Drainage in Rwanda
Senior 2 · Geography and Environment
Drainage in Rwanda
Lesson 2 of 4
22 min
Rwanda's lakes differ sharply. Lake Kivu is almost half a kilometre deep and holds methane gas. Muhazi is long and thin, with arms like the fingers of a hand. Burera and Ruhondo are twin lakes, one 100 m higher than the other. These shapes reveal how each lake formed, and examiners expect you to connect shape to origin. This lesson surveys the lakes and swamps and explains their formation.
| Lake | Location | Key facts |
|---|---|---|
| Kivu | Western border, shared with the DR Congo | About 2,700 km² in all; surface at 1,460 m; about 480 m deep at its deepest; holds dissolved methane |
| Ihema | Akagera National Park | About 100 km²; the largest lake lying entirely in Rwanda |
| Rweru | South-east, shared with Burundi | About 133 km², of which about 47 km² is in Rwanda |
| Cyohoha | Bugesera, shared with Burundi | About 74 km², of which about 19 km² is in Rwanda |
| Burera | North, near the Uganda border | About 55 km², at about 1,860 m; drains into Ruhondo |
| Ruhondo | North, next to Burera | About 28 km²; drains through the Mukungwa River |
| Muhazi | East-centre, north-east of Kigali | About 60 km long but less than 5 km wide, with many narrow arms |
| Mugesera, Sake, Birara | Beside the lower Nyabarongo | Shallow lakes in the Nyabarongo wetlands |
| Type | How it forms | Rwandan example |
|---|---|---|
| Rift valley (tectonic) lake | Faulting lets a block of land sink between parallel faults, making a deep trough that fills with water. Such lakes are long, deep and steep-sided. | Kivu |
| Lava-dammed lake | Lava from a volcano flows across a river valley, cools into a wall of rock, and water backs up behind it. | Burera and Ruhondo |
| Crater lake | Water collects in the crater at the top of an inactive volcano. | The lake in the summit crater of Bisoke |
| Drowned (flooded) valley lake | A river valley is flooded when its outlet is blocked, so water spreads up the main valley and its side valleys. Such lakes are long and narrow, with branching arms. | Muhazi |
| River-deposit (floodplain) lake | A big river deposits silt and grows papyrus across the mouths of side valleys, damming shallow lakes beside it. | Mugesera, Sake and Rweru beside the Nyabarongo; Ihema beside the Akagera |
| Artificial lake (reservoir) | People build a dam to store water for irrigation, livestock or power. | Valley dams in the Eastern Province |
Explain the formation of Lake Kivu.
Tip
Memory hook: "Shape tells the story". Long and very deep = rift valley (Kivu). Next to volcanoes = lava-dammed (Burera, Ruhondo) or crater (Bisoke). Long, thin, with fingers = drowned valley (Muhazi). Shallow, beside a swampy river = river-deposit lake (Mugesera, Ihema).
Solution: Lake Ihema (about 100 km²).
Solution: lava from the Virunga volcanoes blocked river valleys, and water collected behind the lava dams.
Solution: it is a drowned valley: water filled a river valley and the side valleys of its tributaries.
Solution: 47 ÷ 133 × 100 = 35.3%.
Solution: it stores, regulates and filters the water that flows into them.
Summary
Sources and credits
The lake-formation table, worked example and practice items are written by Ganzaa.
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
