The water and carbon cycles in terrestrial ecosystems are the essential database for better understanding of the causes and the current processes of climate change and for the prediction of its future change. CarboKorea and HydroKorea are dedicated research efforts to develop technologies to quantitatively interpret and forecast carbon/water cycles in typical landscapes of Korea. For this, stable isotope studies have been launched to genetically partition various components of carbon/water cycles in terrestrial ecosystems. From stable isotope studies, practical deliverables such as evaporation, transpiration and gross primary productivity (GPP) can be provided at scales from tower (footprint) to large watersheds. Such reliable field-based information will form an important database to be used for validation of the results from various eco-hydrological models and satellite image analysis which constitute main components of Carbo/HydroKorea project. Stable isotope studies, together with other relevant researches, will contribute to derive quantitative interpretation of carbon/water cycles in terrestrial ecosystems and support Carbo/HydroKorea to become a leading research infrastructure to answer pending scientific and socio-economic questions in relation to global changes.