平成27年関東・東北豪雨時における河川流域スケールでの放射性Csの流出実態  [in Japanese] EXPORT OF RADIOACTIVE CESIUM IN AN EXTREME FLOODING EVENT BY TYPHOON ETAU  [in Japanese]

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Abstract

平成27年関東・東北豪雨による福島第一原発事故を由来とする放射性Csの移動実態把握を目的として,福島県浜通り地方河川の宇多川水系の森林渓流(森林小流域),ダム放流水(ダム湖流域),本川下流(流域全体)を対象に放射性Cs動態調査を実施した.観測結果から算定された豪雨時のSSならびにCs-137総流出量は,いずれの流域でも前年の2014年の年間総流出量を大きく上回ったが(SS:1.6~9.5倍,Cs-137:1.4~5.3倍),ダム放流水や流域全体で,SSに比べCs-137の流出規模は下回り,流域内の農地等における面的な除染の影響が示唆された.また,豪雨時におけるダム湖への流入Cs-137の90%以上が沈降,堆積したと推定され,ダム湖による下流域への放射性Cs移動・拡散防止機能が確認された.

 We evaluated the behavior of radioactive Cs deposited by the accident of Fukushima Daiichi Nuclear Power Plant in the Uda River locating in the coastal region of Fukushima prefecture during the super heavy rain event (Typhoon Etau). The estimated total runoff volumes of Cs-137 from small forest catchment, dam lake, and the entire river catchment during the event were 1.4 to 5.3 times greater than the annual total runoff volumes in 2014, respectively. However, the sizes of Cs-137 runoff fell much below those of SS runoff from Matsugabou dam lake and the entire Uda River basin due to the decrease in concentrations of Cs-137 associated with SS by possible effect of decontamination operation in the catchments.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research)

    Journal of Japan Society of Civil Engineers, Ser. G (Environmental Research) 72(7), III_37-III_43, 2016

    Japan Society of Civil Engineers

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