Estimates of a sediment yield sedimentation rate and a outflow variation of radioactive Cs in an erosion control dam with 3D laser scanner

Watanabe, Takayoshi ; Oyama, Takuya ; Ishii, Yasuo; Niizato, Tadafumi  ; Abe, Hironobu ; Mitachi, Katsuaki; Sasaki, Yoshito ; Kitamura, Akihiro   

For an estimate of movement from forest to living spheres, it is important to understand value of movement of soil and radioactive Cs from forest. We measured volumes of deposit with 3D laser scanner in an erosion control dam in Namie town, Fukushima prefecture on August 29, 2013 and December 3, 2014. As a result of measurement, an amount of increase of sediment for 15 months is 0.5 m. A denudation rate is 0.02 mm/year. This value is on the same level with denudation rates in meadows and forest, 10 10 mm/year (Fujiwara et al, 1999). And it is estimated that a variation of radioactive Cs is Cs-137: 200 MBq, Cs-134: 80 MBq.