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Radioactivity Dynamics in River System

（2016）

ＱDo high concentrations of radioactive cesium continue to be deposited on riverbeds? 【Deposition of sediment in riverbeds】

ＡContinuous deposition of sediment containing radioactive cesium are limited to flood plains containing vegetation. The radioactive cesium concentration in sediment in such regions is tending to decrease.

Distribution of air dose rates along a cross section of the riverbed and depth distributions of radioactive cesium for the Ukedo River (near the bridge of JR Joban line)

Fig.1　Distribution of air dose rates along a cross section of the riverbed and depth distributions of radioactive cesium for the Ukedo River (near the bridge of JR Joban line)

※ The amount of deposited 137Cs in the figures is displayed as the amount per 1 m2 area and 1 cm depth.


● The following tendencies were observed for the Ukedo River, Fukushima Prefecture.

  1. Flood channel where water reaches only at high water-level periods e.g. typhoon :　
    There are some places where radioactive cesium is easily deposited. But such places are limited.
  2. Place where water reaches several times a year :
    Deposition and erosion of cesium are repeating. The deposited amount of cesium is typically low.
  3. Place that are easily flooded :
    Radioactive cesium is scarcely deposited.
    ※ Similar tendency was observed for other river systems in eastern Fukushima Prefecture (Hamadori District)

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