Intensive and extensive margin adjustments to water scarcity in France's Cereal Belt

International audienceEfficient water management in agriculture is becoming critical due to increasing environmental constraints and global food and bio-energy demands. Farmers may respond to increased water scarcity along three main adjustment margins: amove towards rain-fed agriculture (super-extensive margin) or towards less water-intensive crops (extensive margin), and a reduction in water intensity for irrigated crops (intensive margin). Using a positive mathematical programming model of regional supply calibrated to economic and agronomic information, we decompose the total effect of reduced water availability on these adjustment margins in Beauce, a productive cereal region that relies on a groundwater resource to meet its irrigation needs. For realistic water scarcity scenarios, 57 per cent of the total response is attributable to super-extensive margin adjustments. The extensive margin represents 28 per cent of the total response, while the intensive margin accounts for 15 per cent. Crop-level analysis reveals more subtle adaptation patterns