Analytical framework for sensitivity evaluation of multi-objective water resources operations in California's Central Valley

Study region California's Central Valley, a critical hub of the state's water management system, serves around 40 million people, sustains productive agriculture, and supports biodiversity. Study focus Effective management of California's water resources requires understanding how operational decisions interact across competing objectives, yet isolating individual and combined policy influences remains challenging given the complexity of integrated water system models. The operational structure encompasses both categorical levers, such as regulatory protection and priority allocation, and numeric drivers, including carryover storage, demand management, and flow requirements, which complicate impact evaluation across water resource measures. To address this, we developed a scenario-driven framework that integrates full-factorial design, rank-biserial correlation, and variance ratio into a Combined Sensitivity Score (CSS) using CalLite model outputs. New hydrological insights for the region The CSS framework quantified sensitivities across reservoir storage, water deliveries, river flows, and Delta salinity under contrasting hydroclimatic conditions. Demand reductions yielded the most significant single-lever response (CSS up to 1.09), while regulatory relaxation under D-1641 produced severe salinity deterioration (CSS = 1.27 in dry years). Three-way interactions among demand, minimum flow, and carryover generated compounded responses (CSS up to 1.3) beyond their individual effects. Dry years showed heightened sensitivity, underscoring system vulnerability to drought. The analysis provides insight into specific operational actions that enhance system outcomes and supports decision-making for adaptive, equitable management of multi-objective water systems.