Avoiding the irrigation trap: Policy-driven adaptation pathways and cross-sectoral trade-offs in Germany’s irrigated agriculture

Hydroclimatic extremes, particularly increasingly frequent and severe droughts and heat waves, are intensifying pressures on agricultural systems even in historically overall water-abundant regions such as Germany. Irrigation is often promoted as an effective adaptation strategy to climate variability and extremes. However, irrigation expansion can create path-dependent lock-ins into high and potentially unsustainable water use, amplifying systemic risks across the food–water–energy (FWE) nexus.

This study examines how food, water and energy sector policies shape farmers’ adaptive land use and irrigation decisions under future hydroclimatic and socioeconomic change, and how these decisions propagate trade-offs across sectors. Using an innovative hybrid modeling framework that links hydrological and machine-learning models with a hydro-economic multi-agent system capturing adaptive farmer behavior, we assess the ex-ante impacts of six sectoral policies on land use, irrigation demand, and FWE nexus indicators for eight major field crops in Germany.

Our results reveal strongly divergent adaptation pathways. Water sector policies such as abstraction limits and pricing can substantially curb irrigation expansion under intensifying climatic extremes and socioeconomic change, while maintaining farm profitability if implemented early. In contrast, bioenergy subsidies further increase irrigation demand and energy use, while irrigation efficiency subsidies fail to deliver net water savings due to rebound effects, and drought compensation payments reinforce maladaptive land use choices.

Overall, uncoordinated policy responses risk triggering an “irrigation trap” that deepens cross-sector trade-offs and constrains future transformation pathways. We show that timely, coordinated governance across the FWE nexus is critical to avoid maladaptation and to steer agricultural systems toward more resilient and sustainable trajectories. By considering heterogeneous and adaptive farmer behavior, the study provides a starting point to assess how far agricultural land use adaptation can mitigate on-farm losses and systemic risks under intensifying hydroclimatic extremes.