to destroy vast areas of wetlands. The people should be made aware that it is destructive to burn the wetlands in favour of agricultural or any other uses.
 (g) A wetland protection task force should be established to ensure close monitoring of the uses of wetlands.
  Proper disposal of wastes should be deviced in order to avoid dumping of dangerous wastes into wetlands.
Task 8.3
1. Name three wetlands in Rwanda.
 2. Discuss the importance of wetlands in the development of Rwanda.
3. (a) Discuss three causes of wetland destructions in Rwanda.
     (b) Suggest measures to promote the sustainable use of wetlands.

Relationships between the drainage system and the human activities
 Activity 8.11
 Work in groups. Using the internet and other geographical sources of information such as personal experiences and the local environment;
1. Find out the relationship between drainage systems and the local environment.
2. Relate your findings to the human activities that take place in the area near your school or home.
3. Write down and present your findings in class.
The relationship between the drainage system and the human activities in Rwanda exists as follows:
 (a) The drainage system in the country facilitates irrigation farming which supports the growth of crops making the country food secure.
(b) The country’s drainage favours water transport that eases the movement of goods and people from areas of abundance to places of scarcity.
(c) Hydroelectric power is generated using water from rivers such as River Nyabarongo. Power is a vital necessity in the execution of human activities such as industrialisation and mining.
 (d) The drainage system in the country has contributed to the development of tourism. For example, tourists go to River Akagera to view its pronounced meanders.
(e) The drainage system offers habitats for aquatic animals such as fish which is used as food. This favours the development of fishing as an economic activity.
(f) Rivers as part of the country’s drainage system are associated with precious minerals such as diamonds and gold. This favours mining.
(g) Clay is also associated with the rivers. The clay is used by ceramic industries.
The drainage system in the country modifies the climate in the country. It enables the formation of rainfall that supports agricultural activities.
 (i) The drainage system in the country is associated with the development of swamps. Swamps have vegetation that are used in art and craft which is a source of income to people staying near them.

Activity 8.12
Work in pairs.
1. Explain how the distribution of water bodies affects human activities and population distribution in Rwanda.
2. Discuss the importance of water bodies in determining and developing different human activities.
3. Write an essay on your findings and present it to your teacher for assessment.
Did you know?
• The country’s hydrological network includes numerous lakes and rivers and its associated wetlands.
 • In Rwanda, the abundance of water resources is reflected by the existence of a network of wetlands in various parts of the country.
 • The drainage of Rwanda is mainly influenced by rainfall and evaporation.
• Drainage and water resources have a direct influence on the quality of life of the people, their health and their overall productivity.
• Drainage supports human activities such as agriculture, industrial development, hydropower generation, transport, socio-economic development and poverty eradication.

End of unit revision task
1. (a) Define the river basin.
     (b) Giving examples, describe the drainage systems of Rwanda.
 2. (a) List four rivers of Rwanda and state their sources.
       (b) Examine the importance of rivers and lakes to the socio-economic development of Rwanda.
3. The drainage system is at the centre of economic development of Rwanda. Discuss.
4. (a) Analyse the causes of wetland destruction in Rwanda.
     (b) Explain the measures put in place to ensure sustainable utilisation of wetlands in Rwanda.
5. “Drainage systems and human activities are inseparable.” Discuss.
6. To what extent are man’s activities influenced by drainage systems in Rwanda?