A societally important but relatively underexplored aspect of the food-water nexus is how groundwater cost influences cropping choices and groundwater demand, especially in large-scale water modeling frameworks. This work combines agent-based crop modeling (ABM) with groundwater cost curves to interrogate how irrigators respond to increasing groundwater cost as aquifers are depleted. We document and employ a consistent methodology for generating groundwater cost curves, which efficiently integrate with the ABM for large-scale applications. Groundwater depth time series are generated using an analytical Theis-based approach that uses superposition in time to generate depth to water estimates over the entire pumping period, which influences cost of pumping. Additional cost factors include annualized capital expense for the well and annual maintenance costs. The accuracy of this approach for representing drawdown in an unconfined aquifer is evaluated by comparing results against numerically modeled drawdown in an unconfined aquifer using MODFLOW. Additionally, USDA irrigation census data is used to guide assumptions about well properties and pumping practices. This ABM – groundwater cost framework is used to gain insight into key questions such as: 1) whether and under what conditions groundwater cost can act as a moderator of groundwater use, 2) how groundwater cost influences the types of crops grown by farmers, and 3) how aquifer properties, climate, and crop mixture representing different archetypal regions of the United State drive groundwater depletion.

This research was supported by the Office of Science of the US Department of Energy as part of research in the Multi-Sector Dynamics, Earth and Environmental System Modeling Program. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE‐NA‐0003525