Drainage in Rwanda
Senior 2 · Geography and Environment
Drainage in Rwanda
Lesson 4 of 4
20 min
Around Kigali, the Nyabarongo is used for washing, cooking and even drinking. It also receives sewage and waste from industry and farms. In the Eastern Province, families walk long distances for water in the dry season. In the north, farming and drainage in the Rugezi marsh reduced the water flowing into Lakes Burera and Ruhondo, on which the Ntaruka power station depends. Keeping water clean and available is one of Rwanda's biggest development tasks. This lesson identifies the problems and the solutions.
| Measure | What it does |
|---|---|
| Protecting catchments | Terraces, grass strips and trees (planted in Umuganda and the national tree-planting season) cut erosion, so less silt reaches rivers and lakes. |
| Buffer zones | The law keeps a protected strip along the banks of lakes and rivers, where farming and building are restricted. |
| Wetland protection and restoration | Farming was stopped in the Rugezi marsh so that it could recover; Kigali restored the Nyandungu wetland as an urban eco-park. |
| Treating waste | Sewage treatment, proper waste collection and the ban on plastic bags keep waste out of water. |
| Managing fisheries | Legal net sizes, closed seasons that let fish breed, and patrols against illegal fishing. |
| Saving and harvesting water | Rainwater tanks on roofs, repairing leaks, and drip irrigation. |
| Institutions and education | The Rwanda Water Resources Board and REMA plan and enforce water management; school environment clubs and Umuganda clean drains and riverbanks. |
A school roof has an area of 200 m². The area receives 1,100 mm of rain a year. How much water could the roof collect in a year if all the rain were caught? And how much if only 80% is caught?
That is enough to reduce a school's demand on piped water and to cut the runoff that causes erosion around its buildings.
Tip
Exam technique. Pair every problem with a matching solution: siltation → terraces and trees; pollution → waste treatment and plastic ban; wetland loss → buffer zones and restoration; over-fishing → net-size rules and closed seasons; scarcity → rainwater harvesting. Matched pairs score better than two separate lists.
Solution: eroded soil is carried down as silt, which fills the reservoir, reduces its storage and wears the turbines.
Solution: untreated sewage and industrial waste (also plastics and farm chemicals).
Solution: Rugezi regulates the flow into Lakes Burera and Ruhondo; when it was drained, less water reached the lakes, so the Ntaruka power station could not run at full capacity.
Solution: 50 × 0.9 = 45 m³ = 45,000 litres.
Solution: enforce minimum net-mesh sizes and closed breeding seasons; patrol against illegal fishing.
Summary
Sources and credits
The challenge and conservation tables, 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.
