Agriculture is the mainstay of the Rwandan economy, yet soil degradation has been a growing problem. Years of deforestation, overgrazing and cultivation on steep slopes is being exacerbated by climate change, with the rainy seasons bringing heavy downpours and flooding that washes away the fertile topsoil on which people rely to grow crops. Accelerating soil erosion is reducing agricultural productivity and water quality, causing landslides and increasing the cost of electricity and water treatment. Overall, it has been costing the economy between 20% and 200% of GDP a year.
We managed Water for Growth, an integrated water resources management (IWRM) programme to help Rwanda better protect, conserve and manage its water resources – and support sustainable socio-economic development and improved livelihoods. Equitable, efficient and environmentally sustainable water resources and land management was the goal of the four-year programme. Catchment and water allocation plans were developed for priority river basins, covering about one third of Rwanda. These were designed to balance the needs of different water users, improve water quality, and physically restore catchment areas by controlling soil erosion and putting in place mitigation measures, such as afforestation, terracing, and buffer zones, to conserve water and soil and minimise flooding.
Reforestation, agroforestry and soil and water conservation were all covered in the Water for Growth IWRM toolkit designed to protect communities from flood and drought, while an IWRM investment fund supported the rehabilitation of more than 4200ha. Measures included:
- land terracing reinforced by agroforestry hedges and grass strips to stop topsoil washing away
- tree planting – combining suitable local species, such as conifers, parasol trees, Kenya croton, Nile tulip and bitter leaf, with exotics like alder, Arabic gum and Australian blackwood – to stem degradation across the catchment and help prevent soil erosion
- vegetative buffer zones help to reduce concentration of nitrates, phosphorus and pesticides from water running off cultivated fields
- gully stabilisation, including revegetation, to prevent loss of property and sediment being deposited downstream
Improved agricultural practices, such as contour ploughing to create a water break and reduce the formation of rills and gullies during times of heavy precipitation, have resulted in less soil erosion and fewer landslides, as well as higher crop yields. The introduction of perennial crops, including coffee, tea, banana, fruit helps to increase agricultural productivity and incomes, and improve environmental sustainability.