Towards a sustainable water supply and sanitation services in Tanzania
Four Dutch water authorities are working on a nature-based solutions pilot project at one of the tributary rivers of the Mindu Dam, Tanzania, to improve the delivery of water and sanitation services in the Morogoro urban area.
The project, that falls under the Dutch WaterWorX programme, aims to implement agroforestry practices to combat sedimentation and increase Mindu Dam’s capacity
Mindu Dam supplies more than 75 percent of the drinking water in Morogoro, Tanzania. The water supply from the Dam is threatened by the effects of climate change, population growth and intensive agriculture. These factors lead to heavy loading on the surrounding riverbanks, causing severe soil erosion. To combat this soil erosion, World Waternet, Rivierenland, Brabantse Delta and Hoogheemraadschap Hollands Noorderkwartier – water authorities in the Netherlands – will introduce agroforestry in the Mindu Dam catchment area in partnership with Morogoro Urban Water Supply and Sanitation Authority (MORUWASA).
This project will run until April 2026 and is a follow-up to an earlier project in which a smart reforestation tool was developed. The NWB Fund has released nearly EUR 100,000 for the project. The collaboration with MORUWASA is made possible by WaterWorX, a Dutch programme in which all drinking water companies in the country have united to work on sustainable drinking water management worldwide.
Janette Worm, Regional Manager at World Waternet, is pleased with the news. "It allows all the stakeholders and ourselves to take new steps towards climate-resilient river basin management and sustainable water supply. Only in this way can MORUWASA, our WaterWorX partner, continue to guarantee sufficient drinking water supplies in the future."
Agroforestry as a solution to sedimentation
Sedimentation is caused by severe soil erosion when soil is washed away and enters the dam as sediment. The sedimentation process, where sand and gravel accumulate, significantly reduces the storage capacity of dams as the silt reduces the space for water intake. Combining water management with agriculture, forestry and the local economy helps retain water better.
Trees, plants and different types of agriculture have a positive effect on erosion and sedimentation. The roots of trees and vegetation create stability for the soil, reducing erosion, slowing down water flow and filtering sediments. These systems also maintain healthy soil structure, promote biodiversity and provide a valuable supplement to the income of local farmers who are much needed to work on successful and sustainable water systems. This in turn creates a more pleasant living environment for the local population.
To set up an agroforestry project, project partners use the NWB Fund Watershed Reforestation Tool, which acts as a simple interface for entering the agronomic, financial, and design details of an agroforestry system. This tool was developed in 2023 in collaboration with the Dutch start-up FarmTree and helps choose the right mix of trees and crops.
Long-term resilience
In addition, a roadmap describing various interventions has been drawn up. One intervention is that local farmers can switch to beekeeping or aquaculture. Small sedimentation dams could also be built to capture sediment before it reaches the Mindu Dam. The suggested roadmap reinforces the application of nature-based solutions for water management and conservation in collaboration with local communities.
The pilot project will be a blueprint for the other four rivers to the dam and eventually for the entire catchment area.
