津波規模に応じた河道内水位変動過程に関する数値実験  [in Japanese] NUMERICAL EXPERIMENT ON WATER LEVEL CHANGE IN RIVER WITH DIFFERENT MAGNITUDE OF TSUNAMIS  [in Japanese]

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Abstract

2011年東日本大震災津波時に河川を遡上した津波は津波周期を超える長時間にわたって河道内の高水位を維持した.本研究では今次津波による高水位維持のメカニズムについて北上川を対象とした数値実験および歴史津波の再現計算によって検討を行った.2011年津波の入射波高を5~100%まで変化させた仮想津波波形に対する河道内水位変動過程を比較することで,入射津波規模が大きくなると河道内への津波の流入量が流出量に対して相対的に大きくなり,水位が低下しにくい条件へと遷移することがわかった.歴史津波の再現計算結果から今次津波以外の過去の津波においても同様な高水位維持現象が見られた.津波周期は流入量と流出量に対して相関が見られない一方で,入射波高に対して流入量と流出量は明瞭な増加傾向があり,その増加率には有意な差が見られた.

 In this study, a numerical experiment on water level change in river induced by tsunamis were conducted to discuss the mechanism of longer duration of high water level in rivers than the period of tsunami, which was observed in 2011 tsunami event. Wave conditions which has 5~100 % of wave heights of 2011 tsunami were made based on the simulated wave form of 2011 tsunami, and the characteristics of water level change with the different magnitude of tsunamis were tested through numerical simulation in Kitakami River. It is found that increase of tsunami height induce larger discharge across the river mouth for both of incoming and outgoing flow, while the increase rate is larger for incoming flow. And that results in the transition of the condition to keep higher water level in longer period with higher waves. This characteristics were observed for many simulated historical tsunami events. And tsunami period does not have significant effect to cause the difference on characteristics of the flow across the river mouth.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)

    Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 72(2), I_271-I_276, 2016

    Japan Society of Civil Engineers

Codes

  • NII Article ID (NAID)
    130005282311
  • Text Lang
    JPN
  • ISSN
    1884-2399
  • NDL Article ID
    027808258
  • NDL Call No.
    YH267-236
  • Data Source
    NDL  J-STAGE 
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