Gopal Krishan, MS Rao and CP Kumar
New scientific knowledge of the modern tools and techniques, including isotope applications is required: (i) to improve the growing scenario of increased water stress and (ii) to resolve resulting conflicts for water for sustainable development. The isotope analysis of�air moisture�can greatly support in tracking the hydrological cycle through fingerprinting the source of water vapor, its transport and its condensation through direct analysis. This can be further used to understand factors controlling the water and energy balance of the atmosphere and guide new studies of clouds and the atmospheric hydrology. This paper presents the work carried out by National Institute of Hydrology, Roorkee to understand the role of water vapor isotopes in�climate studies, vapor source identification and in understanding southwest monsoon dynamics. It has been found that air moisture isotope analysis can be used (i) for studying the climatological changes (ii) to identify the source of air moisture and (iii) for southwest monsoon studies.