When modelling supports farming and averts food crises

Results & impact 24 April 2019
A model developed by CIRAD combines a food crisis early warning system with agriculture-related climate services. It is called SARRA-O, and is the fruit of 30 years' work by CIRAD and of consultations, calibrations, tests and checks with its partners (AGRHYMET, CERAAS, INERA, IER, EMBRAPA, etc). The tool is currently being rolled out, and is due to be presented at AgriNumA, the main digital agriculture event in West Africa.
Burkinabe farmers in a sorghum field © CIRAD, J. Chantereau

Climate services and food crisis early warning system

Determining the best time to sow and crop water requirements, or forecasting yields two months before harvesting... since 2016, the SARRA-O model has served to monitor the growing season for three major West African cereals (millet, sorghum and maize). The tool is based on relations within the soil-plant-atmosphere system. It was developed by CIRAD and its partners, and offers a range of agriculture-related climate services. However, that's not all... compared to previous versions of the model, SARRA-O is novel in that it can model crops on a national and even a regional scale. This shift in scale makes it a real early warning tool for food crises in West Africa. A vital risk management tool that helps local populations and decision-makers act quickly to limit the impact of food crises on communities. This spatialized version of the SARRA (Système d’analyse régionale des risques agro-climatologiques) model is due to be presented at the AgriNumA symposium on 29 April.

SARRA-O, the spatialized version of SARRA-H

SARRA-O is a combination of the SARRA-H model and the OCELET modelling platform, a computer programming language dedicated to modelling and simulating spatial dynamics. SARRA-O is therefore a spatialized version of SARRA-H, which models crops on a plot scale. However, both models use the same data:

  • Data on cropping practices (crop and variety, irrigation, degree of intensification, etc)
  • Climate data (rainfall, temperatures, global radiation, etc)
  • Soil data (type, depth, runoff, etc)
  • Geographical coordinates (latitude, longitude and height above sea level).

A model currently being rolled out…

Since 2016, SARRA-O has been tested in the field by the AGRHYMET regional centre*, which is using the model to produce a monthly bulletin monitoring the agricultural season in West Africa. It has been so successful that Christian Baron, the CIRAD researcher behind the new version of the model, and his partners at AGRHYMET, recently trained national meteorological office staff from 8 West African countries to use it. "SARRA-O is free, simple, quick and robust. It provides continuous information within a few days, using free, easily accessible data" , Christian Baron stresses. The model is fuelling the agriculture component of several development projects being conducted with the World Meteorological Organization, the World Bank, Météo-France and Météo-France Internationale.

… and serving scientific research

SARRA-O is also regularly being used in research in partnership aimed at assessing the impact of climate disruption on agricultural activities and yields, such as AgMIP (Agricultural Model Intercomparison and Improvement Project). In this case, the SARRA-O input data do not correspond to current situations, but are drawn from forecasts generated by climate models.

The fruit of 30 years of calibration and verification

The history of the SARRA modelling tool dates back well before the recent popularity of climate services. In response to the "great drought" in the Sahel from the 1970s onwards, the AGRHYMET regional centre turned to CIRAD to co-build a model capable of estimating crop water stress levels, to prevent food crises. Crop water diagnoses were developed in the 1980s. The model then evolved into the SARRA (Système d’analyse régionale des risques agro-climatologiques) version, then SARRA-H, and lastly SARRA-O. This evolution has been marked by several on-station calibration, assessment and verification stages and field surveys.

* The AGRHYMET regional centre, founded in 1974, is a specialist institution of the Comité permanent Inter-Etats de Lutte contre la Sécheresse dans le Sahel (CILSS), whose mandate now covers the ECOWAS countries.