| Co-Investigator(Kenkyū-buntansha) |
HIRANO Takashi Hokkaido Univ., Grad. School of Agri., Asso. Prof., 大学院・農学研究科, 助教授 (20208838)
ISHII Yoshiyuki Hokkaido Univ., Inst. Low Temp. Sci., Assist., Prof., 低温科学研究所, 助手 (40222955)
KODAMA Yuji Hokkaido Univ., Inst. Low Temp. Sci., Assist. Prof., 低温科学研究所, 助手 (70186708)
CHIKITA Kazuhisa Hokkaido Univ., Grad. School of Sci., Asso. Prof., 大学院・理学研究科, 助教授 (70142685)
URANO Shin'ichi Hokkaido Univ., Grad. School of Agi., Prof., 大学院・農学研究科, 教授 (40096780)
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| Research Abstract |
For understanding the heat, water and carbon cycles of high latitudes, meteorological and hydrological researches have been carried out at the experimental watershed in Interior Alaska from 2001 to 2004. Observed items were radiation, sensible heat, evapo-transpiration, CO_2 concentration above vegetation floor, soil respiration, soil moisture, soil temperature, runoff and chemical contents of river water, groundwater and precipitation. Underground structure was obtained by geophysical exploration and confirmed by well borings at three different points in the watershed.
The main observational results are : (1) Evaporation with the magnitude of 2 to 4 mm/day was obtained in the watershed during summer except over the stream, where condensation occurred because of the low water temperature due to the permafrost thawing. (2) Groundwater of a shallow well showed daily fluctuation, which was influenced by precipitation and evaporation, but not at a deeper well. (3) Soil moisture content in the surface layer depended on slope aspect and micro-topography. (4) Soil CO_2 efflux had a good relationship with soil temperature and water content. The net CO_2 flux at the height of 4m was well estimated by the soil CO_2 efflux and global radiation. (5) Runoff showed the clear dependency with slope aspects ; the runoff radio of the watershed with north-facing slope was larger, but south-facing slope watershed the ratio became small. These results shows that the existence of the frozen soil affects many fields such as surface vegetation, soil moisture, ground water level, evaporation, soil respiration and runoff.
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