To clarify the factors that control the temporal variation of stable isotope ratios in precipitation in the mountainous areas of Japan, monthly quantities of precipitation were collected at 11 locations on Mt. Ontake from Jan 2003 to Dec 2005, and the δ-values of all the water samples investigated. The isotope ratio values were found to be highest in spring, lowest in winter and moderate during the summer. These seasonal variations are unaffected by precipitation amount and temperature, indicating that the δ-values in precipitation at Mt. Ontake do not have a close relationship with local weather conditions. In the warm rainy season, low δ-values were observed in the precipitation when rainfall amount on the windward south side of Mt. Ontake was high, suggesting that the δ-values under such conditions depend on the rainfall amount in response to the vapor mass transportation from the Pacific coast towards Mt. Ontake. The low δ-values found for snow cover in winter reflect the influence of the inland effect, as heavier snow-fall occurred on the windward part of the mountains. These variations of δ-value appear associated with the topographical characteristic of Chubu mountainous area with a certain distance from the coast.

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It has been passed 26 years after the establishment of Japanese Association of Hydrological Sciences, and research directions and social demands for scientific researches have changed largely during this quarter-century. The paper mentions the desired direction of the hydrologic science in a future according to the recent world trends regarding the relationship of the science and society as well as describing the history of the establishment of Japanese Association of Hydrological Sciences briefly. As a new scientific research framework for foreseeable 10 years from 2013 to 2022, ICSU and ISSC have established the “Future Earth” and IAHS the “Panta Rhei-Everything Flows” as the IAHS Scientific Decade 2013-2022. The international project on “Groundwater Governance” programmed by GEF, UNESCO-IHP and other international organizations is now implementing. From those world tendencies, it can be recognized that it is necessary the establishment of the “Science for Society” which takes a serious view of the relation between the science and human-society systems instead of former the “Science for Science”. It was mentioned that now clamed for the hydrologic science is to create a “new wisdom” and to establish its methodology coping with a today’s trend of the world.

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