Drainage in Rwanda
Senior 2 · Geography and Environment
Drainage in Rwanda
Lesson 1 of 4
20 min
A raindrop that falls on the eastern side of Nyungwe may end up in the Mediterranean Sea after a river journey of more than 6,000 km. A raindrop that falls a few kilometres to the west may reach the Atlantic Ocean instead. Rwanda sits on one of the great water divides of Africa. Its rivers supply drinking water, irrigate rice, turn turbines and mark borders. This lesson explains how Rwanda's water is organised into rivers and drainage basins.
The Congo–Nile Ridge in the west is the watershed. About 80% of Rwanda drains east into the Nile basin, mainly through the Nyabarongo and the Akagera to Lake Victoria. About 20% drains west into the Congo basin, through Lake Kivu and the Rusizi River to Lake Tanganyika.
| River | Basin | Key facts |
|---|---|---|
| Nyabarongo | Nile | The longest river entirely in Rwanda. Formed where the Mwogo and Mbirurume meet; their headwaters, such as the Rukarara, rise in Nyungwe. It flows north, turns east where the Mukungwa joins it, then runs south-east past Kigali through a broad swampy valley to Lake Rweru. |
| Akanyaru | Nile | Forms part of the border with Burundi and joins the Nyabarongo south-west of Kigali. |
| Akagera (Kagera) | Nile | Flows out of Lake Rweru along the borders with Burundi and Tanzania, is joined by the Ruvubu, then flows north to Lake Victoria. It is the largest single river flowing into Lake Victoria. Rusumo Falls lie on it. |
| Mukungwa | Nile | Drains Lake Ruhondo and joins the Nyabarongo. |
| Nyabugogo | Nile | Drains Lake Muhazi and flows through Kigali to the Nyabarongo. |
| Sebeya | Congo | A short, steep river flowing into Lake Kivu near Rubavu; it floods quickly after heavy rain. |
| Rusizi | Congo | Carries water out of Lake Kivu south to Lake Tanganyika, forming the border with the DR Congo. Rwanda's lowest point (950 m) is on it. |
In the wet west and centre, rain falls in most months and swamps release water slowly, so the main rivers are permanent. In the drier east (Bugesera, Kayonza, Nyagatare), many small streams are seasonal: they run in March–May and October–December and leave dry channels in the long dry season.
Trace the journey of a raindrop that falls on the eastern side of Nyungwe to the sea.
A raindrop on the western side follows a different route: a stream, then Lake Kivu, the Rusizi, Lake Tanganyika, the Congo River and finally the Atlantic Ocean.
Rwanda covers 26,338 km². The Nile basin share is 80% × 26,338 = 21,070 km²; the Congo basin share is 20% × 26,338 = 5,268 km² (to the nearest km²). Four-fifths of the country drains to the Nile.
Tip
Memory hook. Rwanda's rain has two doors: "East door, Nile, 80; West door, Congo, 20." The Congo–Nile Ridge is the wall between them. In a "trace the route" question, name every river and lake in order and finish at the sea.
Solution: the high ground separating two drainage basins; in Rwanda it is the Congo–Nile Ridge.
Solution: the Rusizi, south to Lake Tanganyika (Congo basin).
Solution: the east has lower rainfall and a long dry season, so streams have no water to carry for part of the year.
Solution: they have many rapids and waterfalls, and many are shallow, narrow or choked with swamp vegetation.
Solution: the Nyabugogo.
Summary
Sources and credits
The river table, worked examples and practice items are written by Ganzaa.
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
