THE DRAINAGE IN UGANDA

Drainage refers to water logged areas of rivers, lakes and swamps. It is the different water sources in a country.

Uganda has got different drainage systems of lakes such as Victoria, Kyoga, Albert, Bisiina, Wamala, etc rivers such as Nile, Katonga, Kagera, etc. and Swamps like along rivers and lakes, others like Rubigi, Nabajuzi, kirihili, etc.

DISTRIBUTION OF DRAINAGE SYSTEM IN UGANDA

Lakes

A lake is a body of water contained in a hollow with in a basin.

The size, depth and permanence of a lake depend largely on the nature of the basin on which it’s located. In Uganda, there are various lakes like Victoria, which is the largest, Kyoga, Wamala, Albert, George, Edward, Mburo, Bisiina and other volcanic lakes found in south western Uganda.

Lakes can be classified as;

1. Depression/crustal warped lakes.

These include L. Victoria, Kyoga, Wamala and Bisiina.They are formed due to crustal warping in down warped basins.Such lakes are generally large and irregular in shape, shallow in depth, surrounded by swamps and their shorelines show influence of drowning inform of numerous inlets.

Formation of Lake Victoria

• Lake Victoria is a crustal warped lake located in a down warped basin in south eastern Uganda.
• Down warping and up-warping of the landscape in Uganda occurred due to an increase in the lateral compression force which affected the earth crust over a wide area.
• Down warping led to the formation of a great basin i.e. Victoria-Kyoga basin and the uplift led to the formation of uplands/plateau.
• Crustal warping also led to a general reversal in the drainage system of Uganda. Rivers such as Katonga, Kagera, Kafu, Mayanja which were originally flowing towards Atlantic Ocean reversed their water due to uplift of western Uganda to over flood the central basin. This led to formation of L. Victoria.

Other rivers like Ruizi, Nzoia also reversed their flow due to uplift of the eastern Uganda to fill L. Victoria.

ILLUSTRATION OF CRUSTAL WARPING

TECTONIC LAKES/ FAULT LAKES

• These are located in the rift valley occupying gradens formed by secondary faulting which was initially caused by tension and compression forces.
• Fault lakes are narrow and elongated in shape, boarded by steep sides or fault scarps, their waters are usually saline and inlets and outlets tend to be confined at their extreme end.
• Such lakes include Albert, George and Edward.

FORMATION OF L. ALBERT

• Albert is a fault lake formed by faulting process due to tension and compression forces in the grabens within the rift valley.
• Albert found in western Uganda in the western rift valley is majorly believed to have been formed by compression forces due to its steep Butiaba escarpments.
• According to compression force theory, the existence of compression forces within the crust acted upon/pushed the adjacent blocks forming fault lines.
• The central block thrusted against the adjacent blocks forming an elongated depression/rift valley as illustrated.

Before faulting                                                             During faulting

• Later secondary faulting acted upon the rift valley forming a graben/ a more defied depression.
• When the graben was filled with water, it became a rift valley lake known as L. Albert.

VOLCANIC LAKES

These are formed by volcanicity and occupy craters and calderas formed as a result of eruption.

When the created craters or calderas are filled with water they form crater lakes or caldera lakes.

These include Lakes like Katwe, Nyungu, Nyamurangira, Nyamunuka, Kyamwoga, Munyanyange, and Nyamusingira all in south western Uganda.

Lava dammed lakes are formed where lava flow blocks the flowing river and floods a valley to form a lake such as Bunyonyi in Kabale, L. Mutanda, Butera, Muhondo, Mulehe, Ndalaga, all in south western Uganda.

GLACIAL LAKES

These occupy cirques on high mountains of Rwenzori formed by glaciations process. The constant erosion caused by glaciers on this snow capped mountain of the moon, shallow steep sided depression are created known as cirques. When these are filled with water, glacial tarns are formed. Examples include Lac du Speke, Lac Catherine, Lac Noir and Lac Vert all on slopes of Mt. Rwenzori in western Uganda.

WEATHERED LAKES

Chemical weathering act on some rocks especially limestone and make them break. In such places large pits are created/formed, when the pits are filled with water small lakes known as solution lakes are formed like in Nyakasura south western Uganda.

MANMADE LAKES

These are lakes made where man digs large depressions like Kabaka’s lake in Rubaga-Kampala and L. Kibimba in eastern Uganda.

Other lakes were formed through digging fishing ponds like in Mawogola and Kapchorwa in eastern Uganda. Others were formed as valley dams like in Nyabushozi, Kashari and Isingiro in south western Uganda.

DEPOSITION LAKES OR OX-BOW LAKES

These are formed as a result of erosion and subsequent deposition along the lower course of a river. Such lakes are usually shallow and small and sometimes temporary. Ox-bow lakes formation is guided by meandering of a river as illustrated;

Meandering river and deposition

Examples of ox-bow lakes in Uganda have been found on rivers such as Semulik near Rwenzori and on R. Ruizi near Mbarara town.

