福島の森林域における森林斜面および渓流を介した放射性セシウム流出量

Radiocesium outflow through the forest slopes and mountain streams in the forested area of Fukushima, Japan

新里 忠史  ; 佐々木 祥人 ; 雨宮 浩樹*

Niizato, Tadafumi; Sasaki, Yoshito; Amamiya, Hiroki*

福島の森林斜面および渓流におけるセシウム137の流出観測に基づいて、河川のセシウム137流出における森林域に存在するセシウム137の寄与を検討し、土砂流出量およびセシウム137濃度の観点から、比較的寄与が低い可能性を指摘した。

Cs outflow associated with hillslope process on the mountain slope and riverbed sedimentation process in the mountain stream was estimated by using of the one-year monitoring result in a mountainous forest of Fukushima, Japan. The Cs outflow rate per monitoring period was 0.23% for the mountain slope (27 April - 14 Dec. 2017) and 0.02% for the mountain stream (27 June 2017 - 17 April 2018). Comparing with the daily flux, Cs outflow in the mountain slope was 18 times higher than that in the mountain stream. In terms of riverbed sediment load and Cs activity, we point out the possibility of a relatively low contribution of Cs-137 in the forested area to the watershed Cs discharge.