Modéliser la réponse des cultures à la contrainte hydrique avec STICS pour anticiper le changement climatique

STICS model evaluates agricultural water management across 10 French regions with diverse soils and climates. It assesses water runoff, evaporation, and crop responses under three land covers—bare soil, irrigated grassland, and rain-fed grassland—showing regional variations in water retention and runoff. Three cultivation systems were tested: fully irrigated, partially irrigated (50% water use), and rain-fed. Maize and sugar beet require significant irrigation (30–50% of needs), while sorghum and sunflower are more water-efficient. Wheat shows higher water use efficiency than maize in Midi-Pyrénées. Nitrogen fertilisation increases irrigation demand, and low-retention soils can raise irrigation needs by up to 100 mm. Droughts (2003–2005) reduced water return and increased nitrogen stress. Partial irrigation and fallow periods improve resilience. The model supports climate adaptation planning, highlighting regional strategies for sustainable agriculture under water scarcity.