This book describes the ecosystem of the Andean watersheds, covering the Californian valley, tropical Andes, and southern Andes. Case studies of the new methods and techniques used for hydrological research in the Andes are provided, and sustainability issues pertaining to Andean water resources are discussed in the context of climate change, social and economic issues, and public policy. Furthermore, the impact of economic development on the Andean ecosystem, specifically the effect on the water cycle and the water-energy-food nexus, are examined.