通常降雨イベントにより同定されたタンクモデルを用いた豪雨イベントの再現精度  [in Japanese] Predicting Hydrographs for an Extremely Large Storm Event Using Tank Models Calibrated by Ordinary Storm Events  [in Japanese]

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Abstract

 地球温暖化による大雨日数の増加傾向を背景に,森林の洪水緩和機能が注目されている.本研究では,植生回復段階の異なる花崗岩流域において,総雨量150 mm以下の通常降雨イベントを対象としてパラメータを同定したタンクモデルを用いて,東海豪雨イベント(総雨量457 mm)のハイドログラフの再現計算を試みた.対象としたのは,裸地流域,裸地解消から約20年経過した植生回復流域,および森林流域の3流域である.その結果,裸地流域および植生回復流域のハイドログラフの再現精度は良好であったが,森林流域のハイドログラフはピーク流量が過小評価となった.土層の発達が進んでいない,裸地流域や植生回復流域では,通常の降雨規模においても地表流成分が卓越することが考えられ,通常降雨イベントで同定したタンクモデルで豪雨イベントのハイドログラフを精度良く再現できることが示された.一方,土層が厚い森林流域は通常の降雨規模では地表流はほとんど発生しないが,豪雨イベント時には地表流成分が増大すると考えられ,通常降雨イベントで同定したタンクモデルでは豪雨イベントのハイドログラフが再現できず,ピーク流量を過小評価することが示された.

 This study evaluated the applicability of tank models calibrated to an extremely large storm event using ordinary storm events. Rainfall and runoff were observed at three granitic watersheds having different forest recovery conditions: we studied a poor-vegetation watershed, a vegetation-recovered watershed, and a forested watershed. Parameters of the tank models were calibrated using rainfall and runoff data observed for ordinary storm events having total precipitation of less than 150 mm. Then those models were applied to simulate hydrographs for an extremely large storm event (Tokai heavy rain) having total precipitation of 457 mm. In the poor-vegetation watershed and vegetation-recovered watershed,which were characterized by thin soil layers, contributions of surface runoff to the total discharge were large even under ordinary storm events. In such watersheds, the tank models calibrated using the ordinary storm events reproduced hydrographs of the extremely large storm event. However, for the forested watershed, where surface runoff was rarely observed because of thick soil layers, the tank model was inaccurate for the extremely large storm event. The simulated hydrograph produced smaller peaks and gentler responses than the observations. We concluded that a large contribution of surface runoff generated only during an extremely large storm event caused underestimation of peak flows for the forested watershed.

Journal

  • JOURNAL OF JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

    JOURNAL OF JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES 26(2), 85-98, 2013-03-05

    THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

References:  38

Codes

  • NII Article ID (NAID)
    10031160387
  • NII NACSIS-CAT ID (NCID)
    AN10088049
  • Text Lang
    JPN
  • Article Type
    ART
  • ISSN
    09151389
  • NDL Article ID
    024407593
  • NDL Call No.
    Z15-619
  • Data Source
    CJP  NDL  J-STAGE 
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