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Topic
Green water
Green water is rainfall stored in soil and available to plants. It supports rainfed agriculture, forests, grasslands and other ecosystems. As water evaporates from soil and is released by plants, it returns to the atmosphere and can contribute to rainfall elsewhere. Decisions about land use therefore influence water availability within and beyond the places where they are made.
Why green water matters
Water security depends on more than rivers, lakes and groundwater. Crops and natural vegetation also depend on moisture held in the soil. How rainfall enters the ground, how much the soil retains and how plants use it all affect the water available to sustain food production and ecosystems.
Forests, farming practices and landscape restoration influence these processes. Protecting soil structure, reducing erosion and helping rainfall infiltrate can improve growing conditions and resilience to dry periods. The results depend on local conditions, making it important to assess water risks and competing needs when planning land-use changes.
The connections extend beyond individual landscapes. Water released by vegetation travels through the atmosphere, sometimes contributing to rainfall far away. Research on Indigenous Peoples’ lands and rainfall illustrates why land stewardship and water security need to be considered together.
The governance challenge
Decisions affecting green water are spread across agriculture, forestry, land-use planning, biodiversity and climate policy. These areas often have separate institutions, funding and objectives, while water governance has traditionally concentrated on rivers, lakes and groundwater.
This separation can leave the effects of land-use decisions on soil moisture and rainfall insufficiently considered. Governing the full hydrological cycle means connecting these responsibilities, using evidence to assess trade-offs and involving the people whose livelihoods depend on the landscape.
How SIWI contributes
SIWI connects science, policy and practice to strengthen how green water is considered in water governance. Through its green water initiative, SIWI is examining gaps in institutions, policy, monitoring and finance, and developing recommendations for international frameworks and national decision-making.
Through TIARA, SIWI works to strengthen investment in Africa’s rainfed agriculture by connecting green water science, policy and finance. Publications on unlocking the potential of rainfed agriculture and financing mechanisms examine how better rainwater management can support food production and climate resilience, and how investment can help expand these practices.
This work also informs practical approaches. SIWI’s Water-smart Forest and Landscape Restoration Tool helps planners and practitioners assess water risks and opportunities, identify relevant stakeholders and strengthen coordination. Across this work, the aim is to connect land and water decisions so that restoration, food production and climate action support water security.