Ex ante evaluation of supplemental irrigation in a Sahelian context: coupling biophysical and economic models. Description of the subject. In Sahelian countries, irregular spatial and temporal rainfall distribution remains a threat for rainfed agriculture despite the use of a wide range of techniques for soil conservation. Objectives. To analyze several irrigation strategies for rainfed crops and to assess the likely economic incentives to support the adoption of supplemental irrigation from farm ponds in response to dry spells. Method. The supplemental irrigation strategies and economic incentives were analyzed using an applied bio-economic model in a typical farm. Results. The simulations showed that supplemental irrigation from small individual ponds would increase farmers' income compared to the situation without irrigation. Maize, sorghum and millet production under supplemental irrigation in a dry year would increase expected income by 26.49% (133,030 CFA francs equivalent to 202.80 euros) compared to the situation without irrigation. Simulations with incentives to promote supplemental irrigation focused on four subsidy modalities and the introduction of a credit system for agricultural households. Conclusions. Of the incentives studied, the food-for-work subsidy to mobilize labor for basin building seems particularly suitable for scaling-up supplemental irrigation.