屋外都市スケールモデルを用いた遮断蒸発実験  [in Japanese] Interception of rainfall at outdoor urban scale model  [in Japanese]

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Abstract

本研究では,降雨-流出過程を完全に閉じることが可能な屋外スケールモデル実験サイト上において,降雨-流出の残差から遮断蒸発量を計測するための装置を整備し,降雨中の遮断蒸発量について検討を行った.その結果,以下のことが明らかになった.1)流出率には降雨量依存性があり,雨量が小さいときは流出率が小さくなる.また同程度の降雨量では夏季に流出率が小さくなる傾向がある.2)遮断蒸発量は飽差に大きく依存し,飽差が大きくなるほど遮断蒸発量が増加する.3)夏季は降雨中においても大きい飽差が維持される.負符号の地中熱流量(地中から地表への熱フラックス)は降雨中においても継続しており,この傾向は冬季よりも夏季に顕著に生じる.これが夏季の降雨中の飽差を大きくする原因の一つであると考えられる.

Rainfall interception was investigated at outdoor urban scale model (COSMO). The following results were obtained. 1) Runoff rate depends on the total amount of rainfall. The runoff rate increased and reached to unity with the increase of rainfall. The runoff rate also showed a seasonal dependency, with tending to be small in summer. 2) The amount of rainfall interception depended on water vapor deficit. A large water vapor deficit which was frequently observed in summer resulted in large rainfall interception. 3) Storage heat flux G was negative (heat was transferred from subsurface to surface) during rainfall. The large absolute value of G in summer would be one of the reasons for the large water vapor deficit during rainfall in summer.

Journal

  • Proceeding of Annual Conference

    Proceeding of Annual Conference 20(0), 117-117, 2007

    THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

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