Balancing agricultural production, groundwater management, and biodiversity goals: A multi-benefit optimization model of agriculture in Kern County, California.

As surface water becomes scarcer and precipitation more variable in a warmer climate, reliance on groundwater reserves for agricultural use is expected to increase. Where efforts to achieve sustainable groundwater management require reductions in aggregate extraction, some of these reductions will entail a decline in agricultural production. However, the degree to which water conservation and other environmental priorities conflict with agricultural production depends, in part, on the spatial configuration of land-use decisions. We explore how to spatially configure groundwater recharge projects to achieve groundwater recharge targets and preserve ecologically important habitat at the least cost. We conduct a field-level analysis for all fields in Kern County, California, the largest crop-producing county in California (and the United States). Results demonstrate that fields selected for cost-effective land retirement can achieve groundwater recharge targets and simultaneously contribute to biodiversity goals via endangered species habitat conservation. However, increasing the amount of habitat conserved raises costs significantly. We discuss conservation actions, economic incentives, and policies that can be leveraged to meet regional biodiversity goals while preserving the economic vitality of agricultural communities. More broadly, this work also provides a proof-of-concept for applying the conservation planning tool, Marxan, to promote efficient allocation of land uses in the face of increasing water resource scarcity and biodiversity threats.