TAGMI maps where AWM interventions are likeliest to succeed
TAGMI maps where AWM interventions are likeliest to succeed (darkest blue). Above, a map for soil water conservation in Burkina Faso.

Agricultural water management technologies such as soil water conservation, small-scale irrigation and small reservoirs have the potential to dramatically improve agricultural productivity – and thus food security – in rural communities across Africa that now rely on rain alone to water their crops.

Yet these technologies are often not employed to their full potential. That’s because many factors –water supplies, cropping patterns, social conditions – affect their likelihood of success.

The new TAGMI tool, which is available online free of charge, is designed to help decision-makers in the Limpopo and Volta river basins to target different tools to the places where they’re likeliest to be widely adopted, given favourable conditions.

The Volta basin spans 407,000 km2 of Burkina Faso, Ghana, Benin, Cote d’Ivoire, Mali and Togo, while the Limpopo basin covers a similar-sized area of Botswana, South Africa, Zimbabwe and Mozambique. Millions of farmers in these regions rely on rainfall to water their crops but suffer from high evaporation, variable and uneven distribution of rainfall, prolonged dry spells and occasional flooding. Climate change is making variable rainfall even less predictable in some areas.

“These farmers, who have few resources, often suffer from crop loss due to a lack of rain or limited access to water,” explains Dr. Jennie Barron, a senior research fellow in SEI’s York Centre and leader of the TAGMI project. “With marginal support structures in place, they are not always able to invest in, and benefit from, tried and tested water management technologies.”

Building the tool

TAGMI was developed by SEI and partners (see credit at end of article) under the three-year CGIAR Challenge Program on Water and Food’s (CPWF) Volta and Limpopo Basin Development Challenge projects. The tool is based on a Bayesian model, which identifies “success” as the likelihood a particular AWM technology will still be in use two years after its introduction to a target community in a particular location, given the continuation of existing social and biophysical conditions.

Factors such as labour availability, appropriate skills and community organization are matched with rainfall regimes and distance to markets; all critical conditions that can affect whether or not farmers have the opportunity to benefit from AWM technologies.

These factors were selected and developed taking into account the views of farmers, extension workers and other local experts, together with the available scientific data. This collaboration was important because the way projects are implemented and the level of local participation can prove more important than human or environmental capital in determining whether a project will succeed or fail.

TAGMI scope

The tool covers 85% of the Volta basin (primarily in Northern Ghana and Burkina Faso), and all the countries of the Limpopo basin (using ground-truthing data from, and lessons learned in, Zimbabwe and South Africa). Based on discussions with stakeholders, it incorporates three AWM options: soil and water conservation measures, small-scale irrigation and small reservoirs.

“These groups of technologies are well known and promoted in the two basins, but have not been widely adopted by the majority of those who stand to benefit,” explains Amy Sullivan, CPWF’s Limpopo Basin Leader. “There is considerable potential for scaling out their use.”

TAGMI is the first step in the targeting process; after identifying districts where a particular technology is likely to succeed, they must confirm, through follow-up investigations on the ground, that favourable conditions indeed exist at local level. If so, they can then target farmers in those locations with appropriate financial incentives or policies.

“Different organizations have their own priorities,” says Dr. Olufunke Cofie, CPWF’s Volta Basin Leader. “They might want to work in very rural areas, or with different population groups or to concentrate on providing technologies. So, they can use the tool to work out where, geographically, there are certain conditions and then find out how likely they are to succeed if they implement each of the technologies in those places.”

So far, the tool has been well received by the stakeholders it is designed to help. Dr. Charles Biney, executive director of the Volta Basin Authority (VBA), described it as “very important”, saying “VBA is very willing to ensure the continuity of the TAGMI tool”. Representatives from WaterAid, the International Fund for Agricultural Development (IFAD) and the Food and Agriculture Organization of the United Nations (FAO) have also expressed interest in it.

In the future, Barron says, TAGMI could be adapted for other regions or other AWM options.

“The technologies in the tool are the ones that were prioritized through our project, but other actors and investors might want to test for other technologies, such as nutrient management, tree planting or livestock systems,” Barron says. “In principle, you could create a different Bayesian technology model with relevant factors that are critical for success and develop that in the same way as we have done for soil and water conservation, small-scale irrigation and small reservoirs. It has the potential to be very versatile.”

Explore TAGMI »

Partners for the Limpopo basin work were the International Water Management Institute, Waternet; and the University of Witwatersrand, in South Africa. Those for the Volta basin research were the Council for Scientific and Industrial Research and the Kwame Nkrumah University of Science and Technology, in Ghana; plus the University of Ougadougou and the Institute of the Environment and Agricultural Research (INERA), in Burkina Faso. The Volta basin research was supported by the European Union.