For integrated water resources management both blue and green water resources in a river basin and their spatial and temporal distribution have to be considered. This is because green and blue water uses are interdependent. In sub-Saharan Africa, the upper landscapes are often dominated by rainfed and supplementary irrigated agriculture that rely on green water resources. Downstream, most blue water uses are confined to the river channels, mainly for hydropower and the environment.

Over time and due to population growth and increased demands for food and energy, water use of both...