Evaluation of Groundwater Resources in Response to Agricultural Management Scenarios in the Central Valley, California

Dependence on groundwater throughout the Central Valley of California has resulted in severe and unsustainable groundwater depletion. In this research, we used the Central Valley hydrologic model (CVHM) to model how crop types and drought scenarios impact groundwater storage throughout the Central Valley. Simulations that decreased the abundance of water-intensive crops, such as fruits and nuts, observed the largest recovery in groundwater storage. Two drought scenarios, which respectively decreased surface water availability by 25% and 75%, were also tested. Combined drought and crop type scenarios were explored to understand the relative influence of either surface condition on groundwater storage. The results showed that water-intensive crops can decrease groundwater storage by over 20 m under water deficit conditions, whereas water-saving crops can recover groundwater storage and alleviate the impact of droughts. This research suggests that under drought conditions, groundwater storage will decline substantially to compensate for the need of water-intensive crops due to loss of surface water. Policy and management implications from this research suggest decreasing water demands, such as decreasing crop water intensity, can mitigate groundwater depletion. (C) 2018 American Society of Civil Engineers.