To evaluate the elevation dependence of precipitation in various regions of Japan, the precipitation amounts from the Baiu Season, Autumn Baiu Season, Typhoon, and Cold Air Outbreaks in winter were extracted from annual precipitation and were analyzed. The distribution of precipitation after extracting the precipitation systems was homogeneous throughout Japan. This homogeneity made it possible to evaluate differences in elevation dependence in the respective regions. Elevation dependences of precipitation after extracting the precipitation system amounts were observed in the Kinki, Setouchi, Kumamoto, Miyazaki, and Tohoku Sea of Japan side and the Tohoku Pacific side, but not in the Kanto region. In the Kyushu and Tohoku regions, where no clear watershed was on the regions' borders, the elevation dependence was greater on the west side of the watershed. The Tohoku Sea of Japan side has the greatest elevation dependence. Miyazaki prefecture has the least. Results show that elevation dependence in Japan has a great degree of regionality.

　The accumulation of high-density and high-frequency long-term water quality data for watersheds and the dissemination of those data to the public is extremely important not only to promote scientific investigation of water cycle processes, but also to elucidate sustainable water resource use. These data can improve hydrologic model accuracy and can improve visualization of invisible water cycle characteristics, thereby raising understanding of phenomena by the general public.

　Since March 2011, the authors have been conducting water quality observations for the entire Kurobe River basin with the aim of clarifying water cycle processes there. The long-term water quality dataset described herein summarizes results of these observations. Land water in the fan-shaped area spreading downstream was observed every month without fail, with observations of 78 land water points in the Kurobe River basin conducted with different frequencies among sites because mountainous areas were difficult to enter during the winter. All observation data and information are available on the web without restriction. As described herein, we introduce the research results of the authors' group using the long-term water quality dataset, with explanation of how the dataset is used.