Dose rate distributions across the flood plains in eastern Fukushima

Nakanishi, Takahiro   ; Oyama, Takuya ; Hagiwara, Hiroki  

At riverbanks in six rivers (Odaka, Ukedo, Takase, Kuma, Tomioka and Kido rivers) of eastern Fukushima, dose rate distribution in the cross section had been observed from January 2013 to December 2016. Dose rates in the flood plain which were flooded periodically were different from the surroundings. In rivers without reservoirs (Odaka, Takase and Kuma rivers), dose rates in the flood plain were affected by average radiocesium inventory in the whole catchments. By contrast, in rivers with reservoirs (Ukedo, Tomioka and Kido rivers), dose rates in the flood plain were affected by those in the downstream area of reservoirs and the erosion effect.