This, in turn, was intended to provide the basic isotopic data to underpin the use of environmental isotopes in hydrological investigations within the scope of water resources inventories, planning and development. Although these primary objectives are still important for the future, the network's database has also proved indispensable in palaeoclimatology, and provides important input data for verification and further improvement of atmospheric circulation models. IAHS represents the hydrological sciences community world-wide. There is still a great need for scientific and technical information to promote the comparison of hydrological investigation using isotope data and classical techniques respectively. For a better understanding of the various processes governing the dynamics of hydrological systems and to improve hydrological modelling, the complementary approaches of tracer hydrology and the application of isotope methods need to be integrated.
Important information is derived from isotope studies of records of past precipitation.
The isotopic ratios of water offer opportunities to study atmospheric temperature, origin of water vapour and atmospheric circulation patterns. This, in turn, provides estimates of past and present interactions within ecosystems, fluvial systems, and the cryosphere which are fundamental to assess the impact of changes in climate and the hydrological cycle. The efforts of the IAEA in promoting isotope methods in studies related to the hydrological cycle, including continuous operation of GNIP over the past three decades, were acknowledged both by the representatives of the international organizations and by top-level scientists participating in the meeting. Specific steps towards strengthening the operation of the network, with broader participation and the support of national and international bodies dealing with water and climate, were discussed and agreed upon. In particular, support for national networks and their integration was expressed.