E-flows in the Limpopo Basin in Botswana, Mozambique, South Africa, and Zimbabwe

Background

The Limpopo River basin in southern Africa is shared by Botswana, Mozambique, South Africa, and Zimbabwe. It is the driest it has been for 35 years with groundwater supplies held in porous rock under the ground aquifers which are at risk of running low, especially at times of drought. Water resources provided by the Limpopo Basin are socially, economically, and ecologically valuable, supporting communities that are highly vulnerable to the effects of climate change. In 2016, reduced rainfall led to the Limpopo Province in South Africa being declared a disaster area with widespread crop failure and economic hardship. Excessive upstream use primarily for irrigation is a threat to the goods and services provided by the biodiversity and ecosystems of the rivers in the basin are affected.

The e-flows (environmental flows) project aimed to enhance biodiversity and ecosystem services of the river basin and support the livelihoods of rural communities that depend on it for their water security, for example, for irrigation of their crops. E-flows are the river flows needed to support vegetation, fish, and macroinvertebrates like snails, worms, and crayfish in both the river and its margins, which in turn provide ecosystem services, like nutrient recycling.

Activities

Implemented by International Water Management Institute (IWMI) in partnership with Rivers for Life and the University of Mpumalanga in South Africa and supported by USAID with help from national departments responsible for water and sanitation including the Limpopo Watercourse Commission, the project carried out a risk assessment to predict how changes in the river’s flow affect the various ecosystem services that people depend on, as well as local biodiversity. The assessment included field surveys and looked at historical data in 27 risk areas to inform a plan to sustainably protect and use the water resources. The project worked with transboundary partners to understand better the needs and challenges of sustainable water management in shared aquifers, for example, the Ramotswa Aquifer, which lies between South Africa and Botswana. To support agricultural water management, the researchers adapted a set of tools that local farmers could use to optimize their groundwater use for irrigation.

Impact

Implementing e-flows  through, for example better management of groundwater, can reduce risks, potentially returning more than 80% of the area to a sustainable state. Under this project, farmers were able to save up to 40% of water, 30% of energy (for pumping groundwater), and 80% of fertilizers on their crops using soil moisture probes and nutrient measurements. Farmers also enhanced crop production creating savings and additional incomes for the farmers.