Abstract
The air temperature change due to altitude variation is approximately 800 times greater than that due to horizontal variation. Therefore, in the mountains, the temperature rapidly changes with altitude and changes in vegetation are particularly sensitive to the influence of global temperature changes. In other words, the influence of environmental change on the global scale will appear clearly in mountainous areas. However, temperature observations by the Japan Meteorological Agency are at Nobeyama (1350 m a.s.l.), which is the highest altitude used for such measurements except for those at Mount Fuji (3775 m a.s.l.). Mountain ranges of 2000m to 3000m are continuous in the central range mountains of Japan, so without observations at these altitudes it is not possible to discuss the long-range fluctuation of the temperature in Japan. Flooding and landslides caused by a large amount of rainfall can directly affect human life with disastrous results, so the Japan Meteorological Agency has more observation sites of precipitation than temperature. However, there are only six such sites with higher altitude than Nobeyama. Significant snowfall plays an important role as a water resource in Japan and snow cover provides a moderate habitat for plants and animals during cold and windy winter seasons. Therefore, fluctuation in the amount of snowfall is one of the most important environmental factors. However, the highest point of observation of snow depth by the Japan Meteorological Agency is Okunikko with only an altitude of 1292m. To accurately discuss the response in the mountainous areas to climate change on a global scale based on the observed data, it is necessary to carry out meteorological observation in higher-altitude mountainous areas. Therefore, Shinshu University has installed meteorological observation equipment at 14 sites in the Japanese Alps at altitudes between that of Nobeyama and Mt. Fuji, to maintain results from these previously blank areas of meteorological observation. Since rainfall and snowfall are not observed in high altitude areas, it is also contradictory to the water balance. The runoff calculated by dividing the discharge by the catchment area basically can be extrapolated to the value of the entire basin depending on the accuracy of discharge observation. However, precipitation and evapotranspiration data are obtained for each point with large variation in value, and are also scarce in spatial representation. There are also various problems when calculating catchment unit. Because meteorological observation data itself is deficient in high altitude areas it is difficult to calculate catchment precipitation and catchment evapotranspiration accurately from observed values. In an attempt to overcome these problems, we attempted to calculate winter precipitation using the snow chemical method and tried to calculate the average water equivalent of snow in the entire river catchment from a snow depth distribution survey using airborne laser scanning. While overcoming various difficulties and continuing meteorological observation in the mountainous area, it is necessary to develop various new methods to calculate the hydrological quantity in catchment units for discussion and evaluation.