ECONOMIC VALUE OF LAKES IN UGANDA

• Lakes in Uganda have got both positive and negative values to the economic development of Uganda and these include;
• Lakes such as Victoria modify the climate of the surrounding areas along its shores of Mukono, Buikwe, Jinja, etc. through the process of evaporation and its breezes it forms heavy and reliable convectional rainfall supporting tea growing at Kasaku and sugar at Kakira for foreign exchange.
• Lakes provide water for irrigation at Lugazi sugar estate from L. Victoria, water to cool machines in steel rolling in Mukono and as a raw-material in Uganda breweries at Luzira from L. Victoria. Such industries have been source of consumer goods to Uganda reducing on imports.
• The water provided by lakes like Mburo has been used for animal consumption by the pastoralists in Kiruhura and by Mburo National park animals. This has diversified Uganda’s economy through tourism and livestock farming. Also water from L. Victoria is used by Kampala and Masaka for domestic purpose.
• Lakes provide cheap water transport which has helped to promote trade and international relationship. Forexample L. Albert link Butiaba in Uganda to Muhanga in Congo, L. Victoria connects Jinja and Port bell of Uganda to Mwanza in Tanzania and Kisumu of Kenya.
• Lakes makes it possible for the generation of HEP like L. Victoria act as a reservoir for R. Nile where Owen falls dam and Bujagali dam are built.

HEP in turn has led to industrialization in Jinja and Kampala for jobs and government revenue.

• The papyrus vegetation and other swampy vegetation around lakes Kyoga and Victoria has led to the development of the craft industry were mats, roofing papyrus mats, etc are made. This has availed jobs to locals earning incomes for better living standards.
• The fresh water lakes of Kyoga and Victoria have provided fish such as Tilapia and Nile perch for proteins and development of the fishing industry. This has led to growth of fishing site like Lambu, Kasenyi, Jinja, Luzira, on Victoria and Lwampanga on Kyoga thus infrastructure development.
• Due to reliable rainfall provided by lakes such as L. Victoria, there has grown a dense forest within i.e. Karangara and Ssese islands forests and around the lake like Mabira. This has developed the forestry industry for job provision and economy diversification.
• Sand which is found at the shores of L. Victoria is used for construction purpose and glass making. Salt mining in L. Katwe, oil Prospects in Albert shores, clay mining in Kajjansi for ceramics on L. Victoria shores, all provide jobs to Ugandans, foreign exchange and infrastructure development.
• Lakes provide natural habitats for millions of plants, animals and birds. This promotes eco-system like at L. Mburo and George. The above coupled with the blue waters and beautiful scenery f lakes like Bunyonyi in Kabale, coastal features of beaches like Liddo, Nabugabo, on Victoria attract tourists for foreign exchange.
• Lakes provide great opportunities for research and study purpose in relation to fisheries, forestry, navigation and soils. There is also a meteological department at Entebbe thus weather studies which all help Ugandans understand their environment and make proper planning especially in the farming sector.

The short comings of lakes to Uganda’s development include;

• Lakes are dumping grounds for industrial wastes like Uganda breweries factory at Port Bell in Luzira dump its wastes into Lake Victoria which pollutes its waters becoming un condusive for domestic use and fish existence.
• Navigation on lakes is associated by a number of accidents caused by strong winds like on L. Albert claiming a lot of important labor in form of people who would be productive for development.
• Lakes are barriers to construction of transport networks of roads and railway. Foristance L. Bunyonyi has made some parts of Kabale remote and backward. The low levels of infrastructure in such areas lead to low trade development and low Uganda’s development.
• The swampy vegetation on crescents of lakes like Kyoga are breeding grounds for dangerous pests like mosquitoes and tsetse flies. Such pests transmit human diseases such as malaria and sleeping sickness respectively to people in Lwampanga on Kyoga.
• Sometimes lakes over flood their shorelines and this leads to property destruction and loss of lives. Foristance L. Bisiina flooded in 2007 causing water borne diseases to people in the area.
• Lakes that are shared by different countries like Albert and Edward by Uganda and Congo, Victoria by Uganda, Kenya and Tanzania, cause conflicts especially during usage of the lake in fisheries, transport and mining as it was between Uganda and Kenya over Mijingo island and on Albert with Congo.
• The changes in water levels lead to submergence and emergence of water which leads to destruction of ports as it has been on L. Albert.
• Some lakes like Albert and George fault lakes have got saline water and fault scarps along their shoreline which discourage fishing activities hence low development of the fishing industry.
• Lakes also harbour dangerous wild animals such as snakes, crocodiles and hippos which destroy crops and claim people’s lives like in L. Albert and Edward.

