UC Merced

The San Joaquin Valley has experienced a significant rise in water demand for irrigation, met to a large extent by groundwater resources. Groundwater serves as a dependable water source not only for irrigation but also for sustaining local communities and ecosystems. However, inadequate management of groundwater over the past few decades has led to detrimental outcomes such as aquifer depletion, subsidence, deteriorating water quality, and the failure of domestic wells. In response, the implementation of the Sustainable Groundwater Management Act (SGMA) since 2014 has fostered the development of Groundwater Sustainability Plans (GSPs) aimed at achieving groundwater sustainability goals by 2040. Consequently, it is crucial to develop approaches that allow us to identify vulnerabilities within the food-water system and evaluate potential strategies for addressing groundwater sustainability challenges. This dissertation is driven by five objectives: 1) model the food-water system, including the feed-back between agriculture and groundwater 2) incorporate uncertainty into water management policy assessment and exploration, 3) seek dynamic and adaptive policies that offer flexibility in wet and dry years, 4) assess the trade-offs between groundwater sustainability and economic revenues derived from food production, and 5) identify factors contributing to domestic well failures to inform domestic well protection efforts. These objectives are addressed through three comprehensive studies, corresponding to manuscripts published or currently under review. Chapter 2 employs Global Sensitivity Analysis to examine influential factors in a candidate groundwater pumping restriction, discovering parameters that affect its performance. Chapter 3 advances the incorporation of uncertainty within a multi-objective optimization framework, enabling the search for dynamic policies adapting to system changes and achieve economic and groundwater sustainability objectives. Finally, in Chapter 4, a spatial analysis is developed to identify specific components within the food-water system that can be targeted through effective land and water management strategies, thus reducing the risk of domestic well failures. This dissertation provides significant insights into the implementation of sustainable groundwater management practices in the San Joaquin Valley, with a particular emphasis on four groundwater basins. However, the findings and results derived from this research have broader applicability across the San Joaquin Valley region, offering valuable implications for groundwater management practices beyond the study area.