Food production, energy generation, and water supply systems are inextricably linked. Achieving clean energy goals requires careful consideration of the various interactions among these systems. With population growth and rising temperatures, demand for water is increasing. As economies develop and income increases, per-capita demand for food, energy, and water grows putting stress on natural systems. Rising demand among competing water uses, coupled with uncertainty from climate change, can lead to critical water shortages. By using a semi-distributed, global rainfall-runoff model and an economic demand model, we can identify tradeoffs among competing demands on irrigation, hydropower and urban water supply across space and time. Example applications of this framework are presented from the Philippines, Laos, Guatemala, and Brazil, with each highlighting region-specific policy goals, including biofuel vs food crop production, hydropower planning and water supply for urban centers.