RIVERS

Uganda is drained by various rivers almost the entire landscape of the country. They are majorly nine rivers which include;

1. Nile which include Victoria Nile and Albert Nile. It has its source in L. Victoria and its mouth in Mediterranean Sea.
2. Katonga which flows from L. George to L. Victoria.
3. Mpologoma-Manafa River, which originates from Mt. Elgon to L. Kyoga.
4. Mayanja-Kato River, which has its source in L. Victoria and its mouth into Kafue.
5. Aswa-Moroto River, it originates from north eastern Karamoja areas to R. Nile.
6. kafue which originates from L. Kyoga to L. Albert.
7. Kagera, it originates from Rwanda hills to L. Victoria.
8. Depeth-Okoth which originates from Karamoja hills to Kyoga.
9. Semulik and Mubuku.

Other rivers in Uganda include R. Rwizi, R. Sezibwa, R. Okere, Birira River, Nyamwamba, etc.

Major rivers in Uganda

River profile

This refers to the measured slope along the bed or surface of the river from its catchment area to its mouth. A river profile is divided into three sections i.e.

• The youthful stage
• The mature stage
• The senile stage.

During the erosion and deposition of a river there are different features formed i.e.

Waterfalls such as Owen falls, Bujagali falls and Muchison falls on R. Nile, Sezibwa falls on R. Sezibwa, Kisiizi falls, etc are formed by river erosion.

River deposition especially in its lower stage form ox-bow lakes as at R. Rwizi, deltas, etc.

DRAINAGE PATTERNS

A drainage pattern is a lay out plan which is made by a river and its tributaries on the landscape. In Uganda, the different patterns can be identified;

• Dendritic drainage pattern
• Radial
• Trellis
• Centripetal
• Annular
• Barbed

N.B   River rejuvenation refers to a renewed river capacity in a river valley. Rejuvenation can be caused by heavy rains and river capture.

River capture or piracy refers to the diversion of part of a river course or whole of it into the system of another adjacent powerful river.

Economic value of rivers in Uganda

• Rivers are source of water for domestic, industrial and recreation purpose. Foristance Mbarara town get water for domestic use from R. Rwizi, Nile breweries use water from R. Nile as raw-material in making beer hence provision of jobs to Ugandans and government revenue.
• The water from rivers like Mubuku and Manafa is used to facilitate irrigation at Mubuku irrigation scheme in Kasese and Doho in eastern Uganda respectively. Such schemes have increased on food production and foreign exchange after rice and vegetable exports.
• Rivers facilitates generation of HEP like Owen falls dam and Bujagali dams on R. Nile, Mubuku power station on R. Mubuku, etc. HEP has lead to industrial development thus infrastructure development and jobs to Ugandans.
• Rivers provide cheap water transport by ferry means like on Victoria Nile. This has developed local trade, provided incomes to transporters hence improved living standards.
• The papyrus swamps which develop along river banks such as on R. Katonga and Mpologoma are potential raw-materials for paper, packing, cardboards, roofing materials and the general development of the craft industry thus employments to Ugandans.
• Rivers are tourist attraction especially waterfalls of Murchison, Bajagali, Sipi and Karuma falls. The meandering nature of R. Rwizi attracts tourists for foreign exchange in terms of invisible export which is used for further development.
• Rivers like Nile provide fishing grounds and fish caught for local consumption and for sale. The swampy areas along R. Katonga provide mud fish, which provide proteins and sold for better incomes to Ugandans.
• The swampy areas and wetlands along river channels are natural habitats for wild animals, birds and other marine life. Shoe bills and crested cranes survive in R. Nile wetlands attracting tourists for foreign exchange.
• There is clay mining along rivers like Katonga and Mpologoma for brick laying thus development of small scale industries for jobs to Ugandans.
• Rivers like Nakivubo channel help to regulate the environmental impurities that would directly enter L. Victoria leading to its pollution. Also rivers modify the climate where they exist like river Manafa form reliable rainfall which supports rice and other crop growing in eastern Uganda.
• River banks like Albert Nile have got fertile soils in West Nile areas supporting tobacco and other crop growing. This also has attracted settlement in the areas of Nebbi, Arua, etc. the grown crops have contributed foreign exchange to Uganda through exportation.

The short comings of rivers include;

• Some rivers tend to over flood their valleys during rainy seasons as it was in 2007 in north eastern Uganda and in 2014 in Kasese by R. Nyamwamba. This cause property destruction, loss of lives and interfere with transport networks since floods wash away bridges.
• Most rivers contain waterfalls and rapids like along Nile at Karuma which make navigation impossible thus resulting into remoteness and inaccessibility of such areas.
• Most rivers like in northern Uganda make the construction of feeder roads hard like at Karuma Bridge which makes such areas remote and inaccessible especially during rainy seasons.
• The swampy vegetation along river channels like along Katonga harbour disease vectors such as mosquitoes and tsetse flies which cause diseases such as malaria and sleeping sickness respectively to human beings.

N.B The economic importance of the drainage system of Uganda includes;

• Values of lakes
• Values of rivers
• Values of swamps