This paper provides a preliminary description of the Chilean study area. It includes five parts: introduction (part 1"); a general description and the economic activities of the study area (part 2"); a general description on the regional climate and hydrology, including ENSO effects on hydrological cycle with emphasis in the study area (part 3"); the climate change vulnerabilities in natural systems with relevance to the study area (part 4"); a description of the social systems and a preliminary assessment of the climate change vulnerabilities and adaptation options in human systems with relevance to the study area (part 5).