Exploring neighbourhood effects of farm-level drought adaptation on groundwater extremes with a coupled agent-based and hydrological model

Increasingly frequent and severe droughts pose substantial risks to agricultural water systems globally. Farmers can mitigate drought impacts through on-farm adaptation strategies, such as reducing drainage or increasing groundwater retention. However, the feedback between farmers’ adaptive behaviour and groundwater dynamics remains poorly understood. To address this gap, we developed an agent-based model to evaluate how individual farmers’ adaptation decisions influence local and regional groundwater systems. The model couples farmer decision-making, grounded in protection motivation theory, with the hydrological dynamics of the eastern Netherlands simulated using the WALRUS hydrological model. We ran scenarios based on different climate conditions and land use configurations to assess the effects of adaptation behaviour. Our findings show that farmers with adaptation measures experience substantially less drought damage associated with low groundwater levels during moderate droughts (65% reduction), but these measures are less effective during extreme droughts (13% reduction). Farmers who adopt these measures also experience slightly increased damage during wet periods, indicating a higher risk of waterlogging. Importantly, both benefits and drawbacks extend beyond the farm scale, affecting groundwater levels of both adapting and non-adapting farmers in the area. Ongoing work explores the spatial distribution of these effects in more detail to better understand the neighbourhood effects for both social and hydrological dynamics. The findings of our study can be used to support strategies that minimise trade-offs between groundwater extremes through both individual and collective adaptation.